From wheat gluten wastewater to functional biscuits: Extraction, characterization, and application of water-unextractable arabinoxylan in low-GI fermented biscuits.

In this study, water-unextractable arabinoxylan (WUAX) was recovered from wheat gluten wastewater, aiming to enhance its utilization and develop low glycemic index (GI) fermented biscuits for diabetics. The study first investigated the influence of crude water-unextractable arabinoxylan (CW) on the digestive and textural properties of biscuits. CW was then purified to obtain pure water-unextractable arabinoxylan (PW), and PW was characterized. Based on the biscuit formulation with CW, the effects of PW on biscuit quality, digestion and fermentation properties were further explored. Results indicated that biscuits with 20 % CW substitution exhibited an estimated GI (eGI) below 55 but increased hardness. Compared to 0 % PW group, the hardness of the biscuits in the 2 % PW group decreased by 29.37 %, the tightly bound water content increased by 68.88 %, and the eGI value decreased to 52.95. Fermentation of WUAX biscuits using fecal microbiota from diabetic or healthy mice reduced pH and sugar content in the system, while promoting the proliferation of probiotics, specifically HT002, Lactobacillus, and Akkermansia, and inhibiting pathogenic bacteria, including Proteus and Enterococcus. This study demonstrates the potential of utilizing wastewater-derived WUAX as a functional dietary fiber in low-GI foods, offering glycemic control and prebiotic benefits.