Batteri sporigeni nella filiera del cioccolato e prodotti derivati. Metodi di rilevazione e controllo

Chocolate is a food product obtained from by processing cocoa beans. At the end of the bean transformation process, characterized by high heat treatments (such as roasting), the chocolate microbiota is mainly composed by members of Bacillus spp. genus. The micro-organisms belonging to this genus are able to generate endospores very resistant to heat treatments, in particular those produced by Bacillus subtilis complex. The most resistant can also survive heat treatments as high as 150°C for 10 minutes. As far as chocolate products are concerned, it has been observed how psychrotrophic spore-former microorganisms can be present in high concentrations and drastically reduce the shelf life of food products in which chocolate is an ingredient; the vegetative spore formers can grow even if refrigeration temperatures are strictly maintained, during storage. Considering the heat resistance of the spores, however, spore-forming bacteria can be included in the chocolate derivate to obtain probiotic chocolate. This is the case of the Bacillus coagulans whose ability to form endospores allow the survival under stressful conditions and to produce active vegetative forms in the final product. The research of spore-forming bacteria can be carried out following the traditional methods (agar enumeration media or MPN technique), but nowadays biomolecular techniques are available for bacteria identification and characterization, used for the study of contamination and microbial dynamics in chocolate (PCR, DGGE and AFLP). In conclusion, the spore-forming microorganisms can contaminate the cocoa and the derivative productions therefore the control of raw materials and environments along the production chain is fundamental. However, their heat resistance can be exploited to improve the characteristics of the final products, through the addiction of probiotics, which can then improve/maintain consumers' health.