Antimicrobial activity of chitosan impregnated into packaging films and chitosan in solution

The antimicrobial effectiveness of chitosan in liquid and in film matrix was examined against three bacteria: Escherichia coli, Listeria monocytogenees , and Salmonella enteritidis. The research also evaluated the feasibility of the usage of chitosan as an antimicrobial additive in food packaging films by applying chitosan impregnated polyethylene films on the fresh red meat surface. Different antimicrobial effectiveness was observed among chitosan added direct to solution, chitosan released from film matrix and chitosan on the meat surface.; Chitosan from shrimp with different molecular weights was dissolved in lactic acid and diluted with 0.1% peptone water to determine the effects of the molecular weight of chitosan on antimicrobial activities. Also, the effects of the concentration of chitosan were evaluated with concentration ranges from 0 to 0.1% in peptone water. The best inactivation was observed with the lowest molecular weight, while the level of concentration of chitosan was not linearly related to the microbial inhibitions.; Chitosan dissolved in lactic acid was blended with LDPE powder with different ratios and impregnated into PE films to examine the effects of concentration of chitosan in PE films. Also, the physical (tensile strength and elongation at break) and barrier (water vapor permeability and oxygen permeability) properties of these films were evaluated. The results showed chitosan could be released from the film matrix and inhibit microbial growth. The antimicrobial activity increased with increasing concentration of chitosan in the film matrix. Chitosan released from film structure inhibited E. coli more rapidly than in solution. The oxygen permeability was not affected by the incorporation of chitosan, while the water vapor permeability was dramatically changed with the addition of chitosan with high concentration (2.14%). The tensile strength was slightly decreased with increasing the chitosan concentration in films. The elongation values were more critically reduced by the addition of chitosan than that of tensile strength.; The chitosan impregnated PE films applied on the meat surface extended the redness (a*) of fresh red meat. However, microorganisms on the meat surface were not inhibited by the chitosan impregnated films in any concentration ratio tested. This inactivity might be caused by the competition of microorganisms and meat components which can react with chitosan.