Effect of solvent polarity and fractionation temperature on the physicochemical properties of squid viscera stearin

Abstract

Complete utilization of squid viscera oil was found to be feasible by solvent fractionation. The effects of solvent polarity and temperature on yield, soft melting point, fatty acid composition and solid fat content of the stearin were studied. Although yield increased with increasing solvent polarity and with decreasing fractionation temperature, the stearin obtained has a lower soft melting point. This makes it unsuitable as a table margarine. Operation at lower temperature also increased the operating cost. Solid fat content of the stearins fractionated at‐1°C was 10% higher than of those at ‐5 or ‐9°C for all solvent polarities studied. Solid fat content of stearin increased with the decrease of solvent polarity at every tested temperature. The combined effects of polarity and fractionation temperature affect the soft melting point and solid fat content, which determine the commercial application of the stearin. The percentage of saturated fatty acids of stearin decreased with increasing solvent polarity, and the percentage of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) increased with solvent polarity and fractionation temperature. The percentage of EPA + DHA in stearin decreased with temperature, except for those from 5.1 p′ solvent. The practical fractionation condition is at ‐1 or ‐5°C with a solvent polarity of 5.1 p′. The stearin fraction can be made into a series of products, such as high EPA‐ and DHA‐containing table margarine.