Antimicrobial
Chitosan and its derivatives have good antibacterial activity, can inhibit some fungi, bacteria, and virus growth and reproduction. Now that its possible mechanism are threefold: First, because the poly cationic chitosan, easy-to-fungal cell surface with the role of negatively charged groups, thus changing the bacteria cell membrane fluidity and permeability; Second, interference with DNA replication transcription; Third, blocking pathogen metabolism. In recent years, many researchers have proposed chitosan through the induction of pathogenesis-related protein, the accumulation of secondary metabolites and signal transduction, etc. to achieve the purpose of anti-bacterial point of view.
 
Papineau and so that, due to the positive charge of chitosan and negatively charged bacterial cell membrane interactions, so that intracellular proteases and other components of leak, so as to achieve antibacterial, bactericidal effect. They found that the amount of 0.12mg/ml chitosan lactate propagation of Escherichia coli has a better inhibition of glutamate and chitosan on the proliferation of yeast such as Saccharomyces cerevisiae, also has good inhibitory effect, and, 1mg/mL of chitosan lactate yeast will completely lose their activity in 17min. Sudharshan, etc. that can penetrate as chitosan and bacterial nuclei and DNA binding, inhibition of mRNA synthesis, thus impeding the mRNA and protein synthesis, to antibacterial effect. They studied the water-soluble chitosan such as chitosan lactate, chitosan glutamate and chitosan glutamate hydrogenation of different bacteria in the rearing of the impact. The results showed that chitosan glutamate and chitosan lactate against Gram-positive bacteria and gram-negative bacteria have a high antibacterial activity. Ghaoth other studies have shown, by B. Cinerea or R. Stolonifer corruption caused by strawberries coated with chitosan solution at significantly inhibited after to extend the shelf life of strawberries. Another study reported that chitosan with different molecular weights of the different corrosion effects, of which 200,000 and 1 million of the chitosan is the best. In addition, the current most used spices and preservatives are sodium benzoate, compared with the same storage conditions, the inhibitory effect of chitosan is more, with less good taste, and without any side effects, is an ideal seasoning preservatives. Yang Jisheng, who carried out the preservative effect of chitosan on soy research, the results show that the 0.1% chitosan added to the soy sauce, soy sauce, causing deterioration of the yeast group significantly inhibited in the summer can be stored under open conditions, 30d without deterioration, and does not affect the taste, color, flavor and ingredients.