RHEOLOGICAL CHARACTERISTICS OF MILKFAT AND MILKFAT-BLEND SUCROSE POLYESTERS

Sucrose polyesters (SPE) are non-absorbable, non-caloric potential fat substitutes in foods. Since SPE will be substituted for fats in foods , it is important to determine and compare the rheological properties of SPE with natural fats. The viscous and viscoelastic properties of m ilkfat were compared to those of milkfat SPE and SPE synthesized from mixtures of 75% milkfat and 25% fatty acids from tallow, myristate, or coconut oil. Liquid viscosities of milkfat and SPE at 50-degrees-C we re Newtonian. Viscosities of milkfat, milkfat SPE and milkfat-blend SP E were significantly different (P less-than-or-equal-to 0.05). Milkfat was the least viscous of the samples. The viscoelastic behavior of th e fats was characterized at 20-degrees-C by oscillatory tests. SPE sto rage and loss moduli (G' and G'') were frequency-dependent while the v alues for milkfat were not. The magnitudes of the storage and loss mod uli of the SPE were different. Milkfat was more elastic at 20-degrees- C as revealed by a smaller loss tangent (tan delta = G''/G'). The visc ous and viscoelastic properties of milkfat SPE can be adjusted by the addition of small amounts of other fatty acids during synthesis. The r heological properties of milkfat and milkfat-blend SPE were different from those of milkfat.