USE OF AUTOCLAVING IN THE PREPARATION OF HOMOGENATES FOR DETERMINING THE PROXIMATE CHEMICAL AND FATTY-ACID COMPOSITION OF FISH

A comparative study was made of the proximate chemical and fatty acid composition of barramundi fish (Lates calcarifer, Bloch) processed by repeated mincing either without (M) or with autoclaving for 4 h at 126 degrees C (M + A). M + A processing caused complete disintegration of the tissue, enabling easy homogenisation by blending. The eviscerated carcase and pooled gill/gut of 12 plate-sized barramundi were individ ually processed by M or M + A procedures and the resultant freeze-drie d product analysed. Processing method did not alter (P > 0.05) the ana lysed ash, nitrogen or fat content of the sample. An additional two sa mples of pooled gill/gut were M or M + A processed and analyzed both b efore or after freeze-drying. Freeze-drying caused a 16 and 19% depres sion (P < 0.05) of eicosapentaenoic acid (C20: 5 omega 3) and docosahe xaenoic acid (C22:6 omega 3) respectively for samples processed by M b ut not by M + A. It is speculated that M + A processing inactivates en dogenous lipolytic enzymes which otherwise cause fatty acid losses dur ing freeze-drying. The present study demonstrates the suitability of a utoclave processing for determining the proximate chemical or fatty ac id composition of fish tissue.