Nanostructured Fat Crystal and Solid Fat Content Effects on the Physical Properties of Water-in-Oil Semisolid Fat Blends.

The effect of nanostructured fat crystals on oil migration properties in water-in-oil-type emulsified semisolid fats was investigated. Model emulsions containing 4 different semisolid fats (palm oil, partially hydrogenated palm oil, partially hydrogenated soybean oil, and milk fat) and 1 bulk fat blend were prepared with rapidly cooling crystallization. The length of the nanoplatelets was observed by cryo transmission electron microscopy, the crystal thickness was calculated by small-angle X-ray diffraction, and the solid fat content (SFC) was determined. Although the interfacial surface of the dispersed water droplets did not influence nanoplatelet size, oil migration in the emulsified samples was lower than in the bulk fat. The crystal sizes in samples with partially hydrogenated soybean oil involving elaidic acid were larger, in contrast to that of milk fat, involving low to medium chain length fatty acids, which had smaller crystal sizes and showed wide length distribution. The length of the platelets and SFC were related to the oil migration value. These results suggest that the oil binding ability of fat products, such as margarine, is influenced by the nanostructure, which is related to fatty acid composition and interfacial structure.