| Popis: |
Objective: Pitaya stem polysaccharide (PSP) was applied as raw materials to study the physicochemical properties and antioxidant activity, as well as the effects of different storage and food processing conditions on PSP's antioxidant stability were further explored. Methods: The active polysaccharide from pitaya stem was extracted using hot-water extraction combining with alcohol-precipitation method. Initially, total sugar, total flavonoid and total phenolic contents in PSP were determined using phenol-sulfuric acid method, NaNO2-Al(NO3)3-NaOH method and Folin-Ciocalteu assay, respectively. Monosaccharide composition of PSP was analyzed using ion chromatography, and surface morphology in PSP was characterized using scanning electron microscope (SEM). Then, antioxidant stability of PSP was systematically determined by simulating various food storage and processing conditions, and hydroxyl radical scavenging activity was used as an evaluation index for PSP. Results: The extraction yield of PSP was around 7.22%, total sugar, total flavonoid and total phenolic contents in PSP were 334.63 mg/g, 5.91 mg/g, and 5.05 mg/g, respectively. The PSP mainly consisted of glucose, galactose, rhamnose, galacturonic acid, arabinose and mannose in the following molar ratios: 5.27:2.77:0.77:0.71:0.32:0.17. PSP presented a compact and porous surface with irregular shape as recorded by SEM images. Additionally, PSP possessed good hydroxyl radical scavenging activity, which was increased with the increase of polysaccharide concentration (P |
