Combined effect of sepia soaking and temperature on the shelf life of peeled shrimp Penaeus kerathurus

The effects of sepia ink (Sepia officinalis) extract solutions with concentrations of 0.0%, 0.01%, 0.2% and 2% on the microbial flora and the chemical composition of stored peeled shrimp (Penaeus kerathurus) were examined at two temperatures (−2 and 0 ° C). The quantification of aerobic and psychotrophic bacteria was performed by a plate count after each 3 days of storage. Results showed that partial freezing and coating treatments had synergistic effects in reducing the aerobic plate counts (APCs) with at least a 10-day extension of shelf life. The inhibition efficacy on the psychotrophic cells in shrimp meat increased with the increase in concentration of the added extract. However, the extract showed no effect after 16 days on the mesophilic bacteria. No detrimental effects of sepia coating on organoleptic parameters such as appearance, odour, and taste were observed. Partial freezing reduced significantly the formation of nitrogenous compounds in all samples, however total volatile bases (TVB) and trimethylamine (TMA) levels were lower in the sepia extract-treated samples. Initially, shrimp tissue ninhydrin positive substances (NPS) level was 9.74 ± 1.05 mM/100 g tissue. No significant change was observed in the treated-samples during the refrigerated storage, conversely, these concentrations increased in the raw shrimps.