Comparative Analysis of Single-Strain and Consortium Probiotic Fermentation on the Chemical, Antioxidant, and Hypoglycemic Properties of Beetroot (Beta Vulgaris) Juice

Yap, Kai Hui (2025) Comparative Analysis of Single-Strain and Consortium Probiotic Fermentation on the Chemical, Antioxidant, and Hypoglycemic Properties of Beetroot (Beta Vulgaris) Juice. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Beetroot (Beta vulgaris) is a nutrient-rich vegetable known for its high content of bioactive compounds, including betalains, phenolics, and nitrates, which contribute to its antioxidant and potential hypoglycemic properties. Fermentation using probiotic bacteria has been widely explored as a strategy to enhance the functional properties of plant-based substrates. This study aimed to compare the effects of single-strain and consortium probiotic fermentation on the chemical composition, antioxidant activity, and hypoglycemic potential of beetroot juice. Three probiotic strains were selected: Lacticaseibacillus casei ATCC393 (LC), Lactobacillus delbrueckii subsp. lactis ATCC12315 (LD), and Lactiplantibacillus plantarum TAR4 (LP). A mixture design was applied to formulate combinations, and fermented juices were analyzed for growth (log CFU), total phenolic content, nitrate content, betalain content, pH, antioxidant activity (DPPH, ABTS, FRAP), and alpha-amylase inhibitory activity. Among the single strain fermentation, LC showed the most prominent fermentation performance by significantly enhancing microbial growth and DPPH radical scavenging activity. LD exhibited the highest alpha-amylase inhibition, indicating a strong hypoglycemic effect, while LP significantly increased nitrate content. The probiotic consortium did not show statistically significant interaction effects on chemical, antioxidant, nor hypoglycemic properties; however, microbial growth was significantly improved, suggesting synergism in viability but not in functional outputs. In conclusion, this study demonstrates that the health-promoting potential of fermented beetroot juice is highly strain-specific. LC, LD, and LP each contribute uniquely to different functional aspects, and targeted selection of strains is essential for desired outcomes. The consortium, while beneficial for microbial growth, may not always yield synergistic bioactive effects. Further research on optimizing co-culture conditions, metabolite profiling, and in vivo validation is encouraged to maximize the benefits of multi-strain probiotic fermentation in functional food development. Keywords: Beetroot; fermentation; probiotic consortium; antioxidant; hypoglycemic