Enzymatic synthesis of 1-octyl oleate using loofa-immobilized Rhizopus oryzae: Role of 3Å molecular sieve as a water absorbent

Catalysis of 1-octyl oleate synthesis using Rhizopus oryzae as a whole-cell biocatalyst has been reported in the present work. Loofa lignocellulosic fibre was used for fungal cells immobilization and the lipase activity of the loofa-immobilized R. oryzae cells (LICs) was found to be 0.196 U per mg biomass. The addition of 3Å molecular sieve to the reaction mixture for removing the water produced during the esterification progress enhanced reaction rates. The ester yield was higher in the presence of molecular sieve (87.6 % after 11 h) than in the absence of absorbent (80.1 %). A further increase of the ester yield up to 94.8 % was observed by changing the substrate molar ratio from 1:1 to 2:1 (1-octanol: oleic acid). The results were discussed in terms of dependency of the ester yield on the water removal index of the molecular sieve as related to the amount of reaction substrates.