ESTIMATION OF THE ABSORPTION-COEFFICIENT OF STEARIC-ACID IN SALATRIM FATS

SALATRIM is the name given to a family of triacylglycerols that contain saturated long-chain fatty acids (LCFA) and short-chain fatty acids (SCFA). The major LCFA component is stearic acid, and the SCFA components are acetic, propionic, and butyric acids. The component acids are positioned statistically with respect to the glycerol backbone. SALATRIM compositions contain up to five triacylglycerol structure types (i.e., LSS, SLS LLS, LSL, and LLL, where S and L refer to the relative positions of SCFA and LCFA substituents on glycerol). It has been shown that SALATRIM fats deliver only about half the calories of common fats and oils. A predictable portion of this caloric reduction is due to the SCFA components. The balance of the caloric reduction is due to the incomplete absorption of stearic acid that is liberated by the action of digestive lipases. We have used data from a caloric availability study in rodents involving SALATRIM compositions which differed in their total molar S/L ratio to show that the coefficient of absorption for stearic acid is a function of the relative proportions of the various triester structure types. A mathematical expression was developed to correlate Abs(St) with the molar S/L ratio. The values of Abs(St) obtained fall predictably in line with those reported for model stearate containing LCFA triacylglycerols. A value for Abs(St) predicted by this methodology was also found to be consistent with result obtained with human subjects, providing a bridge between the rodent and human models. The apparent smooth variation of the absorption coefficient with triacylglycerol structure is not unlike that reported for fully caloric fats and oils.