Effect of post-harvest ozone treatment on secondary metabolites biosynthesis and accumulation in grapes and wine

Abstract

The actual demand by consumers for safer and healthier food and beverage is pushing the wine sector to find alternative methods to avoid the use of sulphur dioxide in winemaking. Ozone is already used in the wine industry to produce sulphur dioxide-free wines through the patented method Purovino®. This study aims to evaluate the effects of ozone treatment used for Purovino® method on grapes berry metabolism and wine quality. Harvested wine grapes (Vitis vinifera L. cv Sangiovese) were fumigated overnight with gaseous ozone. After the treatment grapes were processed to make wine. The technological parameters, volatiles and expression of genes involved in polyphenols and volatile biosynthesis have been analysed in grapes. The aromatic and phenolic profile of the resulting wine has also been assessed. In grapes, ozone treatments increase polyphenols and total flavonoids and consistently specific genes involved in polyphenol biosynthesis were up-regulated. In the resulting wine ozone fumigation increase flavonols content. Additionally, ozone exposition slightly affects the aromatic profile of grapes and wine, mainly due to changes in aroma compounds derived from the lipoxygenase pathway. Overall, the results show that post-harvest ozone treatments applied to avoid the use of sulphur dioxide induce limited but, in general, positive changes in grape and wine. This information could be of great interest for wine makers that, when using ozone treatments are guaranteed in terms of maintenance of quality and typical traits of wines.