Modification of garlic skin dietary fiber with twin-screw extrusion process and in vivo evaluation of Pb binding

This study investigated the effects of a twin-screw extrusion-cooking process on the modification of garlic skin dietary fiber (DF) under optimal conditions (feed moisture 25%, extrusion temperature 170 °C and screw speed 170 rpm). The evaluation of the soluble dietary fiber (SDF) from the extruded garlic skin on the capacity of Pb binding was determined in vivo. Compared with the untreated garlic skin, the content of extruded garlic skin SDF increased from 5.31 ± 0.58% to 15.87 ± 0.88%. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images demonstrated that the macromolecules deteriorated to form smaller SDF fractions during extrusion. Moreover, differential scanning calorimetry (DSC) spectra showed the thermal stability of the extruded SDF was highly improved after extrusion. Additionally, in vivo experimental results indicated that the addition of extruded DF significantly reduced the Pb absorptivity of rats with exposed Pb concentrations at 20, 100 and 200 mg/kg. The findings showed that the extruded garlic skin DF has a positive effect on Pb binding.