The inhibitory effects of natural bioactives on the growth of E. coli and Salmonella typhi during refrigerated storage

Abstract

본 실험의 목적은 냉장기간 동안에 천연 첨가물을 처리한 육계 표면의 E. coli와 Salmonella typhi 증식 억제 효과를 평가하기 위한 것이다. 항균활성 실험을 위한 천연첨가물로는 키토산, EGCG, 마늘, 그리고 세 가지 천연첨가물을 1:1:1로 섞어서 만든 CEG (키토산 + EGCG + 마늘)를 각각 0.5%, 1%, 2% 농도로 사용하였다. 실험 Ⅰ에서는 0.5%, 1%, 2% 키토산, EGCG, 마늘분말, CEG의 E. coli에 대한 항균활성을 paper disc방법을 사용하여 측정하였고, 10^(6) E. coli를 접종한 육계 표면(20㎠)에 키토산, EGCG, 마늘분말, CEG를 각각 농도 별로 첨가하여 4, 8, 12일의 냉장저장 기간 동안에 E. coli 수와 세대기간을 측정하였다. 0.5, 1, 2% 키토산, EGCG, CEG의 항균활성은 모두 대조구에 비해 농도 별로 증가하였고, 냉장기간 동안 육계 표면의 E. coli 수는 키토산, EGCG, CEG 처리시 대조구에 비해 농도에 의존적으로 유의성 있게 감소하였다. E.coli 세대기간의 결과도 1%, 2% 키토산, EGCG, CEG 처리시 대조구에 비해 유의적으로 증가하였다. 실험 Ⅱ에서는 0.5%, 1%, 2% 키토산, EGCG, 마늘분말, CEG의 Salmonella typhi에 대한 항균활성을 paper disc방법을 사용하여 측정하였고, 10^(6) Salmonella typhi를 접종한 육계 표면(20㎠)에 키토산, EGCG, 마늘분말, CEG를 각각 농도 별로 첨가하여 4, 8, 12일의 냉장저장 기간 동안에 Salmonella typhi 수와 세대기간을 측정하였다. 0.5%, 1%, 2% 키토산, EGCG, 마늘, CEG의 항균활성은 모두 대조구에 비해 농도 별로 증가하였고, 냉장기간 동안 육계 표면의 Salmonella typhi 수는 키토산, EGCG, 마늘, CEG 처리시 대조구에 비해 농도에 의존적으로 유의성 있게 감소하였다. Salmonella typhi 세대기간의 결과도 1%, 2% 키토산, EGCG, 마늘, CEG 처리시 대조구에 비해 유의적으로 증가하였다.;Experiment Ⅰ: The inhibitory effects of natural bioactives on the growth of E. coli on chicken skin during refrigerated storage The purpose of this study was to assess the inhibitory effect of natural bioactives for E. coli (Escherichia coli) growth on the chicken skin during refrigerated storage. Natural bioactives used for antimicrobial activity were as follows; chitosan, epigallocatechin gallate (EGCG), garlic, or CEG (chitosan + EGCG + garlic). Chicken skin (20㎠) was inoculated with 10^(6) E. coli. The inoculated chicken skins were treated with 0.5%, 1%, or 2% natural bioactives during storage time (0, 4, 8, 12 days) at 4℃. The numbers of E. coli, and generation time were measured at each storage time. Both EGCG and chitosan showed significant reduction in the number of E. coli at the concentration of 0.5%, 1%, or 2% (P < 0.05). The generation time of E. coli was significantly increase by 1%, or 2% EGCG or chitosan treatment (P < 0.05). The mixture of three bioactives, chitosan plus EGCG plus garlic showed significant decrease in the number of E. coli (P < 0.05). The generation time of E. coli was significantly increased by CEG treatment at dose-dependent manner. These results suggest that natural bioactives such as chitosan, EGCG, or CEG may be used as antimicrobial agents for the improvement of microbial safety during distribution. Experiment Ⅱ: The inhibitory effects of natural bioactives on the growth of Salmonella typhi on chicken skin during refrigerated storage The purpose of this study was to assess the inhibitory effect of natural bioactives for Salmonella typhi (Salmonella. typhimurium) growth on the chicken skin during refrigerated storage. Natural bioactives used for antimicrobial activity were as follows; chitosan, epigallocatechin gallate (EGCG), garlic, or CEG (chitosan + EGCG + garlic). Chicken skin (20㎠) was inoculated with 10^(6) Salmonella typhi. The inoculated chicken skins were treated with 0.5%, 1%, or 2% natural bioactives during storage time (0, 4, 8, 12 days) at 4℃. The numbers of Salmonella typhi, and generation time were measured at each storage time. Both EGCG and chitosan showed significant reduction in the number of Salmonella typhi at the concentration of 0.5%, 1%, or 2% (P < 0.05). The generation time of Salmonella typhi was significantly increase by 1%, or 2% EGCG or chitosan treatment (P < 0.05). The mixture of three bioactives, chitosan plus EGCG plus garlic showed significant decrease in the number of Salmonella typhi (P < 0.05). The generation time of Salmonella typhi was also increased by CEG treatment. These results suggest that natural bioactives such as chitosan, EGCG, or CEG may be used as antimicrobial agents for the improvement of microbial safety during distribution.