Biosynthesis of flavor esters in coconut cream through coupling fermentation and lipase-catalyzed biocatalysis

Abstract

The aim of this research was to study the biosynthesis of natural flavor-active ethyl esters with a commercial lipase, Palatase 20000L, in coconut cream by coupling with yeast alcoholic fermentation. Alcoholic fermentation was carried out by Saccharomyces cerevisiae, which generated ethanol as one substrate for ester synthesis. Lipase was added into the fermentation medium at three different time points (12, 24, and 48h) during the time-course fermentation of 72h. The concentrations of ethyl octanoate, ethyl decanoate, and ethyl laurate were the highest when lipase was added at 12h, indicating early coupling of ethanol production with ester synthesis catalyzed by lipase. Although the growth of S. cerevisiae was slightly inhibited when lipase was added into the fermentation medium due to the formation of fatty acids, no adverse effect on ester synthesis was observed. This novel approach may be useful in the production of relevant flavors of fermented coconut cream with lipase treatment, which could be used as a new food ingredient. Practical applications: Esters are a group of valuable flavor compounds that have wide applications in a variety of food products. In this work, we proposed one effective approach of coupling yeast alcoholic fermentation and lipase-catalyzed biocatalysis to synthesize natural fatty acid ethyl esters in coconut cream. This method provides a novel application of coconut cream for ester synthesis. In addition, the esters formed can be considered as natural according to current regulations. The ethanol generated can be effectively utilized for ester synthesis, therefore, complying with the Halal rules. The end product can be possibly used as a natural flavoring in the food industry after sensory evaluation and proper process. The esters formed may be further separated and purified as pure flavor compounds. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.