抄録
Lipid oxidation and hydrolysis in maruboshi, salted-dried anchovy Engraulis japonica, hira-kiboshi, salted-dried splited anchovy and niboshi, boiled-dried anchovy, were investigated during drying at 30°C for 20h and storage at 20°C for 50 days.
In the case of maruboshi, peroxide value (POV), acid value (AV) and percentage of free fatty acid (FFA) of lipid increased rapidly with decrease in ratio of percentage of (C20:5+C22:6) to that of C16:0 (ratio of HUFA/SFA) during drying, showing lipid oxidation and hydrolysis had occured, During storage, the increases in AV and percentage of FFA and the decrease in HUFA/SFA progressed rapidly for the first 7 days and then slowly for the next 50 days. In hira-kiboshi, POV, AV and percentage of FFA of lipids also increased during drying. During storage, AV, percentage of FFA and ratio of HUFA/SFA in the hirakiboshi lipid changed in similar manners to those of maruboshi, except for relatively slow decrease in the ratio of HUFA/SFA.
Contrary to this, AV and percentage of FFA of lipids in niboshi increased very slowly throughout drying and storage periods, though POV increased rapidly during drying and the ratio of HUFA/SFA decreased rapidly during drying and an early stage of storage. The slow increases in AV and percentage of FFA in niboshi seems to be due to inactivation of endogeneous enzyme system involved in lipid hydrolysis to occur during boiling prior to drying, This implies that the rapid increases in AV and percentage of FFA in maruboshi and hirakiobshi, which are not subjected to boiling process, may be attributed to enzymatic hydrolysis of lipids.
Maruboshi and niboshi, containing internal organs in which lipids were highly susceptible to xidation, were subjected to oxidative rancidity more rapidly than hirakiboshi produced from eviscerated anchovy during prolonged storage.
