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 ...
Read More
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.
