Structural, rheological and functional properties of modified soluble dietary fiber from tomato peels

Modified soluble dietary fiber (M-SDF) were extracted from tomato peels by alkaline hydrogen peroxide (AHP). The modified conditions were 20% H2O2 solution (v/v), pH 10, solid-liquid rate as 1: 15 (w/v) and reaction time as 1.5 h. The extraction yield of M-SDF increased three times than that of original SDF (O-SDF). M-SDF showed smaller molecular weight of 1.24 x 10(6) Da and lower zeta-potential of - 34.3 mV than those of O-SDF. Monosaccharide composition, FT-IR and TEM were used to investigate the differences of structural characteristic between O-SDF and M-SDF. Rheological properties of M-SDF at different pH and ions types were also determined. The results showed that M-SDF could form the ideal gel at pH 5 with Ca2+ existed. M-SDF also showed stronger gelation ability with Ca2+ than O-SDF. M-SDF exhibited excellent capacities of water holding, glucose adsorption and binding bile acids. M-SDF of tomato peels was suggested to be used as a novel kind of functional hydrocolloid or additive in food industry. (C) 2017 Elsevier Ltd. All rights reserved.