CHEMICAL CHARACTERISTICS, BACTERIAL COUNTS, AND POTENTIAL SHELF-LIFE OF SHRIMP FROM VARIOUS LOCATIONS ON THE NORTHWESTERN GULF OF MEXICO1

Abstract

Freshly harvested white shrimp (Penaeus setiferus) were taken from 13 locations on the northwestern coastline of the Gulf of Mexico. Freshly harvested brown shrimp (Penaeus aztecus) were taken from 3 different water depths near Port Aransas, Tex. Brown shrimp taken from commercial fishing boats at time of landing also were examined. Samples were analyzed for amino nitrogen (AA-N), NH3, total volatile nitrogen (TVN), trimethylamine nitrogen (TMN), bacterial content, and pH. A portion of each sample was placed on sterile ice and allowed to spoil. Spoilage odors appeared in white sea-shrimp after storage for 11–50 days, for brown sea-shrimp in 20–30 days, and in brown boat-shrimp after 0–15 days. Both TVN and AA-N varied considerably from sample to sample and did not show a consistent pattern of change during iced storage. TVN/AA-N ratios increased as samples spoiled. TVN/AA-N ratios greater than 1.3 mg N/mm indicated a short shelf-life of boat shrimp. TMN production was evident in boat-shrimp samples (4 out of 9 samples) with high TVN levels. Bacterial counts of fresh shrimp did not exceed 104/g. Nine of the 10 boat-shrimp samples had counts in excess of 106/g. Counts of samples spoiled on sterile ice ranged from 2 × 106 to 1010/g. The estimated reduction of the maximum potential shelf-life of boat-shrimp by handling and storage was 0–15 days.