Identifying Potent Oxalate-Degrading LAB Strains for the Development of Low Oxalate Rhubarb-Based Juice Products

Rhubarb, a popular culinary ingredient, is notably high in oxalates, which can contribute to the formation of kidney stones, particularly in individuals susceptible to hyperoxaluria. In light of emerging evidence showcasing the beneficial properties of lactic acid bacteria in dietary oxalate degradation, this study endeavors to identify specific LAB strains capable of efficaciously reducing oxalate levels in rhubarb-based juice. A total of 34 LAB strains, isolated from traditional dairy products, were screened for oxalate-degrading potential. The strains characterized included Lactiplantibacillus plantarum, Levilactobacillus brevis, Enterococcus faecalis, Enterococcus faecium, and Streptococcus thermophilus. Employing titration, an enzymatic oxalate assay, and HPLC, we evaluated the oxalate degradation capabilities of each isolate. Notably, Levilactobacillus brevis (M8) emerged as the most effective strain, exhibiting remarkable oxalate-degrading activity. Subsequently, the strain was utilized in the fermentation of rhubarb-based juice, leading to an optimized fermentation process that involved varying sugar substrates and incubation periods. Fermentation with Levilactobacillus brevis (M8) over a 96-h period resulted in a significant 17.5% reduction in oxalate content, decreasing the concentration from 10.44 mmol/L in the control to 8.50 mmol/L in the optimized fermented juice, while maintaining desirable sensory attributes. The findings underpin the promising application of Levilactobacillus brevis (M8) as an adjunct in the formulation of functional, low-oxalate beverages for at-risk populations.