Food Technology
Hoda Ghorbanzadeh; Jafar Milani; Ali Motamedzadegan
Abstract
IntroductionWith the growth of the population and more demand for obtaining food and supplying the required food, the interest in the cultivation and consumption of edible mushrooms has increased. Since 1990, the world has focused on the mushroom production industry. In recent years, mushrooms have become ...
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IntroductionWith the growth of the population and more demand for obtaining food and supplying the required food, the interest in the cultivation and consumption of edible mushrooms has increased. Since 1990, the world has focused on the mushroom production industry. In recent years, mushrooms have become one of the most important food and medicinal sources. One of the largest species of edible mushroom is button mushroom (Agaricus bisporus), which has high nutritional and medicinal value. Button mushroom has high nutritional value due to the presence of things such as fiber, carbohydrates, protein, amino acids, minerals, vitamins, etc., and it also has antioxidant, anti-cancer, and anti-diabetic properties. This food has shown good health properties for humans. The quality of button mushrooms is determined by their color, texture, and taste. Color is the first characteristic that is perceived by consumers. Browning is one of the main reasons for the loss of mushroom quality, which reduces the commercial value of mushrooms. One of the most used methods today is the use of edible coatings for perishable foods, these coatings almost prevent the penetration of oxygen, depending on the type of coating used, and reduce the loss of moisture during storage. Chitosan has functional characteristics such as antimicrobial and antioxidant properties, and as an edible film, it can be considered a very good carrier to be combined with antioxidant and antimicrobial agents.Materials and methodsTo make chitosan solutions, first, each type of chitosan (70% deacetylated, 80% deacetylated, 90% deacetylated, and 100% deacetylated) was weighed in amounts of 0.5g, 1g, and 2g. then it was dissolved in 100 ml of 0.5% acetic acid solution and stirred for 12 hours at a speed of 1000 rpm at room temperature to dissolve uniformly. After 12 hours, each sample It was centrifuged for 15 minutes at 6000 rpm at 25 °C to separate the undissolved material. Mushrooms were prepared freshly harvested, washed with water, and then excess moisture was removed. After sorting and screening in terms of size and approximate weight, the mushrooms were added to 0.5%, 1%, and 2% chitosan solutions without being sliced and were immersed in the solution for one minute. The control sample was immersed in 0.5% acetic acid solution for one minute. After that, the mushrooms were air-dried at room temperature for one hour, and at the end, their excess moisture was removed with a tissue. The mushrooms were placed in 18*14 size polyethylene zip-top bags and stored in a refrigerator at 4°C. The effects of chitosan coating on weight loss, mushroom color and browning index, enzyme activity, texture, and total phenolic compounds were studied.Results and discussionThe results indicated that in maintaining the amount of total phenol, controlling the peroxidase enzyme activity, the degree of firmness of the mushroom during storage and the amount of gumminess, the best treatment was chitosan with a deacetylation degree of 70%, while in controlling the weight loss, the activity of poly Phenol oxidase and sensory test, chitosan treatment with 100% and 90% deacetylation degree had better results, and in terms of browning index and texture, chitosan treatment with 80% deacetylation degree showed better performance. This study showed that the use of chitosan coating can be effective in maintaining the characteristics of edible mushrooms.ConclusionsThe spoilage of edible mushrooms happens in a short time, and the storage of mushrooms has become one of the most important things in mushroom production. Coating edible mushrooms is one of the suitable methods to increase the shelf life of edible mushrooms. In this research, chitosan with four degrees of deacetylation and three different concentrations was used as a coating for edible mushrooms. The results indicated that coating the mushroom with chitosan could delay the occurrence of spoilage and change its color or texture.
Food Biotechnology
Shohreh Nikkhah; Fakhri Shahidi; Mohebbat Mohebbi; Farideh Tabatabaei Yazdi
Abstract
IntroductionCucumber is an economically important crop, containing vitamins, minerals, antioxidants, and flavonoids. However, due to loss of weight and firmness, microbial contamination, mechanical damage, and yellowing, the storage duration of cucumber is limited to 3–5 days at room temperature. ...
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IntroductionCucumber is an economically important crop, containing vitamins, minerals, antioxidants, and flavonoids. However, due to loss of weight and firmness, microbial contamination, mechanical damage, and yellowing, the storage duration of cucumber is limited to 3–5 days at room temperature. Therefore, pretreatments are crucial for prolonging its shelf life. Chitosan is a cationic polysaccharide and can interact electrostatically with anionic, partially demethylated pectin. Besides, chitosan has inhibitory effects on fungal rot and prevents weight loss in fruits. Pectin can form excellent films. Because of increasing demand to reduce synthetic chemicals as antimicrobial agents, substances derived from plants, such as essential oils, can play a significant role in the future. Several essential oils and essential oil components have shown antimicrobial activity against spoilage and pathogenic microorganisms during fruit and vegetable storage. Essential oils of thyme and cinnamon contained phenolic groups have been found to be most consistently effective against microorganisms, however, essential oils are volatile and irritant. Therefore, forming an inclusion complex using b-cyclodextrin can improve solubility, control volatile, and induce off-flavors and unpleasant odor of the essential oils. The objectives of this study were to develop the microencapsulated thymol (thyme) and trans-cinnamaldehyde (cinnamon) essential oils to produce antimicrobial agents and subsequently evaluate the effectiveness of edible coating made of chitosan and pectin containing microencapsulated trans-cinnamaldehyde or thymol essential oils to improve qualitative and quantitative characteristics and shelf life of cucumber.Materials and MethodsThe inclusion complexes of trans-cinnamaldehyde and thymol in beta-cyclodextrin (CD) were prepared separately by freeze-drying. Each essential oil was dispersed in 1000 ml of beta-cyclodextrin aqueous solution (16 mmol/L, 18.15 g) in molecular ratio 1:1 (2.4 gr thymol, 2.11 gr trans-cinnamaldehyde) and mixed in a laboratory stirrer for 24 hour at room temperature , then frozen (-70 ºc) and freeze-dried (<20Pa, 48 h). Lyophilized samples were stored inside a freezer (-20 ºc) until further use. Cucumbers cv. Nagene with uniform size, appearance, ripeness and without mechanical damage or fungal contamination were selected. Then They were then sanitized by immersion in chlorine solution (150 mg/kg) for 1 min and air dried. Edible coatings were prepared as three immersion solutions of chitosan, pectin, and calcium chloride (CaCl2). The fruits were coated with pectin (1%) and chitosan (0-0.5%-1%) containing beta-cyclodextrin microencapsulated trans-Cinnamaldehyde or thymol each (0-0.25%-0.5%). After coating by chitosan, the fruits were immersed in 1% Calcium chloride solution to induce crosslinking reaction. After dipping step, fruits dried for 8 minutes at room temperature to remove the excess solution attached to the surface .Uncoated fruits served as control. Then fruits were preserved in cold storage (temperature: 10ºc; relative humidity: 90-95%) for 15 days. chemical (total soluble solids, titratable acidity) and physical (total color difference, Hardness, and weight loss) Characterization of fruits were measured immediately after harvest and after 5, 10 and15 days. Microbial tests (total count, mold, and yeast) were done at the end of preservation time. Analytical data were subjected to analysis of variance and factorial adopted completely randomized design and a Duncan comparison test was used. Results and DiscussionThe results showed that weight loss, total soluble solids, and the total color difference increased and hardness and titratable acidity decreased gradually in all samples during cold storage (<0.05). Chitosan and essential oils slowed down this rising or decreasing trends. Interactive effects of chitosan, essential oil type, essential oil concentration, and storage time had positive effects on these quality attributes. The fruits coated with the highest concentration of chitosan (1%) and thymol (0.5%) essential oils showed the least weight loss, loss of hardness, and color change throughout 15 days of storage. Besides thymol in comparison with trans-Cinnamaldehyde was more efficient to prevent yeasts and molds on the surface of cucumber. By increasing chitosan and essential oil amounts, the ability of inhibiting microbial growth by coating is enhanced. ConclusionThe results of chemical, physical and microbial tests, showed that multi-layer coating solution containing chitosan 1% with thymol 0.5% was effective in extending the shelf life of cucumber. The combined usage of microencapsulated thymol essential oil and chitosan-based coating on cucumber could be considered a healthy and effective treatment that reduces microbial spoilage and preserves quality and color characteristics in cucumber and represents an innovative method for commercial application. Therefore, this coating can be used as an alternative to chemical fungicides to prevent fungal rot of cucumber and other fruits, however, it is suggested that more studies should be done in this field.
Food Technology
Rezvan Shaddel; Shadi Rajabi Moghaddam
Abstract
Introduction
Caffeine is one of the most common bioactive compounds in the world that can enhance mental and physical performance However its bitter taste has created challenges for the use of this compound in food. Nano-encapsulation technology, such as the use of liposomes, is one of the simplest ...
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Introduction
Caffeine is one of the most common bioactive compounds in the world that can enhance mental and physical performance However its bitter taste has created challenges for the use of this compound in food. Nano-encapsulation technology, such as the use of liposomes, is one of the simplest ways to overcome this issue. In this research, caffeine was encapsulated in nanoliposomes coated with chitosan and then the drink powder enriched with caffeine nanochitosome was produced.
