A review on lipase-catalyzed synthesis of geranyl esters as flavor additives for food, pharmaceutical and cosmetic applications

Compared with geraniol, geranyl esters are preferred for their lower toxicity and higher bioactivity in food, pharmaceutical, cosmetic and other fields. Previously, chemical methods for synthesis of geranyl esters were more applied, which has harsh reaction conditions, undesired by-products and environmental unfriendliness. Nowadays, biosynthetic methods are increasingly chosen because of their high efficiency, greenness and environmental safety. In the biosynthesis of geranyl esters, enzymatic catalysis is the most effective, especially lipase as a catalyst. More to the point, biosynthesis produces geranyl esters that are recognized as natural flavors. During the reaction process, not only the catalytic triad (Ser-His-Asp/Glu) of lipases takes a significant role, but also parameters such as reaction temperature, acyl donor as well as water activity all influence the yield. Herein, we review the studies on the lipase-catalyzed synthesis of geranyl esters and the effect of process parameters on the high conversion in the last two decades.