ANTIBACTERIAL EFFECTS OF N-SULFONATED AND N-SULFOBENZOYL CHITOSAN ANDAPPLICATION TO OYSTER PRESERVATION

The antibacterial effects of sulfonated and sulfobenzoyl chitosans wer e evaluated and compared with that of 69% deacetylated chitosan (DD69 chitosan). Minimal inhibitory concentrations of sulfonated chitosan (S C1, 0.63% sulfur content) against Shigella dysenteriae, Aeromonas hydr ophila, Salmonella typhimurium, and Bacillus cereus were found to be l ower than those of DD69 chitosan. A high sulfur content in sulfonated chitosan adversely influenced its antibacterial effect. Sulfobenzoyl c hitosan (SBC) has excellent water solubility and an antibacterial effe ct comparable to that of SC1. SEC at 1,000 and 2,000 ppm extended the shelf life of oysters at 5 degrees C by 4 days at the former or by 7 d ays at least at the latter concentration. The growth of coliforms and Pseudomonas, Aeromonas, and Vibrio species on oysters was retarded by the addition of DD69 chitosan or SBC.