PALM OIL CRYSTALLIZATION: EFFECTS OF COOLING TIME AND OIL CONTENT

Abstract

ABSTRACT Isothermal crystallization behavior of fluid shortening formulation from blends of palm oil and palm olein was investigated. The oil blends filled in nuclear magnetic resonance (NMR) tubes to a height of 2.5 cm were melted at 70C for 30 min crystallization time. A set of 11 tubes for each temperature was placed at selected crystallizing time and the solid fat content (SFC) measured in a Bruker pulse NMR spectrometer. Crystal distribution of the same blend was observed under polarized microscope at the same time interval. A correlation was developed between SFC and crystal distribution. The crystallization curves demonstrated two distinct steps corresponding to two crystallization stages as a result of the occurrence of mixed crystallization. Crystallization was selective to the high melting triacylglycerols (TAG) at all temperatures as shown by shorter induction periods in blends with more than 41.8% palmitic acid. High melting TAG crystallized first and acted as nuclei for recrystallization of the low melting TAG. However, the low melting TAG at the same time could also solubilize the formed crystals. The average SFC as a function of time was 50% lower than the SFC profile. Slow crystallization temperature was able to promote large crystal formation that influences SFC of palm‐based shortenings. Blends of 40–60% palm oil showed promising formulations of stable fluid palm‐based shortening.