Inherent antibacterial/antifungal properties and film-forming ability of chitosan make it ideal for use as a biodegradable antimicrobial packaging material. This study was attempted to develop antimicrobial films from crawfish chitosan. Traditional chitosan production involves: deproteinization (DP), demineralization (DM), decolorization (DC), and deacetylation (DA). Modification of chitosan production affects film properties. Effects of chitosan production protocols, film-casting solvents, and plasticizer contents on physicochemical, mechanical and antibacterial properties were investigated. Four chitosans were prepared from traditional (DPMCA) and modified processes [excluding either DP, DC or both DP and DC]. Chitosan (1%w/v) was dissolved in 1% acetic, ascorbic, citric, formic, lactic and/or malic acid, and cast with and without glycerol (a plasticizer) at a ratio of 1:0.1, 1:0.2, 1:0.3, 1:0.4 and 1:0.5 (chitosan:glycerol, w/w) to form films.
Flexible and transparent films could be prepared from chitosans with acetic, formic or citric acid without a plasticizer. DMCA acetate films showed higher tensile strength (135.8 MPa), but poor antibacterial properties. DPMCA formate films with tensile strength of 76.8 MPa reduced microbial loads of Staphylococcus aureus, Salmonella typhimurium, and Shigella sonnei by more than 2.5 log CFU/mL in 24 hours. DMA citrate films showed tensile strength of 29.3 MPa and reduced Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium, and Shigella sonnei by more than 4.4 log CFU/mL in 24 hours. This study demonstrated the feasibility of developing antimicrobial edible films from crawfish chitosans. Some critical factors required for desirable film properties were identified.