Probiotic Potential of Saccharomyces cerevisiae var. boulardii, Weizmannia coagulans and Lacticaseibacillus rhamnosus as Commercial Supplements: In Vitro Gastrointestinal Kinetics, Pharmaceutical Stability and Antioxidant Support in Chamomile Tea

The gut microbiome plays a central role in human health, and probiotics are widely used to support microbial balance, though their efficacy depends on multiple factors. This study assessed the potential of commercial probiotics Saccharomyces cerevisiae var. boulardii, Weizmannia coagulans and Lacticaseibacillus rhamnosus by evaluating in vitro gastrointestinal kinetics, pharmaceutical stability, and antioxidant effects in chamomile tea. Growth across a broad pH range was modeled kinetically, while survival and inactivation were quantified in simulated gastric and intestinal fluids. Antibiotic and antifungal susceptibility was determined using disk diffusion, and antioxidant activity of fortified chamomile tea was assessed via DPPH radical scavenging. Results revealed distinct strain-dependent responses. S. cerevisiae var. boulardii and W. coagulans showed the highest gastrointestinal tolerance. The increase in fluid volume reduced survival during the gastric phase but improved survival in the intestinal phase, reflecting different stress responses. Antimicrobial susceptibility also varied, with S. cerevisiae var. boulardii exhibiting the highest resistance. Probiotic fortification enhanced chamomile tea’s antioxidant capacity, particularly for S. cerevisiae var. boulardii and L. rhamnosus. These findings provide quantitative insight into strain- and volume-dependent gastrointestinal performance, guiding the optimization of capsule formulations and the development of clean-label products combining probiotic and antioxidant benefits.