Assessment of fermented milk tablets containing Lacticaseibacillus paracasei SD1 and Lacticaseibacillus rhamnosus SD11 in postbiotic and live probiotic forms: an in vitro study

Fermented milk is commonly used to preserve live probiotics, but its limited shelf life is a challenge. Tablet forms offer an innovative solution, and recent researches indicate that postbiotics can provide similar benefits to live probiotics. This study aimed to optimize fermented milk preparation using Lacticaseibacillus paracasei SD1 and Lacticaseibacillus rhamnosus SD11 and to assess their effectiveness when incorporated into fermented milk tablets. The study investigated the effects of temperatures (30 degrees C and 45 degrees C) for fermented milk preparation using single and combined probiotic strains and then examined anti-bacterial activity, suppression of pro-inflammatory cytokines, growth inhibition of Caco-2 cells, and butyrate concentration. Additionally, fermented milk tablets containing either postbiotics or live probiotics were prepared and evaluated for efficacy and stability. The results demonstrated that fermented milk at 45 degrees C using a 1:1 combination of L. paracasei SD1 and L. rhamnosus SD11 exhibited probiotic potential in all parameters. As a result, this formulation was selected to prepare fermented milk tablets. The tablets, whether containing postbiotics or live probiotics, effectively inhibited pathogen growth, reduced pro-inflammatory cytokine levels, suppressed Caco-2 cell proliferation, and promoted butyrate production. The beneficial efficacy remained stable for 6 months of storage, and fermented milk tablets maintained probiotic levels above 8 log cells g-1 after 6 months at 4 degrees C. However, at 25 degrees C, live probiotic tablets lost viability after 2 months, while postbiotic tablets retained heat-killed cells at 4 log cells g-1 for 6 months. Therefore, fermented milk tablets may be an alternative way to preserve probiotics and their biological benefits for longer.