•Dietary fiber was prepared from maca residue by enzymatic and chemical methods.•Higher content of dietary fiber was obtained by enzymatic method (81.1%).•Maca dietary fiber showed good functional properties.Using maca (Lepidium meyenii) liquor residue as the raw material, dietary fiber (DF) was prepared by chemical (MCDF) and enzymatic (MEDF) methods, respectively, of which the physicochemical and functional properties were comparatively studied. High contents of DF were found in MCDF (55.63%) and MEDF (81.10%). Both fibers showed good functional properties, including swelling capacity, water holding capacity, oil holding capacity, glucose adsorption capacity and glucose retardation index. MEDF showed better functional properties, which could be attributed to its higher content of DF, more irregular surface and more abundant monosaccharide composition. The results herein suggest that maca DF prepared by enzymatic method from liquor residue is a good functional ingredient in food products.

•Amylase and glucoamylase can effectively remove starch in maca polysaccharides.•LMPs were mainly composed of rhamnose, arabinose, glucose and galactose.•The contents of monosaccharide in LMP-60, LMP-70, LMP-80, and LMP-90 were different.•LMP-60 exhibited a good antioxidant activity in vitro.Water-soluble polysaccharides were separated from maca (Lepidium meyenii) aqueous extract (MAE). The crude polysaccharides were deproteinized by Sevag method. During the preparation process of maca polysaccharides, amylase and glucoamylase effectively removed starch in maca polysaccharides. Four Lepidium meyenii polysaccharides (LMPs) were obtained by changing the concentration of ethanol in the process of polysaccharide precipitation. All of the LMPs were composed of rhamnose, arabinose, glucose and galactose. Antioxidant activity tests revealed that LMP-60 showed good capability of scavenging hydroxyl free radical and superoxide radical at 2.0 mg/mL, the scavenging rate was 52.9% and 85.8%, respectively. Therefore, the results showed that maca polysaccharides had a high antioxidant activity and could be explored as the source of bioactive compounds.