| The US Food and Drug Administration (FDA) has traditionally used a three-class system based on sensory analysis to evaluate decomposition in shrimp. Additionally, decomposition in shrimp has been chemically confirmed by the presence of indole concentrations of 25μg/100g or greater. However, the FDA revoked Compliance Policy Guide 7108.11, which supported indole at 25μg/100g as confirmatory for decomposed shrimp, because it was subject to misinterpretation and did not reflect agency policy. Further research was necessary to resolve questions concerning the utility of indole and alternative chemical indicators for shrimp decomposition. Possible alternatives include putrescine and cadaverine, which have been shown to increase as spoilage progresses.; The proposed hypothesis was that putrescine and/or cadaverine may be better chemical indicators of decomposition than indole for decomposed shrimp. The experimental approach was to evaluate putrescine, cadaverine, and indole as chemical indicators of decomposition, to determine the levels at which these indicators confirm sensory decomposition, and to identify microorganisms associated with the production of these metabolites in decomposing Penaeid shrimp.; Wild-caught domestic white shrimp (Litopenaeus setiferus), pink shrimp (L. brasiliensis), and Nicaraguan aquacultured white shrimp (L. vannamei) were decomposed at 0, 12, 24, and 36°C. Aerobic plate counts with microbial type characterizations were determined for shrimp at selected decomposition times. Sensory, putrescine, cadaverine, and indole analyses were conducted for each decomposition time. Additionally, commercial shrimp samples collected for sensory evaluation by the FDA were tested for putrescine, cadaverine, and indole.; Decomposition progressed more rapidly at higher temperatures. Bacteria capable of producing putrescine, cadaverine, and indole increased as decomposition temperatures increased and putrescine, cadaverine, and indole levels generally increased with time and temperature.; Overall, this study demonstrated that putrescine concentration at the 3-ppm level was the most effective chemical indicator for decomposition in shrimp decomposed at 0, 12, 24, and 36°C and in field verification studies with FDA samples. It consistently confirmed sensory decomposition more accurately than cadaverine concentration at 3 ppm, indole concentration at 3 μg/100g, and indole concentration at 25 μg/100g. Thus, it is recommended that putrescine concentration at the 3-ppm level be incorporated in industry and regulatory analyses to confirm (pass vs. fail) sensory decomposition in Penaeid shrimp. |
