| Summary: | 碩士 === 國立嘉義大學 === 食品科學系研究所 === 95 === Abstract
Lipid oxidation and microbial growth are the most important food deteriorations among all possible physical, chemical or microbiological causes during processing and distribution. Zein, an excellent material of edible films and coatings, is the principle storage protein of corn and it is an alcohol-soluble prolamine protein composed of a large amount of hydrophobic amino acids. The aims of this study were to investigate the potential use of Zein film as carrier of food antioxidants and preservatives, and to study the feasibility of applying food additive-containing Zein coatings to preserve fish balls during cold storage (4℃).
In the first part of this study, different antioxidant (BHA, BHT, propyl gallate) was incorporated with Zein films individually and the resulting films were characterized with Fourier-transform infrared (FT-IR) spectrometry. Furthermore, fish balls were coated with Zein solutions and then thiobarbituric acid reactive substances (TBARS), peroxide value, weight loss and pH during storage at 4℃ for 15 days were determined. The FT-IR spectra of the resulting films were used to confirm the incorporation. The recoveries of BHA, BHT and PG from Zein films were 81.26%, 23.80% and 95.72% of the initial amount of additive used in the formulation, respectively. Under chill condition, coated with PG-Zein mixture exhibited the best effect on reducing TBARS and peroxide values, and compared to uncoated and coated Zein film reducing 21.09% and 15.02% TBARS value and 28.43% and 23.12% POV, respectively. Moreover, coated with PG-Zein mixture could effectively retard weight loss and pH value decrements.
In the second part of this project, the antimicrobial activity of nisin and/or chelating agent EDTA incorporated Zein films was analyzed by inhibition zone formation. Fish balls were coated with the Zein mixtures, and quality attributes such as the total viable count, volatile basic nitrogen and weight loss were determined during storage at 4℃ for 15 days. The FT-IR spectra of the resulting films confirmed that nisin and disodium EDTA had successfully incorporated with Zein films. Staphylococcus aureus and Bacillus subtilis were inhibited by Zein films containing nisin. The nisin and disodium EDTA incorporated into Zein films showed antimicrobial activity on different bacteria including Escherichia coli, Enterobacter aerogenes and Citrobacter freundii. During refrigeration, fish balls coated with Nisin+EDTA-Zein mixture showed better effects on diminishing total viable count and volatile basic nitrogen content, and achieved the goal of safety assurance, quality maintenance and shelf-life extension. In conclusion, the results indicated that coating Nisin+EDTA -Zein coatings could be used to preserve the food quality.
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