Biorelevant assessment of commercial probiotics using porcine gastrointestinal fluids

Aims: Porcine gastrointestinal fluids offer biorelevant alternatives to human fluids for assessing probiotic viability due to their similar pH, enzymes, and bile salts. Despite extensive research on synthetic fluids, porcine fluids remain underexplored. This study evaluated commercial probiotic survival in porcine gastric fluid (PGF) and porcine intestinal fluid (PIF), bridging in vitro simulations with human and veterinary applications. Methods and results: Representative doses of commercial probiotic products and 10⁶–10⁸ colony forming units (CFU)/ml suspensions of commercial cells were incubated at 37°C in PGF (pH 3.38 ± 0.03) and PIF (pH 6.41 ± 0.01) obtained from healthy pigs from an abattoir. Viability was quantified through serial dilution and enumeration of CFU at different time points. Significant differences were observed between the commercial products and the free cells. The commercial products and cells showed significant decreases in viability in PGF after 180 min. Differences in cell viability were also observed among the products. However, the commercial probiotic products retained their viability during 240 min of simulated small-intestinal tolerance in PIF. A 1–1.5 log reduction in viable count was noted for the commercial cells in PIF during the first 30 min after which viability was maintained. Conclusion: This study established porcine gastrointestinal fluids as a biorelevant alternative to synthetic simulations and human-derived fluids, which involve greater ethical complexity for probiotic viability assessment. The findings highlight the importance of developing strategies to enhance probiotic resilience during gastric transit, the main barrier to oral survival, ensuring their functional delivery to the intestinal tract, where their benefits can be maximized.