Crystallization and polymorphic behavior of enzymatically produced sunflower oil based cocoa butter equivalents

Abstract

A multi‐methodological approach was used to study the isothermal crystallization of cocoa butter (CB) in the presence of sunflower oil based cocoa butter equivalents (CBEs). pNMR, DSC, oscillatory rheology, XRD, and PLM were used for this purpose. All the techniques confirmed that at 20°C isothermal crystallization of all the blends is a two‐step process with formation of α crystals in the first step and formation of β' crystals in the second step. The blends with high amount of CBEs contained more high‐melting triacylglycerols (TAGs) and diacylglycerol (DAG) in compare with CB acting as seed crystals enhancing the formation of α‐ crystals in the first crystallization step. Therefore, the induction time of the first crystallization step was inversely related to the amount of CBE. In contrast, the subsequent polymorphic transition was delayed by the presence of the CBE due to their low‐melting TAGs. However, adding up to 5% CBE did not change the Foubert's parameters for isothermal crystallization significantly. All the blends (except 5% HOSO CBE), had α mediated β' crystallization. Picturing of the microstructure showed that for the CB and the blends up to 50% large microstructures, indicative of the βV polymorph developed during storage. At 100%, a dense network of spherulites was formed at the beginning of the crystallization period, but upon further storage, no large morphological changes were observed.Practical applications: In recent years, the production of CB has been delayed owing to its cultivation difficulty and low yield due to pest attack, while the world cocoa prices have increased with rising demand and higher chocolate consumption. Therefore, there is a need to develop low‐priced and appropriate alternatives to CB. Accordingly, in this study two sunflower oil based CBEs were produced with fatty acid mixtures in the presence of immobilized 1,3‐regiospecific lipase. The results from this study could help the fats and oils industries to extend their knowledge on the crystallization and polymorphic behavior of two enzymatically produced sunflower oil based CBEs.In this study two types of sunflower oil (high oleic and high stearic high oleic) with fatty acid mixtures were inter‐esterified in a solvent‐free system catalyzed by 1,3 specific enzyme, Lipozyme RM IM, to produce sunflower oil based CBEs containing three main triacylglycerols of cocoa butter, that is, POP, POSt and StOSt. A multi‐methodological approach was used to study the isothermal crystallization of CB in the presence of enzymatically produced sunflower oil based CBEs. DSC, pNMR, oscillatory rheology, XRD, and PLM were used for this purpose.