An improved method for rapid quantitative analysis of the insoluble dietary fiber in common cereals and some sorts of beans

An improved rapid analysis for determining the content of insoluble dietary fiber (IDF) in common cereals and some sorts of beans is described in this paper. The procedure includes starch gelatinization in water bath for 20 min at 100 °C and 2.5% (w/w) α-amylase hydrolyzed reaction followed by neutral detergent wash and acetone extraction. Compared with 1.5 h for filtration (estimated) and 18 h for the enzymatic hydrolysis required by the typical American Association of Cereal Chemists (AACC) method, the filtration and enzymatic treatment procedures in the improved method was completed within 15 min and 1.5 h, respectively. The length of time for the filtration and the enzymatic hydrolysis for the improved method was significantly shortened from 19.5 h (AACC method) to 1.75 h. In addition, orthogonal array design (OAD) has been applied to optimize parameters of the improved method. The recovery yield of microcrystalline cellulose was 97.75% (w/w), in agreement with the result obtained using the typical AACC method, demonstrating the reliability of the improved method. Furthermore, several common cereals and beans were employed to validate the accuracy and universality of this improved method.