Influence of Processing on Bacteriological Quality of Frozen Shrimp

Abstract

Line and finished product samples (668) from two shrimp processing plants located at the Karachi fish harbor were collected and examined bacteriologically. Frozen shrimp samples (100) collected from Plant A had the following bacterial profile: average (geometric) total aerobic plate count 9.4 × 106 CFU/g; MPN coliforms 94/g; and MPN fecal coliforms 41/g. The bacterial profile of 114 frozen shrimp samples from Plant B were 8.3 × 106 CFU/g, 180/g and 133/g for total plate count, MPN coliform and MPN fecal coliforms, respectively. Samples (126) of raw and laboratory-processed (simulating commercial processing) shrimp were also examined. Processing conditions of Plant A were better and resulted in a better quality end-product as compared to that of Plant B. Three of 338 samples from Plant B yielded Salmonella. The composition of microbial flora was nearly the same for both species of shrimps from both plants. Pseudomonads were the predominant microflora followed by Micrococcus sp. When shrimp were handled expeditiously under good sanitary conditions in the laboratory, the bacterial counts were significantly lower than on shrimp from the plants. Laboratory-processed shrimp had an average (geometric) total aerobic plate count of 8.1 × 105 CFU/g and average (geometric) coliform and fecal coliform MPNs were <3/g.