Materials and methods
In this research, pure caffeine powder was purchased and stored in dry environment at room temperature. Ethanol (96%) and acetic acid were obtained from Mojallali Company, Tween 80 from Merck Company (Germany), lecithin (P3556), cholesterol (C8667), and chitosan (medium molecular weight) purchased from Sigma Aldrich Company (Germany). Sugar, essential oil and citric acid used in the formulation of the drink were purchased from a local store.
First, nanochitosomes in ratios of 9:1, 8:2 and 7:3 lecithin-cholesterol, were prepared using thin-layer hydration method. Then, the particle size and zeta potential were measured to determine the characteristics of the produced particles. Encapsulation efficiency was measured for 9:1, 8:2 and 7:3 lecithin-cholesterol ratios. The stability of the chitosomal sample with a ratio of 9:1 lecithin-cholesterol was evaluated through visual observation of precipitation formation and the amount of release of encapsulated caffeine during 60 days of storage at ambient temperature was calculated. FTIR was performed for each of the components of the wall of chitosomes, caffeine powder, chitosomal solution containing caffeine and chitosomal solution without caffeine with a ratio of 9:1 lecithin-cholesterol. Nanochitosomes with 9:1 lecithin-cholesterol ratio were used in the formulation of beverages due to having the smallest particle size, favorable zeta potential, the highest microencapsulation efficiency, and high stability during storage. The drink samples were prepared in different formulations (samples containing 3 and 5% free caffeine solution, samples containing 3 and 5% chitosomal caffeine solution and the control sample). Then, the drinks were evaluated in terms of sensory characteristics and other physico-chemical characteristics (pH, acidity, Brix degree, etc.). The drinks produced were turned into powder with a freeze-dryer machine, and two important characteristics of powdered products, i.e. water solubility index and their hygroscopicity, were evaluated.
Results and Discussion
The average particle size and zeta potential for different ratios of lecithin -cholesterol were obtained in the range of 133.3-443.6 nm and +40.96 to +48.36, respectively. The encapsulation efficiency for 9:1, 8:2 and 7:3 lecithin-cholesterol ratios were 91.2%, 86.18% and 79.09 %, respectively. The chitosomal sample with 9:1 lecithin-cholesterol ratio showed good stability during 60 days of storage at ambient temperature. FTIR results showed that caffeine was loaded in nanochitosomes. The results of the sensory evaluation of the prepared beverages showed the acceptability of the taste of the samples containing caffeine nanochitosome compared to the samples containing free caffeine, which indicates the success of chitosomal nanocarriers in covering the bitter taste of caffeine. The results of measuring the color of different drink samples showed that there is no significant difference between the color of samples. The results of measuring pH and acidity did not show significant differences between different drink samples. The results of measuring the solubility of different drink powder samples showed that the samples containing caffeine nanochitosomes have low solubility compared to other drink powder samples. Also, the hygroscopic amount of the drink powder containing caffeine nanochitosomes was lower than the other samples, which is considered as an advantage for powdered products.
The results obtained in this research showed that nanochitosomes are an efficient system in covering the bitter taste of caffeine. Therefore, with the production of caffeine nanochitosomes and its usage in the formulation of powder drinks, it is possible to produce energizing and desirable drinks without the need to use high amounts of sucrose.
Food Technology
Azade Farazmand; Hossein Jalali; Ali Najafi
Abstract
Introduction Potato strips are one of the most widely consumed products, and due to their high oil content, they have caused public health concerns. Therefore, efforts to reduce oil absorption can alleviate these concerns to some extent. Edible coating is an effective way to reduce oil uptake, because ...
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Introduction Potato strips are one of the most widely consumed products, and due to their high oil content, they have caused public health concerns. Therefore, efforts to reduce oil absorption can alleviate these concerns to some extent. Edible coating is an effective way to reduce oil uptake, because the oil absorption is a surface phenomenon. Edible coatings should adhere well to the surface of the product and provide a uniform and complete coverage for the product. Preventing the migration of oxygen, carbon dioxide, aromas, oils, moisture, improving the appearance of food and mechanical properties. In this study, the possibility of reducing oil absorption in French fries was investigated using okra mucilage and chitosan as edible coatings. Material and Methods The okra was washed and then cut into about 1 cm pieces and poured into containers with lids. Then water in a ratio of 2:1 weight of okra was added to the container and completely covered its surface. The okra were refrigerated for 72 hours until the mucilage was completely extracted. Then the mucilage was smoothed. This solution was considered as 100% mucilage solution. To prepare a 50% solution of okra mucilage, 100% solution was mixed with an equal amount of distilled water and filtered. To produce a solution of 0.75 and 1.5% of chitosan, 7.5 and 15 g of chitosan powder was dissolved in 1000 ml of 1% acetic acid and then adjusted to pH 5. Then 5 g of glycerol was added as a plasticizer. The potato slices were first blanched in 0.5% calcium chloride solution at 90°C for 5 minutes. Then, they were immersed in coating solutions at 60°C for 5 minutes. After coating, the potato strips were fried at 180°C using a fryer and then various characteristics including coating percentage, oil absorption, and moisture content, texture firmness, peroxide value, acid number, color indices and sensory properties were examined. Design Expert 8.0.7.1 software was used to analyze the results and to draw the curves. Results and Discission The results showed that the increasing the amount of chitosan led to better coating formation in comparison with okra. The highest coverage was observed in the concentration of 1.2% chitosan and 0% okra mucilage (2.38%) and the lowest was observed in the control sample (0.11%). It was also observed that with increasing the concentration of chitosan and okra mucilage, the amount of oil absorption decreases. However, the amount of oil absorption in high concentrations of okra mucilage increased slightly. The highest oil uptake in the control sample was 20% and the lowest was observed in the sample of fried strips covered with 41% okra mucilage and 1.5% chitosan at 15.44%. The obtained model of oxidation index was not significant. The effect of okra mucilage and chitosan concentration on the texture of the samples (p <0.05) and the color indices of a* (p<0.01) and L* (p <0.05) were significant. For sensory attributes, the highest and the lowest taste score was observed for samples coated with 100% okra mucilage and 0.75% chitosan and samples coated with 18% okra mucilage and 0% chitosan respectively. Conclusion The aim of this project was to reduce the oil absorption of fried potato strips by coating them with chitosan and okra mucilage. Optimization to minimize the consumption of okra and chitosan mucilage showed that coating with 74% okra and 0.89% chitosan is suitable for coating potato slices. The desirability of this optimization was 71%, which is a reasonable percentage.
Zabihalh Bahmani; Parastoo Abolfathi
Abstract
[1]Introduction: With increasing demand for chicken meat, the chemical composition of meat carcasses has become more important. Despite advances in medical care and food technology in recent years, foodborne infections and food poisoning, as well as food spoilage in developed and developing countries ...
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[1]Introduction: With increasing demand for chicken meat, the chemical composition of meat carcasses has become more important. Despite advances in medical care and food technology in recent years, foodborne infections and food poisoning, as well as food spoilage in developed and developing countries are still a major problem for human health and the economy. During the storage period, the quality characteristics of meat is shortened due to bacterial and oxidative spoilage. Oxidative spoilage causes unpleasant odors, unpleasant changes in taste, and changes in the structure of nutrients and reduces the nutritional value of the product. While spoilage and microbial contamination lead to product wastage and poses serious health risk to consumers. Increasing interest in using less synthetic preservatives has led to use of natural derivatives with antimicrobial properties. Biodegradable coatings are a good alternative to plastic packaging, given the problems they have with recycling and environmental pollution. Chitosan coating containing Zataria multiflora essential oil is known to possess good antioxidant and antibacterial properties due to the presence of thymol and carvacrol compounds and their ability to establish hydrogen bonds with other monoterpenes such as γ-tropenes. Materials and methods: Zataria multiflora was purchased in the spring from Sari Medicinal Plants Store. It’s essential oil was prepared by distillation method using Clevenger and then dehydrated with sodium sulfate and passed through 0.45 μm syringe filters and stored in dark containers at 4°C (Rezaie et al., 2015).In this study, the use of biodegradable and edible coating of chitosan with thyme essential oil to increase the shelf life of chicken fillets during refrigeration was investigated. Treatments included control, 2% chitosan, 1.5% essential oil and treatment containing 2% chitosan with 1.5% essential oil, which were stored at 4 ° C for 24 days. The antioxidant and antimicrobial properties of chitosan and thyme essential oil were evaluated by measuring the total amount of phenolic compounds, free radical scavenging (DPPH), and FRAP. Quality assessment with chemical tests; pH, TBA, TVB-N, and microbial count (mesophilic bacteria and Pseudomonas) were measured at 4-day intervals. Results and discussion: The results of quality assessment during the refrigeration period for all treatments showed an increasing trend in pH. TBA (mg MDA/kg fat), TVB-N (mg N/100g), TMC and Pseudomonas (CFU/g) in coated treatments with 2% chitosan and 1.5% essential oil on day 24 of storage were 6.6, 1.78, 26.8, 6.7 and 6.42, respectively, and showed the highest shelf-life. Since, thyme essential oil and chitosan have increased the shelf-life of chicken fillets due to their antioxidant and antimicrobial activity.The use of biopolymers such as chitosan, gelatin, etc., which have a good ability to maintain and release antioxidant and antimicrobial compounds, is increasing in food packaging. In this study, the preservation effects of chitosan coating containing Zataria multiflora essential oil on increasing the shelf life of chicken fillets were investigated and it was found that chitosan coating and Zataria multiflora essential oil alone and in combination had good preservation effects. According to the results, 2% chitosan coating containing Zataria multiflora essential oil can increase the shelf life of chicken fillets, which is due to the very good performance of chitosan coating containing Zataria multiflora essential oil due to its synergistic effect on antimicrobial and antioxidant properties. Between chitosan coating and thyme essential oil in preventing microbial growth and chemical spoilage and shelf life for control treatments, chitosan 2%, thyme essential oil 1.5%, and chitosan 2% containing thyme essential oil 1.5% respectively 8, 16, 16 and 24 days. Therefore, they can be used to store chicken fillets and meat products.
