Optimization of Preparing Process of Soluble Dietary Fiber from Tea Stalks and Its Monosaccharide Composition and Physicochemical Properties

In order to improve the value of tea by-product, this paper used fermentation to prepare the soluble dietary fiber (SDF) of tea stalks. The yield of SDF was affected by the inoculums of Trichoderma viride, fermentation time, fermentation temperature and pH. Results showed that, the optimum parameters were determined by single factor and orthogonal tests as follows: Inoculums of Trichoderma viride 6%, fermentation time 60 h, fermentation temperature 30 ℃, pH5.0. Under these conditions, the yield of SDF was 7.15%, water retention rate was 549.20%, the expansion rate was 5.22 mg/L, the DPPH radical scavenging capacity was 12.41%, and the reduction capacity was 14.71%. The surface of the particles was found to be uneven and porous by scanning electron microscopy. High performance liquid chromatography showed that the SDF contained 10 monosaccharides, the contents of galacturonic acid, arabinose and galactose were higher, 2766.23, 2721.37, 1905.82 mg/kg, respectively. The study would broaden the channel for the comprehensive development and utilization of tea stem, and provide theoretical reference for the development of health food.