Abstract
It is well established in the scientific community that agro-food wastes represent economic advantages and contribute to circular economy. For instance, wine industries of Região Demarcada do Douro involve the production of large quantities of by-products, such as stem, pomace, trimmed vine shoots, or wine lees, presenting a remarkable valuable composition in phytochemicals with putative health-promoting qualities. Nevertheless, the bioactive compounds obtained from these natural sources depends on the extraction process employed. In order to reduce production costs and optimize processes, new technologies—such as ultrasound-assisted extraction (UAE)—have been employed to decrease energy consumption and increase the product or process safety/control and quality. This work aims to characterize the phenolic compounds extracted from winery by-products (WBPs), namely grape stems, grape pomace, and wine lees of two grape (Vitis vinifera L.) varieties (Sousão and Tinta Barroca) from the same geographical site, as well as the antioxidant capacity. Wine lees and grape stems presented the highest concentration of phenolic compounds and the highest antioxidant capacity for Tinta Barroca variety, while grape pomace presented the highest values of these parameters for Sousão variety, demonstrating the high influence of the variety studied. Furthermore, wine lees revealed to be the winery by-product with the lowest antioxidant capacity and content of phenolics. These by-products revealed to be a rich source of phenolic compounds with high antioxidant capacities reveling to be of interest for pharmaceutical and cosmetic industries.
Highlights
The main strategies for the valorization of food wastes are related to their biotechnological transformation into chemicals or even the recovery of important substances, such as polyphenols that typically appear in the winery by-products (WBPs)
Wine lees and grape stems presented the highest values of phenolic content in Tinta Barroca samples which has not been observed for the grape pomace extracts, which can be explained by the different phenolic compounds present in these WBPs
It is well known that the extraction method, the cultivars, the geographical conditions, the growing season, the plant diseases, among others, affect the chemical composition of WBPs, namely the secondary metabolites which are highly present in these matrices. It is well established in the scientific community that wine has an important role in the prevention of some cardiovascular diseases, resulting from their content in bioactive phytochemicals with antioxidant capacity
Summary
The main strategies for the valorization of food wastes are related to their biotechnological transformation into chemicals or even the recovery of important substances, such as polyphenols that typically appear in the winery by-products (WBPs). The implemented alternatives for reducing the environmental impact of agronomic residues involves the development of new feeds and their use as soils amendments Given the relevance of the winemaking companies, at Douro region, and the high amount of underexploited wastes produced, the development of innovative applications for these materials urges [1]. On these materials ongoing research ( relevant studies developed by the research group) has revealed the valuable quantitative profile of bioactive compounds in WBPs, namely a variety of (poly) phenols and stilbenes that could be responsible for remarkable biological activities, such as anti-inflammatory, antioxidant, and antibacterial, among others [2–5]
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