# Technological Aspects and Potential Cutaneous Application of Wine Industry By-Products
## 2 Opportunity to Obtain Value-Added Products in Circular Economy
However, it decreased in skin and pomace (-52% and 75%, respectively) [25]. Muscat grape pomace drying revealed the negative impact of time and temperature (6 h at 80 \({}^{\circ}\)C) on flavanol and monomeric anthocyanins content and radical scavenging potential compared to the untreated (fresh) material. Catechin was the most thermolabile among several compounds isolated from those raw materials, and it was followed by rutin. The researchers pointed out that the recovery of polyphenols should be carried out using low-impact extraction [37]. Even though many investigations indicate the abundance of polyphenols and the high antioxidant potential of the fermented residues from wine production after simulated gastrointestinal digestion, further studies are needed for exploring their applicability in human health and well-being. Bioactives from winemaking residues have attracted attention due to their health benefits and potential economic and social improvements for the cosmetic and pharmaceutical industries [49]. An example is tocopherol, which can act as an antioxidant, anti-inflammatory, hepatoprotective, cardioprotective, and anticancer agent. Grape pomace pre- and post-fermentation from red and white wines demonstrated considerable concentrations oftocopherol. The red grapes were slightly richer in tocopherols than the white ones, and the alcoholic distillation of the waste mixture moderately reduced thetocopherol concentration, even so, resulting in a valuable secondary ethanolic extract for health applications [6]. The efficient industrial extraction of waste phytochemicals provides greater extractive yield, reduction in discard, and economic gains with high-value substances, such as alcohol, tartaric salts, food pigments, and grape seed oil. Tempranillo grape has been shown to contain higher phenolic content and antioxidant activities in red grape seeds and similar values in washed grape pomace [7]. The main compounds found in hydroethanonic grape pomace extracts were flavonoids and proanthocyanidins, which corroborated the antioxidant capacity of such material [50]. Although many papers proved the significant content of antioxidants, mainly polyphenols, the number of studies in the cosmetic and pharmaceutical areas that attest to these benefits in humans is still insufficient to stimulate the large-scale production of phenolic derivatives from winemaking in promoting health. Highly bisphenol-stable aqueous grape pomace extracts were obtained using microwave hydro-diffusion and gravity (MHG) of Sicilian grapes, including Syrah, Perricone, and N. d'Avola. In the aqueous extract, high levels of enocyanin were found. Gallic acid and its ethyl ester derivative reached considerable amounts in the Perricone grape, followed by hydroxybenzoic and syringe acids. Quercetin was predominant in the Perricone and Syrah aqueous extracts, and resveratrol was abundant in the Perricone pomace [51]. Figure 1: Simplified outline of the circular economy application for the valorization of winemaking by-products.