The effect of enzymatic interesterification on the high oleic-high stearic sunflower oil fractionation and the physico-chemical properties of stearins

Abstract

Oil fractionation processes typically involve the crystallization of the most saturated triacylglycerols to facilitate the separation of the liquid phase. However, the fractionation of new high stearic oils derived from sunflower (HOHS) is not as efficient as that of tropical fats. In the present work we studied the effect of enzymatic inter esterification (EIE) on the HOHS sunflower oil fractionation. EIE altered the properties and melting point of the HOHS oil, so it eased fractionation allowing operation at lower temperatures (8 °C). These fractionations produced stearins with high saturated fatty acid contents at higher yields than the non-EIE oil (28.3% vs 18.7%). The melting profile of the stearins were also characterized. EIE stearins displayed broader melting profiles with higher crystallization onsets (from 26.3 °C to 34 °C). Fractionations proved to be reproducible at pilot plant scale. The resulting stearins exhibited a solid content of 30% at 20 °C and displayed solidification curves similar to palm-based filling fats. The results indicate that changes in fatty acid distribution in the TAG backbone critically affect TAG crystallization, which was faster and more reproducible, not requiring prior dewaxing and seeding. Moreover, the fractionation products differed, yielding stearins with higher levels of solids.