Purification of Polyphenols from Distiller’s Grains by Macroporous Resin and Analysis of the Polyphenolic Components

Abstract

We aimed to purify polyphenols from distiller’s grain extract using macroporous resins and to identify its polyphenolic components. The influence of operational parameters on purification efficiency was investigated. The polyphenolic composition was analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and then quantified by UPLC-MS using authenticated standards. The results showed that the optimal purifying conditions were D101 resin with a dosage of 3 g, four hours adsorption, three hours desorption time, and 60% ethanol as the eluent, producing the highest purification rate of 51%. The purified distiller’s grain extract exhibited stronger antioxidant activity than the unpurified extracts, which was assessed using DPPH and ABTS methods (IC50 DPPH = 34.03 and 16.21 μg/mL, respectively; IC50 ABTS = 20.31 and 5.73 μg/mL, respectively). UPLC-MS results indicated that (−)-epicatechin is the major compound found in distiller’s grain extract which was quantified as 562.7 μg/g extract, followed by ferulic acid (518.2 μg/g), p-hydroxybenzoic acid (417.7 μg/g), caffeic acid (217.1 μg/g), syringic acid (158.0 μg/g) and quercetin (147.8 μg/g). Two compounds, vanillic acid (66.5 μg/g) and gallic acid (41.4 μg/g), were found in lower concentrations. The findings of this study suggest that purification of polyphenolic compounds from distiller’s grain by macroporous resins is feasible, providing a new and effective method for the secondary use of distiller’s grain resources.

Bioactive Phenolic Compounds From Agri-Food Wastes: An Update on Green and Sustainable Extraction Methodologies

“…Lignocellulosic agri-food byproducts such as wheat straw (28,30), wheat bran (66) and distiller's grain (67), spent coffee grounds from the industrial production of soluble coffee (68,69), sawdust (70,71) and other wastes from the wood industry (72) have been widely described as a clean source of phenolic compounds, mainly deriving from hydrothermal and/or autohydrolysis processing of lignin, that could be exploited for application in a variety of sectors given their antioxidant and antimicrobial properties (28) (Figure 2).…”

Recovery of Polyphenols from Agri-Food By-Products: The Olive Oil and Winery Industries Cases

“…Resins are synthetic polymeric adsorbents that include materials such as polystyrenedivinylbenzene copolymers, polymethacrylate, etc., and can be functionalized with ionexchange groups [128]. The adsorption properties of resins are related to a polymer composition, surface properties, pore structure, and solubility of adsorbents [130].…”

Adsorption and Desorption Characteristics of Total Flavonoids from Acanthopanax senticosus on Macroporous Adsorption Resins

“…In selecting the optimum macroporous resin, we mainly considered the adsorption capacity, desorption ratio, and desorption capacity [ 40 ]. Six kinds of macroporous resins were placed into conical bottles.…”

“…The antioxidant capacity was estimated from the IC50, which is the concentration of a sample when the inhibition ratio is 50%. The DPPH scavenging assay of EAS and ASTFs were tested according to the procedure described by Andrade [45], where 1 mL of samples of different concentrations (40,80,120,160, 200 µg•mL −1 ) or L-ascorbic acid solution were taken, and 2 mL of DPPH solution (0.2 mmol•L −1 ) was added, mixed well, and allowed to react at room temperature in the dark for 30 min. We then measured the absorbance at 517 nm [34].…”