engleski

Vinification by-products as a row material for procyanidin-rich wines ; Proceedings of the fourth international symposium on cool climate viticulture& enology, Rochester, New York, USA July 1996.

The grape seeds are a vinery by-product and may be considered to be an readely avalilable source from which to obtain low molecular flavans for pharmaceutical, cosmetic and nutritive purposes, as well as for the production of procyanidin rich-wines. Polyhidroxyflavans: catechinss and procyanidins are important phenolic compounds in the seeds and berries. According to the present state of knowledge low molecular flavans (catechins and procyanidins) have positive physiological properties: they have a protective effect against cardiovascular diseases, and are very good acceptors of free radicals and a factor of economy for vitamin C. The positive health effects of red wines has received considerable attention in recent years. Low molecular flavans (LMF) in grape seed extracts from ten different grappe cultivars grown in Dalmatia were investigated over a period of three years. Analyses were carried out on seven red cultivars (Plavac mali, Trnjak, Vranac, Merlot, Cabernet sauvignon, Plavina, gamey, and three white cultivars:Kujundžuša, Okatica bijela, Rjaciteli. The cultivars Plavac mali, Trnjak, Plavina, Kujundžuša, Okatica bijela, are indigenous to this part of dalmatia while the others were introduced. LMF were dtermined by HPLC techniques on the reverse phase using gradient elution. Acidic and neutral phenolic compounds were previously fractionated on Sep Pak C18 cartridges. The results indicate that grape seed extracts contain a specific flavane fingerprint which can be used to identify the origin of grape cultivar. The LMF content depended on the cultivar and the vintage. The predominant monomer in grape seed extract depended on the cultivar, while the predominant dimer was procyanidin B2. The presence of catechin monomer and procyanidin dimer group B was detecte, and their share depended on the grape cultivar and the vintage. The ratio between the highest average LMF levels and the lowest average LMF levels over the three -year period was 6, 5 :1. However, if the LMF level was calculated in relation to the quantity of seeds in the cultivar, this ratio was lower. It is interesting that the cultivars Plavac mali and Plavina, the seed extracts of which had the highest LMF levels, had the smallest amount of seeds in the grape. The mofified vinification process, which includes maceration and results in a higher amount of solid phase, makes it possible to produce wine with a greater amount of (+)-catehin, (-)-epicatechin and procyanidin dimers B1, B2, and B3.

vinification; by-products; HPLC; procyanidins

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