**4. Grape Pomace Generation**

Historically, the first evidence of wine production was found in south Caucasus and dated back as far as 6000 BC. From there, traces of wine production were discovered in Syria, Palestine, and Egypt. It spread around the Mediterranean basin during Roman times and further in Europe as long as the Roman Empire was further invading [20,66].

In European Union, as of 2020, 3.2 million hectares were used for grapevine growing and grape production, about 45% of total global grapevine growing surfaces [67]. Most of the grapes produced are sent to the wine industry, which leads to large quantities of waste products, such as GP. Grape pomace is generated through the vinification process which comprises all the technological phases from grape harvesting to wine bottling. Destemming is the first process after harvesting grapes, removing stems and grape stalks. After this, crushing takes place in which grapes are mashed into juice, skins, pulp, and seeds [66]. Maceration follows when juice (must) remains alongside grape skins and pulp seeds for different periods depending on what type of wine is produced. In the case of aromatic white wine, the maceration takes a shorter time, while for red wine it will be longer [20,66].Afterwards, in the pressing process, the must is extracted from grape waste. Therefore, there are two types of GP, red and white, according to the grapes used in the vinification process. The main difference between red and white wine is that white must is separated from pomace before fermentation. In contrast, in the case of red wine, pressing happens only after fermentation. Also, while pressing, the wine will gain its color and flavor [12,20,68]. After the pressing process, where must (red or white) is extracted, the remaining GP has different properties. For example, in terms of pressing and fermentation, white GP is sweet due to its higher sugar content because it didn't undergo fermentation. At the same time, red GP is a fermented matrix containing different concentrations of alcohol [20]. At the same time, the polyphenols content varies depending on the vinification technology, respectively red or white.
