Food Technology
Elham Ahmadi; Sara Panahi; Amirhossein Karimzadeh; Hamed Hassanzadeh; Mohammadyar Hosseini
Abstract
IntroductionIn recent years, with increasing concerns about food safety and environmental issues related to waste generated by non-degradable plastic packaging, study on novel biodegradable packaging materials has attracted the attention of researchers. Active packaging based on biopolymers, which offers ...
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IntroductionIn recent years, with increasing concerns about food safety and environmental issues related to waste generated by non-degradable plastic packaging, study on novel biodegradable packaging materials has attracted the attention of researchers. Active packaging based on biopolymers, which offers a sustainable and environmentally friendly way to improve food shelf life, considered one of such packaging technologies. Edible coatings and films, are a thin layer of edible compounds and biopolymers applied on the surface of foodproducts that play important role to control physicochemical, microbial and physiological changes in food. Gelatin is obtained from partial degradation of collagen. Due to its availability, relatively cheap price, biodegradability and good properties such as its excellent ability to form a film and reduce the transfer of oxygen, oil and moisture, it is highly regarded as an edible film and has antimicrobial and antioxidant activity. In general, the gelatin film showed high water absorption due to the presence of several hydrophilic groups, which may weaken the mechanical properties and water vapor transport of the film. For this reason, the combination of gelatin with other biopolymers such as chitosan, starch and gum is a suitable method to eliminate the drawbacks of gelatin-based films.Materials and MethodsTo prepare the composite film of the four formulations studied in this research, gelatin powder (3% by weight/volume of water) and glycerol (30% by weight/volume of gelatin powder) were added to deionized water and magnetically stirred for 10 minutes at 2400 RPM. To prepare an aqueous suspension of carboxymethyl cellulose, powder (CMC 2% by weight/volume of water) and glycerol (30% by weight/weight of carboxymethyl cellulose powder) were mixed with deionized water. This suspension was heated to boiling temperature and kept at this temperature for 15 minutes and then kept for 30 minutes at 90°C water bath and stirred. The G/CMC coating was also prepared by dissolving 40 grams of gelatin, 10 grams of carboxymethyl cellulose and glycerol (30% by weight/weight of polymer materials) in one liter of water. The mixture was stirred for 1 hour at 60 degrees Celsius. The mixture was then dried at 25-35 degrees Celsius. Different concentrations of the extract (0, 0.5, 0.75, 1.5 and 3.25%) were added to the mixture and stirred for 2 minutes. In the next step, the mixture was added to a plastic Petri dish with a diameter of 15 cm and placed under a vacuum hood for 1 hour. Then it was transferred to a fan oven and kept for 20 hours. In the final stage, the dried films were placed in a desiccator at room temperature for testing. The effect of different concentrations of Dorema aucheri extract for the production of edible films on the physicochemical, mechanical, antioxidant and antimicrobial properties was analyzed with one-way analysis of variance (ANOVA) and comparing the average data was performed based on Duncan's multi-range test using SPSS26 software at probability level of 0.05.Results and DiscussionThe highest tensile strength and elongation at break point and Young's modulus in the treatment was 1.5%. In all concentrations, solubility and permeability were significant (p<0.05). The lowest solubility was observed in the control. The highest permeability and turbidity were observed in the treatment of 1.5% Dorema aucheri extract. In all edible film treatments, the antioxidant property using DPPH radicals was significant (p<0.05). The results of the evaluation of the antimicrobial activity of the film with the help of diffusion discs showed that the maximum diameter of the inhibition halo in the concentration of 3.25% was related to Escherichia coli with an average halo diameter of 5.33 mm. Average halo diameter for Pseudomonas aeruginosaand Staphylococcus aureus was reported as 4 mm and 3.99 mm, respectively. The overall results showed that the addition of Dorema aucheri extract at a concentration of 1.5% produced films that, in addition to inhibiting the growth and proliferation of bacteria, have strength and can be used for perishable food.
Food Engineering
Sanaz Golmohammadzadeh; Farid Amidi-Fazli
Abstract
[1]Introduction: The biodegradability of synthetic plastics derived from petroleum is a very slow process and complete decomposition of them lasts several years. This increases environmental pollution. Extensive efforts have been made to develop and improve biopolymers-based packaging. Biopolymers derived ...
