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.

Research on quality changes of grass carp (Ctenopharyngodon idellus) during short‐term starvation

“…The determination of lactic acid was carried out according to the previously established method with minor modifications (Wang, Shi, et al, ; Wang, Zhu, et al, ). 2.00 g of samples were homogenized separately with 18 ml of cold 0.85% physiological saline for 60 s. The homogenate was centrifuged at 10,000 g for 10 min, and the supernatant was collected for further test.…”

“…Taste‐active substances in fish are water soluble, among which free amino acids, nucleotides, small peptides, and minerals are the main components (Jiang & Su, ). Free amino acids play a very important role in maintaining the protein homeostasis of fish tissue and body, and are also essential for flavor indicators (Wang, Shi, Qiu, & Wang, ; Wang, Zhu, Zhang, Wang, & Shi, ). The components of free amino acids contribute a lot to taste, and they can interact with nucleotides to promote each other (Shirai et al, ).…”

Research on the changes of water‐soluble flavor substances in grass carp during steaming

“…16291.1‐2012 of the People's Republic of China, and sensory experiments were conducted in sensory evaluation laboratory of Shanghai Ocean University (jointly established with Pepsi Food Co., Ltd. (China) in 2001). The evaluation criteria were referred to the methods of Wang, Zhu, et al () and Lin et al (), and slightly modified (Table ). The score range of each index was 1–20 points, in which 20 points was deemed the best and 1 point was the worst, and the total score was 100 points.…”

“…Extraction methods of ATP-related compounds were modified and improved slightly according to the previous methods (Wang, Zhu, Zhang, Wang, & Shi, 2018;Yokoyama, Sakaguchi, Kawai, & Kanamori, 1992). Five grams of each sample were weighed and homogenized by FM-200 homogenizer (Shanghai Fokker Equipment Co. Ltd., Shanghai, China) with 10-ml cold perchloric acid with a volume fraction of 10% for 30 s and then centrifuged at 10,000 g for 15 min below 4°C.…”

“…The 10 sensory evaluators in 2001). The evaluation criteria were referred to the methods of Wang, Zhu, et al (2018) and Lin et al (2013), and slightly modified (Table 1). The score range of each index was 1-20 points, in which 20 points was deemed the best and 1 point was the worst, and the total score was 100 points.…”