Effect of Submerged Fermentation with Bacillus subilis var. natto and Lactiplantibacillus Plantarum TAR4 on the Chemical, Physicochemical, Antioxidant, and Anti-Diabetic Properties of Jicama Juice and Pomace

Teo, Shi Yan (2025) Effect of Submerged Fermentation with Bacillus subilis var. natto and Lactiplantibacillus Plantarum TAR4 on the Chemical, Physicochemical, Antioxidant, and Anti-Diabetic Properties of Jicama Juice and Pomace. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Fermentation is an age-old process used to enhance bioactive compounds in food. Jicama, a nutritious root vegetable rich in dietary fiber and prebiotic properties remains underutilised. This study aimed to investigate the effects of submerged fermentation with single and co-cultured lactic acid bacteria (LAB) (Bacillus subtilis var. natto and Lactiplantibacillus plantarum TAR4) on the chemical, physicochemical, antioxidant, and anti-diabetic properties of jicama juice and pomace. Sterile jicama pomace and juice were inoculated with 10% (v/v) LAB cultures (B. subtilis, L. plantarum or their co-culture) fermented for 24 hours. The result showed a significant increase in titratable acidity and a decrease in pH post-fermentation. L. plantarum thrived in both single and co-cultures, while B. subtilis growth was not favoured in neither juice nor pomace. Antioxidant activity (DPPH, ABTS, FRAP) of both juice and pomace was not significantly enhanced by any fermentation. However, fermentation significantly increased TPC and TFC in pomace, while reducing both contents in juice. Total sugar in pomace was significantly reduced after fermentation with L. plantarum and the co-culture, although total dietary fiber remained unchanged. Fermentation significantly increases the α-amylase inhibitory activity of all samples (P<0.05), with L. plantarum in a single culture showing the highest activity in juice and pomace. This study concluded that jicama juice and pomace are suitable substrates for L. plantarum growth. Although B. subtilis supported L. plantarum growth in co-culture, it did not significantly increase the antioxidant or anti-diabetic activity of neither jicama juice or pomace. These findings provide valuable insights for transforming jicama into functional foods through L. plantarum fermentation.