Crystallization and polymorphism of blends based on cocoa butter and shea stearin for the development of novel lipid systems

Abstract

Cocoa butter (CB) is a natural edible fat mainly composed of three main 1,3-disaturated-2-unsaturated triacylglycerols (TAGs): 1,3-dipalmitoyl-2-oleoyl-glycerol (POP), 1,3-distearoyl-2-oleoyl-glycerol (SOS), and rac-palmitoyl-stearoyl-2-oleoyl-glycerol (POS) and is responsible for the unique physicochemical properties of chocolate. In recent days, the increase in the demand for cocoa beans in the market has led to a rise in CB price, and for that reason the search for alternatives fats to CB is promoted. Some of these alternatives are Cocoa Butter Equivalents (CBEs), which usually are fat blends compatible with CB because of their similar physical and textural characteristics (melting, rheology, plasticity, etc.) compared to those of CB, and, generally, are obtained by blending fats rich in POP and SOS. One of the fats used as a source of SOS is shea butter from which shea stearin (ShS) is obtained by fractionation. This work focuses on studying blends based on cocoa butter and shea stearin as a way to develop new lipid systems with improved properties for specific applications, and also to find out how ShS influences some properties of CB. To achieve all of these, in this research, the polymorphic and crystallization behaviour, the solid fat index (SFI), and the crystal morphology of CB, ShS, and some CB:ShS blends were investigated through differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized light microscopy (PLM) techniques