Defatted rice bran arabinoxylan: Improved extractability, prebiotic potential, and application in reduced-fat ice cream

This study aimed to improve arabinoxylan (AX) extractability from defatted rice bran (DFRB) using hydrothermal, acid, and enzymatic pretreatments prior to alkaline extraction, followed by evaluation of their physicochemical, in vitro prebiotic, and specific application properties, including solubility, color characteristics, antioxidant activity, in vitro digestibility, bacterial growth responses, and functional performance in reduced-fat ice cream (overrun and melting stability). Hydrothermal pretreatment produced AX with the highest purity (24.71 %), solubility (87.67 %), and antioxidant activity (6.19 mg TE/g), along with improved lightness compared with untreated, acid-treated, and enzymatically treated fractions. In vitro digestion confirmed that hydrothermally pretreated AX (H-AX) resisted hydrolysis (< 23 %), supporting its classification as a non-digestible dietary fiber. H-AX selectively stimulated Lactobacillus casei and Lactobacillus sake, providing preliminary in vitro evidence of fermentability rather than confirmed in vivo prebiotic efficacy. Incorporation of H-AX into reduced-fat ice cream maintained overrun and reduced melting rate, enhancing stability. While AX imparted darker coloration, this trait could benefit darker-flavored products. Overall, hydrothermal pretreatment was the most effective strategy under the conditions examined in this study to enhance AX recovery and functionality, although long-term stability, process economics, and industrial scalability were not evaluated. The findings demonstrate a sustainable approach to valorize DFRB into multifunctional food ingredients with dual in vitro prebiotic and techno-functional potential, while highlighting the need for further in vivo validation before physiological benefits can be claimed.