Development of innovative methods for the preparation of red wine grape extracts and microemulsions enriched in polyphenolic antioxidants.

Abstract

In an ever-changing society where the world's population is growing, the demand for more food and energy production is a fact. This ever-increasing production is a severe problem in our time. Many food wastes could be raw materials for the creation of new products of high nutritional value. Wine waste constitutes one of the most important environmental problems of our time, as it presents a very high organic load and high concentrations of phenolic compounds, which are toxic to the environment. The phenolic substances contained in wine waste on the one hand cause environmental degradation, but on the other hand, with appropriate treatment, they can be used as a raw material in the pharmaceutical, food, and cosmetic industry. From the continuous study of the literature, it emerged that a wide range of actions of polyphenols have been investigated and the results highlight this group of molecules as antioxidants and in many cases antimicrobials, making further investigation necessary. As a result, the phenolic components of wine are the center of attention of scientists and researchers around the world because of their beneficial effects on human health. The main interest is mainly focused on the extraction process of these components from various sources, in which phenolic components are the dominant secondary metabolites. The purpose of this doctoral study is the recovery of phenolics from winery waste using chemically clean techniques, for the creation of added-value products. To isolate these bioactive substances, the existing literature has been reviewed regarding the means and conditions of their extraction. During the review of the literature, it was observed that most solvents used for the reactions are volatile organic compounds (Volatile Organic Compounds, VOCs), which easily evaporate into the atmosphere with harmful effects on the environment and human health. There has also been some research replacing traditional organic solvents with "green" solvents with low viscosity and no measurable vapor pressure, developed to overcome these barriers of traditional solvents. These are the Deep Eutectic Solvents (DESs). Deep-melting solvents are a relatively new class of ionic solvents that typically consist of polyols (proton donors, H-) and organic salts (proton acceptors, H+). Their main characteristic is a lower melting point compared to that of the parent substances. Also, deep-melting solvents attract the interest of many researchers due to their excellent properties such as low vapor pressure, low toxicity, and low cost. They are considered biodegradable, while at the same time exhibit particularly attractive characteristics as extraction solvents.