Postharvest quality evaluation of masu salmon (Oncorhynchus masou) during ice storage by spinal cord and bleeding

Abstract

The study investigated the impact of spinal cord-treated and bleeding processes on the quality changes of postharvest aquaculture masu salmon during ice storage. Fish underwent ice storage for 0–70 h, and the rigor mortis, ATP-related compounds, K-value, free amino acids, drip loss, and pH were monitored. Spinal cord-treated and bleeding fish started rigor mortis at 1.5 h, reaching full at 4.5 h, and persisted for 21 h, while control samples exhibited an earlier onset of rigor mortis at 0.5 h, reaching a maximum of 1 h. The ATP content showed a significant difference during the initial storage period from 0 to 3 h, with spinal cord-treated and bleeding fish showing a higher ATP content and lower K-value, and followed a similar trend, reaching around 20–23 % after 70 h of storage. The most abundant free amino acid detected was Ans, which occupied over 70 %, with others including Tau, Gln, Thr, Ser, Gly, Ala, His, and Glu. Spinal cord-treated and bleeding fish exhibited higher contents of Thr, Ser, and Gly, contributing to sweetness (p < 0.05). The umami flavor compound Glu increased with storage time, particularly in the spinal cord and bleeding fish, while IMP was most abundant during the mid-storage period, with higher levels in the spinal group with the prolong of storage time. HxR and Hx primarily contributed to bitterness, increasing with storage time, whereas His did not show a significant increase in the later storage period. Spinal cord and bleeding treatment demonstrated reduced drip loss (p < 0.05). The pH value fluctuated between 6.2 and 6.5 with no significant differences between the two treatments. The spinal cord-treated and bleeding treatments minimized stress and resulted in overall better postharvest quality, aligning with fish welfare.