Extraction Process of Insoluble Dietary Fiber from Lotus Root Residue and Its Physicochemical Properties Analysis

The lotus pomace was used as raw material to extract insoluble dietary fiber (IDF), and the extraction process was optimized by single factor test and response surface methodology, and the physicochemical properties of the product under its optimal extraction conditions were analyzed.The results showed that, the optimum conditions of extraction of lotus residue IDF as follows:NaOH concentration of 0.60 mol/L, alkaline hydrolysis time of 90 min, amylase hydrolysis time of 60 min and the alkaline protease addition of 2% (g/g).The extraction rate and purity of lotus residue IDF were 29.90% ±0.06% and 91.93% ±1.16%.The water holding capacity of IDF was (6.58 ±0.25) g/g, the oil holding capacity was (4.73 ±0.33) g/g, and the swelling property was (3.03 ±0.12) mL/g.Meanwhile, the values of L^*, a^* and b^* were spearately 38.266 ±0.187, 3.412 ±0.027 and 5.268 ±0.042.It showed that the root residue IDF obtained by this method had high yield, high purity and good physicochemical properties.