Stability and antibacterial activity of chitosan solutions affected by storage temperature and time

摘要

Stability of chitosan (M_w of 2025 and 1110 kDa)solutions and their antibacterial activity against gram-positive (Listeria monocytogenes and Staphylococcus aureus)and gram-negative {Salmonella enteritidis and Escherichia coli)bacteria were investigated at 4 and 25 deg C after 15-week storage.Viscosity of chitosan solutions (1% (w/v)in 1% (v/v)acetic and/or lactic acid)decreased with increased storage time and temperature.After 15-week storage,the decrease in viscosity ranged from 44 to 48% and 81 to 90% of the initial viscosity value,respectively,at 4 and 25 deg C.Antibacterial activity of chitosan solutions (1% (w/v)in 1% (v/v)acetic acid)before and after 15-week storage differed depending on the molecular weight of chitosans,the storage temperature,and the bacteria.In general,chitosan solutions before storage showed higher antibacterial activity than those after 15-week storage.Chitosan solutions stored at 25 deg C possessed similar or weaker antibacterial activity compared with those at 4 deg C.