Ultrasonication and enzymatic treatment of apple and orange bagasses: Molecular characterization of released oligosaccharides and modification of techno-functional and health-related properties

Apple and orange bagasse were subjected to ultrasonication (US) and subsequent enzymatic hydrolysis (EH) with a cellulase-pectinase mixture. US did not affect oligosaccharide profile and water and oil holding capacities (WHC/OHC) in both substrates but enhanced bile acid adsorption capacity (BAC) and total phenolic content (TPC) in orange bagasse. EH increased glucose/xylose and xylobiose (XOS-2) contents and caused the release of cellobiose (COS -2) and pectin derived oligosaccharides (POS), mainly methylated oligogalacturonides with degree of polymerization (DP) 3-4. Hydrolyzed orange bagasse exhibited higher total POS content (31.56 g/100 g bagasse) than apple bagasse (21.13 g/100 g bagasse), but apple bagasse showed higher diversity in methylated and acetylated POS. After combined treatment, POS quantities in apple bagasse were enhanced whereas in orange bagasse COS -2 and POS-2 formation significantly increased, making physical opening before enzymatic degradation an effective strategy for maximizing oligosaccharide concentrations. EH decreased techno-functional properties and TPC but led to a 24.9 % increase of BAC in apple bagasse and a 7.8 % increase in orange bagasse, highlighting that the efficacy of US and EH depends on the applied DF substrate. This study offers guidance for selecting modification technologies for fruit by-products to obtain ingredients with elevated oligosaccharide content, improved techno-functional and health -related properties.