Lipase activity and fatty acid typoselectivities of plant extracts in hydrolysis and interesterification

Lipase fatty acid typoselectivities of Euphorbia characias latex and commer cially available crude preparation of bromelain were determined in the hydr olysis of homogeneous triacylglycerols (TAG) and natural TAG mixtures. Thei r activities were compared to a commercially available crude preparation of papain. Under optimal lipolysis conditions at pH 8.0 and 10 min of incubat ion time, maximal activities were observed at 45, 55, and 50 degrees C, res pectively, for E. characias latex, crude bromelain, and crude papain, Comme rcially available crude preparations of bromelain exhibited very poor hydro lysis activity. Latex from E. characias, which contained 340 mg of dried ma terial per milliliter of fresh latex, exhibited a high lipase activity and a short-chain fatty acid preference in the hydrolysis of homogeneous TAG. F or all substrates, it showed a better activity than crude papain. Lipase fa tty acid typoselectivities of crude bromelain and crude papain also were st udied in interesterification reactions of tributyrin with a series of homog eneous TAG. Experiments showed that crude bromelain [water activity (A(w)): 0.21] had no activity in interesterification. Regarding reactions with cru de papain (A(w): 0.55), yields of newly formed TAG decreased with increasin g chain length of TAG, except for the reaction with trimargarin. For intere sterification of tributyrin with unsaturated TAG, triolein reacted faster t han polyunsaturated TAG. During these interesterification reactions, the pr oportion of new TAG with two butyroyl residues was higher than new TAG with only one butyroyl residue. This phenomenon was more pronounced for reactio ns with long-chain TAG.