Effects of Food Emulsifiers on the Crystallization of a Molecular Compound of Two Types of Triacylglycerols in Bulk and Solution Systems

Abstract

We studied the effects of food emulsifier additives, sucrose fatty acid esters (SEs) and monopalmitin (MP), on the non-isothermal crystallization of a molecular compound (MC) composed of a 1:1 ratio of two triacylglycerols (TAGs) in bulk and n-dodecane solution, using differential scanning calorimetry, X-ray diffraction and polarized light microscopy. The purpose of this study was to reveal the effects of additives on the crystallization rate, size and morphology of the MC crystals. These parameters are known to be affected by the addition of different types of additives (i.e., those containing sucrose or glycerol, and saturated or unsaturated acid moieties) as well as the concentration of the additive, cooling rate and presence of solvent. We found that MC crystallization was retarded by SEs, P-170 and POS-135, containing saturated or saturated-unsaturated mixed fatty acids. On the other hand, MC crystallization was promoted by MP, which may serve as a seed crystal to initiate heterogeneous nucleation of the MC crystals. The formation of MC crystals that produced the most stable structure of β form was not disturbed by the addition of emulsifiers. Furthermore, the addition of P-170 and POS-135 produced MC crystals of finer morphology, while MP addition produced needle shaped crystals. It appeared that the different effects of the two types of emulsifiers on the nucleation process of MC crystallization were dependent on differences in the hydrophilic-hydrophobic structure and balance.