PREPARATION OF DIGLYCERIDES BY LIPASE-CATALYZED ALCOHOLYSIS OF TRIGLYCERIDES

Lipase from Penicillium roquefortii immobilized on porous polypropylen e particles was used for enzymatic preparation of 1,2-diglycerides by alcoholysis in organic media. A screening of commercially available li pases showed that lipases fi om Penicillium species produced high amou nts of 1,2-diglycerides from triglycerides. Reaction parameters such a s solvent, alcohol, water activity, and fatty acid chain length were i nvestigated. The positional selectivity of the lipase as well as the s electivity for type of glyceride specie were studied using pure isomer s of the the partial glycerides. The enzyme showed high selectivity fo r triglycerides and 1-monoglycerides and very low activity towards dig lycerides. The lipase had a clear preference for the 1- and 3-position s. The highest lipase activity was observed at low water activity, but the yield increased with increasing water activity. Above all, the re gio-isomeric purity of the diglycerides increased with increasing wate r activity. The yield of dilaurin was 75% and furthermore, 95% of the total dilaurin was 1,2-dilaurin. Alcohol concentration and chain lengt h of the alcohol had insignificant effect on yield and enzyme activity , but product stability increased when alcohol was present in the reac tion medium. The best solvents were ethers; higher enzyme activities w ere obtained in aliphatic hydrocarbons but yields and regio-isomeric p urities were low presumably due to acyl migration. (C) 1997 by Elsevie r Science Inc.