Effect of Fatty Acid Composition of Monoglycerides and Shear on the Polymorph Behavior in Water-in-Palm Oil-Based Blend

Effect of the fatty acid composition of monoglycerides and shear on the polymorphic behavior in a water-in-oil (W/O) emulsion semi-solid fats blend was investigated. The bulk fat blend and the W/O emulsion fat blend with added either unsaturated or saturated monoglycerides were prepared using a rapid cooling heat exchanger, and the polymorphic transitions from beta' to beta-form during storage were compared by X-ray diffraction. The peak intensity of the beta-polymorph of the samples with added saturated monoglycerides was stronger than that of unsaturated monoglycerides, and the peak intensity of the beta-polymorph of the W/O fat blend emulsions was stronger than that of the bulk fat blends. The polymorphic transition to the beta-form during storage of the W/O emulsion fat blend was promoted by the applied shear. In contrast, that of the bulk fat blend was retarded by shear. These results suggested that fatty acids, which combined to monoglycerides on the surface of water droplets, influenced the polymorph transformation of the fat crystal network in a continuous semi-solid fat phase because of the acyl-acyl interactions between the fatty acid residues of the monoglycerides and triacylglycerols in the fat crystal network.