Food Technology
Elham Safaei; Hannan Lashkari; Sara Ansari; Alireza Shirazinejad
Abstract
Introduction Manufacturers are trying to replace plastic materials in the food packaging industry with biodegradable and edible films. Biodegradable edible films and coatings are mainly made from carbohydrates, lipids and proteins and their mixtures. In recent decades, various carbohydrates from ...
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Introduction Manufacturers are trying to replace plastic materials in the food packaging industry with biodegradable and edible films. Biodegradable edible films and coatings are mainly made from carbohydrates, lipids and proteins and their mixtures. In recent decades, various carbohydrates from plant sources have been investigated and introduced as new compounds for the preparation of these films. Flaxseed gum is a white to cream-colored powder that dissolves in water and produces a gel, and is a desirable compound for forming films and coatings. Recently, through the integration of reinforcements or fillers with at least one nanometer dimension in the substrate of one or more natural biopolymers, the physicochemical, mechanical, optical, thermal and barrier properties of pure biofilms have been improved. The use of cellulose nanoparticles in biofilms as a reinforcing agent for polymer materials leads to the creation of composite films with better quality characteristics and leads to the creation of functionalization activities in film production. Therefore, the aim of this research was to produce and characterize edible and biodegradable film based on the combination of flaxseed gum and cellulose nanocrystals. Materials and Methods Cellulose nanocrystals (Degree of crystallinity: 42% and average particle size: 58 nm) were extracted from cotton linters. Glycerol and other chemicals used for this research were obtained from Merck, Germany. Flaxseeds were purchased from the local market of Shiraz (Iran). Bionanocomposite films were prepared from different ratios (0:100, 30:70, 50:50, 70:30 and 100:0) of flaxseed mucilage (2% w/v) and cellulose nanocrystal (6% w/v) solutions. The prepared solutions were poured on a petri dish with a diameter of 15 cm and dried in an oven at 80°C for 4 hours. Their physical, color and mechanical properties were investigated and the best ratio was selected for the preparation of bionanocomposite film. The produced films were subjected to different analysis to determine thickness, solubility, water absorption capacity, permeability to water vapor, tensile strength, elongation at break point, and colorimetry. The microstructure of the produced film was studied using a scanning electron microscopy (SEM).The average data were analyzed by analysis of variance in a completely randomized design using SPSS 22.0 software. Differences between treatments were expressed in Duncan's multiple range test at the 95% probability level (p<0.05) and the corresponding graphs were drawn with Excel 2013. Results and Discussion The results of the film thickness test showed that the film containing 100% mucilage has the lowest thickness and with the addition of cellulose nanocrystals, the thickness increased significantly (p<0.05). The results of the water solubility and water absorption capacity of the film samples showed that the addition of cellulose nanocrystals to the flaxseed mucilage film initially led to a significant decrease in the water solubility and water absorption capacity (p<0.05), so that the lowest level ofthese two physical parameters were obtained in the film containing the combination of 70% flaxseed mucilage and 30% cellulose nanocrystal, and then with the increase of cellulose nanocrystals, an increase in water solubility and water absorption capacity of the films was observed. Nanocrystal cellulose at low levels (30%) acted as a filler and was uniformly dispersed in the network of the film and by filling the empty pores of the biopolymer film based on flaxseed mucilage, it caused the transfer of water vapor more complicated and reduced the permeability to water vapor. However, its higher amount increased the permeability of the film to water vapor.The results showed that by adding cellulose nanocrystal to the film based on flaxseed mucilage and increasing its amount, the brightness of the films decreased and the intensity of redness, yellowness and turbidity of the films increased significantly (p<0.05). By combining flaxseed mucilage and cellulose nanocrystals in a ratio of 30:70, the best film was produced in terms of mechanical strength and stability against moisture and water vapor. The SEM image of this film showed a smooth, even surface and a uniform distribution of cellulose nanocrystals in the film network. Conclusion The results finally showed that the combination of flaxseed mucilage and cellulose nanocrystals in a ratio of 30:70 was able to produce a biodegradable and edible film with favorable structural and barrier properties. The characteristics of this film include; thickness (0.313mm), solubility (53.42%), water absorption capacity (44.44%), permeability to water vapor (0.350 g.m-1s-1Pa-1 × 10 -10), tensile strength (0.973 MPa), elongation at break point (30.52%) were obtained. The colorimetric indices L*, a*, b* and turbidity were determined as 79.73, 1.95, 3.48 and 1.335 mm-1 respectively. Acknowledgement The authors would like to express their sincere gratitude to Islamic Azad University, Sarvestan Branch.
