Ultra-high pressure assisted extraction of water-soluble polysaccharides from <i>Moringa oleifera</i> seed husks and their antioxidant activities

The process conditions and antioxidant activity of ultra-high pressure assisted extraction of polysaccharides from Moringa oleifera seed husks were studied. Taking the yield of polysaccharides as the index, the effects of degree of crushing, extraction pressure, holding pressure time and material-to-liquid ratio on the yield of polysaccharides from Moringa oleifera seed husks were investigated. The optimal extraction conditions were determined by single-factor test and orthogonal test: a holding time of 10 min, a material-to-liquid ratio of 1:25, an extraction pressure of 350 MPa, and a polysaccharide yield of 0.264%. Its antioxidant activity can be determined by measuring the total antioxidant capacity and their ability to scavenge DPPH and ·OH radicals. The results showed that the IC50 of Moringa oleifera seed husk polysaccharides on DPPH and hydroxyl radicals were 0.0662 g/L and 0.0844 g/L, respectively. The total antioxidant capacity was 0.1826 mm/g (expressed as the equivalent concentration of ferrous sulfate). Compared with hot water extraction methods, ultra-high pressure assisted extraction methods can shorten extraction time, improve extraction efficiency. The water-soluble polysaccharides extracted from Moringa oleifera seed husks by ultra-high pressure assisted extraction technology also have higher antioxidant activity than that by hot water extraction method at the same concentration.