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

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 degrees C isothermal crystallization of all the blends is a two-step process with formation of alpha crystals in the first step and formation of beta' 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 alpha- 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 alpha mediated beta' crystallization. Picturing of the microstructure showed that for the CB and the blends up to 50% large microstructures, indicative of the beta(V) 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.

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