30A-23 |
Stabilizing polymorphic transitions using diacylglycerols and sucrose polyesters |
J. H. OH and B. G. Swanson. Food Science and Human Nutrition, Washington State University, P.O. Box 646736, Pullman, WA 99164-6376
The stability of desirable a or b' polymorphic forms is of great interest to producers of high fat products. Sucrose polyesters (SPEs) are approved as emulsifiers at less than 1% concentration in emulsions and as fat substitutes in savory snacks to reduce calories. Information on the functionality of SPEs other than as fat substitutes is not well studied. The objective of this study was to investigate the effects of diacylglycerols (DAGs) and SPEs on polymorphic transitions. Five percent of DAGs or sucrose fatty acid polyesters were added to the melt of synthesized tristearin. The a and b' crystal forms were induced by tempering a melt at 100oC to room temperature or 55oC over 25 min, respectively. The crystal forms were stored at 53oC or 59oC, and stability was determined using Differential Scanning Calorimetry and X-Ray Diffractometry. The addition of 5% of distearin (DS) to the tristearin melt stabilized a crystal forms during a constant heating rate of 5oC /min. The 1,2-DS stabilized the a crystals more than 1,3-DS. The addition of dioleins and dilinolenins reduced the stability of the a crystals of tristearin. Stearic acids esterified to SPE with an HLB value of 1 (S1) also stabilized a crystal forms. Similarly, the stability of the a crystal forms stored at 53oC was increased by addition of DS and S1. The life times of crystals from the melt containing DS and S1 were increased to more than 60 min compared to 45 min life times of pure a crystals. The crystallization rate of b' forms from a tristearin melt were delayed by addition of DS and S1, however, the stability of b' crystal forms at 59oC was increased. One of the major efforts to stabilize selected polymorphic crystal forms and retard transitions to undesirable b crystal forms is the addition of emulsifiers to the melt. Stabilization of desirable crystal forms provides a desirable function for SPEs.
Session 30A, Food Chemistry: Lipids
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