Study on changes in the quality of grass carp in the process of postmortem

Abstract

Grass carp is an important freshwater fish but little is known about its quality postmortem. We tracked changes in the pH, texture, lactic acid, ATP-related compounds, K value, free amino acids (FAA) contents in grass carp stored at 4°C for 192 hr. Sensory and electronic tongue assessment were also performed. The results showed a consistent trend in the hardness and chewiness. pH were closely correlated with the lactic acid content and hardness. The fresh sweet amino acids gradually decreased with time while the opposite occurred with the bitter amino acids. The content of Hx and HxR increased gradually. The K value remained increased throughout the storage. Sensory assessment followed the opposite trend. The electronic tongue indicated that the differences were distributed in various areas between the first 2 days and the last 6 days. Overall, we recommend that grass carp should be consumed within 6 days when stored at 4°C. Practical applications In fish, the process of quality change after death can normally be divided into four stages: the early biochemical change, rigidity and dissolving, self-dissolution and finally, corruption. Rigidity can delay the process of corruption somewhat as fish in the rigid period are almost as fresh as newly caught fish. Preservation may thus be described as an extension of the period of rigor mortis. Postmortem changes in grass carp meat were studied over a period of 192 hr by measuring its pH, texture properties, lactic acid, ATP-related compounds, K values, and FAA content. Sensory assessment and electronic tongue measurements were also conducted. In addition to establishing a theoretical basis for the quality control and processing of grass carp, these results provide useful information for manufacturers and product developers seeking to improve the quality of their grass carp products and will also provide farmers with valuable insights into quality retention.