Effect of Agaricus bisporus polysaccharide flour and inulin on the antioxidant and structural properties of gluten-free breads

Enrichment of gluten-free bread (GFB) with mushroom polysaccharide and prebiotic is necessary to enhance its organoleptic and health attributes. This work investigated the enrichment effect of the GFB with Agaricus bisporus polysaccharide (ABP) flour and inulin. Volatile compounds, as well as the antioxidant and structural properties of the fortified GFB were evaluated. Sweet potato-glutinous rice flour was fortified with ABP flour and the same with inulin at different levels (3, 6 and 9%), besides a constant percentage of xanthan gum (0.5%) was added to all the blends. Addition of ABP flour resulted in higher levels of volatile compounds compared to inulin addition and the control. ABP flour formulation (F-3) had the highest total phenolic content (19.05 mg GAE/g), reducing power (5.31 mg/mL, EC50 value), DPPH (6.85 mg/mL, EC50 value), ABTS (8.86 mg/mL, EC50 value) radical-scavenging activities, and beta-carotene bleaching (13.22 mg/mL, EC50 value). Conversely, the control and inulin formulation (F-1) showed the lowest levels of these activities. The micrographs of the ABP flour formulations showed polyhedral, aggregated, and some spherical granules, whereas inulin formulations revealed spherical granules bound together with deformed granules. FTIR spectroscopy confirmed the presence of the amide I band and both alpha- and beta-glycosidic linkages. The current findings exhibited that ABP flour and inulin had good attributes to improve the antioxidant activity of GFB and modify its structural characteristics.