Tempering, polymorphism and fat crystallization during industrial chocolate manufacture: Regimes, behaviours and their effects on finished chocolate quality

Abstract

Tempering, a technique of shearing chocolate mass at controlled temperatures is used to promote cocoa butter crystallization in a thermodynamically stable polymorphic form. During chocolate manufacture, the process is used to obtain the stable form V (or β2) of cocoa butter having a melting temperature of 32-34 °C, which gives the desired glossy appearance, good snap, contraction and enhanced shelf life characteristics. However, the tempering sequences, their behaviour during pre-crystallization, the consequential regimes attained and their effects on product quality characteristics are not very well understood. Variations in temper regimes attained during pre-crystallization of chocolates influence their crystallinity, polymorphic status and other physical quality characteristics. Over-tempering causes increases in product hardness, stickiness with reduced gloss and darkening of product surfaces. Under-tempering induces fat bloom in products with consequential quality defects in structure, texture, melting properties and appearance (colour and surface gloss). Thus, the different temper regimes attained during pre-crystallization result in wide variations in product quality attributes with varied influences on quality. In a modern competitive confectionery market, understanding the variables leading to chocolate pre-crystallization during tempering and effects of the regimes attained on the quality of the finished products are vital to assurances in quality and shelf characteristics. © 2011 by Nova Science Publishers, Inc. All rights reserved.