Physical Properties of Cocoa Butter/Vegetable Oil Blends Crystallized in a Scraped Surface Heat Exchanger

Abstract

AbstractBlends of cocoa butter with soybean oil (CB/SO) or canola oil (CB/CO) were crystallized at either of two agitation rates (100 or 1,000 rpm) and at two process temperatures (14 or 17 °C) in a scraped surface heat exchanger (SSHE). The physical properties were characterized at the SSHE output and during storage (14 and 28 days) at 15 °C. At the SSHE output, the CB/CO and CB/SO systems that had been processed at 100 rpm presented a more solid‐like character than systems processed at 1,000 rpm despite the fact that the former systems contained a higher solid fat content than the latter. The degree of secondary crystallization increased with increasing shear rate. Nevertheless, the polymorphic behavior of cocoa butter crystals resembled the behavior observed under static isothermal crystallization conditions. At the SSHE output, systems of either blend contained a mixture of β′ and β crystals. During storage, β′ converted to β in both blends, although it did so to a higher extent in the CB/CO systems. Crystal ripening, observed in the CB/CO blend, provided stability to the systems during storage. In contrast, the CB/SO system increased its hardness by a slow sintering process. The polymorphism and hardness evolution in the blends under study were found to be associated with the molecular compatibility of the triacylglycerols in the cocoa butter and the vegetable oils tested.