Blood removal and water behavior in horse mackerel Trachurus japonicus muscle using water perfusion

Abstract

Blood removal is widely applied in the fisheries and aquaculture industries because it maintains the quality of fish muscle during storage, which improves the market value and effective utilization of marine resources. Water perfusion, such as Tsumoto-shiki, has recently attracted attention as a novel blood removal procedure; however, its detailed effect has not been clarified thus far. Herein, to utilize water perfusion as a novel blood removal technology, the influence of water perfusion according to Tsumoto-shiki with modifications, for 4–60 s on the blood removal and water behavior in horse mackerel Trachurus japonicus muscle was investigated compared with that of a sample conventionally bled by cutting the gill. The results were subjected to multiple comparison tests using the Tukey–Kramer method. The hemoprotein content in the perfused sample was significantly lower than that in the control sample without blood removal and the bled sample (p < 0.05), independent of the perfusion time. The moisture content and expressible drip in the perfused sample increased in a perfusion time-dependent manner. Low-field nuclear magnetic resonance (LF-NMR) measurements showed that 1H T2 relaxation time was prolonged in samples perfused for 30–60 s (p < 0.05). In 1H T2-weighted images obtained using magnetic resonance imaging (MRI), high signal intensities were mainly observed in the dark muscle and segmental arteries and veins of samples perfused for 30–60 s, indicating the presence of free water that leaked from blood vessels. Therefore, water perfusion is an effective procedure for blood removal compared with conventional bleeding. Furthermore, in this study, water perfusion for 4–10 s was appropriate for both removing blood and preventing the quality deterioration induced by increased moisture content and expressible drip in horse mackerel muscle.