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[1]Introduction: The biodegradability of synthetic plastics derived from petroleum is a very slow process and complete decomposition of them lasts several years. This increases environmental pollution. Extensive efforts have been made to develop and improve biopolymers-based packaging. Biopolymers derived from renewable agricultural resources are an appropriate alternative to synthetic plastics. The use of nanotechnology in the field of polymer science has led to the production of nanocomposite polymers. The valuable nanocomposites would be produced if natural nanoparticles are used in composites preparation. Because of the importance of nanocomposites in the production of biodegradable films and due to desired properties of gelatin and carboxymethyl cellulose in film production, this study aimed to investigate the effect of glycerol and nanocellulose on the properties of gelatin-carboxymethyl cellulose nanocomposites. Materials and Methods: To prepare 12 different treatments based on statistical design, 1 g of gelatin and 1 g of carboxymethylcellulose were dissolved in distilled water to form a uniform solution. Then, glycerol as a plasticizer was added to the prepared solutions at different levels (20 to 60% w/w). The determined amount of nanocellulose (0- 30% w/w), based on the biopolymers weight, was added to the cooled blend at 70°C. Nanocellulose was extracted from cotton through the chemical method, cotton was gone under chemical hydrolysis by the sulfuric acid solution (65% w/v). The properties of gelatin-carboxymethylcellulose nanocomposites were studied. The produced nanocellulos evaluated by scanning electron microscopy and X-ray diffraction techniques. The thickness of the films was measured using a caliper with a precision of 0.01. At five different parts of each film. Water vapor flux and water vapor permeability through the film samples were determined. The dry matter of 20× 20 mm film samples before and after immersion in 50 ml of distilled water for 24h at 25 °C was determined to calculate the solubility in water of the films. To measure the moisture absorption of the nanocomposite samples, 20× 20 mm film pieces were kept in a container containing potassium sulfate saturated solution (RH= 97%) at 25°C for 4 days. Films were weighted initially and at the end of the experiment. Sessile drop method, a common technique for determining the wetting properties of solid surfaces, was then used to determine the contact angle. Ultimate tensile strength and elongation at break were measured. The belt-shaped sample (8× 1 cm) of the film was stretched by the instrument at a velocity of 1 mm/s. The color and transparency of the samples were evaluated in the black box by image processing technique. Total color difference (ΔE), yellow index (YI), and white index (WI) of the samples were calculated. Treatments were prepared according to central composite design (CCD) and were statically analyzed by response surface method (RSM). Results and Discussion: The prepared films showed low water vapor permeability (3.62× 10-11 to 2.23× 10-12 gm/m2Pas). The lowest amount of water vapor permeability was obtained when the low level of nanocrystalline cellulose (4.4%) was used. The high amounts of glycerol and nanocellulose increased the solubility of the films and even in some treatments the samples were completely dissolved in water. The hydrophilic nature of the gelatin and carboxymethyl cellulose used in the preparation of composites may be the reason for the high solubility of the produced films. At the same time, the samples showed high moisture absorption. Moisture absorption decreased as a result of the glycerol content increased, also the effects of the presence of nanocrystalline cellulose as a filler on the moisture absorption decrease cannot be neglected. A moderate contact angle of about 60º was observed, the interactions between the polar and the hydroxyl groups of the biomaterials used in the production of composites caused different behaviors observed in the various treatments. The interaction of nanocellulose and glycerol had a significant effect on the contact angle. The films had high ultimate tensile strength (84.37 MPa) while the elongation at break was 4.14% for the same treatment, which indicates low flexibility of the produced films. The color of the samples was evaluated as suitable. The use of 60% glycerol and 4.4% nanocellulose results in the production of films with desirable properties. The use of gelatin and carboxymethylcellulose produced composites that had improved properties in the terms of water vapor permeability and surface wetting compared to pure films.Composites made of gelatin and carboxymethylcellulose showed high ultimate tensile strength, although the elongation at break of them was not desirable. In terms of barrier properties against the water vapor, prepared composites demonstrated improved properties when compared to other bio-based made films. On the other hand, in terms of hydrophilicity, they are classified as moisture-sensitive films, which limits their use for foods with high moisture content. The use of carboxymethyl cellulose can improve the water vapor permeability of pure gelatin films. Also, the use of gelatin increases the contact angle of water of pure carboxymethyl cellulose films. Gelatin-carboxymethyl cellulose nanocomposite contains 60% glycerol and 4.4% nanocellulose presents improved and desirable properties.
Food Biotechnology
Zhila Ghasemi; Mohammad Alizadeh khaled abad; Hadi Almasi; Mehdi Nikoo
Abstract
Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization ...
