Selective enrichment of symmetric monounsaturated triacylglycerols from palm stearin by double solvent fractionation

The aim of this study was to produce a fractionated palm stearin enriched in symmetric monounsaturated triacylglycerols (SMUT), such as 1,3-dipalmitoyl-2-oleoyl-glycerol (POP), 1-palmitoyl-2-oleoyl-3-stearoyl-rac-glycerol (POS), and 1,3-distearoyl-2-oleoyl-glycerol (SOS) using two-stage acetone fractionation. Palm stearin, containing 27.2 g/100 g total SMUT and 33.8 g/100 g tripalmitin was used as the starting material for the fractionation. A liquid fraction produced from palm stearin under the best conditions (temperature, 17 degrees C; volume-to-weight ratio of acetone to palm stearin, 8; crystallization time, 8 h) established in this study was free of tripalmitin (<0.5 g/100 g) and contained 44.5 g/100 g total SMUT (similar to 37.3 g/100 g POP, similar to 6.4 g/100 g POS, and similar to 0.8 g/100 g SOS). The yield of the liquid fraction was 61.3 g/100 g of the initial palm stearin weight. The liquid fraction was crystallized to further increase SMUT concentration. After fractionation at 4 degrees C for 24 h, a solid fraction with total SMUT content of 63.2 g/100 g (similar to 53.0 g/100 g POP, similar to 9.1 g/100 g POS, and similar to 1.1 g/100 g SOS) was obtained and its yield was 30.8 g/100 g of initial palm stearin weight. The resulting fractionated palm stearin would be suitable for use in preparing cocoa butter equivalents due to the high SMUT content. (C) 2012 Elsevier Ltd. All rights reserved.