Evaluation of the phenolic profile, antioxidant and antibacterial activities of grape (Vitis vinifera L.) stems extracts

• Autor(a) principal: Gouvinhas, Irene Pereira
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/9173
• topic: Subprodutos; Engaço; Composição fenólica; Atividade antioxidante; Atividade antibacteriana

The winery industry represent an important economical and social impact in several regions in the world, with large quantities of by-products generated annually, causing economical and environmental problems. Thus, a growing interest on recycling or reuse the winery wastes have been paid due to their antioxidant properties and putative healthpromoting effects. Grape stems are one of the by-products generated seasonally in high quantities, being stressed as a valuable candidate to be used by various industrial sectors due to its constitution rich in phenolic compounds with remarkable biological activities, such as antioxidant, antibacterial and anti-inflammatory, which would allow to replace synthetic antioxidants currently used. However, due to the high moisture content in grape stems, it would be necessary an high energy consumption to eliminate the water content for further applications. So, the alternative is to store this residue during some time (days, months) and verify the effect in its composition after that. In this study, the grape stem samples were collected immediately after destemming, washed and stored during 64 days, in order to obtain more information about the potential of grape stems, namely concerning samples varieties cultivated in the highest production region in Portugal (Douro). This work was carried out to generate data on the phenolic composition of stems during their storage, as well as their antioxidant activity in vitro. Also, information about the potential antibacterial activity of the phenolic extracts present in this winery byproduct against several Gram positive and Gram negative bacteria was explored to find promising industrial uses to add value to this waste. The results demonstrated that after 64 days of storage at room temperature, some varieties did not present significant differences in terms of phenolic composition, while others presented a maximum decrease of 35% in their polyphenolic content. Furthermore, the antibacterial and antioxidant activity remained intact at the last day of study, revealing the great potential of this matrix to be stored at least 60 days being always a great source of bioactive compounds.