Food Technology
Mohammad Sadegh Arab; Hannan Lashkari; Mehrdad Niakosari; Mohammad Hadi Eskandari
Abstract
This study aimed to evaluate the effects of intelligent pH-sensitive composite film based on gelatin and Persian gum incorporated with purple carrot extract (PCE) on the freshness of wrapped mozzarella cheese. In this regard, the color, pH, yeast and mold count of control and treatments wrapped with ...
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This study aimed to evaluate the effects of intelligent pH-sensitive composite film based on gelatin and Persian gum incorporated with purple carrot extract (PCE) on the freshness of wrapped mozzarella cheese. In this regard, the color, pH, yeast and mold count of control and treatments wrapped with intelligent pH-sensitive composite film during 60 days were evaluated. The results showed that the pH significantly reduced in wrapped cheese with and without PCE (control) samples during storage. However, this reduction was more pronounced in the control sample (P<0.05). Additionally, the application of composite film on cheese affected the color during storage. It was observed that L* and a* values of the composite film-wrapped cheese were significantly higher than the control sample, but the b* values were significantly lower than the control sample. Moreover, poor microbial growth (yeasts and mold) was observed in cheese samples wrapped by composite film with purple carrot compared to the control. Also, the pH of the composite film with extract significantly decreased from 6.33 to 4.85 during storage (P < 0.05), which showed the changes of color from purple to pink. After 40 days, the color changed to pink, indicating the end of the cheese storage. Therefore, it was concluded that the pH-sensitive film, while being an effective method to improve the shelf life of mozzarella cheese, can also use as an indicator for freshness.
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.
Marziyeh Momeni Sarvestani; Hannan Lashkari
Abstract
Introduction: Black cumin is one of the most important and valuable herbal plants that are wildly found in regions of Iran with dry weather such as Kerman, Fars, Isfahan and Yazd. Black cumin seed in traditional medicine is used as anti- flatulence, anti-diarrhea, antipyretic, blood fat and cholesterol ...
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Introduction: Black cumin is one of the most important and valuable herbal plants that are wildly found in regions of Iran with dry weather such as Kerman, Fars, Isfahan and Yazd. Black cumin seed in traditional medicine is used as anti- flatulence, anti-diarrhea, antipyretic, blood fat and cholesterol reducer, anti-allergic and digestive enhancers. Essential oils are oily liquids that are obtained from different parts of the plant. Different compounds in the essential oil of black cumin include cumin-aldehyde, gamma trypinene, paracymon and other active ingredients, which are often terpene compounds and have numerous uses as anti-bacterial and antioxidant agents. In recent years, consumers have become more concerned with the health issues and are looking to eat foods with higher functional characteristics, as well as higher nutritional value. Therefore, it can be suggested that essential oil of Cumin as a natural and vegetable preservative was used in food. Because cheese is a nutritious environment for the growth of microbes, it always has microbial degeneration. Materials and Methods: Identification of essential oil compound was performed by GC/MS chromatography. In order to evaluate the effect of Black Cumin essential oil on physicochemical, microbial and sensory properties of cheese, different percentages of Black Cumin essential oil (0, 0.05, 0.1% and 0.15%) were added to cheese. Iranian white cheese production was done by ultrafiltration method in Arjan Fars Company. Cheese sample were analyzed at days 3, 30 and 60 of storage time. Acidity, pH, fat, protein and dry matter were measured according to National Standard No. 2852, 2852, 8785, 1811, 1753 respectively. To measure the inhibition of free radicals of DPPH, method of Rezai et al(2012) was followed. Microbial characteristics were performed according to the standard microbial milk and dairy products number 2406. The color analysis was performed based on Hosseini et al (2019) method. The parameters of color include L* (lightness), a* (redness) and b* (yellowness) were measured. The sensory attributes were evaluated by 9 panelists. A five-point hedonic scale rating (1= very bad, 2=bad, 3= neither bad nor good, 4= good, 5= very good) was carried out. Data analyzed with SPSS: 22 software and Means were compared with Duncan multiple range test (p<0.05). Results and Discussion: The analysis of black cumin essential oil with GC/MS chromatography showed that the main ingredients of it were α-Thujene, p-Cymene, Linalool, Thymoquinone, Carvacrol and Longifolene. The results showed that Changes in essential oil percentage had significant effect (p<0.05) on acidity, pH, IC50. With increasing essential oil percentage, an increase in the level of acidity and decrease in the level of IC50 and pH was observed. Changes in essential oil percentage had no significant effect(p<0.05) on protein, fat, salt and dry matter content of cheese. The results showed that storage period had no significant effect (p<0.05) on protein, fat and salt content. Increasing the essential oil percentage of cheese significantly decreased the L* index and increased the b* index. The microbial analyses showed no microbial contamination (coliforms, sataphylococcus aureus, mold and yeast) was found during the storage time therefore, the essential oil of Cumin can be used as a natural preservative in cheese production. Analyses of the sensory characteristics during storage time showed that the addition of essential oil to cheese did not have any significant effect on color and texture but had a significant effect on taste and acceptance of cheese. In all treatments, the taste score changed significantly with time (p <0.05). Over time, the flavour rating began to increase until the twentieth day, and then decreased to the end of the storage time. In general, the treatment containing 0.05% Black Cumin essential oil has the highest acceptance in sensory evaluation and since its other characteristics were standard, it was selected as the best treatment.
