Recovery of Phenolic Compounds from Red Grape Pomace Extract through Nanofiltration Membranes.

Ana S Figueiredo,Maria N De Pinho,Andrea Versari,Jaime A Arboleda Mejia,Giuseppina P Parpinello,Alfredo Cassano,Arianna Ricci

doi:10.3390/foods9111649

Abstract

The winemaking process generates a large amount of residues such as vine shots, stalks, grape pomace, and wine lees, which were only recently considered for exploitation of their valuable compounds. The purpose of this work was to investigate the performance of nanofiltration for the recovery of phenolic compounds, with bioactive capacity like antioxidant, from red grape pomace extract. Four membranes were compared in this study—three cellulose acetate (CA series: lab-prepared by phase inversion) and one commercial (NF90). All membranes were characterized for their hydraulic permeability and rejection coefficients to reference solutes like saccharose, glucose, raffinose, polyethylene glycol, sodium chloride, and sodium sulfate. Permeation flowrates and rejection coefficients towards total phenolics content, antioxidant activity, proanthocyanidins, glucose and fructose were measured in the nanofiltration of grape pomace extract using selected operating conditions. Among the investigated membranes, the CA400-22 exhibited the highest permeate flux (50.58 L/m2 h at 20 bar and 25 °C), low fouling index (of about 23%), the lowest rejection coefficients towards the reference solutes and the best performance in terms of separation between sugars and phenolic compounds. Indeed, the observed rejections for glucose and fructose were 19% and 12%, respectively. On the other hand, total phenolics content and proanthocyanidins were rejected for 73% and 92%, respectively.

Highlights

The wine industry, with estimated worldwide annual grape processing of 78 million tons, produces one of the most abundant agro-waste resources represented by leaves, stems, pomaces and lees [1].The oenological wastes are usually conferred to distilleries for ethanol and tartaric acid recovery, or alternatively used as animal feed, fertilizers, or vineyard amendment [2,3]
The pomaces contain molecules of biological interest, such as essential oils, proteins, minerals, sugars, dietary fibers, and pectins, which might enhance the nutritional value of food ingredients and bioactive supplements obtained by oenological waste valorization [4,10,11]
We evaluated the feasibility of phenolic compounds recovery from red grape pomace through a combination of ultrasound-assisted enzymatic extraction, followed by a membrane separation process

Summary

Introduction

The wine industry, with estimated worldwide annual grape processing of 78 million tons, produces one of the most abundant agro-waste resources represented by leaves, stems, pomaces (including grape skins and seeds) and lees [1].The oenological wastes are usually conferred to distilleries for ethanol and tartaric acid recovery, or alternatively used as animal feed, fertilizers, or vineyard amendment [2,3]. Organic waste disposal practices might have environmental impacts, causing soil and groundwater contamination, Foods 2020, 9, 1649; doi:10.3390/foods9111649 www.mdpi.com/journal/foods. The valorization of agro-wastes was boosted through the biorefinery approach, offering a great potential for wine companies to reduce the environmental impact and create profit, adopting sustainable practices that deal with the principles of the Circular Economy [6]. Grape pomaces constitute a valuable source of polyphenolic compounds (flavonoids, tannins, and benzoic acids derivatives), which are biomolecules of both technological and nutraceutical interest, acting as antioxidants in biological matrices, through the inhibition of lipid peroxide radicals and reactive oxygen species [7,8,9]. Several studies demonstrated the protection activity of grape seed and pomace extracts against microbial inflammation, cancer, and degenerative diseases [12,13,14,15]

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