Fermented Aloe vera Juice: A Prebiotic Potential and Metabolite Profile Analysis

Probiotics are health-beneficial microorganisms found in the human digestive tract, and Aloe vera (Aloe vera var. chinensis (L.) Baker) is potentially a source of prebiotics that support the growth of probiotics. Therefore, this research aims to analyze the effect of Aloe vera juice on Lactobacillus rhamnosus ATCC 9595 growth, total lactic acid, total reducing sugars, antioxidant activity, total Short Chain Fatty Acid (SCFA), and metabolite profile. Four experimental groups of Aloe vera concentration were used (0%, 25%, 50%, and 75%), each with three different incubation times (0, 24, and 48 hours). Bacterial growth was analyzed using Total Plate Count and pH measurement, while total lactic acid, total reducing sugars, and antioxidant activity were analysed by titration, 3,5-dinitrosalicylic acid (DNS) technique, and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) test, respectively. SCFA was measured using Gas Chromatography-Mass Spectroscopy (GC-MS), and substances potentially associated with probiotic metabolic activities were identified using targeted Ultra High-Performance Liquid Chromatography (UHPLC)-High-Resolution Mass Spectrometry (HRMS). The results showed that after 48 h, Aloe vera juice with a concentration of 50% (v/v) significantly increased bacterial colonies by 85.49% and antioxidant activity by 36.13%, 75% (v/v) significantly decreased pH by 24.67%, and 25% (v/v) significantly increased total lactic acid. Acetic acid was detected during SCFA assessment, with the highest concentration found in the group of 25% Aloe vera. Targeted UHPLC-HRMS analysis identified aloe emodin, butyric acid, lactic acid, citric acid, and hydroxy aloin in the fermented Aloe vera juice. The highest metabolite content was citric acid (area max 2.95x10 9 ), a tricarboxylic acid, and all experimental groups had no significant effect on lowering total reducing sugars. These results present the promising prospects of Aloe vera juice as a natural resource for prebiotics to thrive and generate beneficial metabolites with antioxidant properties through metabolic processes.