Effect of citric acid on the quality and shelf-life of dried shrimp

Abstract

Dried shrimp was processed by soaking fresh shrimp in citric acid solution of 0, 0.1, 0.3, 0.5% for 20 minutes, then boiling in 5% brine to select appropriate concentration of citric acid. Shelf-life storage of dried shrimp under vacuum and air packed at 30 ± 2°C and 10 ± 2°C was studied. Chemical (astaxanthin, ammonia, moisture, NaCl, pH), microbiological (TVC, anaerobe, yeast and mould, E. coli, S. aureus, Salmonella, Vibrio), physical (Aw colour using L. a, b system) analysis, and sensory evaluation were conducted. It was found that astaxanthin content and overall acceptability of samples soaked in 0.1; 0.3, 0.5% citric acid solution were not significantly different (P>0.05) but they were significantly better than samples without citric acid dipping. Therefore the lowest concentration of citric acid solution, 0.1% was selected for studying the changes of quality during storage under vacuum and air packed. The results showed that dried shrimp under all conditions of packaging stored at 10 ± 2°C had shelf life longer than 14 weeks, and had better quality than samples stored at 30 ± 2 °C. Samples stored under air packed and vacuum at 30 ± 2 °C had shelf life of 6 and 8 weeks, respectively. Moreover dried shrimp dipped in citric acid solution had better colour, higher astaxanthin content and higher acceptability score as well as lower ammonia content than samples without citric acid dipping (P<0.01) both stored under vacuum and air packed at 30 ± 2°C and 10 ± 2°C.