Mechanisms of ammonia-like off-flavors formation in dried shrimp: Contribution of spoilage microbiota and their metabolism

Dried shrimp is susceptible to ammonia-like off-flavors (ALOF) during storage, yet the formation mechanisms are still not fully clear. This study analysed the contribution of different parts of dried shrimp to ALOF and characterised the formation mechanisms mainly from microbiological spoilage and amino acid metabolism points. Results showed that head viscera were the main contributors to ALOF, and visceral bacteria were the primary source of microorganisms in stored dried shrimp. The sensory scores of groups without head viscera kept at 0–1 during the storage, indicating no smellable ammonia odour. Analysis of off-flavor indicators showed that visceral bacteria promoted protein degradation and amino acid metabolism. Both amino acid deamination and decarboxylation activities of spoilage microbiota contributed to ALOF formation; however, deamination activities of visceral microbiota were more prominent, particularly for bitter amino acids metabolism. These results provide guidelines for controlling ALOF generation in dried shrimp products during storage. [Display omitted] •Bacteria in head viscera contribute the most to ALOF.•Deamination plays more dominant role than decarboxylation in amino acid utilization.•Bitter-taste amino acids were easily deaminated by spoilage microbiota.