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Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization of probiotic cells in the matrix of edible films. So in this study, edible carboxymethyl cellulose (CMC) probiotic films containing Lactobacillus casei, and the silver carp muscle protein hydrolysates (SCMH) prepared by using limited Alcalase hydrolysis, were analyzed and the viability of bacterial cells was determined at 25, 4, and -18°C for 30 days. An alkaline solubilization/acid precipitation method was used to isolate silver carp white muscle proteins. Protein isolate (3%, W/V) was hydrolyzed with 5% E/S ratio (w/w) Alcalase at 50°C and pH 8.0 for 3 min. Briefly, films were prepared by dissolving SCMH and CMC powder (1.5%, w/v) in a ratio of 1:2 in distilled water and L. casei was added to a final concentration of 108 CFU/mL. Probiotics were counted at intervals of 1, 10, 20, and 30 day. The physical, mechanical [Ultimate tensile strength (UTS) and elongation at break (EB)], thermal and structural properties were determined. XRD patterns of the film samples collected by X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy of the film samples were recorded. The results indicated that the addition of SCMH significantly (p˂0.05) improved the L. casei viability at all three temperatures. Thickness, moisture absorption, and water vapor permeability (WVP) of the films were not influenced by addition of the probiotic. However, the addition of SCMH negatively affected the film’s mechanical properties. The FT-IR analysis confirmed the formation of hydrogen bonds between L. casei and the CMC matrix, the XRD and differential scanning calorimetry (DSC) analyses confirmed the plasticizing effect of SCMH on the films. Thus, CMC films containing L. casei showed the highest UTS (3.7 MPa) and EB (29.9%). Generally, the results indicated that the SCMH incorporated CMC-based film can be a good carrier for probiotics as bioactive food packaging system with promising potential for shelf life extension of perishable foods.
Food Technology
Amir Rezaie; Masoud Rezaei; Mahdi Albooftileh
Abstract
Introduction: Films with appropriate mechanical properties and low permeability are very important for food packaging. Natural polymers have gained increasing attention for the development of biodegradable films due to the environmental problems caused by petroleum-based polymers. Carboxymethyl cellulose ...
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Introduction: Films with appropriate mechanical properties and low permeability are very important for food packaging. Natural polymers have gained increasing attention for the development of biodegradable films due to the environmental problems caused by petroleum-based polymers. Carboxymethyl cellulose (CMC) is a linear polysaccharide that exhibited good film forming properties. Gum Arabic (GA) is another polysaccharide that can be used for preparing the edible and biodegradable films. However, several studies have shown that biopolymers like CMC and GA films have high water vapor permeability and poor mechanical properties in moist conditions. One of the strategies that can be used for improving the properties of biopolymers films is blending the different polymers and formation the composite films. Various studies on the preparation of biocomposite films have been performed, however, to the best of our knowledge, studies on combinations of the CMC and AG have not been reported yet. Thus, the main objectives of this study were to prepare CMC/AG composite films using solvent casting method and investigate the effect of different CMC/AG blending ratio on the physical (water vapor permeability (WVP), water contact angle (WCA), color, opacity and light-barrier properties), mechanical and thermal properties. Furthermore, in order to determine the structural characteristics of the films, fourier-transform infrared spectroscopy (FT-IR) and x-ray diffraction (XRD) measurements were also performed. Material & Method: The CMC and AG solutions were prepared by dissolving 1 g in 100 mL of distilled water at 45 °C for 24 h under magnetic stirring. The prepared solutions were then blended in different proportions (75:25, 50:50, and 25:75). After mixing, glycerol (0.3% w/w) was added as a plasticizer and the solution was stirred for 15 min. The prepared solutions were poured into a glass plate, then dried at 45 °C for 24 h in the oven. Finally, the properties of CMC, GA and composite films were determined. Result and Discussion: In this study, biodegradable films composed of CMC and AG were successfully prepared. Results showed that some properties of the composite films were greatly influenced by addition of AG. So that, WVP of films was decreased significantly in the blend films and the lowest WVP was observed in the 25:75 (AG: CMC) films (p < 0.05). The films hydrophobicity was significantly increased from 41.33o to 61.10o by addition of AG to the CMC films (p < 0.05). With increasing the ratio of AG, the tensile strength (TS) of blend films decreased. Opacity and light transmission of the composite films increased and decreased, respectively with increasing the AG ratio. The differential scanning calorimetry (DSC) test demonstrated that the thermal properties of blend films improved with increasing the AG content. The FT-IR analysis indicated that new interaction was generated between the components of the blend films. Generally, it can be concluded that blending the AG and CMC can improve some of the physico-mechanical properties of the blend films
Mahyar Rad; Hamed Ghafori; Zohreh Gholami
Abstract
Introduction: Edible mushrooms are among the most perishable products that begin to lose quality immediately after harvest, and the short shelf-life of these products will cause problems when it comes to the marketing and distribution of these products in a fresh form. Edible coatings are a good tool ...
