抄録
Niboshi (boiled and dried anchovy) was prepared from fatty and lean raw materias, pulverized, packed in a plastic pouch with and without an oxygen absorber, then stored at 25nd-20°C for 60 days. Lipid oxidation and changes in the free amino acid compositions of the pulverized niboshi duringstorage, were investigated.
In the fatty samples, lipid oxidation and brown discoloration significantly occurred during storage at 25°C. At the same time, the contents of the free amino acids such as taurine, glutamine, methionine, histidine, and lysine decreased. In contrast, in the lean sample, lipid oxidation and brown discolorationonly slightly occurred during storage at 25°C. The taurine content remained unchanged during storage.When packed with an oxygen absorber, both the fatty and lean samples were effectively protected fromlipid oxidation during storage, though a brown discoloration developed with decreases in the glutamine and histidine contents. In the case of storage at -20°C, lipid oxidation in both the fatty and lean samples proceeded gradually. However, the brown discoloration was not observed throughout the 60-daystorage.
From these results, it was presumed that methionine was decomposed by the action of the lipidperoxides, histidine, lysine, and taurine that reacted with the carbonyl compoundsproduced during the course of oxidative degradation of the lipids to form brown pigments, while glutamine decreased at room temperature.