Soheyl Reyhani Poul; Sakineh Yeganeh; Reza Safari
Abstract
[1]Introduction: Nisin is one of the antimicrobial substances that is used today as a preservative in various foodstuffs. It is a bacteriocin comprised of 34 amino acids and a molecular weight of 3.5 Da. With all the benefits of nisin, there are barriers to its use in dairy and protein rich products. ...
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[1]Introduction: Nisin is one of the antimicrobial substances that is used today as a preservative in various foodstuffs. It is a bacteriocin comprised of 34 amino acids and a molecular weight of 3.5 Da. With all the benefits of nisin, there are barriers to its use in dairy and protein rich products. One of these barriers is the combination of nisin with fats, proteins and sugars and the consequent reduction of its antibacterial activity. In the food science and industry, the use of the technique of encapsulation and production of liposome is the best possible solution in such cases. Also, by adding an antimicrobial agent such as chitosan to the coating of nanoliposomes, the antibacterial activity of the product may be increased. The aim of the present research was to produce nanoliposomes carrying nisin with (and without) chitosan coating and to evaluate the physical and antibacterial properties against two gram-positive bacteria, Bacillus cereus and Staphylococcus aureus. Materials and Methods: In this study, four treatments of nanoliposomes carrying nisin (NN), nanoliposomes carrying nisin coated with chitosan 0.05% ((NN-CH (0.05)), nanoliposomes carrying nisin coated with chitosan 0.1% (NN-CH (0.1)) and nanoliposomes carrying nisin coated with chitosan 0.5% (NN-CH (0.5)) were prepared and examined in terms of physical properties (average particle size, particle dispersity index, zeta potential and encapsulation efficiency) and antibacterial activity (against two gram-positive bacteria, Bacillus cereus and Staphylococcus aureus with two diffusion methods in agar medium and microdilution test). This research was conducted in a completely randomized design and SPSS and EXCEL softwares were used for statistical analysis and drawing of diagram, respectively. Data were analyzed by one-way analysis of variance and the difference between the means was evaluated by Duncan's test at 95% confidence level. Results and Discussion: The results showed that the average particle sizein different treatments with each other are significantly different (P<0.05) and vary from about 110 to 327nm; Also as the amount of chitosan in the coating increased, the particle size increased (P<0.05). This indicates the successful binding of chitosan to the surface of the nanoliposome, which results in the formation of a layer around the nanoliposome and an increase in particle size. Particle dispersity index was recorded less than 0.3 in all treatments and was not related to the amount of chitosan in the coating. With increasing the amount of chitosan in the coating of nanoliposomes, zeta potential increased significantly (P<0.05). This index changed from -55.34 in NN treatment to 53.14 mV in NN-CH (0.5) treatment. In fact, chitosan as a cationic polysaccharide changes the potential to positive values. As the amount of chitosan in coating of nanoliposomes increased, the encapsulation efficiency increased significantly in the treatments (P<0.05); this index increased from 32.19% in NN treatment to 75.14% in NN-CH (0.5) treatment. The results of the antibacterial activity of nisin in two methods of diffusion in agar medium and microdilution test showed that its antibacterial activity increased with nanoencapsulation of nisin with (and without) chitosan coating (p<0.05). Also, with the increase in chitosan concentration, the antibacterial activity of carrier nanoliposomes increased and the highest antibacterial activity was recorded in NN-CH (0.5) treatment (p<0.05). The diameter of the non-growth halo of Bacillus cereus against the research treatments (with five concentrations of 2.5 to 25 μg/ml) varied from about 4.5 to 17.5 mm. This amount for Staphylococcus aureus was recorded from 2.1 to 26.5 mm. By increasing the concentration of nisin and carrier nanoliposomes, the diameter of the halo of non-growth of both bacteria increased significantly (p<0.05). But an exception was recorded in this case; The diameter of the non-growth halo for Staphylococcus aureus in two concentrations of 2.5 and 5 μg/ml of treatments was the same and had no significant difference (p>0.05). The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the examined treatments for Bacillus cereus were in the range of 100 to 400 and 200 to 500 μg/ml, respectively. These two concentrations for Staphylococcus aureus were recorded as 50 to 200 and 100 to 400 μg/ml respectively. Based on the values of diameter of non-growth halo, MIC and MBC it can be claimed that Bacillus cereus is more resistant to the examined treatments than Staphylococcus aureus.Nanoencapsulation of nisin in the form of carrier nanoliposomes with chitosan coating is a suitable solution to improve its physical and antibacterial properties. In such a way that by increasing the concentration of chitosan in the coating, both of the aforementioned properties improved significantly. Nanoliposomes carrying nisin with (and without) chitosan coating have the ability to inhibit the growth and killing Bacillus cereus and Staphylococcus aureus bacteria. The antibacterial activity increases with the increase in nisin and carrier nanoliposomes concentrations. The value of non-growth halo, minimum inhibitory concentration and minimum bactericidal concentration confirm that Bacillus cereus is more resistant to nisin and its carrier nanoliposomes than Staphylococcus aureus.
Food Technology
Maryam Gohargani; Hannan Lashkari; Alireza Shirazinejad
Abstract
Introduction: In recent years, the tendency to use antimicrobial edible film and coating has increased, which has increased the quality, safety and shelf life of food. Cheese is one of the most important dairy products that has a special nutritional value in human nutrition. UF-Feta cheese, which is ...
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Introduction: In recent years, the tendency to use antimicrobial edible film and coating has increased, which has increased the quality, safety and shelf life of food. Cheese is one of the most important dairy products that has a special nutritional value in human nutrition. UF-Feta cheese, which is a type of cheese, is contaminated by microorganisms such as coliforms, spore-forming bacteria and lactose-fermenting yeasts. The causative agent of listeriosis, Listeria monocytogenes, is transmitted through the consumption of cheese. In this study, the effect of composite edible coating based on chitosan and whey protein containing titanium dioxide (TiO2) nanoparticles and Zataria multiflora essential oil on shelf life, microbial, physicochemical and sensory properties of UF-Feta type cheese was investigated. Furthermore, the inhibitory effect of films from coating solutions on the growth of Listeria monocytogenes was also investigated. Materials and Methods: Chitosan, whey protein isolate (WPI) (higher than 91% protein), Zataria multiflora essential oil (ZEO), TiO2 nanoparticles, and glycerol were procured from Bio Basic (Canada), Hilmar Canada, Barij-Essence Co. (Iran), Acros Co. (USA), and Merck Co. (Darmstadt, Germany), respectively. In order to prepare the coatings, a solution of WPI and chitosan was prepared separately. Whey protein suspension (3%, w/v) was made by dispersing WPI in DDW subsequently heated at 90°C for 30 min at pH value of 8.0 and then cooled rapidly. Chitosan solution (10 g/L) was made by dispersing chitosan in 2% (v/v) acetic acid solution with constant mixing for 3 h at 60°C. Based on preliminary experiments, whey protein–chitosan suspension was made using blending two polymer suspensions at constant ratio of WPI/chitosan (70:30) and mixed magnetically for 15 min at 25ºC. In the next step, TiO2 NPs (1 and 2% w/w) were incorporated and after mixing for 15 min, glycerol (30% w/w) was incorporated to the composite suspension and again stirred for 30 min. Next, ZEO (0 and 1% v/v) was incorporated into the composites suspension and sonicated for 30 min with power of 100 W.To produce cheese samples, milk was subjected to bactofogation, pasteurization (76°C for 15 seconds), ultrafiltration and then the retentate was homogenized at a pressure of 70 bars. By adding a starter culture (10 units /1000 L), the pH of the retentate was decreased to 6.2. Then, rennet (0.004 g/ 100 g) and salt (2 g/ 100 kg) were mixed with water and added to the cheese container. Retentate was transferred to a coagulation tunnel at 37 ° C for 30 minutes to form a coagulum. After incubation, the coating solutions were sprayed on the clot using a spray device equipped with a spray gun and packed with aluminum foil. Finally, the samples were stored at 4°C. Samples were subjected to microbiological tests (contaminating microbes and starters), physicochemical (fat, titratable acidity, pH, and moisture content, texture analysis) and sensory evaluation at different ripening periods (3 to 60 days). To evaluate the growth inhibitory of Listeria monocytogenes on the surface of cheese by composite films, pieces of cheese (23× 21× 1.7 mm) were first cut under aseptic conditions and their upper surface was inoculated with 40 μl of Listeria monocytogenes (ATCC19115) until the initial bacterial count was about 3.5 log cfu /g. The composite films placed on the surface of the inoculated cheese and stored at 4°C. Film-inoculated cheese samples were used as a control. Microbial counts were done at intervals of days 0, 3, 8, 11, 14. Data analyzed with SPSS software and means were compared with Duncan multiple range test. Results and Discussion: The results showed that TiO2 NPs and ZEO significantly reduced total bacterial count, lactic acid bacteria and coliforms compared to control with increasing storage period. Mold and yeast colonies also increased considerably over time in the control compared to the nanoparticle-treated samples, while the While in treatments containing ZEO did not grow at all. Physicochemical analysis exhibited that the content of moisture, fat, and pH of all cheeses decreased, acidity and texture hardness increased. Sensory evaluation of UF-Feta cheeses showed that the aroma, taste and overall acceptability of the control and nanoparticle-containing coatings improved compared to the brine-treated cheese. Nevertheless, in the coating samples containing ZEO due to the negative effect of the essential oil on the organoleptic properties of cheese, consumer acceptance was significantly reduced. On the other hand, the use of composite films to inhibit the growth of Listeria monocytogenes on the surface of UF-Feta cheese at 4 °C for 14 days showed that composite films, especially films containing ZEO, had a significant effect on the reduction of the Listeria monocytogenes population. As a conclusion, composite films containing TiO2 NPs and ZEO could be applied in food packaging systems, particularly at the UF-Feta cheese packaging.
