Stability of Adenosine Deaminase and Adenosine Monophosphate Deaminase During Ice Storage of Pink and Brown Shrimp From the Gulf of Mexico

The stability of adenosine deaminase and AMP deaminase from pink and brown shrimp muscle extracts was assayed during postmortem ice storage. AMP deaminase activity was lost rapidly during the early stage of ice storage, and no activity could be detected after 10 days for pink and 16 days for brown shrimp. Even though there was a gradual loss in activity, adenosine deaminase could be detected in both species through the entire storage period of 21 days. The stability of these two enzymes was also correlated with the traditional spoilage indicators: total volatile nitrogen (TVN), total plate count (TPC) and organoleptic evaluations. During the lag‐phase of bacterial growth, AMP deaminase lost 50% of its original activity while adenosine deaminase remained active. During the log phase, bacterial counts and TVN values gradually increased to 10 3 /g and 30 mg TVN‐N/100g, respectively, while AMP deaminase lost its activity. Finally, during the stationary phase, adenosine deaminase (with low activity) was the only ammonia producing tissue enzyme that could be detected. The activity of adenosine deaminase and AMP deaminase could potentially be used as quality indices for fresh shrimp held on ice.