Ultrasound-assisted enzymatic extraction of soluble dietary fiber from fresh corn bract and its physio-chemical and structural properties

The soluble dietary fiber from fresh corn bract (FCB-SDF) was extracted by ultrasonic-assisted cellulase method. The process parameters of FCB-SDF were optimized by Box–Behnken design (BBD), and the physio-chemical properties and structure of FCB-SDF obtained were investigated. The results showed that the optimal extraction conditions for FCB-SDF were enzyme concentration 1.58%, ultrasonic power 300 W, and extraction time 90 min. Under the above conditions, the FCB-SDF yield reached 21.21%. Compared with ultrasonic treatment group (U-SDF) and enzymatic treatment group (E-SDF), ultrasound-assisted enzymatic treatment group (UE-SDF) had higher WHC and OHC, but lower WSC. Its particle size was smaller, and a more microscopic pore structure was formed. UE-SDF had a low molecular weight of 204.41 KDa, and its monosaccharide composition had the highest arabinose content, followed by glucose. The SDFs obtained might be mainly composed of pectin and hemicellulose, E-SDF and UE-SDF contained more hemicellulose, and U-SDF contained more pectin.