| Food antimicrobial packaging can inhibit the microbial populations of the food surface, extend shelf-life and maintain the quality of the food. China is the largest aquatic products producer and the largest aquatic products consumer in the world, however, the aquatic products are easy perishable, the bio-antimicrobial packaging systems and their application on the aquatic products to maintain their quality were researched in this dissertation. The key results are followed:(1) By comparing the antimicrobial activity of 13 essential oils on eight food spoilage and pathogentic bacterial species, cinnamon oil was the strongest antimicrobial agents in them, the MICs of it against Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium were 0.2,0.1,0.1,0.4 and 0.4μL/mL. EDTA was added into nisin to increase its antimicrobial activity, and when its content was 150 ug/mL, nisin could most encomically inhibit the bacteria.(2) The synergy effects of cinnamon were evaluated by the agar dilution checkerboard method when it was combined with thyme, clove or nisin against the food related bacteria. This study indicated that the combination of cinnamon oil with other essential oils and nisin had synergistic effects or additive effects. The effects of food ingredients and pH on the antimicrobial efficacy of cinnamon were performed using a range of model media and E. coli as the indicator strain. The results indicated that:The antimicrobial activity of cinnamon oil increased when it was at pH 4-5 food models; The anitimicrobial activity of cinnamon oil was not affected by food starch; When the content of food protein was lower than 2.5%, the antimicrobial activity of cinnamon oil was not affected by food protein, but when the content was higher than 2.5%, the activity of cinnamon oil decreased; With the increase of food fat, the antimicrobial activity of cinnamon oil decreased significantly.(3) The different factors on the antimicrobial activity of film, film thickness, film transparency, film color and film water vapor permeability (WVP) of cinnamon/alginate film were tested. The results showed that:The film thickness was affected significantly by alginate concentration, pH of film formation solution and volume of film formation solution; Cinnamon content, alginate concentration and volume of film formation solution affected significantly the film transparency, furthermore, they also affected the color of the films to some extent; And the WVP and the antimicrobial activity of the films were significantly affected by the cinnamon content and the temperature of film formation.(4) The release of cinnamaldehyde (the main composition of cinnamon) from cinnamon/alginate film to water was accorded with the first order model. The apparent diffusion coefficients of cinnamaldehyde and the concentrations of cinnamaldehyde in water when the films were put into water were calculated.(5) The antimicrobial coatings of calcium-alginate containing nisin and EDTA were applied to maintain the quality of northern snakehead. The results showed that calcium-alginate coating containing 1000 IU/mL nisin and 150μg/mL EDTA could inhibit the microbial growth, maintain lower TVB-N content, and extend the shelf-life of northern snakehead.(6) The antimicrobial coatings and films containing cinnamon, nisin, or cinnamon and nisin were used to keep the quality of northern snakehead. The results showed that: The coatings and films containing antimicrobial agents could maintain the quality of northern snakehead, but the coatings, especially the coatings containing cinnamon had a better effect than the films containing cinnamon on inhibiting the microbial growth, decreasing the TVB-N and restraining the lipid oxidation of northern snakehead. However, the coating treatments containing cinnamon could change the fish fillets color into more yellow than the film treatments containing cinnamon. |
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