Enhancement of antimicrobial activity of chitosan by irradiation

• Published in: Journal of the science of food and agriculture Vol. 73; no. 2; pp. 237 - 241
• Main Authors: Matsuhashi, S, Kume, T
• Format: Journal Article
• Language: English
• Published: London John Wiley & Sons, Ltd 01.02.1997; Wiley; Published for the Society of Chemical Industry by Elsevier Applied Science
• Subjects: antibacterial properties; antimicrobial activity; Biological and medical sciences; chitosan; degradation; Escherichia coli; Food additives; Food industries; Fundamental and applied biological sciences. Psychology; gamma radiation; General aspects; irradiation; molecular weight; physico-chemical properties; physicochemical properties; surface charge; Physical dressing; Escherichia coli; Food additive; Biological activity; Antimicrobial agent; Molecular weight; Optimization; Radiation dose; Gamma irradiation; Ionizing radiation; Preservative; Correlation analysis; Microorganism culture; Bacteria; Chitosan; Physicochemical properties; Enterobacteriaceae
• ISSN: 0022-5142; 1097-0010
• DOI: 10.1002/(SICI)1097-0010(199702)73:2<237::AID-JSFA711>3.0.CO;2-4

Antimicrobial activity of irradiated chitosan was studied against Escherichia coli B/r. Irradiation of chitosan at 100 kGy under dry conditions was effective in increasing the activity, and inhibited the growth of E coli completely. The molecular weight of chitosan significantly decreased with the increase in irradiation dose, whereas the relative surface charge of chitosan was decreased only 3% by 100 kGy irradiation. Antimicrobial activity assay of chitosan fractionated according to molecular weight showed that 1 x 10(5)-3 x 10(5) fraction was most effective in suppressing the growth of E coli. This fraction comprised only 8% of the 100 kGy irradiated chitosan. On the other hand, chitosan whose molecular weight was less than 1 x 10(5) had no activity. The results show that low dose irradiation, specifically 100 kGy, of chitosan gives enough degradation to increase its antimicrobial activity as a result of a change in molecular weight.