Modification of insoluble dietary fiber from garlic straw with ultrasonic treatment

The aim of this study was to investigate modification of insoluble dietary fiber (IDF) from garlic straw with ultrasonic processing technology. The functional, physicochemical, and structural properties were evaluated. Based on the uniform design (UD) method, initial temperature of 45 °C, ultrasonic power of 535 W, and time of 41 min were considered as the optimum ultrasonic conditions for preparation of IDF with good in vitro hypolipidemic ability. Ultrasonic‐treated IDF exhibited better functional and physicochemical properties than untreated IDF with significant difference (p < .05). Structural analysis from scanning electron microscope and Fourier transformed infrared spectroscopy indicated that ultrasonic treatment destroyed the microstructures of IDF from garlic straw, resulted in the honey‐comb network structure and increased hydrophilic groups, which illustrated the good functional and physicochemical properties.

Practical applications

With the trend toward increased consumption of garlic bulb, millions of tons of straw are generally discarded every year. The productive use of such by‐products as garlic straw could offer substantial economic benefits. In this work, ultrasonic technology was chosen for the modification of insoluble dietary fiber (IDF) from garlic straw. Uniform design technique helped us to get the optimum ultrasonic conditions for preparation of IDF with good in vitro hypolipidemic ability. The functional and physicochemical properties of garlic IDF were significantly influenced by ultrasonic pretreatment. The positive effect of ultrasound and application of the statistical model may be useful for functional modification and utilization of dietary fiber from garlic straw.