Title : Assessment of prebiotic activity and stability of synbiotic metabolites in irradiated adlay bran (Coix lacryma-jobi) and bifidobacterium consortium through in-vitro simulated digestion
Abstract:
The growing demand for functional foods has directed research into prebiotic ingredients that enhance gut microbiota. Adlay bran, a nutrient-rich by-product of Adlay grain processing, contains fiber, phenolics, flavonoids, and antioxidants with potential functional applications. Electron beam irradiation is a promising technology for sterilizing and modifying plant-based prebiotics to improve their bioavailability. This study investigates the effects of electron beam-irradiated Adlay Bran (Coix lacryma-jobi) and a Bifidobacterium consortium that consists of 5 strains on prebiotic activity and metabolite stability under in- vitro simulated digestion. The goal is to determine the optimal irradiation dose for enhancing soluble dietary fiber (SDF), polyphenols, and flavonoids while evaluating its prebiotic potential in supporting Bifidobacterium growth and metabolic activity. Adlay Bran was irradiated at 0–30 kGy, and its SDF, total phenolics, and flavonoids were analyzed using MCDA-TOPSIS and Response Surface Methodology (RSM) to determine the optimal dose. Prebiotic activity was assessed based on Bifidobacterium growth, fermentation capacity (optical density and CFU counts), and pH changes under controlled conditions. Results indicate that 15 kGy maximized SDF content and bioactive compound retention, while 10 kGy provided a balance between food safety and nutrient preservation. Bifidobacterium growth significantly improved with 10 kGy-irradiated Adlay Bran, yielding higher optical density (2.316 OD) and CFU counts (2.21 CFU/mL) than controls, confirming enhanced metabolic activity. Metabolite stability analysis revealed that bacteriocins and organic acids maintained their structural integrity and bioactivity post-fermentation, contributing to antimicrobial effects. Phenolic compounds and flavonoids exhibited increased bioavailability that may due to microbial bioconversion, enhancing their antioxidant potential and functional stability during in-vitro digestion. The findings demonstrate that electron beam irradiation enhances the prebiotic properties of Adlay Bran by optimizing dietary fiber conversion and bioactive compound stability. This study supports its application as a functional prebiotic ingredient in synbiotic formulations, offering a novel approach to gut health enhancement.
