LIPID OXIDATION IN MINCED HERRING (CLUPEA-HARENGUS) DURING FROZEN STORAGE - EFFECT OF WASHING AND PRECOOKING

A 2(3) factorial experimental design was used to investigate the effec t of washing in combination with precooking on the oxidative stability of lipids in minced herring (Clupea harengus) at -18 inverted perpend icular degrees C. The following variables were studied: washing (no, y es), cooking time (38, 54 min), and cooking temperature (55, 100 degre es C). The responses monitored were peroxide value (PV), absorbance at 234 nm (A(234)), absorbance at 268 nm (A(268)), and lipid soluble flu orescent products(FP). A partial least-squares regression analysis (PL S) revealed that the best lipid stability was obtained at minimum cook ing time and at lower temperature. On the basis of compositional analy ses and in vitro experiments, this finding was proposed to be due to h eat inactivation of catalytic enzymes, without simultaneous activation , for example, of hemoproteins. Washing reduced these benefits from pr ecooking by removal of pro-oxidative enzymes and also through a reduct ion in the amount of antioxidants as well as a relative increase in ph ospholipids and free fatty acids in the fat.