Optimization of soluble dietary fiber extraction from hulless barley grass

Background and objectives The key factors determining the extraction conditions of soluble dietary fiber from hulless barley grass (HBG) are still unclear. Impact of enzymatic treatment on the yield of soluble fiber of HBG under different reaction conditions was investigated. Findings Response surface methodology (RSM) was carried out to establish the optimal combination of reaction conditions based on Box‐Behnken design (BBD), using xylanase concentration ( X 1 : 400–1200 unit/g), cellulase concentration ( X 2 : 200–600 unit/g), and enzymatic hydrolysis time ( X 3 : 1–5 hr). The optimum reaction condition increased soluble dietary fiber (SDF) of HBG from 1.6% to 22.8%, when HBG was subjected to a combination of xylanase (995 unit/g) and cellulase (392 unit/g) for 2.4 hr. The experimental value (22.8%) was close to the theoretically predicted yield (23.0%), indicating that the model could be used to predict the yield of SDF in HBG. Conclusions SDF level was correlated to xylanase concentration and cellulase concentration, but the main factor was enzymatic hydrolysis time. Reaction conditions were not significantly related to particle size and water to raw material ratio. Significance and novelty This study could provide support for production of SDF‐based functional food products.