Survival in simulated gastric conditions

Samples (0.5 g) of dry, free and microencapsulated, probiotics were added to tubes containing 4.5 mL of pre-warmed (37 °C) and filter-sterilized simulated gastric juice (SGJ) based on a modified method (Wei et al. 2011). The SGJ consisted of 0.02 M phosphate-buffered solution (PBS) with 10 mg mL⁻¹ pepsin (P7000, Sigma), and pH was adjusted to 3.0 using 1 M HCl. The samples were incubated at 37 °C for 0, 30, 90, or 180 min at 80 rpm. After incubation, the splitting solution was added to neutralize the pH and release bacteria from the capsules, and the survivors were enumerated as described above. The challenge experiments were performed with three samples.