Influence of Grape Density and Harvest Date on Changes in Phenolic Composition, Phenol Extractability Indices, and Instrumental Texture Properties during Ripening

Abstract

Changes in the phenolic composition, phenol extractability indices, and mechanical properties occur in grape berries during the ripening process, but the heterogeneity of the grapes harvested at different ripening stages affects the reliability of the results obtained. In this work, these changes were studied in Nebbiolo grapes harvested during five consecutive weeks and then separated according to three density classes. The changes observed in chemical and mechanical parameters through the ripening process are more related to berry density than harvest date. Therefore, the winemaker has to select the flotation density according to the objective quality properties of the wine to be elaborated. On the other hand, the stiffer grapes were associated with a higher accumulation of proanthocyanidins. The harder grapes provided the higher concentration and extractability of flavanols reactive to vanillin, whereas the thicker ones facilitated the extraction of proanthocyanidins.

Berry Heterogeneity as a Possible Factor Affecting the Potential of Seed Mechanical Properties to Classify Wine Grape Varieties and Estimate Flavanol Release in Wine-like Solution

“…The study of the effect of berry heterogeneity on the mechanical properties of the seeds also required an analysis of all the seeds belonging to the same berry for one set of 10 Pinot Noir berries randomly sampled. Afterwards, in order to better define the different ripening states present at the same harvest date and to improve intra-sample homogeneity, the remaining Pinot Noir berries were sorted according to their density by flotation using different saline solutions (from 100 to 170 g/L sodium chloride) and following the protocol described by Rolle et al (2011). The berry density classes selected were: A = 1 075 kg/m 3 , B = 1 081 kg/m 3 , C = 1 088 kg/m 3 and D = 1 094 kg/m 3 .…”

Anthocyanin yield and skin softening during maceration, as affected by vineyard row orientation and grape ripeness of Vitis vinifera L. cv. Shiraz

“…The variability among single measures (relative standard deviation) was quite high for all the samples, as also previously observed on cv. Nebbiolo skins with a similar testing probe (Rolle et al, 2011b).…”

“…The evaluation of the grape mechanical properties was used in recent years to study modifications in grape texture that may occur under different vine growing conditions (Sato, Yamada, Iwanami & Mitani, 2004;Rolle, Gerbi, Schneider, Spanna & Río Segade, 2011a;Giordano, Zecca, Belviso, Reinotti, Gerbi & Rolle, 2013;Zsófi;Villangó, Pálfi, Tóth & Bálo, 2014) and to monitor the grape ripening process (Maury, Madieta, Le Moigne, Mehinagic, Siret & Jourjon, 2009;Rolle et al, 2011b). Literature on the relationships among vineyard-related characteristics, such as bunch sunlight exposure and berry skin mechanical properties, is scarce.…”

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

“…With the aim of evaluating whether changes occurring in skin mechanical properties during grape ripening are mainly due to the heterogeneity of the berries harvested or to their evolution through the final ripening weeks, a recent study examined Nebbiolo grapes harvested during five consecutive weeks and then separated according to three density classes (1088, 1094, and 1100 kg m -3 ) (Rolle et al 2011d). The changes observed in the mechanical parameters through the ripening process were more related to berry density than to harvest date.…”

“…A recent study with Nebbiolo grapes evaluated the puncture parameters as potential estimators of the facility of berry skins to yield anthocyanins, flavonoids, proanthocyanidins, and flavanols reactive to vanillin, irrespective of the effect of harvest date and/or berry density (Rolle et al 2011d). Harder grapes provided the higher extractability of flavanols reactive to vanillin, whereas thicker grapes facilitated the extraction of proanthocyanidins.…”