Influence of Physical Properties of Fat on Product Quality, Shelf-Life and Consumer Acceptance of Chocolate-Coated Products

In chocolate-coated products, oil migration in fats can lead to chocolate softening, filling hardening, discoloration, and lower consumer acceptance. This study examined three different fats (soy- palm-, and palm-kernel (PK) based), crystallized under different conditions (cooling rate and use of high intensity ultrasound (HIU)) to examine how the crystallization conditions impact the physical properties of confectionery products. These conditions produced fats with high and low oil binding capacities (OBCs); the ability of crystal networks to entrap liquid oil. Model systems were created to examine measurable quality degradation and consumer acceptance of chocolates placed in contact with the fats; one with fat alone while the second mixed the fat into sugar or nut flour. At 48 hours, 1, 4, 12, and 24 weeks, measurements of quality of the fillings and the chocolates were taken (including melting behavior, liquid/solid rheological behavior, texture, color, and crystal structure. After 12 weeks, a consumer acceptance panel ranked their chocolate liking based on overall acceptance, appearance, aroma, flavor, texture, and mouthfeel. The most significant differences were seen with the chocolate color, hardness, and melting behavior. Control chocolates typically increased in whiteness, had consistent hardness, and increased in the amount of melting energy. Sample chocolates, especially those with low OBC fats, frequently significantly decreased in whiteness, primarily due to significant increases in yellowness. All chocolate samples softened significantly over time, as solid crystal material dissolved as seen with a lower melting energy and less defined crystal structures in x-ray diffraction analysis. The high OBC PK (75% fully hydrogenated PK, fast cooled, without HIU) performed the best in the measurements as it contained the most solid material, softened the least, and had the latest decrease in the required energy to melt the chocolate. However, the high OBC palm (100% palm-based oil, fast cooled, with HIU) performed the best in the consumer acceptance panel, showing no significant differences from the control in four of the six parameters. In conclusion, the condition with a high OBC and the least quality degradation during the measurements was not liked the most by consumers. This highlights the importance of understanding all aspects of shelf-life.