Pectinase-assisted extraction of onion polysaccharide and analyze its antioxidant activity

The influence of pectinase enzyme extraction onion polysaccharides was discussed by using the single factor and orthogonal experimental method.The optimum extraction conditions were obtained as follows:Extracting temperature was 50 ℃,enzymatic hydrolysis time was 90 min,buffer solution pH was 3.7,pectin enzyme dosage was 2mL of 5 000u·mg-1·mL-1,and solid-liquid ratio was 1∶15(W/V).Under the condition,onion polysaccharide extraction yield was 7.4%,the purity was 45.6%.In the meantime,the characterization of compound of onion polysaccharide was characterized by UV spectrometry and IR spectrometry.The onion polysaccharides have the effect of scavenging radical.It has a remarkable antioxidant effect and can effectively delay the reaction of oxidation.