Gloss and colour of dark chocolate during storage

Abstract

The appearance of chocolate is greatly affected by bloom, which occurs during storage under unfavourable conditions. This phenomenon develops due to different causes, such as poor tempering, addition of incompatible fats, incorrect cooling methods, warm or fluctuating storage temperature, etc. The effect of storage temperature (4, 20, 25 and 30°C) on gloss (60 and 85° angle) and colour (CIE L*a*b*) of dark chocolate bars was analysed throughout 30 days of storage. Three kinds of dark chocolate were studied: two from the same brand containing 99 and 70% cocoa, and a third one from another brand, containing 70% cocoa. Gloss change of chocolate throughout storage time followed a similar pattern in all cases: a decrease until an asymptotic value is reached, which is exacerbated at higher storage temperatures. The influence of temperature was related to the difference between storage temperature and the melting range of cocoa fat. Only when the visual fat bloom reaches a relevant level is the colour of the product affected. Changes in both optical parameters were highly-position dependant within the same sample. © 2007 SAGE Publications.