Microbiological and chemical changes of shrimp Acetes vulgaris during Kapi production.

Microbiological and chemical changes in shrimp Acetes vulgaris during production of Kapi (salted shrimp paste of Thailand) including salting, drying and fermentation were monitored. Moisture content of samples decreased rapidly after salting and drying steps. The lower water activity was found in the final product (0.694). The pH decreased within the first 10 days of fermentation and continuously increased as fermentation progressed. Protein underwent degradation throughout Kapi production as indicated by increasing TCA-soluble peptides and degree of hydrolysis. The increases in peroxide value as well as thiobarbituric acid reactive substances value revealed that lipid oxidation occurred throughout all processes. Total viable count, halophilic, proteolytic and lipolytic bacteria counts increased continuously during Kapi production, while lactic acid bacteria count slightly decreased at the final stage of fermentation. Thus, proteolysis and lipolysis took place throughout Kapi production, and contributed to the characteristics of finished product. These changes were governed by both endogenous and microbial enzymes.