LOW-CALORIE TRIGLYCERIDE SYNTHESIS BY LIPASE-CATALYZED ESTERIFICATION OF MONOGLYCERIDES

Monoglycerides of erucic acid (C-22:1, Delta 13), prepared by conventional methods were reacted with caprylic acid (octanoic acid, C-8:0) by using lipases as catalysts with the intention of synthesizing a triglyceride that contains two molecules of caprylic acid and one molecule of erucic acid (caprucin). The reaction was carried out by mixing lipase powder, a small quantity of water, and the reactants in a temperature-controlled stirred batch reactor. Organic solvents or emulsifying agents were not required. When the nonspecific lipase from Pseudomonas cepacia was used, a yield of approximately 37% caprucin was obtained, together with a complex mixture of di- and triglycerides that resulted from the random transesterification of the erucic acid. The fatty acid-specific lipase from Geotrichum candidum promoted minimal transesterification of erucic acid and resulted ina yield of 75% caprucin and approx approximately 10% interesterification products. Lipase from Candida rugosa exhibited a similar, although less pronounced, specificity to that from G. candidum and promoted more transesterification of erucic acid. Optimum conditions for G. candidum lipase were at 50 degrees C and an initial water content of 5.5%. After the reaction, erucic acid was converted to behenic acid by hydrogenation, thereby converting caprucin into caprenin, a commercially available low-calorie triglyceride.