Biotechnological valorization of almond milk through fermentation with Lacticaseibacillus paracasei SP5, Pediococcus pentosaceus SP2, and Lactiplantibacillus plantarum ATCC 14,917

Abstract Plant-based beverages have gained significant market interest as alternatives to dairy milk due to lactose intolerance, allergies, and sustainability concerns. This study evaluated the fermentation of almond milk with three probiotic strains— Lactiplantibacillus plantarum ATCC 14917 (commercial), Pediococcus pentosaceus SP2, and Lacticaseibacillus paracasei SP5 (wild-type)—during 24 h fermentation and 3 weeks of refrigerated storage. Fermentation significantly enhanced the functional and microbiological properties of almond milk. Viable probiotic populations reached approximately 7.0 log CFU/mL after fermentation, peaked at ~ 8.5 log CFU/mL after 2 weeks of storage, and remained above 7.5 log CFU/mL by week 3. Total phenolic content increased from 0.98 ± 0.21 mg GAE/mL in control samples to 1.56–1.87 mg GAE/mL after fermentation (up to ~ 91% increase), with L. paracasei SP5 showing the highest values. Antioxidant activity also improved, reaching up to 0.90 mg Trolox equivalents/mL (2,2 Diphenyl-1-picrylhydrazyl, DPPH) and 0.70 mg Trolox equivalents/mL ({2,2 azinobis-(3-ethylbenzothiaziline-6-sulfonate}, ABTS), depending on strain and storage time. Fermentation induced substantial acidification, reducing pH from 6.5 to 6.8 in controls to 3.63–3.99 after storage, accompanied by increased titratable acidity (up to 0.89% lactic acid equivalents). Additionally, fermented samples exhibited reduced yeast and mold growth, indicating improved microbiological stability. Overall, probiotic fermentation enhanced the functional, antioxidant, and preservative properties of almond milk, with L. paracasei SP5 demonstrating the most pronounced effects.