Comparative study of chemical and technological properties of Brazilian cocoa butter and industrial blends: crystallization kinetics and polymorphic behavior

摘要

Cocoa butter is the characteristic fat ingredient of chocolate industries, presenting itself as the most important component in all formulations. Its crystallization is a critical factor associated with the structure and properties of many confectionery foods. The stability of rich-fat processed products is influenced by changes in crystallization processes. With respect to these characteristics, the crystallization kinetics, which involves the stages of nucleation and crystal growth, profoundly influences the final solidification of cocoa butter. Polymorphism can be defined as a result of differences in crystal packing. Depending on the origin of cocoa almonds, the chemical composition of cocoa butter may vary and this reflects mainly on crystallization rates and polymorphic changes during the processing steps. In this work, the parameters of crystallization kinetics and polymorphism of three industrial standardized cocoa butter samples and cocoa butter samples from three different Brazilian states were compared. The crystallization kinetics was performed by nuclear magnetic resonance and characterized according to induction period (τ_(SFC)), maximum solid fat content (SFC_(max)) and time required to obtain 50% of maximum solid fat content (t_(1/2SFCmax)). The original Avrami equation was used to model the crystallization process. The polymorphic habit was determined through X-ray diffraction. τSFC values ranged from 6 to 8 minutes for the evaluated samples and proved to be identical and slightly lower for the industrial blends of cocoa butter. The percentages for the SFC_(max) varied between 78.4 and 89.5% for all samples. In particular, the values of t_(1/2SFCmax) and the Avrami parameters differentiated the industrial blends and the Brazilian samples on the crystallization rate. The standardized blends were characterized by higher crystallization rates and more uniform structuring, suitable for use in tropical areas. All evaluated samples exhibit the polymorphic form V, desirable for the production of chocolates, in the conditions of analysis.