Food Technology
Nasim Najafi; Hajar Abbasi
Abstract
Introduction highly sensitive to fungal and biochemical changes such as respiration and enzymatic activity, as a result, it has a short shelf life: wheat is an important cereal crop used as staple food in many parts of the world and provides 20% of the energy and 78-93% of the protein in the human diet. ...
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Introduction highly sensitive to fungal and biochemical changes such as respiration and enzymatic activity, as a result, it has a short shelf life: wheat is an important cereal crop used as staple food in many parts of the world and provides 20% of the energy and 78-93% of the protein in the human diet. Seed germination is a process which begins with activating proteinase due to uptake of water. Metabolic activity occurs during the germination process, leading to the hydrolysis of proteins and carbohydrates, and the synthesis of metabolites that have health-promoting properties for human. Sprouted wheat is a rich source of protein, dietary fiber, minerals, vitamins and phytosterols. Using chemical preservatives to extend the shelf life of food has a great health concern for many years. Therefore, developing safe methods to control perishability and maintain quality of perishable foods during storage is crucial. Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-D-glucosamine and N-acetyl-D-glucosamine. Chitosan coating is beneficial to maintaining the storage quality and prolonging the shelf life of postharvest fruits and vegetables. Dracocephalum kotschyi is one of the medicinal herbs with special constituents including caryophyllene, limonene, α-pinene, geranial, and flavonoids. The essential oil of this plant has significant biological activities, including antiviral, antibacterial and anti-corruption. Considering the successful application of chitosan and essential oils in edible coating formulae and its proven antifungal properties due to its nano-particles prompted us to initiate this study aiming at assessing the efficiency of an edible coating for maintaining quality and increasing the shelf life of wheat sprout. Therefore, in the present study, nano-emulsion of Dracocephalum Kotschyi essential oil in chitosan was considered for coating sprouted wheat in order to delay its perishability. Materials and Methods: Materials used in this study consisted of wheat (Pakanbazr Co.), chitosan (Shayan Chemical Co.) and Dracocephalum kotschyi were supplied from Isfahan's medicinal plants market. All chemicals were from Merck Co. In order to prepare wheat germ, wheat grains were immersed in water containing 0.07 % sodium hypochlorite for 10 min. Then, the disinfected samples were soaked in water at 25 °C for 12 h. After soaking, the samples were placed in a germination chamber at 30 °C and 98% relative humidity for 48 h. Quality properties of sprouted wheat such as moisture, ash, fat, protein, mineral, fiber and ascorbic acid concentration were measured. Sprouted wheat was coated by immersion in nano-emulsion and then was packed at modified atmosphere (30% oxygen, 70% nitrogen), for 12 days at 4° C. The pH, weight loss, total phenol content, antioxidant activity and hardness of the samples were determined. Optimal and control samples were examined in terms of qualitative characteristics such as pH, weight loss, total phenol content, antioxidant activity and hardness during 0, 4, 8, 12, 16 and 20 days after production. In the present study, effects of independent variables such as essential oil concentration (A), chitosan concentration (B) and immersion time (C) on total phenolic content, antioxidant activity, ascorbic acid content, and hardness were investigated by Response Surface Method in the form of a central composite design with 6 central point (α=1.5). Comparison of the optimal and control samples was done in a completely randomized design using SAS ver: 9.1 software. Results and Discussion: An increase in chitosan and immersion time resulted in better preservation of total phenolic. The interaction effect of essential oil concentration and immersion time also resulted in better retention of total phenolic compounds. An increase in essential oil and chitosan concentration up to intermediate level increased the antioxidant activity. Chitosan and Dracocephalum Kotschyi essential oil play a key role in maintaining the total phenolic content and antioxidant capacity of sprouted wheat by reducing gas exchange, respiration rate and the activity of polyphenol oxidase and peroxidase enzymes. Interaction effects of variables up to intermediate level resulted in higher level of preservation of ascorbic acid. The interaction effect of essential oil and chitosan at high levels led to better preserved of hardness. Coating treatment contains 25% chitosan with 84.18 ppm Dracocephalum Kotschyi essential oil and 25s immersion time can be introduced as a safe and effective method to maintain the quality characteristics and increase wheat sprout shelf life. Coating of wheat sprout reduced the changes in pH, weight loss, total phenol content, ascorbic acid, antioxidant activity and hardness in coated samples during storage compared to the control sample. Furthermore, sensory properties did not change significantly after storage time. The results revealed that the use of chitosan- Dracocephalum Kotschyi oil coating delay bacterial and fungal decay and improved the quality characteristics and shelf life of sprouted wheat during storage. The results of this study indicated the positive effect of chitosan-Dracocephalum Kotschyi oil nano-emulsion coating on preserving the quality of sprouted wheat
Soheyl Reyhani Poul; Seyed Ali Jafarpour
Abstract
Introduction: Following extensive research on antibacterial and antioxidant properties of chitosan and hydrolyzed proteins and their satisfactory results, the use of these compounds as natural preservatives and good alternative to antibacterials and synthetic antioxidants in various nutrients is essential. ...
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Introduction: Following extensive research on antibacterial and antioxidant properties of chitosan and hydrolyzed proteins and their satisfactory results, the use of these compounds as natural preservatives and good alternative to antibacterials and synthetic antioxidants in various nutrients is essential. The aim of the present study was to investigate the properties of chitosan coating containing FPH in the preservation of rainbow trout (Oncorhynchus mykiss) fillets at refrigerated temperatures. Materials and methods: The hydrolyzed protein powder (FPH) used in this study was produced by enzymatic hydrolysis of frame (skeleton with the meat attached to it) of common carp (Cyprinus carpio) with flavourzyme enzyme. Accordingly, this powder was added to the chitosan coating (2% w/v chitosan + 2% w/v FPH). In order to investigate antibacterial and antioxidant properties of chitosan coating containing FPH, rainbow trout fillets were coated with chitosan (treatment 2) and chitosan containing FPH (treatment 3). Then, these sample treatments and control (treatment 1) were subjected to chemical (PV, TVN-B, TBA, FFA and pH) and microbial (count of aerobic mesophilic and psychrophilic bacteria) tests on days 0, 4, 8, 12, 16 and 20 in refrigerated storage. This study was implemented in form of completely randomized design and data were analyzed by one-way ANOVA and significant differences between the means were tested by Duncan's test at 95 confidence level. Results and discussion: According to the chemical tests, TBA, TVN-B and FFA indices showed an increasing value during the refrigeration period significantly (P<0.05) while their trend was lower in treatment 3 compared to the treatments 1 and 2. TBA index for treatments 1, 2 and 3 in day 0 was 0.017, 0.015 and 0.014 mg MDA/kg fillet respectively that this amounts reached to 1.49, 0.99 and 0.52 mg MDA/kg in day 20. At the beginning of the preservation period, TVN-B index was calculated 13.36, 13.18 and 12.46 mgN/100gr fillet for treatments 1, 2 and 3, respectively. But these values changed to 43.36, 30.19 and 22.11 mgN/100gr fillet for mentioned treatments at the end of preservation period. FFA index was 0.16, 0.14 and 0.12 percentage of oleic acid for treatments 1, 2 and 3 in day 0 whereas after 20 days of storage, this index increased to 2.55, 1.76 and 0.98 percentage of oleic acid for mentioned treatments respectively. The PV index was significantly less in treatment 3 compared to the treatments 1 and 2 in days 12, 16 and 20 (2.72, 4.42 and 4.12 meq o2/kg lipid respectively) but continuous incremental trend was not recorded in this index with increasing preservation time, even the end of the experimental period (day 20), the index decreased in all of treatments compared to the 16th day. The results of pH changes showed the stability of this index in treatment 3 during the preservation period (pH~6.30). Meanwhile, in day 12, 16 and 20, the pH of treatment 3 was significantly less than treatments 1 and 2 (p<0.05). The bacterial load count of aerobic mesophilic and psychrophilic bacteria in treatments (while having an increasing trend during the preservation period) showed that in day 8, 12, 16 and 20, the bacterial levels of treatment 3 were significantly less than treatments 1 and 2 (p<0.05). In this study, adding FPH produced from common carp fish (with degree of hydrolysis 15.9%) to chitosan resulted in enhanced antioxidant and antibacterial properties of chitosan coating. So that, the film obtained from the combination of chitosan and FPH was much stronger barrier against lipids oxidation and bacterial proliferation in rainbow trout fillets (at refrigerated temperatures) than pure chitosan film.
