Oil Migration Through Cocoa Butter: The Solubilization-Recrystallization-Diffusion (SRD) Model

Abstract

Oil migration is a serious quality problem for the food industry and is a leading factor in the deterioration of most products. Chocolate enrobed products (e.g. chocolate-coated biscuits, filled chocolate bars or shells, wafers with fat-based cream fillings and, pralines) are particularly vulnerable to this phenomenon and it causes significant softening of chocolate coatings, hardening of fillings, bloom formation and a corresponding decrease in consumer acceptability. Many studies have already tested the effects of storage conditions and variations in filling and chocolate compositions; however, the exact mechanism of oil migration still remains hypothetical and controversial. A diffusion model, commonly used in biology and medicine to define mass transfer, has also been applied to food systems in order to explain mass transport processes. However, considering the heterogeneous characteristics of certain food media such as chocolate (mixture of cocoa, sugar and milk particles in a fat matrix), it is conceivable that other mechanisms like capillary flow, matrix dissolution and recrystallization may also play a role in oil migration.