Utilisation digestive comparée et formes d'excrétion fécale chez le rat, des acides érucique et brassidique estérifiés dans différentes structures glycéridiques

Abstract

The digestibility and fecal excretion patterns of erucic (cis n-9 docosenoic) and brassidic (trans n-9 docosenoic) acids, esterified in triglycerides of different structure, were compared in the rat. Synthetic triglycerides were prepared either by mixing or interesterifying trierucin or tribrassidin with an equal amount of corn oil. Rapeseed and peanut oils were used as references. The apparent digestibility of trierucin mixed or interesterified with corn oil was similar to that of peanut oil but higher than that of rapeseed oil. The high amount of 2-monoerucin resulting from diets containing trierucin explained the improved digestibility of erucic acid as compared to that of rapeseed oil which had a very small erucic acid content on the 2-position. It also seemed that 2-monoerucin enhanced the digestibility of saturated fatty acids. Tribrassidin mixed with corn oil had a poor digestibility because pancreatic lipase hydrolysis was delayed in the intestinal lumen. The high melting point of the homogeneous triglyceride was responsible for that phenomenon. The interesterification of tribrassidin with corn oil, which drastically lowered the melting point of the mixture from 52 to 37 degrees C, improved both the hydrolysis of the triglycerides and the digestibility of the C22: 1 trans fatty acid as well as that of the other fatty acids in the diets. Nevertheless, the unabsorbed brassidic acid in every case was principally excreted in the form of a compound insoluble in organic neutral solvent. In that respect, brassidic acid behaved like shorter chain saturated fatty acids such as palmitic and stearic acids.