The objective of this study was to investigate the effects of superfine grinding on the physicochemical and antioxidant properties of oat bran polysaccharides (OBP). The solubility of OBP increased from 8.1 to 11.3 mg/mL.The average molecular weights of raw OBP (rOBP) and superfine ground OBP (sOBP) were 655.6 and 489.6 kDa, respectively. The intrinsic viscosity of sOBP (4.58 mL/mg) was extremely lower than that of rOBP (94. It was demonstrated that some natural polysaccharides were effective at preventing oxidative damage in living organism, thus could be a potential resource of novel antioxidants (Ge et al., 2009;Tsiapali et al., 2001;Xu et al., 2009).75Oat belonging to the genus Avena in the family Gramieae has been widely cultivated and was used as a traditional Chinese herb medicine (Duan et al., 2014;Hu et al., 2014;Zhang et al., 2012).In addition, oat bran is an important source of natural functional polysaccharides. The high content of functional polysaccharides in oat bran has showed significant positive health effects in lowering cholesterol, modulating glucose absorption, improving gastrointestinal function, and preventing heart diseases (Alfredo et al., 2009;Chen, He, et al., 2006;Tapola et al., 2005). Oat bran polysaccharides (OBP) have been considered as potential ingredients in health-promoting functional foods because of their health benefits, including antioxidant properties (Lazaridou et al., 2006).Superfine grinding is a new technology, which is a useful tool for making superfine powder normally with a particle size of less than 10 _ 25 μm and good surface properties (Tkacova and Stevulova, 1998;Hu et al., 2012). The surface of superfine powder can undergo some changes, which bring out a series of important characteristics that coarse particles do not possess. Nowadays, superfine grinding technology has shown a great potential in producing nutraceuticals and functional foods (Chen, Weiss, et al., R. Liu et al. 102 2006). Some studies have shown that the superfine powder possessed higher dispersibility, solubility, and water holding capacity, and thus the quality of food products produced by superfine grinding technology was improved (Wu et al., 2012; Zhao et al., 2009). Furthermore, it considerably enhances the efficiency of the extraction and is friendly to environment, and thus has been widely employed to extract natural polysaccharides from different bioresources with great extraction efficiency and antioxidant properties (Chun-yu et al., 2004;Hu et al., 2012;Zhang et al., 2014).Physicochemical properties of OBP play fundamental roles in their functionality in food systems. Various OBP sources have developed by different processing methods, such as acid or enzymatic hydrolysis, extrusion, and steam heating, for improving their functionality (Gamel et al., 2014;Zhang et al., 2009) In this study, the superfine grinding technology was applied to influence the physicochemical and antioxidant properties of OBP.The raw OBP (rOBP) and superfine ground OBP (sOBP) extracts were obtained by...