Esmail Khazaei; Mikhalil Piruzifard; Fariba Zeynali; Mohammad Alizadeh khaled abad
Abstract
Introduction: Meat and meat products are important sources of protein, fat, essential amino acids, minerals and vitamins, and other nutrients. Bologna sausage, a cooked meat product, is one of the most accepted processed meat products and is consumed and enjoyed worldwide. Among the meat products, sausage ...
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Introduction: Meat and meat products are important sources of protein, fat, essential amino acids, minerals and vitamins, and other nutrients. Bologna sausage, a cooked meat product, is one of the most accepted processed meat products and is consumed and enjoyed worldwide. Among the meat products, sausage and bologna in vacuum packages due to their variety, easy to use applications and being economical, have become commonplace. The most important problem with the production, storage, and sale of this kind of meat products is their syneresis in the vacuum packages. In addition to an unpleasant appearance, syneresis leads to accelerating microbial growth and undesirable changes in the flavor and odor of the product.The addition of functional ingredients helps to modify the overall technological and sensorial characteristics of a meat system such as water holding capacity (WHC), fat holding capacity, and texture properties and decrease the syneresis. Syneresis and purge are seen as a result of retrogradation of starch and this is very common in sliced and vacuum-packed meat products. Storage of meat products containing high-amylose starches, at low temperatures from around –1 °C to 0 °C for a prolonged time also favors retrogradation. The level of retrogradation depends on the type of starch and wheat starch demonstrating the greatest tendency towards retrogradation. Chitosan is a natural cationic polysaccharide antibacterial activity and antioxidant properties in muscle foods during storage. The aim of this study was Investigation the addition of functional ingredients such as chitosan and potato modified starch in the formulation on the amount of syneresis, pH, total microbial count and sensory evaluation in two type of products including beef ham and chicken ham were examined during storage. Then, the effect of vacuum packaging type and the amount of vacuum created in the package on the amount of syneresis were investigated. Material and methods: In this study, first various factors such as three levels of chitosan (0, 0.3 and 0.6%) and replace the wheat starch with three levels of potato modified (0, 5 and 10%) in the formulation on the amount of syneresis, pH, total microbial count and sensory evaluation in two type of products including beef ham and chicken ham were examined during storage time (1, 15 and 30 days). In this part of the study, samples with the least syneresis were selected. After that various factors of packaging such as two types of vacuum packaging(simple vacuum pack and skin pack) and the amount of vacuum(5 and 30 millibars) created in the package on the amount of syneresis were examined during storage(1, 15 and 30 days). Wheat starch, potato starch, and chitosan were purchased, respectively, from Faradane Company, KMC Company, and Sinaseven Company. The chicken meat was purchased from Fileh Amol Company. The beef was purchased from the Minerva Company of Brazil. All steps of samples’ preparation were performed in the Kalleh Amol Meat company. The chicken ham samples in this study consisted of 90% of the chicken meat and beef ham samples consisted of 90% of beef. Vacuum packaging was done using the machines which were manufactured by the German company Multivac. Syneresis was measured using the method suggested by Cesare et al. (e 2013). The initial weight of the ham slices before vacuum-packed was measured (P1); on the day of the analysis, the packaging was opened and the slices were dried with a disposable absorbent towel, then the dried ham slices were weighed again (P2). Syneresis was expressed as Syneresis= (P1- P2) ×100/P1. This study was conducted in a completely randomized design and Duncan multi-ranged test was used to determine differences between samples at 95% confidence level. Results and discussion: According to the results of analysis of variance, there was no significant difference between the syneresis of beef and chicken ham. The effect of storage time was significant on the syneresis and the syneresis rate increased with increasing storage time. Also, the results showed that adding chitosan and potato modified starch significantly (p<0.05) reduced the product's syneresis during storage. Potato starch has more water storage capacity and more amylopectin than wheat starch. For this reason, potato starch has a weaker retrogradation and less syneresis. Chitosan is a cationic polysaccharide with water-absorbing polar groups. Chitosan also was prevented from decreasing the product’s pH during storage time, that this result showed the antimicrobial effect of chitosan on acid lactic bacteria, especially in 15 and 30 days of storage. For that reason, chitosan prevents product’s pH to reach to its isoelectric pH. According to the sensory evaluation results, during the maintenance period, the sensory quality decreased significantly while chitosan had a significant positive effect on sensory parameters during storage time (P<0.05). The type of vacuum packaging and the amount of vacuum created in the package showed a significant effect on the amount of samples’ syneresis. Skin packaging showed less syneresis rates than simple vacuum packages. This result can be due to two reasons: one is the shrinkage of the product in the package, and the other is the amount of the film packing tangency on the surface of the products. So that by increasing the amount of vacuum, syneresis value increased significantly. Increasing the negative pressure inside the package caused increase the mechanical pressure by the packaging film on the product. In total, it can be concluded that with the addition of modified potato starch and chitosan to the formulation, as well as the use of lower-vacuum Skin packaging, the amount of syneresis of meat products can be significantly reduced.
Fakhri Shahidi; Farideh Tabatabaei Yazdi; Majid Nooshkam; Zahra Zareie; Fereshte Fallah
Abstract
Introduction: Lipid oxidation leads to the generation of off-flavors and potential toxic compounds. Synthetic antioxidants are frequently applied for inhibiting this reaction, however; there is a concern regarding to the potent toxic effects of synthetic antioxidants on human health. The non-enzymatic ...
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Introduction: Lipid oxidation leads to the generation of off-flavors and potential toxic compounds. Synthetic antioxidants are frequently applied for inhibiting this reaction, however; there is a concern regarding to the potent toxic effects of synthetic antioxidants on human health. The non-enzymatic glycosylation reaction (Maillard reaction) has been broadly used to ameliorate the biological and functional features of proteins and polysaccharides. The Maillard reaction produces products with versatile functions such as antioxidant, antimicrobial, antihypertensive, anti-browning, and prebiotic properties. In this regard, the Maillard reaction products (MRPs) can be used in the food industry to inhibit the oxidation reaction due to their superb antioxidant effect. In this study, chitosan was glycosylated with inulin, fructose, and glucose. Chitosan is a chitin derivative with cationic nature having antimicrobial, antioxidant, metal chelation, and film-forming features. Inulin is recognized as a prebiotic sugar with vast applications in food and pharmaceutical sciences. The purpose of this study was to chemically modify chitosan through the Maillard reaction in order to boost its antioxidant and antimicrobial properties. Materials and methods: Chitosan (0.5% w/v) was dissolved in 1.0% v/v acetic acid solution followed by stirring for 1.0 h at room temperature. Afterwards, sugars inulin, glucose, and fructose were separately added to the chitosan solution at final concentration of 1.0% w/v. The obtained solutions were then stirred until complete sugar dissolution. The pH of solution was adjusted to 6.07 by adding 2.0 M sodium hydroxide and then the chitosan-sugar Maillard conjugates were fabricated through autoclaving the solutions at 121 °C. Changes in pH after the reaction were measured using a pH meter. The extent of the Maillard reaction was estimated via measuring the absorbance of the conjugated solutions at 294 nm (the intermediate products) and 420 nm (final products). Fourier transform infrared (FTIR) spectroscopy at transmission mode and 400-4000 cm-1 was employed to evaluate the structural changes of chitosan upon conjugation. Antioxidant activity of the conjugates was evaluated based on the reducing power assay. One mL of the samples was charged with 1.0 mL of distilled water and 1.0 mL of potassium ferricyanide (1.0% w/v). The solution was mixed and incubated at 50 °C for 20 min. After adding 2.5 mL of tri-chloroacetic solution (10% w/v), the obtained solution was centrifuged at 5000 g for 5.0 min. Afterwards, 2.0 mL of the supernatant was mixed with 2.0 mL of distilled water and 1.0 mL of ferric chloride (0.1% w/v). The solution was stand for 10 min at ambient temperature and then its absorbance was recorded at 700 nm. Antimicrobial effect of the conjugates against pathogenic microorganisms (E. coli, S. aureus, B. subtilis, P. aeruginosa, A. niger, and C. albicans) was measured according to the minimum inhibitory (MIC) and microbiocidal (MBC) concentrations. SPSS software (version 21) and one-way ANOVA were applied for data analysis. Duncan’s multiple range test was employed to determine the differences between means. Results & discussion: The Maillard reaction led to a significant decrement in pH value of chitosan-saccharide systems, mainly due to the covalent coupling of amino groups of chitosan to carbonyl groups of reducing sugars in conjugation with the production of acetic and formic acids. The highest intermediate compounds (A 294nm) and lowest browning intensity (A 420nm) observed in chitosan-fructose conjugate, which was likely attributed to the lower reactivity of fructose. Chitosan-inulin conjugate presented the highest A 420nm and lowest intermediate-to-final ratio (A 294nm/A 420nm), probably due to the lower inulin molecules and subsequently carbonyl groups compared to fructose and glucose. These groups may react with amino groups of chitosan at initial reaction times, leading more conversion rate of the intermediate compounds to the final ones. FTIR spectra of the chitosan and conjugates revealed that absorbance peak at 1661 cm-1 in chitosan spectrum decreased and shifted to 1578 cm-1 (in chitosan-fructose conjugate), 1579 cm-1 (in chitosan-glucose conjugate), and 1580 cm-1 (in chitosan-inulin conjugate), indicating the stretching C-N group and -C=N group and the formation of Schiff base (-C=N) between reducing end of the saccharides and amino groups of chitosan. Reducing power of the chitosan-saccharide systems improved after the thermal process. Although, chitosan-glucose and chitosan-fructose conjugates had significantly higher reducing power than unconjugated counterparts, but chitosan-inulin conjugate showed non-significantly improved antioxidant activity compared to its non-heated mixture. Antioxidant activity of the Maillard conjugates was ascribed from the electron donating ability of their hydroxyl and pyrrole groups. The conjugates had lower MIC and MBC in comparison to their unconjugated pairs, except for chitosan-glucose conjugate, which showed no differences in MIC and MBC compared with its non-heated mixture. Antimicrobial property of the Maillard products, especially melanoidins has been attributed to their metal chelating features; melanoidins exert a bacteriostatic effect at low concentration and bactericidal effect at high levels through sequestering ionic iron from medium and magnesium from outer membrane, leading to the cell membranes destabilization. Additionally, antioxidant capacity, high surface activity, and inhibiting effect towards catabolic enzymes have been reported as another antimicrobial mechanisms of the Maillard products. In general, it can be concluded that chitosan-saccharide Maillard-based conjugates, particularly inulin-chitosan one could be used in the food sector as a novel prebiotic-based active bio-compound with antioxidant and antimicrobial features.
