Unlocking Value-Added Biomolecules and Prebiotic Potential in Defatted Rice Bran
through Deep Eutectic Solvent Extraction

This study investigates the phenolic acids and other biomolecules (such as phytic acid, reducing sugar, and protein) present in the extract of defatted rice bran ( DFRB) , as well as its primary prebiotic properties. The DFRB was extracted using a sodium propionate/glycerol (Na:Gly deep eutectic solvent (DES) at a ratio of 1:8 (w/v) at 70°C for 5 h. The results revealed that Na: Gly DES yielded soluble- bound glycosylated phenolics ( 47% w/ w) and soluble- bound esterified phenolic acids (45% w/w), with a minor presence of free phenolic acids (8% w/w). Moreover, value-added biomolecules, including protein, reducing sugar, and phytic acid, were detected in the DFRB extract at concentrations of approximately 7. 08, 4. 26, and 1.14 mg/g, respectively. Additionally, a correlation between antioxidant activities and phenolic content was observed. The study also examined the main prebiotic capabilities of DFRB extract, which led to enhanced growth of Lactobacillus plantarum ATCC14917. Conversely, the observed growth of Escherichia coli ATCC 25922 is restricted, reaching statistical significance. Furthermore, the DFRB extract demonstrated the ability to inhibit Staphylococcus aureus ATCC 25923, as evaluated by the agar well diffusion method. In conclusion, Na:Gly DES effectively extracts bioactive compounds from DFRB, demonstrating promising prebiotic potential. These findings underscore the potential of novel green solvents for extracting

valuable compounds from agricultural sources, offering opportunities for sustainable utilization and value addition across various industries