POLYMORPHIC STABILITY OF SOME SHORTENINGS AS INFLUENCED BY THE FATTY-ACID AND GLYCERIDE COMPOSITION OF THE SOLID-PHASE

A number of North American vegetable and animal fat shortenings, which had been analyzed previously for their physical and textural characteristics, were analyzed also for their chemical composition. The fatty acid and triglyceride composition of the solids were calculated by analyzing the composition of the original product and the liquid phase, and by determination of the solid fat content (SFC) of the fat. The solids were also isolated by isopropanol (IP) separation, and the high melting glycerides (HMG) by acetone crystallization at 15-degrees-C. There was not much difference in total saturates and trans content between vegetable and animal fat shortenings. Changing formulations from soy-palm to soy-cottonseed does not change the total saturates plus trans content. The solids of the vegetable shortenings in the beta-form contained about 20% of 16:0, those in the beta' form 30% or more. The animal fat shortenings were mainly in the beta-form, their solids contained 30% or more of 16.0. C54 triglyceride content of the solids of beta-vegetable shortenings (calculated and IP-separated) was > 45%, that of all animal fats was < 25%. Solids of animal fat shortenings contain high levels of C52. The C54 triglycerides are beta-tending and should be kept low in vegetable shortening. In the HMG the C54 should not exceed 30%. This can only be achieved by incorporation of a beta' hard fat, preferably palm hard fat. Animal fat, especially lard, crystallizes in the beta-form because the palmitic acid in the glyceride molecule is located in the 2-position, whereas those of vegetable fats are in the 1- and 3-position.