Evaluating the impact of temperatures and exposure times on probiotics viability under pre- and post- technological...

Microorganisms such as probiotic yeasts and lactic acid bacteria are capable of surviving-and in some cases thriving-under challenging conditions, including varying feed compositions, moisture levels, and high temperatures typically encountered during feed processing, such as steam pelleting. The primary objective of this study was to evaluate the effect of different temperatures and exposure times on the viability of yeast- and lactic acid bacteria-based probiotics in aqueous solution. Following this, the probiotics were freeze-dried and incorporated separately into a feed matrix to assess their survival during both simulated and actual pelleting processes. In addition, a comparative analysis was conducted to evaluate the viability of Saccharomyces boulardii RC009 under two different drying methods: freeze-drying and fluidized bed drying. All strains evaluated exhibited thermoresistance across the tested temperature range, with yeasts demonstrating greater resistance than bacterial strains. Notably, Saccharomyces spp. and Pediococcus pentosaceus showed the highest thermal tolerance. This enhanced resilience may be attributed to the presence of heat shock proteins (Hsps) and antioxidant defense systems in yeasts, and the production of heat-stable exopolysaccharides (EPS-DPS) in P. pentosaceus. Building on these findings, the freeze-dried probiotics were successfully integrated into a feed matrix and subjected to granulation processes to evaluate their viability post-processing. To our knowledge, this is the first study to systematically assess the impact of temperature and exposure time on probiotic viability during both pre- and post-technological treatments in the context of feed production.