Biochemical changes of Atlantic salmon (Salmo salar) ﬁllets during superchilled storage were evaluated. Due to the signiﬁcant differences in ice crystal sizes observed, the biochemical changes were evaluated both at the top and centre parts of the superchilled samples. No signiﬁcant differences were found in biochemical changes between top and centre parts of the superchilled samples. The amount of cell tissue fluid (CTF) increased significantly from day 1 to 3 in the top and centre parts of the superchilled samples. The amount of CTF was stable between day 3 and 14 but increased significantly from day 21 to 28. A significant increase in the activity of β-N-acetyl-glucosaminidase in the CTF at the top was observed between day 3 and 7, while at the centre at day 7 of storage. There was also a significant increase in β-N-acetyl-glucosaminidase both at the centre and the surface of the superchilled samples between day 21 and 28 of storage whereby the activity in these samples was on the same level as in the frozen samples. In the superchilled samples, the cathepsin B activity in CTF and homogenates were stable for the first one week of storage. There was significant increase in activity of cathepsin B in cell tissue fluid and homogenates between day 21 and 28 for both chilled and superchilled samples. These ﬁndings provides valuable information on the quality of food products for the food industry in relation to ice crystallisation/recrystallisation during superchilled storage.
Key words: Partial freezing, biochemical changes, superchilled storage, salmon fish (Salmo salar).
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