Polyphenol Profiles and Antioxidant Activities of Non-centrifugal Sugars Derived from Different Varieties of Membrane-Clarified Sugarcane Juice

The objectives of this research were to determine the sugar compositions, polyphenol contents and antioxidant effects of non-centrifugal sugars (NCS) of different sugarcane varieties. The polyphenols contents and compounds of nine NCSs obtained from the juices of different sugarcane varieties clarified with a 50 nm ceramic membrane (M-NCSs) were measured via ultraperformance liquid chromatography–mass spectrometry (UPLC–MS). Their antioxidant activities were investigated via 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, 2, 2′-azino-bis-(3-ethylb-enzothia-zoline-6-sulfonic acid (ABTS) assay, β-carotene–linoleate assays, and ferrous and cupric ion chelating assays. Results showed that the phenolic compound with the highest content was gallic acid, and all samples were abundant in phenolics, including flavonoids, with high antioxidative activities. The content of phenolics and flavonoids, ranged from 17.24 to 21.14 mg/mL and from 203.55 to 350.37 µg/mL, respectively. Among these M-NCSs, Funong 41 (G) genotype had the best DPPH free radical scavenging activity. The GUC 23-2 (A1) genotype showed the best ABTS free radical scavenging activity. β-carotene–linoleate assays revealed that the 15-6013 (B2) genotype exhibited the best antioxidant activity. The Guitang 42 (E) genotype displayed the best ferrous ion chelating activity. The Zhongzhe 9 (F) genotype presented the best cupric ion chelating activity. In summary, sugarcane variety influenced the polyphenols contents and antioxidant effects of M-NCSs. This study lays a foundation for the further study of M-NCSs.