The effect of variation in berry size on berry composition was studied in irrigated Syrah/R99 grapevines, located in a temperate area of South Africa. Berries from 45 clusters, sampled from both sides of the canopy (east and west), were weighed to create four categories: 1. less or equal to 1.5 g; 2. between 1.51 g and 2.00 g; 3. between 2.01 g and 2.50 g; 4. more than 2.50 g. Berry physical characteristics were determined and total anthocyanins and seed flavonoids were analysed by spectrophotometry and anthocyanin profiles by HPLC. The ratio of skin weight:berry weight did not change with increasing berry size, but the ratio of seed weight:berry weight increased. For total anthocyanins, varying results were obtained if values were expressed in mg/berry, mg/g skin, mg/kg grape and mg/cm2 skin. The quantity of total anthocyanins changed positively with increasing berry weight if expressed in mg/berry and remained almost similar if expressed in mg/cm2 of skin. In contrast, total polyphenols decreased with berry weight if the values were expressed in mg/kg grape and in mg/g skin. Total anthocyanins expressed in mg/kg grape and in mg/g skin were correlated positively to the number of berries as well as to the total skin surface in one kilogram of grape. In this study, the largest berries seemed to have lower quality characteristics. In order to obtain better wine quality, it seems important to reduce berry weight and, in general, berry size variability of Syrah. The obtainment and continuity of a particular wine style may be affected by berry variability.

The main aim of this work was to study in a model, hydroalcoholic solution containing 12% of ethanol and with a pH of 3.20, the kinetics of anthocyanin extraction from Vitis vinifera L. cv. Nebbiolo berries of different skin hardness. This mechanical property was evaluated as the breaking skin force measured by Texture Analysis, a rapid and low-cost analytical technique. Using a TAxT2i Texture Analyzer, a puncture test was carried out on two groups of berries separated according to their density by flotation in order to obtain more homogenous samples and minimize the effect of different stages of ripening of the berries. Among the berries containing 242 ± 8 g/L of reducing sugars in the pulp juice, two groups of berries with different skin hardness were selected: soft (0.26 ± 0.04 N) and hard (0.47 ± 0.05 N). In our experimental conditions, at the end of maceration, the extracts from the higher skin hardness group showed the higher contents of total anthocyanin: +25 mg/L (+9.4%). The anthocyanin profile of extracts, obtained at different extraction times, showed no significant differences among the distribution of different anthocyanins. Only in the early phases of dissolution, did the extracts reveal a dissimilar anthocyanin profile and in the extracts of hard skins higher percentages of cyanidin and peonidin derivatives were present. Additionally, the evolution of skin mechanical properties from veraison to overripe and the influences of biotype on these parameters at harvest are reported in this work.

Aims: The aim of this work was to study the color of the wine grapes using the CIELAB parameters and to develop colorimetric indexes which can be used as a rapid method to assess the anthocyanin content of the wine grapes in the vineyard.Methods and results: L*, a*, b* parameters were measured by a reflectance spectrophotometer on eighteen red winegrapes at harvest. Two indexes were calculated: CIRG2, used as colorimetric index for table grapes and CIRWG (Color Index for Red Wine Grapes). These indexes showed effective potentialities for descriptive, taxonomic and ampelografic studies. Particularly the CIRWG index is more correlated to the total anthocyanin amount, while the CIRG2 is more correlated to the different forms of the anthocyanins.Conclusion: The colorimetric indexes applied directly in the vineyard permit to assess the total anthocyanin content and to give further quickly information on grape quality and maturity.Significance and impact of study: The development of analytical methods for the evaluation of anthocyanin immediates, easily applicable, at low cost in the field by grape-growers and winemakers, can be very useful in deciding the harvest date.

Anthocyanin and mechanical properties were evaluated on Shiraz grapes, picked from both sides of North-South and East-West vineyard row orientations at two harvest dates. Wines were made from each combination. The evaluation and evolution of crushed skin mechanical properties during maceration-fermentation, as also affected by grape ripeness, are shown for the first time. No significant differences in anthocyanin content were found in the grapes between the two vineyard row orientations. However, a significant decrease in anthocyanins and berry skin break force (also referred as skin hardness or strength) was found between the two harvest dates. During maceration, a reduction in the crushed berry skin break force of more than 15% occurred. The intact berries and macerated skins showed similarity in skin break energy values. The anthocyanin profile of the grapes and of the wines prominently displayed malvidin forms, changed mainly by the ripeness level of the grapes.