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Introduction: Edible mushrooms are among the most perishable products that begin to lose quality immediately after harvest, and the short shelf-life of these products will cause problems when it comes to the marketing and distribution of these products in a fresh form. Edible coatings are a good tool for prolonging the useful life of foods and increasing their quality without contaminating the environment. Materials and Methods: In this study, the possibility of increasing the shelf-life of a button mushroom using blanching followed by coating with carboxymethyl cellulose and sodium metabisulfite was studied. Independent variables included concentrations of carboxymethyl cellulose and sodium metabisulfite (0-2%) and storage time up to 16 days at 4 ° C. This experiment was designed on the basis of three-level factors consisting of 6 central points after 0, 4, 8 and 16 days of storage at 4°C. Factors determined on a button mushrooms included pH measurements, weight loss percentage, soluble solids, texture, color, browning level, total microorganisms count as well as mold and yeast count. Results & Discussion: The results of this study indicated that the sample coated with 2% carboxymethyl cellulose and 2% sodium metabisulfite resulted in an increase in pH level as well as soluble solids. In addition, the slightest color change, weight loss and reduction in tissue stiffness were observed in this sample. The sample coated with 2% carboxymethyl cellulose with 2% sodium metabisulfite had also the lowest total microorganisms count and the count of mold and yeast stored at 4 ° C after 16 days. Based on the results of this study, carboxymethyl cellulose and sodium metabisulfite coatings can be used as an appropriate coating agents for the preservation of organoleptic, chemical, microbial properties and shelf-life of button mushrooms.
Nasser Sedaghat; Sara Khoshnoudi
Abstract
Introduction : Pistachio (Pistaciavera L.) is a tasty nut and a good source of nutrients. Ithas a high content of numerous beneficial nutritive and bioactive compounds such as proteins, carbohydrate, moisture, vitamins, minerals, fiber and other micronutrients compounds, but the most exceptional components ...
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Introduction : Pistachio (Pistaciavera L.) is a tasty nut and a good source of nutrients. Ithas a high content of numerous beneficial nutritive and bioactive compounds such as proteins, carbohydrate, moisture, vitamins, minerals, fiber and other micronutrients compounds, but the most exceptional components are the amount of fats and especially unsaturated fatty acids. Therefore, this nut is highly susceptible to rancidity, especially after roasting. Despite the high quality, raw pistachio and pistachio processing industry at Iran, export of roasted and packaged pistachio, due to low shelf life and drastic changes intaste, is not very successfull. An effort was made to investigate the efficacy of gelatin in comparison with carboxymethyl cellulose (CMC) as edible coating to retard fat oxidation in roasted pistachio.Materials and methods:Five coating formulations were investigated in this study as follow: A) Gelatin (4% w/v) + ascorbic acid (1% w/v): TGA, B) CMC (1% w/v)+ ascorbic acid (1% w/v): “TCA”, C) ascorbic acid (1% w/v): “TA”, D) Gelatin (4% w/v) + CMC (1% w/v) + ascorbic acid (1% w/v): “TCGA” and 5) control sample (uncoated sample): “TCO”.Roasted pistachio nuts were coated by dipping the nuts in the coating solutions. For each treatment, 100 gram of pistachio nuts were packaged (BOPP/Al/CPP, 80 micron plastic bags) in triplicate. The physicochemical analysis included measurement of free fatty acid (FFA), peroxide value (meq.O2 kg-1),hardness (N), moisture (%) and the sensory evaluation (texture, rancidity, taste and overall acceptability) were performed on coated and uncoated pistachio nuts stored at 35 and 50 °C. The nuts were sampled on the 0th, 1st, 2nd and 3rd month of storage. Data was analyzed using Minitab 16. Analysis of variance (ANOVA) and general linear models (GLM) procedure wereused to compare the mean values of each treatment and Significant differences between the means of parameters were determined based on the results of the Tukey’s multiple range test (p0.05).FFA content of TCGA sample was significantly lower than other samples.The highest protection, according to these criterions, was provided by gelatin-CMC coating containing ascorbic acid.The control samples exhibited more bitterness and off flavor than the coated samples, seemingly on account of chemical reaction and second products of oxidation content. Instrumental and sensory hardness of pistachio nuts which were coated with gelatin and/ or CMC (TCA, TGA and TCGA) were significantly (p
Leila Abolghasemi Fakhri; Babak Ghanbarzadeh; Jalal Dehghan nia; Ali Akbar Entezami
Abstract
The high hydrophilic property of biopolymer based plastics is one of the most important defects of them. Blending biopolymers with compatible synthetic polymers and using nano particles such as nanoclay as nanofiller are improving methods that have been extensively considered in recent years. Carboxymethyl ...
