New vineyard fields: Grape Juice. Selection of grapevine species, juice making, stabilization / Nouvelle filière : jus de raisin. Sélection des cépages, élaboration, stabilisation

Abstract

Proposed by FOULON-SOPAGLY society and INRA, a six years applied research program was developed in France to enable creation of create specific lines to elaborate high quality juice with new adapted grapevine varieties and specialized vineyards, with adapted technology. 448 vine varieties from INRA Vassal first international collection of grapevine species were evaluated to finally select 14: 2 V.vinifera,9 hybrids, and 3 from INRA creation (ref A. Bouquet) by hybridization. These last references, obtained from 4 or 5 back crossing between Muscadinia. rotondifolia.X.V.vinifera, have in particular a high level of resistance against mildew and oidium.These varieties have RUN 1 and RPV1. resistance genes, with several other secondary genes on one chromosome locus. This makes access to organic market easier. Agronomic criteria are studied for this selection. Among the 14 selected grapevine species, some have high level of polyphenols (6 times more than alicante). Others (white and red) have a high aromatic potential. Others have a low sugar content 135 g/l to 150 g/l) and adapted sugar/ acidity ratio. -In the cellar: The absence of fermentation and alcohol requires optimization of the process for juice making. For example by increasing polyphenols extraction and colour stability by using thermo-treatment. Flash release process coupled with enzymatic soaking on grapes at 45°C for example, increases 2 or 3 fold polysaccharide juice content, and increases anthocyanins extraction and hence colour intensity. With this process the draining of grape marc and juice production increase. Pressure technology by on line horizontal decanter is possible. -In juice storehouse. Electro membrane process, (oenodia membrane process) with specific membranes gives possibilities to achieve two objectives on juice: - Decrease pH and increase acidity of juice and colour stabilization, without any additive.