Nutritive value, total phenolic content and radical scavenging activity before and after digestion of the leaves of six grapevine (Vitis vinifera L.) cultivars.

In Mediterranean countries, grapevine leaves are an important source of forage for ruminants during the critical period when quality and quantity of pasture herbage is limited. They are also used in human nutrition for the preparation of various typical dishes. The aim of this study was to compare the chemical composition and nutritive value of the leaves of six grapevine (Vitis vinifera L.) cultivars (Barbera, Cabernet Sauvignon, Grenache, Nebbiolo, Pinot Noir and Sirah). The same leaves have also been tested to determine the impact of in vitro simulated human gastrointestinal digestion on total phenolic content and radical scavenging activity before and after digestion. This study demonstrates that the nutritive value for ruminants and the content of bioactive compounds and related antioxidant capacity for humans depends on the grapevine cultivars. These leaves are rich in bioactive compounds and might provide a significant source of dietary bioaccessible polyphenols with high antioxidant capacity.