Quality determination of commercially frozen prawns using nucleotide-based products, sensory assessment and texture measurements

Abstract

The nucleotide degradation profile of two species of farmed shrimps, kept in ice and frozen storage showed high AMP and IMP accumulation for a prolonged period. Quality of frozen shrimp during storage was evaluated by measuring the levels of AMP, IMP, inosine, hypoxanthine and K­ value. Sensory assessment and instrumental texture measurements were also employed to assess the quality of prawns. Prawns in their prime quality had AMP and IMP levels >3micromol/g each K-value below 25% indicated prime quality. The overall acceptability score was closely related to IMP level or the sum of (AMP+IMP), Hx and also K-value. For acceptablequality prawns, K-value should be in the range of 40-46% and the sum of (AMP+IMP) values should be >2micromol/g. Based on these findings, a number of commercial frozen prawns from the industry were evaluated for their quality. These samples were grouped into grade I, II and III based on organoleptic assessment, K-value and levels of nucleotide components. Thus, 30% of the frozen shrimp (HL, PD or PUD) from the industry was rated as grade I (K-value=25%), 50% as grade II (K-value-36.5 to 43.6%) and 20% as grade III (K-value 60%). Instrumental texture measurements were compared with organoleptic rating.