The objective of this investigation was to study the influence of pulsed electric field application on fermentation process and wine characteristics. Investigations were related, in particular, to the effects of pulsed electric field pretreatment (500–700 V/cm) of grapes with a short treatment duration (40–100 ms) on the evolution of color intensity, anthocyanins, and phenolic content during the alcoholic fermentation of Merlot grapes and seven months after bottling. The kinetics of the extraction of valuable compounds during the vinification stage was established. Sensory analyses of untreated wines were compared to those of pulsed electric field-treated wines. These results showed that the permeabilization of Merlot skin by a pulsed electric field treatment resulted in increased extraction of polyphenols and anthocyanins. Pulsed electric field of moderate intensity and short duration accelerated the flow kinetics of phenolic compounds through the cell membranes. Compared to the classical process, pulsed electric field treatment has the advantage of nonthermal selective extraction (<5°C) involving no loss of product quality. Phenolic compounds have an important role in enology owing to their contribution to the sensory properties of wine and to their participation in various phenomena during the vinification and aging processes. Sensory analysis indicated that pulsed electric field treatment contributes to the enhancement of the sensory attributes of wine. This technique seems to be an interesting alternative to current prefermentative techniques.

The acid component of grape berries, originating in the metabolism of malate and tartrate, the latter being less well-known than the former, is a key factor at play in the microbiological stability of wines destined for distillation. Grape acidity is increasingly affected by climate changes. The ability to compare two vintages with contrasted climatic conditions may contribute to a global understanding of the regulation of acid metabolism and the future consequences for berry composition. The results of the analyses (molecular, protein, enzymatic) of tartrate biosynthesis pathways were compared with the developmental accumulation of tartrate in Ugni blanc grape berries, from floral bud to maturity. The existence of two distinct steps during this pathway was confirmed: one prior to ascorbate, with phases of VvGME, VvVTC2, VvVTC4, VvL-GalDH, VvGLDH gene expression and abundant protein, different for each vintage; the other downstream of ascorbate, leading to the synthesis of tartrate with maximum VvL-IdnDH genetic and protein expression towards the beginning of the growth process, and in correlation with enzyme activity regardless of the vintage. Overall results suggest that the two steps of this pathway do not appear to be regulated in the same way and could both be activated very early on during berry development.

The re-emergence of Grapevine Trunk Diseases (GTDs), mainly Esca, has been observed in most of the world’s vineyards during the last two decades. Development of necrosis in grapevine wood, especially white-rot, is typically associated with Esca-diseased plants. One of the different methods being used in attempts to eradicate GTDs is curettage. This old cultural practice, which consists in surgically removing the necrotic wood, specifically white-rot, retaining only the non-necrotic tissue of Esca-diseased grapevine, is used in some European vineyards (Spain, France, Italy, Portugal), and is being increasingly reintroduced since 10 years ago in France. We, therefore, wanted to study the effect of curettage on vigour, fertility and berry quality, and year after year plant recovery. Our study synthetizes a 3-year experiment on Esca-diseased cv. Sauvignon blanc grapevines curetted in a commercial plot in the Bordeaux region. Asymptomatic control grapevines were compared to Esca-diseased grapevines without curettage (with typical foliar symptoms), and with curetted Esca-diseased grapevines (without foliar symptoms). Even if the curetted grapevines recovered lower vigour and fertility than the control plants, their grape berry quality was comparable, unlike for Esca-diseased grapevines. This cultural practice proved particularly effective in helping Esca-symptomatic grapevines to recover asymptomatic after treatment. Over time, curettage induces the resilience of grapevines, allowing them to recuperate their full physiological functioning, thereby compensating for Esca’s detrimental impact on berry quality.