Liela Mahsouli; Hannan Lashkari
Abstract
Introduction: Milk-based dessert is one of the dairy products which in addition to the nutritional value, makes a variety in the consumer basket of goods. The most important property of desserts is their high energy and a pleasant feeling that is created by the consumer due to its ingredients. These ...
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Introduction: Milk-based dessert is one of the dairy products which in addition to the nutritional value, makes a variety in the consumer basket of goods. The most important property of desserts is their high energy and a pleasant feeling that is created by the consumer due to its ingredients. These products contain mainly milk, thickeners, sugar, flavoring compounds and colorant, and have a jelly structure. Sugar is used as a sweetener in the production of desserts. The grape juice concentrate is one of the traditional products of Iran's grapevine region, which accounts for about 5 to 20 percent of Iranian grapes used to make grape juice concentrate. Grape juice concentrate contains high levels of natural sugars, minerals, vitamins, organic acids and antioxidants. Therefore, grape juice concentrate can be used as a sugar replacer sweetener. Materials and Methods: In order to reduce the amount of sucrose in dessert and its replacement with grape juice concentrate, different ratio of grape juice concentrate (0, 5, 7.5 and 10%) were used. To prepare dessert samples, wheat starch was first added to milk at 4%w/w, and then 0.5%w/w gelatin and sugar were added and mixed until all ingredients were completely dissolved in the milk. Then, it was heated to 95°C and stirred at 270 rpm for 15 minutes, then cooled to 40 °C, and grape juice concentrate and water were added. The mixture was finally filled into the dishes. Samples were subjected to physicochemical, microbial and sensory evaluation after 48 hours of storage at 4 °Ċ. The AOAC (2000) methods were used for measuring the moisture content and fat. The amount of carbohydrate, acidity, and pH were calculated based on method of Ebrahimi et al (2018). To measure the free radicals inhibition by DPPH, method Kamkar (2009) was followed. The color analysis was performed based on the method of Hosseini et al (2019). The parameters of color include L* (lightness), a* (redness) and b* (yellowness) were measured. Texture parameters include hardness (N), cohesiveness, springiness (cm), gumminess (N), chewiness (N.cm), adhesiveness were determined by texture analyzer as described by AOAC (2000). The sensory attributes were evaluated by 15 panelists. A five-point hedonic scale rating (1= very bad, 2=bad, 3= neither bad nor good, 4= good, 5= very good) was carried out. Data analyzed with SPSS software and means were compared with Duncan multiple range test. Results and discussion: The results showed that the increase in the amount of grape juice concentrate in dessert samples caused a significant (p< 0.05) increase in acidity, hardness, total solid, a*, and b* value, and percentage antioxidant activity and a significant (p<0.05) decrease in fat, sucrose, pH and L* index. Grape juice concentrate has no significant (p˃0.05) effect on the texture indexes, total count, mold and yeast. The results of microbial tests showed that the total bacterial count increased in samples of grape juice compared to control (p <0.05) but mold and yeast counts were not significantly different in dessert dairy samples (p˃0.05). It should be noted that the microbial count of the samples is in accordance with the standard dairy dessert No. 14725. Sensory evaluation indicated that the addition of grape juice concentrate in the dessert samples did not have any significant effect on the textural characteristics but increased the score of other sensory factors. The sample containing 10% of grape concentrate juice obtained the highest score in odor, sweetness, color, and acceptance, and since its other characteristics were standard, it was selected as the best treatment.
