Triacylglycerol migration and bloom in filled chocolates: effects of low-temperature storage

This study investigated die effect of storage temperature on triacylglycerol (TAG) migration, visual fat bloom and taste of industrially produced milk chocolates with a hazelnut-based filling. The chocolates were stored for up to 10 months at 18 degrees C, either directly after production or with the inclusion of a variable time at -20 or 4 degrees C immediately after production and prior to further storage at 18 degrees C. TAG migration from the filling through the chocolate shell was quantified by HPLC analysis of chocolate sampled from the chocolates' surface. Both [OOO/SOS] and [LOO/SOS] were used as markers for oil migration. Compared to storage at 18 degrees C only, chilling or freezing of the chocolates for part of the storage time was found to reduce the amount of TAG migration. Effects on diffusion, capillary transport and TAG immobilization during the thermal treatment can be raised as possible reasons for this decrease. Furthermore storage at -20 degrees C decreased oil migration during subsequent storage at 18 degrees C. This suggests a crystallization effect during the storage at -20 degrees C, leading to permanent (micro) structural changes. Although a thermal treatment at 4 degrees C compared to -20 degrees C was less effective in retarding TAG migration, storage at low positive temperatures immediately after production appears already beneficial in the prevention of visual fat bloom. Adverse effects of the thermal treatments on the chocolates' taste were not observed