Maryam Ein Ali Afjeh; Rezvan Pourahmad; Behrouz Akbari Adergani; Mehrdad Azin
Abstract
Introduction: The aim of this study was to investigate the effect of immobilized glucose oxidase on magnetic chitosan nanoparticles on the content of organic acids (lactic acid and acetic acid), viability of probiotic bacteria and sensory properties of probiotic drinking yogurt.
Materials and ...
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Introduction: The aim of this study was to investigate the effect of immobilized glucose oxidase on magnetic chitosan nanoparticles on the content of organic acids (lactic acid and acetic acid), viability of probiotic bacteria and sensory properties of probiotic drinking yogurt.
Materials and methods: Different concentrations (0, 250, 500, 750 and 1000 mg/kg) of free and immobilized glucose oxidase were used in probiotic drinking yogurt. The samples were stored at 4˚C for three weeks.
Results and discussion: During storage, the content of acetic acid, counts of Lactobacillus acidophilus and Bifidobacterium lactis decreased and the content of lactic acid increased significantly (p<0.05). Addition of enzyme increased the viability of probiotic bacteria in test samples as compared to control sample (without enzyme). The viability of Bifidobacterium lactis in the samples containing high levels of enzyme (750 and 1000 mg/kg) was higher than other levels. The samples containing 500 mg/kg of free and immobilized enzyme had the highest count of Bifidobacterium lactis (7.88 log CFU/mL) and the amount of acetic acid in these samples (0.82 and 0.87 g/L, respectively) was more than other samples. There was no significant difference between the samples in regards to sensory properties. Therefore, addition of glucose oxidase immobilized on magnetic chitosan nanoparticles can decrease oxidative pressure and create suitable condition for the viability of probiotic bacteria in drinking yogurt and maintain overall acceptability. Moreover, it is economically feasible.
Atosa Assarzadegan; Mohammad Fazel
Abstract
Introduction: The fruit, with the scientific name of Cydonia oblonga comes from apple family, has a dry and fluffy flesh that, due to high vitamin C, Potassium and fiber has commercial and nutritional value. However, this fruit is as corruptible as other fruits and destructive microbial, chemical and ...
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Introduction: The fruit, with the scientific name of Cydonia oblonga comes from apple family, has a dry and fluffy flesh that, due to high vitamin C, Potassium and fiber has commercial and nutritional value. However, this fruit is as corruptible as other fruits and destructive microbial, chemical and mechanical factors that reduce its effective longevity. Enzymatic browning is a major problem for reducing the shelf life of freshly chopped fruits and vegetables. This reaction often occurs due to the activity of polyphenol oxidase (PPO) and peroxidase (POD) enzymes. Blanching is used to deactivate the relevant enzymes. Blanching is done before such processes as drying, canning, and freezing and somewhat determines the quality of the product. Sulfites are multi-functional compounds that inhibit enzymatic and non-enzymatic browning. Dehydration is one of the oldest techniques for keeping food products. Osmotic dehydration process has been emphasized in recent years due to the negative effects of conventional drying procedures, this process is done to partially remove the water from the plant tissue by immersion in a salt or salt solution. Chitosan is non-toxic, biodegradable substance that can be used as an edible coating to maintain the quality and increase the life after the fruits and vegetables harvest. This protective performance improves by adding antimicrobial, antioxidant. The lemongrass extract was added to the chitosan coating as antimicrobial. The purpose of this study is to investigate the effect of chitosan coating containing lemongrass extract on the shelf life of dehydrated quince fruit slices.
Materials and methods: Metabisulfite was used in order to prevent the browning reactions of slices prepared from blanching, water vapor and chemical solution of sodium. Then, quince slices are dehydrated with osmotic solutions of sorbitol, sucrose by immersion with chitosan containing (0, 0/5, 1 and 2 % lemongrass extract) coated and kept in sterile plates at refrigeration temperature (4±1˚C) for 4 weeks. The experiment was carried out in factorial method based on a completely randomized design with three iterations. Variables include the type of osmotic solution (sucrose, sorbitol) and coating treatments (chitosan coating containing 0, 0/5, 1 and 2% lemongrass extract). The studied characteristics included weight loss (%), acidity, pH, ascorbic acid concentration, total phenol, inhibitory activity of free radical (RSA), color properties (components L*, a*, b*, BI) of tissue that was investigated in the first, second, third and fourth week.
Results & discussion: Fruits coated with chitosan containing 2% lemongrass extract had less weight loss changes than other treatments. This can be due to the role of the extract in preventing decay, its antimicrobial properties and the formation of the semipermeable membrane by coating, which prevents weight loss. Edible coatings containing extract, by changing the internal atmosphere and reducing the respiration rate of the fruit, help to maintain better organic acids .Lemongrasses extract causes the delay in the consumption of organic acids in metabolic reactions, including respiration, due to its antioxidant properties. It seems increasing the pH of the fruit is the result of biochemical changes in the fruit during storage time, such as the decomposition of organic acids into sugars and participating the respiratory cycle in which the coating of chitosan containing extract can reduce the breakdown of organic acids by reducing respiration rate. The decrease in the drop of Vitamin C and phenolic compounds of the coated sample is due to oxygen permeation reduction and the creation of adapted atmosphere by coating. The high level of antioxidant activity of lemongrass extract is because of high phenolic compounds of which the highest amount was observed in treatment coated with chitosan containing 2% lemongrass extract. By increasing the concentration of the extract, its phenolic compounds increases which preserve more vitamin C and phenolic compounds and consequently antioxidant properties. Free radical inhibition activity was preserved due to better preservation of phenolic compounds, ascorbic acid and increasing the antioxidant capacity of fruit by chitosan coating containing lemongrass extract. The product brightness decreases during storage. Before the hot-water blanching coating process, sodium metabisulfite and osmotic dehydration have inactivated browning enzymes. Therefore, in quince coated with chitosan, the amount of color changes was not tangible due to the less respiration and as a result, less enzymatic activity of fruit. Coating containing lemongrass extract has created due to the color of coating extract with the green-tinted color. The increase in the extract concentration reduces the redness and increases the greenness of fruit, which is because of the extract color and as the effect increases, the concentration increases. By decreasing the brightness, increasing the greenness and yellowness during storage time and the browning increased. In quince coated with chitosan, the amount of softening wasn’t tangible due to less respiration and as a result, less enzymatic activity of fruit. As the concentration of lemongrass increases the stiffness of the tissue is reduced due to the effect of lemongrass on the fruit tissue cells that cause structural changes. Based on the results, the edible coating containing 2% lemongrass extract is suggested as the best formulation.
Fahimeh Tooryan; Maryam Azizkhani
Abstract
Introduction: Nowadays, consumers are applicant to usage of natural replacements causing to side effects of synthetic preservatives such as carcinogenicity and teratogenicity. The tendency to use natural preservatives and replacing them with chemical preservatives has led to various studies of natural ...
