Enzymatic synthesis of position-specific low-calorie structured lipids

Abstract

An immobilized sn-1,3-specific lipase from Rhizomucor miehei (IM 60) was used to catalyze the interesterification of tristearin (C_18:0) and tricaprin (C_10:0) to produce low-calorie structured lipids (SL). Acceptable product yields were obtained from a 1:1 mole ratio of both triacylglycerols with 10% (w/w of reactants) of IM 60 in 3 mL hexane. The SL molecular species, based on total carbon number, were 44.2% C₄₁ and 40.5% C₄₉, with 3.8 and 11.5% unreacted tristearin C₅₇ and tricaprin C₂₇, respectively, remaining in the product mixture. The best yield of C₄₁ species (44.3%) was obtained with zero added water. Tricaprylin (C_8:0) was also successfully interesterified with tristearin in good yields at 1:1 mole ratio. Products were analyzed by reverse-phase high-performance liquid chromatography with an evaporative light-scattering detector. Reaction parameters, such as substrate mole ratio, enzyme load, time course, added water, reaction media, and enzyme reuse, were also investigated. Hydrolysis by pancreatic lipase revealed the specific fatty acids present at the sn-1,3 positions of SL.