Hydrophilization of bixin by lipase-catalyzed transesterification with sorbitol. (1st December 2018) - Jahangiri, Amita
Highlights: Lipase catalyzed reaction of bixin with sorbitol results a transesterification. Among different lipases only immobilized C. antarctica lipase B catalyzed the reaction. Highest reaction yield (50%) was obtained at aw = 0 and 20% THF. Sorbitol ester of norbixin was the final product. Abstract: Bixin is one of the most used yellow-orange food colorants in the food industry. The polyene chain of bixin makes it highly hydrophobic and less suitable for water-based food formulations. Lipase-catalyzed reactions of bixin with sorbitol were studied to synthesize a new derivative of bixin with potential hydrophilic properties. Interestingly, we show that the lipase-catalyzed reaction of bixin leads to a transesterification reaction and formation of a transesterified product, sorbitol ester of norbixin (SEN). The reaction efficiency was optimized with various immobilized lipases at different water activity levels in the organic solvent, 2-methyl-2-butanol. Among the examined lipases, immobilized Candida antarctica lipase B (Novozyme 435) provided the highest reaction yield at a water activity close to zero. Tetrahydrofuran (THF) was used as co-solvent to improve bixin solubility. The optimization of the reaction conditions with 20% THF lead to a total reaction yield of 50% of SEN.