Dried date paste as carrier of the proposed probiotic Bacillus coagulans BC4 and viability assessment during storage and simulated gastric passage

This work aimed to determine the suitability of dried date paste, an intermediate a_w (0.5–0.6) matrix, as a carrier of the spore-former Bacillus coagulans BC4 in terms of survival during storage and in vitro gastric simulation. Freeze-dried B. coagulans BC4, mostly in the spore form, was added to 5 different dried date paste preparations obtaining an initial concentration between 7.87 and 8.12 log CFU g⁻¹. Although the characteristic a_w of the tested matrix has previously been described as non-optimal for maintaining the viability of non-spore-forming dehydrated probiotics, no significant variation (P > 0.05) regarding viability and spores percentage was detected between the pastes after 45 days of storage under aerobic and anaerobic conditions. Furthermore, after in vitro gastric passage, B. coagulans showed no significant viability loss (P > 0.05) neither when embedded in date paste nor as free spores. Our results showed that B. coagulans BC4 spores embedded in dried date paste are highly stable during storage at room temperature and in vitro gastric passage.