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The high hydrophilic property of biopolymer based plastics is one of the most important defects of them. Blending biopolymers with compatible synthetic polymers and using nano particles such as nanoclay as nanofiller are improving methods that have been extensively considered in recent years. Carboxymethyl cellulose (CMC) is one of the lowest cost biopolymers that have enormous applications in different industries and polyvinyl alcohol (PVA) is a synthetic polymer which has a high compatibility with biopolymers. In this research, CMC-PVA nanocomposites containing 3-10% Montmorillonite (W/W CMC) were prepared by casting method. The X-ray diffraction (XRD) results indicated the formation of an exfoliated nanostructure in all MMT content samples. Nanocomposites containing 10% MMT exhibited 29.06% reduction in water vapor permeability (WVP) compared to the blend film without nanoclay. Samples with 10% MMT, showed the lowest surface hydrophilisity (contact angle = 65.1o). The differential scanning calorimetry (DSC) results indicate that by increasing of MMT contents, the glass transition disappeared gradually and no glass transition was observed in the thermograms of the films containing 5, 7 and 10% MMT.
Azam Seraji; Babak Ghanbarzadeh; Mahood Sowti Khiabani; Sara Movahhed
Abstract
In this study, the effect of edible coating and osmotic dehydration, as pre-treatments before drying of cucurbit, were investigated. Cucurbit samples were cut spirally and coated by carboxy methyl cellulose (CMC) 1% and ascorbic acid 0.1% solutions and then processed by osmotic dehydration. Proportion ...
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In this study, the effect of edible coating and osmotic dehydration, as pre-treatments before drying of cucurbit, were investigated. Cucurbit samples were cut spirally and coated by carboxy methyl cellulose (CMC) 1% and ascorbic acid 0.1% solutions and then processed by osmotic dehydration. Proportion of sample to solution was 1:10 and the solution containing sucrose %45, salt%25 and citric acid %1 (W/W) was selected as the best osmotic solution. Finally, the cucurbit samples were dried by oven (at 80 ˚C for 3 hours). The effects of CMC based coating on water loss (WL), solid gain (SG), immersion time, amount of salt, sucrose, citric acid absorption and color and sensory acceptability of samples were evaluated. The results showed that CMC based coating decreased SG without decreasing effect on WL which in turn decreased drying time of osmotic dehydrated samples in oven. Furthermore, the coated, osmotic dehydrated samples showed higher color quality and sensory acceptability in comparison to the control samples.
Shahram Mohammadi; Babak Ghanbarzadeh; Mahood Sowti Khiabani; Shiva Ghiyasifar; Seyed Hossein Jalali
Abstract
During storage of eggs, unfavorable changes occur due to exertion of CO2 and water vapor from through of crust pinholes. One of the practical methods for preventing or reducing these changes is to use biopolymer-based coatings. In this research, five coating solutions based on carboxymethyl cellulose ...
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During storage of eggs, unfavorable changes occur due to exertion of CO2 and water vapor from through of crust pinholes. One of the practical methods for preventing or reducing these changes is to use biopolymer-based coatings. In this research, five coating solutions based on carboxymethyl cellulose (CMC) and glycerol as plasticizer, oleic acid (1 and 2% V/V) and antimicrobial agents (potassium sorbate, natamycin and butylated hydroxyanisole) were prepared and their effects on physicochemical properties of the eggs (weight loss, pH, Haugh unit (HU) and yolk index (YI)) were evaluated at room temperature (25 ) during 5 weeks storage. The results showed that CMC- based coatings have considerable effects on quality of eggs and shelf life of them increased 1-3 weeks (depending on coating type). As well as, adding oleic acid to the CMC- based coating had positive significant effects (P < 0.05) on quality parameters of eggs during 5 week storage. Adding antimicrobial compounds also caused significant difference in all parameters, except yolk index, in comparison to CMC coating without antimicrobial compounds.
