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Patricia Hamaguchi

Nikkei Brazilian
Tokyo University of Marine Science and Technology Graduate

Research Theme:
Physical and Chemical Properties of Edible Protein Films

Containingε-Polylysine Made From Blue Marlin (Makaira mazara)

(ε-ポリリジンを添加した可食性タンパク質フィルムの物理化学的性質)

Objective】The increase in food-born microbial outbreaks has intensified the researches on antimicrobial packaging technology. The antimicrobial packaging is prepared by adding antimicrobials to food packaging.

ε-Polylysine is a homo-poly-amino acid produced by Streptomyces albulus . This natural compound is reportedly stable at high temperature and under acidic or alkaline conditions and has a wide antimicrobial spectrum, including Gram-positive and Gram-negative bacteria. In this research, the effect of

ε-polylysine added to blue marlin protein films on their physical and chemical properties was investigated.

Methods】Fish protein films were prepared from the flesh of blue marlin (Makaira mazara). Film-forming solutions (FFS) containing 2% protein and 0.5% glycerol were prepared. ε-Polylysine was added to FFS at 2.5, 5, 7.5, or 10% (w/w) of protein prior to pH adjustment to alkali using 1 M NaOH (pH 11) or to acidic using 1M HCl (pH 3). Then, FFS were cast on rimmed silicone plates and dried at 25℃for 24 h. The following properties were determined; tensile strength (TS), elongation at break (EAB), water vapor permeability (WVP), color, and SDS-PAGE. Also the release of ε-polylysine from films in distilled water at 30℃ was determined.

Results】In general, the addition of ε-polylysine did not affect TS, EAB, WVP, and color properties. The release of ε-polylysine from films showed that it increased with increasing concentration of ε-polylysine in films. It was also estimated that a fixed amount (about 20 μg) of ε-polylysine was reacted per mg of protein. SDS-PAGE showed no difference between control films and films containing ε-polylysine, suggesting that the amount of ε-polylysine added to films is not enough to induce the polymerization of proteins. The next step of this study is to determine the antimicrobial properties of films.

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