Optimization of Extraction Conditions of the Insoluble Dietary Fiber from Pomelo Peel and Its Physicochemical Properties Analysis

In order to improve the comprehensive utilization value of pomelo resources, to establish an efficient extraction method of the insoluble dietary fiber in pomelo peel. The insoluble dietary fiber (IDF) was extracted from pomelo peel by response surface alkali methodology. Taking the yield of pomelo peel IDF as an index, on the basis of single factor test, response surface methodology was used to optimize the alkali extraction process of insoluble dietary fiber from pomelo peel. The physicochemical properties of pomelo peel insoluble dietary fiber were evaluated. The results indicated that the optimum conditions of alkali extraction of pomelo peel IDF were as follows: liquid-solid ratio of 15:1 mL/g, alkaline hydrolysis temperature of 50 ℃, pH9.0, alkaline hydrolysis time of 75 min. Under the optimal conditions, the yield of pomelo peel IDF was 35.28%. The infrared spectrum showed that the absorption peaks of pomelo peel IDF had 1160 cm⁻¹ carboxyl absorption peak, but there was no such absorption peak in the original pomelo peel. The results showed that the hydrophilic group of pomelo peel increased. Compared with original pomelo peel, the water holding capacity of pomelo peel IDF was increased by 4.52 times, the oil holding capacity was increased by 0.32 times, the swelling property was increased by 0.41 times. In this study, the alkaline extraction process of pomelo peel was optimized to provide a theoretical basis for the development and utilization of pomelo peel.