Effect of a vacuum-leaching technology on the proteins and lipids of lean sardine (Sardina pilchardus) mince

A study on the effect of the vacuum level and leaching time on the washing of lean sardine (Sardina pilchardus) mince was carried out. An experimental design was performed according to the statistical model of central composi te design of response surface methodology. Proximate composition, water-hol ding capacity (WHC) and soluble protein were determined in the mince. Lipid classes and fatty acids were further analysed in the minces and in the ext racted solutions. The WHC was greatest in the mince washed at atmospheric p ressure for 40 min, and corresponded to the lowest fat content. The highest soluble protein extraction was obtained at intermediate values of pressure (382 mmHg) and time of washing (20 min). The fat initial content (4.6%) wa s reduced by approximately 50% and was significantly affected by extreme va cuum levels (4 mmHg and 760 mmHg) and longer washing periods. Triacylglycer ols were extracted the most, mainly at intermediate pressure values and inc reased washing periods. Polar lipids were next in abundance and were not ex tracted during washing. Polyunsaturated fatty acids were the major group of fatty acids, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DH A) the most representative, being predominantly extracted at extreme pressu re levels and increased periods of washing. DHA was more abundant in the wa shed mince, whereas the level of EPA was proportionally higher in the emuls ions.