Artificial ripening of grape seed phenolics in Pinot noir and Cabernet Sauvignon

¹ Department of Horticulture, Plant & Soil Sciences Building, Michigan State University, East Lansing, MI, 48824, United States
² Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Università di Udine, via delle Scienze 206, Udine 33100, Italy
³ Università del Salento, Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Centro Ecotekne, via Provinciale Monteroni, Lecce 73100, Italy
⁴ Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122, Piacenza, Italy

^* Corresponding author: sabbatin@msu.edu

Abstract

Red Vitis vinifera cultivars are often limited in their performance by climate conditions (e.g., rain, humidity, cold winters, and cool summers). Cool climate viticulture regions are characterized by short growing seasons that reduce fruit quality, limiting technological and phenolic maturity. Management of fruit technological ripening, in vineyard or post-harvest, is pivotal for wine quality. However, the impact of vineyard or cellar practices on seed phenolic fraction remains poorly understood. The aim of our project was to evaluate seed color change, phenolic composition, and their extraction potential after an oxidation induced by a freezing treatment. The freezing treatment was followed by 24 hours of incubation at different temperatures in two Vitis vinifera cultivars: Pinot noir and Cabernet Sauvignon. Results are reporting that the freezing caused the seed color darkening and significant phenolic changes, suggesting similarities with the natural process. The phenolic evolution reported different behaviour between cultivars and compound classes. Most of the changes occurred during the first three hours of incubation, indicating that the oxidation reactions take place at the beginning of the thawing process.