The chemical, thermal and textural characterization of fractions from Macauba kernel oil

Abstract

Macauba (Acrocomia aculeata) kernel oil is rich in short- and medium-chain saturated and unsaturated fatty acids, the most abundant of which are lauric and oleic acids. The oil also has high oxidative stability and contains bioactive compounds. Like other oils rich in lauric acid, Macauba kernel oil is solid at low temperatures but has a low solid fat content at room temperature. The hypothesis of this study is that the thermal and textural characteristics of Macauba kernel oil can be modified by fractionation. Fractions were obtained and analysed with respect to their fatty acid profile, oxidative stability, crystallization and melting profile, firmness and physical state at different temperatures. The fatty acid profiles of the fractions remained virtually unchanged, but the oxidative stability of stearins was greater than that of oleins. An increase in the percent enthalpy of crystallization and melting at lower temperatures was observed in oleins, with a consequent decrease in solid fat content, firmness and oxidative stability (compared with stearins) without a relevant change in the fatty acid profile, suggesting that triacylglycerols with unsaturated fatty acids were prevalent in positions sn1 and sn3 in oleins and in position sn2 in stearins. Thus, it was possible to obtain an olein with 26% less solid fat at 25 °C that was 22% less firm and that remained liquid until 3 °C below the oil, as well as a 23% firmer stearin.