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Phenolic Profile and in Vitro Antioxidant Capacity of Insoluble Dietary Fiber Powders from Citrus (Citrus junos Sieb. ex Tanaka) Pomace as Affected by Ultrafine Grinding

Tao, Bingbing, Ye, Fayin, Li, Hang, Hu, Qiang, Xue, Shan, Zhao, Guohua
Journal of agricultural and food chemistry 2014 v.62 no.29 pp. 7166-7173
Citrus junos, antioxidant activity, antioxidants, crude protein, dietary fiber, grinding, hesperidin, phenolic compounds, pomace, powders, proximate composition, sugars
The effects of mechanical and jet grindings on the proximate composition, phenolics, and antioxidant capacity of insoluble antioxidant dietary fiber powder from citrus pomace (IADFP-CP) were investigated in comparison with ordinary grinding. IADFP-CP from jet grinding showed higher levels of crude fat, total sugar, and free phenolics and lower levels of crude protein and bound phenolics than that from ordinary grinding. Totally, 14 phenolics (9 free, 1 bound, and 4 free/bound) in IADFP-CP were identified by RP-HPLC-DAD/ESI-Q-TOF-MS/MS. Hesperidin accounted for >57% of total phenolics in IADFP-CP. Among IADFP-CPs, the jet-ground presented the highest free phenolics but the lowest bound phenolics. The IADFP-CP from jet grinding presented the highest antioxidant capacity of free phenolics (by DPPH and FRAP assays), followed by the ones from mechanical and then ordinary grinding. The present study suggests that jet grinding could improve the extraction of phenolic compounds from IADFP-CP and increase the antioxidant capacities of free phenolics and the resultant powder.