CONTRIBUTION OF PARTICLE SIZES AND PARTICLE-SIZE DISTRIBUTIONS IN CRYSTALLINE FRACTIONATION OF LARD

Particle sizes and particle size distributions of lard in the process of multiple-step crystalline fractionation were studied by natural sedimentation spectrophotometry according to Stokes's law and Beers's law. The average particle size diameter and their distributions of lard fractions varied with the crystallization temperatures. Average particle size decreased significantly (p < 0.05) with the crystallization vessel cooling rates (0.5, 1.0, and 2.0 degrees C min(-1)) and agitator speeds (50, 100, and 150 rpm). Furthermore, the firmness of lard crystal fractions decreased with the vessel cooling rate and agitator speed. Decreases in average particle sizes in addition to the firmness of lard crystal fractions were related to the increase in unsaturated fatty acid and to their triglyceride compositions.