Probiotic bacilli incorporation in foods: is really so easy?

Foods containing probiotic bacilli spores are becoming more and more popular because of their resistance to acidic pH, low water activity, and, most importantly, heat processes. Even though spores may engage in some functions, such as immunomodulation, the majority of the beneficial characteristics are unique to vegetative cells. As matter of fact, the development of foods fortified with spores ought to even ensure the germination of the spores along the gastrointestinal tract. In this perspective, vegetative cells derived from spore germination were separately counted on a minimal medium because the traditional approach is based on the use of complex media that allows the spores to germinate independently by stimuli arising from processing or digestion. In more detail, three Bacillus spp. cultures with claimed probiotic properties were added to two entirely unrelated foods (pasta and croissants), and tolerance, as well as germination, was monitored before and after exposure to simulated GIT, as well as at the beginning and end of the products shelf life. For the first time, potential probiotic bacilli were included in a frozen ready-to-bake product. Germination appears to be prevented in this instance, and the impact of baking, matrix and cold storage on spores was examined independently. All of the parameters appeared to contribute, although further research is needed due to the unpredictable behavior exhibited by spores during freezing.