A new system to preserve quality of grapes harvested by machine

Many negative effects of mechanical harvesting of grapes are attributed to damage and subsequent leakage of juice, often accentuated by high time between harvest and processing as well as high temperature. The presence of must in the product harvested by machine, which can reach very high levels (25-30% of the total mass), can cause several negative effects such as phenols oxidation, abnormal fermentation, skins maceration, etc. For that reason, an innovative system of handling and grapes transporting was developed in order to separate, once harvested, the liquid part (must) from the solid one (bunch of grapes and single grape), and then to apply different working process on each of them. Thanks to this system, it was possible to isolate the must in a closed tank and thus, immediately, preserve it by dry ice or liquid carbon dioxide, with the addition of enological chemicals (sulphur dioxide, ascorbic acid and tannin) to avoid chemical and microbiological modifications. The evaluation of wines throughout tests and sensorial analysis highlighted the better quality of the wines, obtained by the proposed technique compared with the traditional one, cause of higher presence of primary fragrances, better color, and a better balanced structure of the wine preserved by oxidation action.