Antioxidant and physicochemical properties of soluble dietary fiber from garlic straw as treated by energy-gathered ultrasound

This study evaluated the effect of energy-gathered ultrasound treatment on the antioxidant and physicochemical properties of soluble dietary fiber (SDF) from garlic straw. Results showed ultrasonic power and time play an important role in the antioxidant activity of SDF. The strongest activity of scavenging hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was obtained at ultrasonic treatment of 100 W for 20 min. SDF modified by ultrasound exhibited improved water holding capacity, oil holding capacity, swelling capacity and cholesterol binding capacity. Ultrasonic-treated SDF had lower viscosity than that of untreated SDF. Furthermore, atomic force microscopy (AFM) measurement showed that ultrasound degraded SDF into fragments with smaller particle size. Ultrasound treatment did not change the primary structure of SDF in the test conditions according to the result determined by FTIR. The overall results indicate that SDF from garlic straw treated by energy-gathered ultrasound has great potential to be used in functional foods