Shelf Life Extension of Shrimp (White) Using Modified Atmosphere Packaging

Wild caught shrimp can have a shortened shelf life compared to farm raised shrimp due to handling and on-ship limitations. The loss of freshness in shrimp is partly due to autolytic reactions caused by endogenous enzymes such as polyphenol oxidase. The objective of this study was to determine the effect of sulfites combined with modified atmosphere packaging (MAP) on the shelf life of non-frozen shrimp. Fresh South Atlantic white shrimp were subjected to one of four treatments, no bisulfite rinse-air packaged, 1.25% bisulfite rinse-air packaged, 1.25% bisulfite rinse-MAP (60% CO2, 18% O-2 22% N-2) and 1.25% bisulfite rinse-MAP (36% CO2, 64%N-2). The quality and freshness of shrimp was measured by determining total aerobic bacterial populations, package gas headspace analysis, shrimp volatiles (GC-MS), meat pH, nucleotide degradation, and visual analysis. Fresh non-frozen shrimp treated with a combination of sulfites and MAP maintained the shelf life of fresh shrimp up to 10 days while shrimp in non-MAP without sulfite and non-MAP with sulfite developed black spots within 2 and 6 days, respectively. Both MAP treatments slowed bacterial growth while the MAP with high CO2 and with O-2 was more effective in preventing off odors and nucleotide degeneration.