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Introduction: Nowadays, consumers are applicant to usage of natural replacements causing to side effects of synthetic preservatives such as carcinogenicity and teratogenicity. The tendency to use natural preservatives and replacing them with chemical preservatives has led to various studies of natural compounds with antioxidant properties such as essential oils. Considering the environmental problems raised from current plastic packaging, edible and biodegradable coating could be developed and also be effective in controlling the chemical and microbial properties of food; especially if their effect be strengthened by adding natural antioxidant and antimicrobial agents like herbal essential oils. Various herbal compounds such as black pepper essential oils with antioxidant properties can be effective in combining with natural biodegradable coatings such as chitosan in oxidation control and enhance the effects or prevent or delay the chemical spoil. Safety and shelf-life of foods can be improved by using this technologies such as using natural preservatives. Adding essential oil, as a suitable source of antioxidant, for improvement the quality of the fish is the main purpose. Many fruits, especially orange, are rich in polyphenols. These materials are the most commonly existing phytochemicals in most fruits. Orange juice concentrate can be a good source of antioxidant and can be employed as a preservative in food products. Omega-3 fatty acid is used in daily healthy diet and plays an important role in prevention of disease. Being a considerably main source of Omega-3 fatty acid groups, fish preservation against oil oxidation and any other similar causatives seems quite necessary. In the present study, the effects of orange juice concentrate and chitosan coating enriched with black pepper essential oil on the chemical degradation of rainbow trout fillet stored in a refrigerator investigated.
Materials and methods: The chemical composition of black pepper essential oils were determined using a gas chromatography equipped with mass spectroscopy (GC/MS). GC-MS analysis of the essential oil was performed using Agilent-Technologies 6890N Network gas chromatographic (GC) system, equipped with Agilent Technologies 5975 inert XL Mass selective detector and Agilent-Technologies 7683 B series auto injector (Agilent-Technologies, Little Falls, CA, USA). Samples were stored at 4 ± 1 C° up to 12 days and evaluated periodically ( on days 0, 4, 8 and 12) for chemical and sensory characteristics. The samples were divided into 8 groups and assessed for PH-values, total volatile nitrogen (TVN), thiobarbituric acid (TBA), peroxide value (PV), free fatty acids (FFA) and sensory evaluation .The samples were also evaluated for antioxidant activity by measuring their scavenging abilities to DPPH radical (2,2 diphenyl-1-picril hydrazyl) and RP (Reducing power). Statistical analysis was performed using SPSS 20 software.
Results & Discussion: Results showed that More than 21 compounds were identified in oil, representing 97.75% of the total oil. The major constituents of essential oils obtained from the black pepper were β-caryophyllene (25.56%), Limonene (15.19%), Sabinene(12.2) , α-copaene(8.5) and beta –bisabolene (7.81) respectively. Results revealed that in comparison to the other treatments the control showed a significant increase in the trend of oxidative and sensory indexes and In the coated samples, the sample of fish coated with orange juice concentrate ,chitosan, and black pepper essential oil was the least amount of indexes than the rest (p<0/05) and showed lower indexes during the storage time .The radical scavenging DPPH, orange juice concentrate with a Brix 1/39 (66/9 %)and pepper essential oil 2% (64/1%) have more ability and had a greater antioxidant activity. In investigating corruption oxidation and sensory evaluation in all samples,chitosan coating with pepper essential oil and orange juice concentrate was higher(score:7/2) than other treatments and there were significant differences between treatment and control (p<0/05). Final peroxide value (meq O2/Kg oil) and tiobarbituric acid (m gr/kg oil MD) number using chitosan coating with pepper essential oil and orange juice concentrate in sample was 0.14 and 0.015, respectively. This significant deference was also observed when comparing to control sample (p<0.05)Minimum oxidative changes were observed in samples treated with orange juice concentrate,chitosan, and black pepper essential oil and had the best conditions in reduction of oxidative rancidity. The results obtained in this study showed that the chitosan coating enriched with black pepper essential oil with orange juice concentrate has a good potential to being employed as an active packaging to preserve food products. Overall, this study demonstrated that using concentrated juice incorporated with chitosan coating with pepper essential oil has a good effect on the quality of rainbow trout fillets and can keep on the sensorial attributes acceptably during 12 days storage time and present a good potential for their application in the food industry.
Vahid Alizadeh; Hassan Barzegar; Behzad Nasehi; Vahid Samavati
Abstract
The present work describes the physicochemical and antimicrobial properties of active films developed by incorporating different concentrations (0.5, 1, and 2% v/v) of Satureja hortensis essential oil (SEO) and 3% (w/w) nanoclay into a chitosan- montmorillonite nanocomposite film. The tensile strength ...
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The present work describes the physicochemical and antimicrobial properties of active films developed by incorporating different concentrations (0.5, 1, and 2% v/v) of Satureja hortensis essential oil (SEO) and 3% (w/w) nanoclay into a chitosan- montmorillonite nanocomposite film. The tensile strength (TS) of the films significantly decreased and elongation at break (EAB) increased with the incorporation of SEO. The control film exhibited the lowest water vapor permeability. In addition, decreases in water solubility (WS) and transparency were observed with increasing the concentration of SEO. Thermogravimetric analysis (TGA) indicated that films incorporated with SEO exhibited a higher degradation temperature compared with the control. The structural properties and morphology of the nanocomposite films were examined by X-ray diffractometry (XRD) and Scanning electron microscopy (SEM). SEO-incorporated films were more effective against gram positive bacteria (Staphylococcus aureus and Bacillus cereus) than gram negative ones (Salmonella typhimurium and Escherichia coli). The results suggested that SEO, as a natural antibacterial agent, has the potential to be applied in antimicrobial biodegradable films.
Ehsan Azadbakht; Yahya Maghsoudlou; Morteza Khomeiri; Mahboobeh Kashiri
Abstract
Introduction: The edible films and coatings had remarkable growth in recent years to increase the shelf life and to enhance food quality, stability, and safety and expected to have an important impact on the food market in the following years. In addition, these matrices can be used as carriers of antimicrobials ...
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Introduction: The edible films and coatings had remarkable growth in recent years to increase the shelf life and to enhance food quality, stability, and safety and expected to have an important impact on the food market in the following years. In addition, these matrices can be used as carriers of antimicrobials to minimize the risk of foodborne contamination by pathogens and inhibit the development of spoiler microbes. Antimicrobial packaging is a type of active packaging that provides the continuous migration of antimicrobial components to the surface of the foods. Chitosan is a linear copolymer of β-1, 4-linked D-glucosamine and N-acetyl-d-glucosamine. It is a cationic polysaccharide for food packaging applications, due to its unique characteristics of films, including excellent oxygen barrier properties, good mechanical properties, nontoxicity and good antimicrobial activity. Eucalyptus is a plant native from Australia and the Myrtasya family that includes about 900 species and sub-species. There is abundant scientific evidence regarding the efficacy of different species Myrtasya as the antibacterial and antifungal compounds used in health products, and food industry. Using natural antimicrobials are interesting strategies for reducing the use of chemical additives in the food industry. Essential oils (EOs) are defined as a mixture of volatile water insoluble substances to be incorporated into the edible films due to exhibit antimicrobial effects. Moreover, evaluation EOs on the physical, optical and structural properties of the resulting film is also important. Therefore, the aims of this work were to determine the effect Eucalyptus globulus essential oil on antibacterial properties (2) to determine the antimicrobial activity of chitosan based films containing Eucalyptus globulus essential oil against S. aureus, B. cereus, E. coli and S. intertidis.
Materials and methods: The foodborne microbial strains were prepared from Persian Type Culture Collection. The essential oil was analyzed by gas chromatography (GC) (Thermoquest 2000, UK). In this study, the antimicrobial activity of Eucalyptus globulus essential oils (EGOs) was evaluated against two gram positive (S. aureus and B. cereus) and two gram negative (E. coli and S. intertidis) bacteria by the agar diffusion technique and microdilution test. The effect of EGO was evaluated in liquid media and vaporous phase too. Chitosan solution were prepared by dissolving 1.5 % (W/V) of chitosan in aqueous solution containing 0.7% (V/V) of acetic acid under a magnetic stirrer at 40°C until chitosan was completely dissolved. Glycerol as plasticizer (10% weight of chitosan powder) was added to the solution and stirred for 10 minutes. The EGO with concentrations of 0.5, 1 and 1.5% v/v was added to the solution and was stirred for 5 minutes. The film forming solutions using a homogenizer (Heidolph, Germany) were homogenized with 12000 rpm for 4 min, then degassed for 5 min and 25 ml were cast on a 10 cm diameter petri dish. After drying the film in the oven at 38°C for 24 h, they were peeled from the plate surface and were evaluated. The antimicrobial activity of the films was evaluated in contact with liquid and vaporous media.
Results and discussion: Minimum inhibition concentration for gram negative (E. coli, S. enteritidis) and gram positive (B. cerus and S. aureus) bacteria showed 3.125 and 1.562 µg/l respectively. The inhibition zone for gram positive bacteria was bigger than gram negatives. The effect of EGO on bacteria based on Log reduction value (LRV) of S. aerus > B. cerus > E. coli> S. enteritidis. Thses results confirmed that gram positive bacteria were more sensitive to inhibition by plant essential oils than the gram-negative bacteria. Our results showed that chitosan film containing 1 and 1.5 % essential oil was able to reduce the density of bacteria. The Log reduction value of chitosan bioactive film was increased by increasing the concentration of E. globulus essential oil than 0.5 to 1.5 % in liquid media. The results of this work had demonstrated that chitosan bioactive film containing 1.5% EGO can be used an effective antimicrobial film for food packaging in direct contact.
