Recovery of Polyphenols from Grape Pomace Using Polyethylene Glycol (PEG)-Grafted Silica Particles and PEG-Assisted Cosolvent Elution

Abstract

Adsorption on a functionalized surface can be an effective way of purifying polyphenols from complex plant extracts. Polymeric resins that rely on hydrophobic interactions suffer from low selectivity, weak affinity towards polyphenols, and lack tunability therefore making the purification of polyphenols less efficient. In this study, a purification process for the recovery of polyphenols from grape pomace extract was successfully developed using hydrogen bonding affinity ligands grafted on silica particles and PEG-assisted elution solvents. Bare silica (SiO2) and polyethylene glycol (mPEG)-grafted silica microparticles with molecular weights of 2000 and 5000 were tested to determine their polyphenol binding and release characteristics. Functionalizing the surface of bare silica with mPEG ligands increased the adsorption capacity by 7.1- and 11.4-fold for mPEG-2000 and mPEG-5000 compared to bare silica particles, respectively. This was likely due to the introduction of more polyphenol binding sites with mPEG functionalization. Altering the molecular weight (MW) of mPEG grafted on silica surfaces provided tunability in the adsorption capacity. A complete recovery of polyphenols (~99.9%) from mPEG-grafted silica particles was achieved by utilizing PEG–ethanol or PEG–water cosolvent systems. Recovered polyphenols showed up to ~12-fold antioxidant activity compared to grape pomace extract. This study demonstrates that mPEG-grafted silica particles and elution of polyphenols with PEG cosolvents can potentially be used for large-scale purification of polyphenols from complex plant extracts and simplify the use of polyphenols, as PEG facilitates remarkable solvation and is an ideal medium for the final formulation of polyphenols.

PEG-Coated Large Mesoporous Silicas as Smart Platform for Protein Delivery and Their Use in a Collagen-Based Formulation for 3D Printing

“…A significant weight loss has been observed from 250 °C until 600 °C and can be ascribed to the decomposition of PEG. In particular, examining the derivative TGA curve (dotted line), PEG started to degrade at about 300 °C, in accordance with data reported in the literature [ 94 ]. An additional weight loss in the range of 25–100 °C due to the release of the surface, adsorbed water and water bound to the protein was noted for both loaded and coated samples.…”

Physicochemical parameters of grape pomace subject to grape processing technology applied

“…The use of alcoholization and, especially, enzyme products led to reduction of the quantity of polyphenols, including anthocyanins, in grape pomace. Phenolic compounds are known to be localized mainly in grape skins [20][21]. Consequently, the effect of ethanol and enzyme products upon red grape must that led to enrichment of wine with phenolic compounds, caused depletion of phenolic compounds in grape pomace.…”

An efficient protocol for extracting thylakoid membranes and total leaf proteins from Posidonia oceanica and other polyphenol-rich plants

“…We were able to inhibit this deleterious process by adding 0.1 up to 5% PEG to the grinding buffer (5% being the concentration we use for our work in Posidonia oceanica ). PEG molecules own repeated ether groups all along the molecules, which bind to the hydroxyl groups of phenolic compounds via hydrogen bonds, thereby blocking their very high reactivity [ 35 , 36 ].…”