The extracellular crude Rhizomucor variabilis lipase was used for synthesis of flavor ester butyl caprylate and 1-butyl oleate often used as a diesel additive, a polyvinyl chloride plasticizer, a water-resisting agent, and an additive to hydraulic fluids. The influence of various reaction parameters such as the molar ratio, time, enzyme and substrate concentration, and effect of various fungal polysaccharides was estimated. The rate of catalyzed synthesis of esters largely depends on the solvent medium, and the maximum activity was found when n-hexane was used as a solvent. The maximum conversion yield of 58.2% and 59.3% was obtained for butyl caprylate and butyl oleate, respectively, under the following conditions: amount of free lipase 500 U; caprylic acid:butanol molar ratio 1:1; oleic acid:butanol molar ratio 2:1. The addition of naturally obtained fungal polysaccharides significantly enhanced the ester synthesis. The highest conversion rate of 95.2% was observed for butyl caprylate in the presence of AbEPS after 24 h with 500 U of free R. variabilis lipase. In the case of butyl oleate synthesis in the presence of LsPS, a maximum conversion yield of 91.2% was observed after the 24-h reaction.
Keywords: Ester synthesis; Lipase; Polysaccharide; Process optimization; Rhizomucor variabilis.
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