Caratterizzazione microbiologica di polvere di cacao e di cioccolato del commercio [Microbial characterization of retail cacao powders and chocolate bars]

A microbial characterization was performed in cocoa powder and chocolate bars of three batches of 5 different brands marketed in Italian supermarkets. The results showed a variable microbial population consisting of mesophilic and thermophilic spore-forming in both types of products. The chocolate bars were also contaminated with molds of environmental origin. The spores mainly originate from the raw materials, the cocoa beans, as the heat treatments involved (roasting of the beans and conching of the chocolate) are not sufficient to produce commercial sterility. Furthermore, the identified spore-forming species have often been isolated from cocoa beans. Molds, isolated from chocolate, seem to have a strictly origin linked to the final production environment (packaging). In any case, the level of contaminants is limited (<2 log CFU/g), they do not develop in both products, due to their low aw (<0.6) and do not affect the healthiness of the products. However, a case of mold development in chocolate bars has been observed. The growth can be explained by a flowering of cocoa butter accompanied by the presence of humidity originating from flowering or acquired during the packaging phase. Among the isolated species Penicillium lanosocoeruleum is known for its high xerotolerance.