Comparative changes in peeled white shrimp (Metapenaeus affinis) during ice and refrigerator storage

To improve shrimp quality, it is of importance to evaluate shrimp spoilage characteristics. Therefore, physicochemical, microbiological and sensory changes of white shrimp (Metapenaeus affinis) during storage at ice (0ºC) and refrigerator (4±1ºC) were assessed. Mesophilic, psychrophilic, Entrobacteriaceae, Staphylococcus sp., H2S producing bacteria (white colony) and H2S producing bacteria (black colony) counts of stored in ice at day 16 were 7.50, 7.83, 7.13, 6.42, 7.06 and 6.45 log10 CFU/g, respectively. Mesophilic, psychrophilic, Entrobacteriaceae, Staphylococcus sp., H2S producing bacteria (white colony) and H2S producing bacteria (black colony) counts of stored at refrigerator at day 16 were 8.76, 9.80, 8.13, 6.95, 8.28 and 7.20 log10 CFU/g, respectively. Mesophilic, psychrophilic, Entrobacteriaceae, Staphylococcus and H2S producing counts were higher in white shrimp stored at refrigerator compared to white shrimp that stored at ice. Thiobarbituric acid, free fatty acid, total volatile bases nitrogen and pH indexes were higher in white shrimp stored at refrigerator compared to white shrimp stored at ice (p<0.05). The lowered rate of increase in pH, total volatile basis nitrogen (TVBN) were obtained in shrimp stored at ice. H2S-producing bacteria were the dominant group of microorganisms at refrigerator whereas Enterobacteriaceae were dominant at ice. Total volatile basic nitrogen correlated well (r= 0.859) with the sensory scores in shrimps stored at ice and correlated well (r= 0.987) with the sensory scores in shrimps stored at refrigerator. Correlation coefficient of bacteria count and sensory evaluation in shrimp stored at ice and refrigerator was above 0.824. The results showed that using of ice could improve the microbiological count and delay the spoilage and extend the shelf life of white shrimp (M. affinis).

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