Thành phần hoá học cơ bản và một số tính chất vật lý của cá ngừ đại dương đánh bắt tại Việt Nam

Abstract

     This research focused on proximate analysis and determination of some physical properties of ocean tuna caught in Vietnam for further study on fish cooling and storage. The study was conducted for yellowfin and bigeye tuna of size 20 kg up and 40 kg up. It was found that flesh was the main component of tuna, accounting for almost 70% (w/w), intestine proportion was above 10%, and the rest belonged to other parts (head, fin, bone, and skin). Average proximate compositions of ocean tuna were 74 - 81% water, 20 - 22% protein, around 3% lipid, 0.1 - 0.2% glucid, and 0.87 - 0.92% ash. Density of chilled tuna at 0 - 4^oC was 1.006 - 1.108 (kg/m³). Some thermophysical properties of ocean tuna flesh were as follows: freezing point from -1.85 to -2.00^oC; specific heat 0.8140 - 0.835 (kcal/kg^oC) (above freezing point) and 0.454 - 0.459 (kcal/kg^oC) (below freezing point); enthalpy 20.356 - 20.869 (kcal/kg) and 21.914 - 22.466 (kcal/kg) for a temperature change of fish flesh from 25^oC to 0^oC and from 25^oC to freezing point, respectively.

Keywords: Ocean tuna, proximate compositions, mass compositions, thermophysical properties