Chemometric Optimization of Biologically Active Compounds Extraction from Grape Marc: Composition and Antimicrobial Activity.

Aliona Ghendov-Mosanu,Rodica Sturza,Ildiko Lung,Maria-Loredana Soran,Greta Balan,Antoanela Patras,Ocsana Opriş,Elena Cristea,Daniela Cojocari

doi:10.3390/molecules27051610

Abstract

The article focuses on the optimization of the extraction process of biologically active compounds (BAC) from grape marc—a by-product of the wine industry. The influence of temperature, specifically 30 °C, 45 °C and 65 °C, and ethanol concentration in solutions, specifically 0–96% (v/v) on the extraction yield of polyphenols, flavonoids, tannins and anthocyanins, were investigated. The composition of individual polyphenols, anthocyanins and organic acids, antioxidant activity (DPPH and ABTS) and CIELab chromatic characteristics of the grape marc extracts (GME), were characterized. The microbiostatic and microbicidal effects in direct contact of GME with pathogenic microorganisms, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, were determined in vitro. The influence of extraction parameters on the total polyphenol content (TPC), total flavonoid content (TFC), tannin content (TC), total anthocyanin content (TAC) and their interdependencies were studied using information analysis. A mathematical model was developed on cubic spline functions. The analysis of individual compounds showed the presence of a wide range of flavonoids (procyanidin B2, procyanidin B1, hyperoside and quercetin), flavones (catechin), hydroxybenzoic acid derivatives (gallic, protocatechuic, p-hydroxybenzoic acids, m-hydroxybenzoic acid, syringic acid), hydroxycinic acid derivatives and ferulic acid methyl ester. The malvidol-3-glucoside was the main anthocyanin identified in the extract. A high amount of tartaric acid was also found. GME showed significant antimicrobial activity against Gram-positive bacteria and lower activity against Gram-negative bacteria.

Highlights

Alcoholic and non-alcoholic beverage production generates waste and by-products that can be recovered
The extraction yield of bioactive compounds was influenced by the polarity and viscosity of the hydroalcoholic extract, increasing in the range 0–60% (v/v) and decreasing to 96% (v/v)
Increasing the temperature from 30 ◦ C to 65 ◦ C led to an increase in the extraction yield of total polyphenol content (TPC), total flavonoid content (TFC), tannin content (TC) and total anthocyanin content (TAC) from grape marc

Summary

Introduction

Alcoholic and non-alcoholic beverage production generates waste and by-products that can be recovered This would minimize their disposal costs and environmental hazards, and add value to the development of new products. Efforts must be made to isolate and structurally elucidate new bioactive compounds This will lead to achievements in the recovery of bioactive molecules, important for the development of innovative products, but it will contribute to reducing environmental pollution [2]. A significant amount of residues is generated by the processing of grapes, among them, grape marc [3] These residues are generally undervalued and used in animal feed (with low nutritional value), turned into fertilizer and even dumped in the environment, generating other problems, i.e., increased soil acidity, phytotoxicity, methane gas production, etc. Grape marc can become a product with potential economic profitability because it is a source of BAC (phenolic compounds, fatty acids, pectins, etc.) that can be used in the manufacture of food, cosmetics, dyes, supplements [5–8]

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