Frozen Storage of “Ikura”, a Salted Product of Salmon Eggs

Two salinity levels of “ikura”, a salted product of salmon eggs, were prepared from fresh ovaries of the chum salmon Oncorhynchus keta, divided into many lots, and kept frozen for 11 months at —10°, —20°, —30°, —40° and — 60°C. At one or two-month intervals, a portion of each lot was analyzed for toughness of egg membrane, carotenoid content, and thiobarbituric acid (TBA) value as parameters for quality change. The results obtained showed that — 10°C is reasonable for a short-term storage (up to 3 months) of ikura of either salinity, whereas — 40°C, and not — 60°C, was found best for a long-term storage up to 11 months. In addition, non-salted salmon eggs were found to be processed to a high quality ikura even after 11 months of frozen storage. Vacuum packaging was very effective against the lipid oxidation of ikura.