Conclusion: Chitosan is a good biopolymer for active food packaging. The result of this study showed that chitosan films containing EGO could be used as active films due to enhanced the antimicrobial properties which are important in food packaging applications. Films containing essential oil had unique properties that are useful for coating of perishable foods such as fish and poultry.
Vahid Alizade; Hassan Barzegar; Behzad Nasehi; Vahid Samavati
Abstract
Introduction: The environmental effect of synthetic plastic wastes is of increasing global concern. There is an urgent need to develop and apply renewable biopolymer materials. Development of edible and biodegradable films can help solving the waste disposal problem by partially replacing synthetic plastics ...
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Introduction: The environmental effect of synthetic plastic wastes is of increasing global concern. There is an urgent need to develop and apply renewable biopolymer materials. Development of edible and biodegradable films can help solving the waste disposal problem by partially replacing synthetic plastics (Martins et al., 2012). Chitosan; a linear polysaccharide composed of (1, 4)-linked 2-amino-deoxy-b-d-glucan, is a deacetylated (to varying degrees) product of chitin, which is the second most abundant polymer found in nature after cellulose. It has been proved to be biodegradable, biofunctional, biocompatible, nontoxic and have strong antifungal and antimicrobial properties (Aider, 2010). Thus, this work was undertaken to investigate the physical, optical, barrier, mechanical, microstructural, and antimicrobial properties of chitosan films incorporated with PEO, to examine its potential applications as a packaging material.
Materials & method: The films were prepared according to the solvent casting technique reported by (Abdollahi et al., 2012) with some modifications. Tensile strenght (TS) and elongation at break (E) of the films were measured with texture analyzer according to Barzegar et al. (2014) method. Equilibrated film strips (at 53% RH for 48 h) were fixed between the grips with an initial separation of 50 mm and the cross-head speed was set at 50 mm/min. TS was calculated by dividing the maximum force by the initial area of the film and E% was calculated through dividing the extension at the moment of specimen rupture by the initial gauge length and multiplying by 100. The WVP of the films was determined at according to the Shojaee-Aliabadi et al. (2013). The test cups containing anhydrous calcium chloride (0% RH) were sealed by the test films, then were placed inside a desiccator containing sodium-chloride-saturated solution (75% RH). Weight gain of the cups along time were recorded periodically and plotted as a function of time. Antimicrobial properties of the films were assessed using the disc-diffusion method according to Dashipour et al. (2015). Four gram-positive or gram-negative bacteria, including B. cereus, S. aureus, E. coli and S. typhimurium were used for testing.
Results and discussions: The influence of PEO incorporation on thickness, TS, EAB, WVP and water solubility of films can be seen in Table 1. The incorporation of PEO into the film-forming dispersion led to an increase in the thickness of the films, which varied between 0.131 mm and 0.185 mm. It could be due to the entrapment of PEO micro droplets by the polymer matrix (Dashipour et al. 2015). By increasing PEO concentration from 0.5 to 2 % in the film solutions, WS decreased markedly from 22.46 to 16.15 (P < 0.05). This behavior can be explained by the cross-linking effects of PEO components to esters and/or amide groups. Cross-linking in the chitosan film leads to a polymer with lower water solubility, which is useful when product integrity and water resistance are intended (Hosseini et al., 2009).
Table 1. Physical and mechanical properties of chitosan films.
PEO (% v/v) Thickness (mm)
Solubility in water (%) WVP
(g s-1 m-1 Pa-1 × 10-10) TS
(MPa) EAB
(%)
0.0 0.131 ± 0.01d 22.46 ± 0.73a 1.04 ± 0.05c 21.22 ± 1.97a 49.05 ± 1.63c
0.5 0.153± 0.01c 21.19 ± 1.22a 1.12 ± 0.06c 20.09 ± 1.40a 50.36 ± 2.98c
1 0.167 ± 0.01b 18.47 ± 0.53b 1.35 ± 0.09b 17.04 ± 1.26b 55.25 ± 2.95b
2 0.185 ± 0.01a 16.15 ± 0.54c 1.73 ± 0.09a 13.23 ± 1.35c 59.37 ± 2.49a
The incorporation of PEO into chitosan-based films leads to an increase in WVP values from 1.04 to 1.73 g s-1 m-1 Pa-1 × 10-10. A similar trend has been found by Bonilla et al., (2011) in chitosan-based films incorporated with thyme essential oil. The structural discontinuities induced in the polymer network by the addition of PEO could be the reason for the lowest resistance to breakage of the emulsified films. These discontinuities greatly reduced the film cohesion and mechanical resistance (Bonilla et al., 2012). Conversely, the EAB value of the films increased significantly (P < 0.05) from 49.05% to 59.37%, because the essential oil acted as a plasticizer even at small concentrations and enhanced the flexibility of the polymer chains.
The effects of PEO on the antimicrobial properties of the chitosan films are shown in Table 2. The films containing 1% PEO showed a certain inhibitory effect against B. cereus and S. aureus but no inhibition against S. typhimurium and E. coli. As the concentration of PEO increased, the zone of inhibition also increased significantly (P < 0.05). The films containing 2% PEO were effective against all studied bacteria and a greater inhibitory power was observed on S. aureus with the zone area of 49.67 mm2. The inhibitory effect of PEO is due to the two monoterpene hydrocarbons, α-pinene, and β-pinene (Barrero et al., 2005).
Table2. Antimicrobial activity of chitosan films.
PEO (% v/v) Inhibition zone (mm2)
S. aureus B. cereus E. coli S. typhimurium
0.0 0.00c 0.00c 0.00b 0.00b
0.5 0.00c 0.00c 0.00b 0.00b
1 22.58 ± 1.76b 15.63 ± 0.63b 0.00b 0.00b
2 49.67 ± 3.02a 41.96 ± 1.40a 21.12 ± 1.87a 12.49 ± 1.57a
Conclusion: The results obtained in this study showed that the chitosan films incorporated with PEO has a good potential to being empolyed as an active film to preserve food products. Addition of PEO decreased water solubility and tensile strength, while increased the thickness, WVP and percent elongation of the films. Overall, this study demonstrates that PEO-containing films present a good potential for their application in the food industry.
Ali Shahdadi Sardoo; Nasser Sedaghat; Masoud Taghizadeh; Elnaz Milani
Abstract
Introduction: In Iran, the main problem in greenhouse cucumber production and post-harvest shelf life is short due to the application of traditional packaging and storage methods. This research was carried out in order to investigate on the effects of packaging type and chitosan edible coating on the ...
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Introduction: In Iran, the main problem in greenhouse cucumber production and post-harvest shelf life is short due to the application of traditional packaging and storage methods. This research was carried out in order to investigate on the effects of packaging type and chitosan edible coating on the physicochemical and sensory characteristics of Royal Greenhouse cucumber during storage conditions, in order to prevent of Royal greenhouse cucumber postharvest losses.
Materials and methods: Royal greenhouse cucumbers placed inside the three-layer plastic bags of PE/PA/PE and the effect of different chitosan coating (0, 0.5 & 1 %), concentration of oxygen (3,12 & 21%), storage temperatures (5, 15 & 25 ˚C) and storage time (3, 12 & 21 days) on cucumber quality and shelf life was studied. The quality of cucumber samples was evaluated by weight loss, firmness retention, surface color development (L*, a*, b*), shrinkage and sensory evaluation (taste and freshness).
Results and discussion: The obtained results showed that firmness and organoleptic properties decreased with increasing temperature and time storage, while weight loss and shrinkage was increased, that Leading to loss of cucumber samples quality during storage. Increasing of chitosan coating to 0.5% also showed a beneficial effect on physicochemical and sensory characteristics of the samples during the storage time compared to the control fruit, but by increasing it to 1%, decreased the quality of the final product. The results showed that using modified atmosphere packaging and storage at low temperatures can be in addition to the slow breathing fresh cucumbers from softening and prevent moisture loss the maintenance of cucumber. MAP packaging leads to keeping cucumber green and quality properties compared to the control samples. The optimum condition was obtained at chitosan coating 0.5 %, O2concentration 8.5 %, storage temperatures 9˚C and storage time of 14 days. At this optimum point maximum of firmness, L*, taste, freshness and minimum of shrinkage, weight loss and a* were found to be 10.4 (N), 48.9, 4.35, 4.5, 6.25 %, 2.75 % and -37.28 respectively.
Nasrin Faraji; Mohammad Alizadeh khaled abad; Asghar Khosrowshahi; Soheila Faraji
Abstract
Heart disease - cardiovascular, cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study, ...
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Heart disease - cardiovascular, cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study, the effect of different levels of three hydrocolloids (inulin, chitosan and xanthan) at three levels (1, 2 and 3%) on survival of Lactobacillus acidophilus, physicochemical and sensory properties of yogurt during 15 days of storage was explored using a combined design. Increased levels of inulin and chitosan positively affected La-5 count, apparent viscosity, acidity and sensory scores during storage. Using graphical method of optimizing (overlaid contour plots), optimum ratios were: inulin 93.4%, xanthan 0.6% and chitosan 6%.
