Changes in microbial flora of Pacific oysters (Crassostrea gigas) during refrigerated storage and its shelf-life extension by chitosan.
Changes in microbial flora of Pacific oysters (Crassostrea gigas) during storage at 5+/-1 degrees C were analyzed and the antimicrobial activity of chitosan was studied to identify its potential in shelf-life extension. The dominant microorganisms were found to be Pseudomonas (22%) and Vibrionaceae (20%) in raw oysters. During storage, proportion of Pseudomonas increased significantly and reached 73% at the end of storage, while Vibrionaceae preserved a level of approximate 20%. Wide-spectrum antibacterial property of chitosan against the bacteria isolated from oysters was discovered, and chitosan concentration of 5.0 g/L was eventually determined for application in oyster preservation. Based on microbiological analysis, biochemical indices determination and sensory evaluation, shelf-life of oysters stored at 5+/-1 degrees C was determined. Data showed that chitosan treatment extended the shelf-life of oysters from 8-9 days to 14-15 days.
Cao
Rong
R
College of Food Science and Engineering, Ocean university of China, Qingdao, Shandong Province 266003, PR China.
Xue
Chang-Hu
CH
Liu
Qi
Q