Abstract
Grapes and their by‐products have drawn attention thanks to high antioxidant activities and phenolic compound contents. The antioxidant activity of fresh leaves varied from 84.46% (Palieri variety) to 88.46% (Narince variety). Fermentation process caused a reduction in antioxidant activity of brined and unbrined vine leaves, while an increase is observed in total flavonoid and phenolic contents of vine leaves (except unbrined leaves of Yapıncak variety). The maximum increase was determined in total flavonoid amount of brined leaves belonging to Yapıncak variety (867.11 mg/g) and also in total phenolic content of unbrined leaves of Cinsaut variety (1692.04 mg/100 g). In general, total carotenoid contents of fresh leaves were higher than the fermented leaves (except for unbrined Palieri variety). The main phenolic compounds of vine leaves were (+)‐catechin,1,2‐dihydroxybenzene,3,4‐dihydroxybenzoic acid and trans‐ferulic acid. The amount of phenolic compounds was increased with fermentation process. It could be concluded that fermented vine leaves are a good source of flavonoids and phenolic acids.
Practical applications
At the viticultural countries, mainly of the Mediterranean coast (Italy, France, Spain, Turkey, and Greece), have benefited from by‐products of wine, vinegar, grape juice, and “jam” (boiled grape juice). Brine leaf production is a preservation method that has been continuing for centuries in Anatolia. In Turkey, the production of brine leaves is increasing rapidly and in some regions grape income is put into the second plan. Brine vine leaves have become an important export product in recent years. Brine leaf is a fermented product obtained by the biochemical change of carbohydrates, proteins, and other organic substances in the composition of fresh vine leaves by microorganisms and, especially lactic acid bacteria.