15A-15 |
Synthesis of short chain citronellol esters by Rhizopus sp. lipase |
G. M. PASTORE, M. M. Soberón, J. G. Oliveira, and Y. K. Park. Food Science Dept., Univ. Estadual de Campinas, Laboratory of Bioflavour, FEA - Cidade Universitária Zefferino Vaz - CP 6121, Campinas, 13083-970, Brazil Short chain fatty acid esters of citronellol are important flavour and fragrance compounds widely used in food, cosmetic and pharmaceutical industries; among these, citronellyl acetate and citronellyl butyrate are the most used. The production of these esters by extraction from plants and by fermentation is often expensive for commercial production and the chemical synthesis requires elaborated purification steps. There is a great interest to synthesize these compounds by “natural” methods and enzymatic processes offer this possibility. Capabilities of synthesize these esters by a non-commercial and partially purified lipase from Rhizopus sp. was a focus of this work. Reaction mixture for direct esterification of (±)-b-citronellol with acetic and butyric acids (1:1 molar proportion) was carried out at 45 ºC of temperature, both with and without hexane. Transesterification reactions of citronellol with ethyl acetate and butyl acetate, was also prepared at the same conditions. The products were identified and measured by gas chromatography. The results showed that enzyme was able to synthesize only citronellyl butyrate by esterification. The highest ester yield in 24 hours was 100% both with and without hexane in the reaction medium. Citronellyl acetate was produced by transesterification reaction with the two esters as substrates. Maximum conversion of 58% were achieved in 48 hours of reaction for ethyl acetate and 48% for butyl acetate, both with and without hexane. These results suggest that the size of the aliphatic chain of the acyl donor group was important to catalyze citronellol esters by esterification; fatty acid with more than two carbons was a good substrate for Rhizopus sp. lipase. The size of the chain of the ester substrate in the transesterification reaction also affected the citronellol ester conversion yield, four carbons was better substrate than six carbons. Synthesis of flavour and fragrance compounds in solvent-free systems is interesting for food industry.
Session 15A, Biotechnology
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