Modifications of mechanical characteristics and phenolic composition in berry skins and seeds of Mondeuse winegrapes throughout the on‐vine drying process

Abstract

BACKGROUND: Among several common drying systems used in the enological sector the dry-on-vine (DOV) method assumes particular importance because famous wines such as Sauternes, Tokay and Ice Wines are produced by grapes dried using this system. Knowledge about trends in mechanical properties and phenolic composition during on-vine grape drying is scarce. The objective of this current study is therefore to increase the knowledge on these aspects.

Instrumental Texture Analysis Parameters as Markers of Table-Grape and Winegrape Quality: A Review

“…In fact, from veraison to ripeness, an increase was observed for the berry skin hardness and thickness in Nebbiolo grapes, particularly in the first ripening phases, with a steady value or a slight decrease close to the technological maturity (Rolle et al 2012b). A renewed increase was then observed in overripe berries (Rolle et al 2009a). These results disagreed with the rapid decrease in the puncture force at veraison that then continues to decrease at a slower rate up to ripeness (Lee and Bourne 1980).…”

“…This is in accordance with the only current study on the effect of climatic and bioclimatic indices on instrumental texture parameters ). The influence of rainfall has also been reported on whole berry mechanical properties of Cabernet franc, providing firmer and more turgescent grapes (Maury et al 2009) as well as less cohesive ones (Le Moigne et al 2008a), and on the skin thickness of Mondeuse grapes during on-vine drying (Rolle et al 2009a), causing a decrease in this puncture parameter.…”

“…Despite the high variability of the skin's mechanical properties, because different berries often show a heterogeneous dehydration, berry skin hardness, assessed by break force and energy, increased progressively during on-vine drying of Mondeuse, Becuét, and Fumin grapes used for icewine production in Piedmont (Rolle et al 2009a. However, this phenomenon was more evident for berry skin break energy, particularly in Mondeuse and Becuét grapes.…”

“…The effect of berry temperature, the number of berries or of their parts (skins, seeds) by sample, and berry position on the platform are among the most important conditions, but detailed experimental conditions are not always reported. Grape berries are generally analyzed at ambient temperature (20 ± 2°C) and, prior to the test, thermal conditioning in a thermostatically controlled chamber is highly recommended (Rolle et al 2009a). …”

“…In the traction test of winegrapes, the peduncle is anchored to the pliers of the probe ( Figure 2H). During the traction, the peduncle passes through the specific perforated platform of the UTM (5-mm diam) ( Figure 2H), while the berry is blocked, permitting the determination of force (F ped ), expressed in N, and energy (W ped ), expressed in mJ, of the peduncle detachment from the force/ time curve ( Figure 3H) (Rolle et al 2009a …”