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Adsorption and desorption characteristics of adlay bran free phenolics on macroporous resins

Yang, Qingyun, Zhao, Mouming, Lin, Lianzhu
Food chemistry 2016 v.194 pp. 900-907
Coix lacryma-jobi, adsorption, bran, desorption, ethanol, functional foods, heat production, ingredients, kinetics, models, oxygen radical absorbance capacity, phenolic compounds, porous media, resins, sorption isotherms
In this study, the adsorption and desorption characteristics of six macroporous resins including XAD-7HP, XAD-16, HP-20, HP-2MGL, SP-207 and SP-825 for enrichment of adlay bran free phenolics were studied. XAD-16, SP-207 and SP-825 were chosen for further study due to their strong adsorption and desorption capacities. XAD-16, SP-207 and SP-825 had similar phenolics adsorption/desorption behaviors. Pseudo-second-order kinetics model and Freundlich isotherm model were suitable for describing the whole exothermic and physical adsorption processes of adlay bran free phenolics on XAD-16, SP-207 and SP-825. After treatment with gradient elution on XAD-16 resin column, the free phenolics were mostly enriched (from 89.61 to 1015.26mg/100g) in 50% ethanol fraction. The oxygen radical absorbance capacity of 50% ethanol fraction was eight times higher than that of the crude extract. Therefore, the production of highly concentrated phenolics might expand the application of adlay bran used as a bioactive ingredient in functional food.