In order to exploit and utilize peanut industry resources and produce additional high value products, the use of microwave-assisted technology for extracting water soluble dietary fiber (SDF) from peanut hull was investigated. The factors that influence the SDF extraction were studied via response surface methodology. Regression models for the relationships between these factors and SDF extraction yield as well as the percentage content of non-starch polysaccharides (NSP) were established. The optimum parameters were a liquid-to-solid ratio of 1:16, microwave power of 700W, heating time of 6min, and heating temperature of 90℃. Under these conditions, the SDF extraction yield and NSP percentage content reached 2.68% and 56.06%, respectively. The IC 50 values for SDF scavenging of hydroxyl free radicals, superoxide anion free radicals, and DPPH free radicals were 0.78 mg/mL, 6.66 mg/mL, and 5.12 mg/mL, respectively. Moreover, the iron and molybdenum reduction capacities were similar to 8.015 μg/mL and 28.505 μg/mL ascorbic acid reduction capacities, respectively.Keywords: peanut water soluble dietary fiber, microwave-assisted extraction, optimum extraction conditions, antioxidant activity *To whom correspondence should be addressed. E-mail: lhtyln0626a@yahoo.com.cn IntroductionDietary fiber (DF), including polysaccharides, oligosaccharides, lignin, and related plant materials, refers to some edible vegetative carbohydrates and similar substances that are resistant to intestinal digestion and absorption and can be fully or partially fermented in the colon or rectum (Hu, 2003). DF can be divided into two types on the basis of solubility: water soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) (Kutoš et al., 2003). SDF is composed of non-starch polysaccharides (NSPs) that cannot be digested by the human digestive system but can be dissolved in warm or hot water. An aqueous solution of SDF can be precipitated by a quadruple volume of anhydrous alcohol. SDF is mainly substances that are accumulated in and secreted from plant cells as well as some microbial polysaccharides and synthetic polysaccharides. The main constituents of SDF are some gums (i.e. pectin, arabic gum, carrageenin, guar gum, xanthan gum, agar, and galactomannan), dextran, alginate, carboxymethyl cellulose, and fungal polysaccharides. Research has shown that DF has many physiological functions and can prevent and treat diseases of modern civilization, including regulating blood glucose levels and preventing diabetes (Esposito et al., 2005;Kalkwarf et al., 2001), inhibition effects on breast cancer (Adlercreutz et al.,1987;Goldin et al., 1982;Roy et al., 2002), oxidation resistance and free radical scavenging effects (Alía et al., 2003;Pillai et a., 1999), inhibition of poisonous fermentation products and prevention of colorectal cancer (Levi et al., 2001), treatment of cardiovascular disease (Theuwissen et al., 2008), and reduction of blood pressure and lowering of blood lipids (Jiménez-Escrig, et al., 2000;. Therefore, it is suggested that...

In heat-denatured peanut meal (HDPM), proteins are denatured and polysaccharides are degraded and browned. It can only be used as feed or fertilizer, and not using it as such is a waste of resources. To achieve high-value HDPM use, solid-state fermentation by Aspergillus oryzae and Saccharomyces cerevisiae was investigated. Conditions were optimized by response surface methodology and high-value antioxidant peptides (APs), nonstarch polysaccharides (NSPs), and fermentation products of heat-denatured peanut meal (FHDPM) were obtained. Optimal culture conditions were strain ratio 6:5, inoculation volume 2 mL, and fermentation for 42 h at 35 °C. Under optimal conditions, the theoretical soluble nitrogen concentration, 1,1-Diphenyl-2-picrylhydrazyl radical scavenging rate, hydroxyl free radical scavenging rate, and NSP yield reached 44.78 mg/mL, 62.44%, 94.95%, and 3.73%, respectively; however, their experimental values were 46.80 ± 1.23 mg/mL, 72.18 ± 0.78%, 96.79 ± 0.55%, and 4.42 ± 0.21%, respectively. NSPs, Aps, and FHDPM exhibited four higher classes and eight types of antioxidant activities. Moreover, levels of amino acids and trace elements, and physicochemical properties including emulsion activity index, emulsion stability index, foam capacity, foam stability, water holding capacity, and oil absorption capacity were enhanced by fermentation. The results indicate that APs and NSPs could serve as promising natural antioxidants in the food industry, and FHDPM could be used as a new type of high-value nutritional product in the feed industry. The findings provide new insight for comprehensive processing and utilization of HDPM.

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