Changes in Biochemical Compositions and Quality of White Shrimp (Litopenaeus vannamei) During Storage

To understand biochemical characteristics, storage stability, and freshness indicators of white shrimp (Litopenaeus vannamei), changes in extractable nitrogenous compounds, microbial count, and sensory rating of white shrimp during storage at 25 and 4 degrees C were investigated. Free amino acids showed a slow increase during storage at 25 degrees C, but no obvious change was found at 4 degrees C. Adenosine triphosphate (ATP) and adenosine diphosphate (ADP) were found at initial stage and decreased rapidly after storage. Both inosine 5-monophosphate (IMP) and adenosine monophosphate (AMP) increased and then decreased during storage. Inosine, hypoxanthine, and the K-value gradually increased with time. The levels of total volatile basic nitrogen (TVB-N), NH3, and trimethylamine (TMA) of white shrimp increased with storage time at 25 and 4 degrees C. The TVB-N, NH3, TMA, inosine, hypoxanthine, and K-value could be considered as freshness indicators of white shrimp during storage. However, the total plate count did not corroborate the acceptability recommended limits for white shrimp during storage. The sensory evaluation, associated with TVB-N, TMA, and K-value, showed the quality was unacceptable after 6 h storage at 25 degrees C and 7 days at 4 degrees C.