Chitosan is derived by deacetylation of chitin, a major component of the shells of crustacea such as crabs and shrimps. In this experiment using the Ames test, there was antimutagenic effect by the water-soluble chito...Chitosan is derived by deacetylation of chitin, a major component of the shells of crustacea such as crabs and shrimps. In this experiment using the Ames test, there was antimutagenic effect by the water-soluble chitosan that dissolved in hard water （CHW）. The Ames test was performed using Salmonella typhimurium TA98 and TA100. For the antimutagenic test, and the desmutagenic and bioantimutagenic tests, Trp-P-2, 2AA and AF-2 were used as mutagens. Tests for spontaneous mutation rate without mutagens were performed using S. typhimurium TA98 and TA100. When several concentrations of CHW were directly added to Minimal Glucose Plates, there were no changes in the number of His＋ revertants of TA98 and TA100. In desmutagenic and bioantimutagenic tests, the number of His^＋ revertants of TA98 and TA100 decreased. In the test for spontaneous mutation rate, the number of His＋ revertants of TA98 and TA 100 decreased slightly. When a concentration of CHW was added to examine antimutagenic effects, there was no change in the viable cell count of TA98 and TA100. From these results, AF-2 that is a direct mutagen may combine with CHW, and that may also be carrying out the inactivation. CHW possibly acts directly on the DNA by decreasing the rate at which mutation is caused to the strain＇s promutagens, Trp-P-2 and 2AA. This is evident from the decreased spontaneous mutation rate without a decreased viable cell count.展开更多
In recent years, research on biopolymer based-coating containing natural antimicrobial agents is developing significantly. The objective of this study was to evaluate the antimicrobial efficiency of six formulations c...In recent years, research on biopolymer based-coating containing natural antimicrobial agents is developing significantly. The objective of this study was to evaluate the antimicrobial efficiency of six formulations containing pre-selected natural antimicrobial compounds against Listeria monocytogenes, Escherichia coli O 157：H7, Salmonella typhimurium, the total bacteria and total yeasts and molds in cauliflower. Each formulation was subjected to a sensory test in parallel to microbiological analysis and the efficiency during storage at 5 ℃ was evaluated for the two best formulations, based on their ability to eliminate the target microorganisms. Both formulations were able to reduce all pathogens and total flora below detectable levels after 24 h of storage at 5 ℃. Using washing or spraying treatments, the two formulations were able to reduce Listeria to undetectable levels for 3 d. This efficiency was extended to 7 d when the formulations were incorporated into an edible coating. Washing treatment with the two formulations was also able to limit the growth of yeast and molds at levels lower than 2 log, for more than 7 d. The population of E. coli was reduced to below the detection limit during 14 d of storage, after washing treatment with the two formulations. The spraying treatment of cauliflower with the formulations allowed the use of very small amounts of antimicrobials while maintaining a fairly good efficiency, greatly reducing the potential costs of implementing this method in the industry. Future research may focus on development of nanoemulsion of antimicrobial formulations based on the developed antimicrobial formulations in this study to improve the better coating efficiency.展开更多
文摘Chitosan is derived by deacetylation of chitin, a major component of the shells of crustacea such as crabs and shrimps. In this experiment using the Ames test, there was antimutagenic effect by the water-soluble chitosan that dissolved in hard water （CHW）. The Ames test was performed using Salmonella typhimurium TA98 and TA100. For the antimutagenic test, and the desmutagenic and bioantimutagenic tests, Trp-P-2, 2AA and AF-2 were used as mutagens. Tests for spontaneous mutation rate without mutagens were performed using S. typhimurium TA98 and TA100. When several concentrations of CHW were directly added to Minimal Glucose Plates, there were no changes in the number of His＋ revertants of TA98 and TA100. In desmutagenic and bioantimutagenic tests, the number of His^＋ revertants of TA98 and TA100 decreased. In the test for spontaneous mutation rate, the number of His＋ revertants of TA98 and TA 100 decreased slightly. When a concentration of CHW was added to examine antimutagenic effects, there was no change in the viable cell count of TA98 and TA100. From these results, AF-2 that is a direct mutagen may combine with CHW, and that may also be carrying out the inactivation. CHW possibly acts directly on the DNA by decreasing the rate at which mutation is caused to the strain＇s promutagens, Trp-P-2 and 2AA. This is evident from the decreased spontaneous mutation rate without a decreased viable cell count.
文摘In recent years, research on biopolymer based-coating containing natural antimicrobial agents is developing significantly. The objective of this study was to evaluate the antimicrobial efficiency of six formulations containing pre-selected natural antimicrobial compounds against Listeria monocytogenes, Escherichia coli O 157：H7, Salmonella typhimurium, the total bacteria and total yeasts and molds in cauliflower. Each formulation was subjected to a sensory test in parallel to microbiological analysis and the efficiency during storage at 5 ℃ was evaluated for the two best formulations, based on their ability to eliminate the target microorganisms. Both formulations were able to reduce all pathogens and total flora below detectable levels after 24 h of storage at 5 ℃. Using washing or spraying treatments, the two formulations were able to reduce Listeria to undetectable levels for 3 d. This efficiency was extended to 7 d when the formulations were incorporated into an edible coating. Washing treatment with the two formulations was also able to limit the growth of yeast and molds at levels lower than 2 log, for more than 7 d. The population of E. coli was reduced to below the detection limit during 14 d of storage, after washing treatment with the two formulations. The spraying treatment of cauliflower with the formulations allowed the use of very small amounts of antimicrobials while maintaining a fairly good efficiency, greatly reducing the potential costs of implementing this method in the industry. Future research may focus on development of nanoemulsion of antimicrobial formulations based on the developed antimicrobial formulations in this study to improve the better coating efficiency.
