Grape cluster

Traube, /. bunch of grapes grape cluster, (Bot.) raceme. 

Figure 2. Zinfandel grape clusters at harvest, from vines sprayed April 28 with KGAS...

FIGURE 6.1 Botrytized grape cluster in Tokaj with aszu (dark) and shriveled (light) berries. Photograph courtesy of Dr. Z. Bene, Tokaj, Hungary. 

In California, the environmental conditions typically do not support the development of noble rot. Nonetheless, a few wineries are occasionally able to produce botrytized sweet wines, mainly by vineyard inoculation of grape clusters with Botrytis spores. 

Several other varietal properties influence susceptibility to noble rot. Very thin cuticles and the compact grape clusters favor gray rot, whereas thick cuticles resist Botrytis attack (Ribereau-Gayon et ah, 2000). High stomatal number, which is variety- or even clone-dependent, favors infection by Botrytis (Pucheu-Plante and Leclair, 1990 Pulcheu-Plante and Mercier, 1983). 

Souquet, J.-M., Veran, F, Mane, C., Cheynier, V. (2006). Optimization of extraction conditions on phenolic yields from the different parts of grape clusters - Quantitative distribution of their proanthocyanidins. XXlll International Conference on Polyphenols. Winnipeg, Manitoba, Canada. 

Sun, B. S., Pinto, T, M.C. Leandro, Ricardo-Da-Silva, J. M., Spranger, M. I. (1999). Transfer of catechins and proanthocyanidins from solid parts of the grape cluster into wine. Am. J. Enol. Vitic., 50, 179-184. 

Follow recommended cultural practices and use resistant varieties to reduce disease pressure. An example is the practice of pruning and leaf removal around grape clusters to increase air movement and reduce gray mold. 

Hashizume, K. and Samuta, T. (1997). Green odorants of grape cluster stem and their ability to cause a wine stemmy flavor, J. Agric. Food Chem., 45, 1333-1337. 

The main distillation step is carried out imder high vacuum ( 10 mm.) at the lowest possible temperature, so as to ensure high-purity metal. The last fraction is discarded. At 850°C the calcium deposit on the cold finger builds iqj as grape clusters of long silver-white, luminous crystallites, which will not tarnish to any appreciable extent on brief e qiosure to air. At higher temperatures the distillates obtained are richer in chlorine. 

Durmishidze, S. V. 1950d. Transformation of tannin compounds in grape clusters in the process of ripening (transl.). Biokhimiia vinodeliia 8, 7-24. 

The grape clusters cut from vine stocks using grape shears are cleaned of rotten and dried berries and then, as fast as possible, separated from the stems. This is done in a roller emsher... 

Fig. 10.1. Fruit of the grape vine (a) grape bory at maturity (b) structure of grape cluster...

In general, not all of the flowers borne by the cluster are fertilized and become berries. The berry setting ratio decreases as the number of flowers formed on the grape cluster increases. The causes of this phenomenon have been known for a long time. As a general rule, a plant can only supply 100 to 200 berries per bunch with sugar, depending on the variety. 

The stalk rachis represents around 3-7% of the weight of a ripe grape cluster. Its chemical composition is similar to the composition of leaves. It contains little sugar (less than 10 g/kg) and an average acid concentration (180-200 mEq/kg). These acids are in the form of salts, due to the large quantity of cations present. 

Stalks are rich in phenolic compounds. They can contain up to 20% of the total phenolic compound concentration of the grape cluster, even though they represent a lower proportion of the total weight. These phenolic compounds are more or less polymerized and have a very astringent taste. 

There is considerable heterogeneity between different grapes on the same grape cluster. Similarly,... 

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