Inosine Monophosphate (IMP) Concentration in Shrimp Flesh Cannot Be Used as an Index of "Freshness" When Comparing Shrimp That Have Been Harvested in Different Ways

Abstract

The concentration of inosine monophosphate (IMP) and other ATP-related compounds, as well as lactic acid, was measured in the abdominal muscle of several species of penaeid shrimp (Metapenaeus endeavouri, Penaeus esculentus, Penaeus monodon) harvested using different methods. The effect of harvesting on the accumulation of IMP in shrimp was studied in order to define how this influences the possible role of this compound as a general measure of "freshness" or biochemical deterioration in shrimp stored after harvest. About half of the adenosine monophosphate (AMP) was deaminated to IMP in trawled shrimp, though in one trial, the "missing" AMP was already present as hypoxanthine in living shrimp taken from the catch. The level of IMP in dead trawled shrimp was about 4.4 μmol/g, even though more than twice this amount of adenylates was estimated to be present in the live shrimp before trawling. In comparison, farmed shrimp had negligible levels of IMP and high levels of ATP in their tissues when harvested. IMP concentration in shrimp flesh cannot be used as an index of "freshness" when comparing shrimp that have been harvested in different ways.