WEAK GELS OF FAT CRYSTALS IN OILS AT LOW-TEMPERATURES AND THEIR FRACTAL NATURE

The formation of fat crystal gels in soybean oil has been studied by s edimentation in a low concentration region at 10-25 degrees C. At 10 d egrees C, weak gels were formed with 1% crystals, and no gels formed a t concentrations of 2-5%. At temperatures of 15-25 degrees C, no gels were formed at concentrations of 1-5%, and samples sedimented. Stronge r gels of fat crystals were formed with similar to 10% fat crystals at all temperatures examined. Formation of weak gels is a consequence of the fractal nature of fat crystal aggregates and sediments. At low te mperature, the interaction is weak. The fractal dimension is then high , and the flee size is large for low crystal concentrations. These lar ge flocs form a three-dimensional network that act as a weak gel and w ithstand gravitational force. When the temperature is increased, the f at crystal interaction becomes stronger, fractal dimension decreases, and flee size decreases. Smaller flocs have a higher density, pack mor e easily, and sediment. Similar effects are observed when the concentr ation of fat crystals is increased at low temperature due to a decreas e in flee size.