In vitro digestibility study of thermal oxidized palm oleins Estudio de la digestibilidad in vitro de oleínas de palma termooxidadas

Abstract

Information on digestibility and absorption of oils and fats used for frying is under debate. To get knowledge on this, unused palm olein (9.27 ± 0.10% w/w polar content), used frying palm olein with a moderate degree of alteration (14.81 ± 0.90% w/w polar content) and highly altered used frying palm olein (26.36 ± 0.30% w/w polar content) and their respective nonpolar and polar fractions were studied. Samples were analyzed by high-performance size-exclusion chromatography before and after a 20-min in vitro incubation with pancreatic lipase. Formation of monoacylglycerols and free fatty acids reflected no relevant differences between unused and moderately altered oleins, whereas the most altered olein was hydrolyzed to a much lesser degree. The presence of oligomers (dimers and polymers of triacylglycerols) negatively affected the hydrolysis of triacylglycerol monomers in whole oleins. The hydrolysis of these monomers in the isolated nonpolar and polar fractions ranked between 60.2% and 78.5%. Oligomers were efficiently hydrolyzed by pancreatic lipase in whole un used and moderately altered oleins but not in the most altered one. Polymers from isolated polar fractions were poorly hydrolyzed or not hydrolyzed at all. These data suggest that whole oleins contained some compounds that increase susceptibility of oligomers to enzymatic hydrolysis and that such compounds were not present in the polar fraction.