Handbook of Enology, Volume 2: The Chemistry of Wine: Stabilization and Treatments (2nd Edition)
Pascal Ribéreau-Gayon, Denis Dubourdieu, Y. Glories, A. Maujean
Format: PDF / Kindle (mobi) / ePub
The Handbook of Enology Volume 2: The Chemistry of Wine Stabilization and Treatments uniquely combines chemical theory with the descriptions of day-to-day work in the latter stages of winemaking from clarification and stabilization treatments to ageing processes in vats and barrels.
The expert authors discuss:
* Compounds in wine, such as organic acids, carbohydrates, and alcohol.
* Stabilization and treatments
* The chemical processes taking effect in bottled wine
The information provided helps to achieve better results in winemaking, providing an authoritative and complete reference manual for both the winemaker and the student.
content of the extract is obtained by the equation: The procedure The procedure requires two samples of 200 grapes each. The ﬁrst is pressed in order to obtain the weight of the pomace, as well as the weight and volume of the must, sugar content and acidity. The second is crushed. One 50 g of sample is added to its own volume of HCl N/10. Another 50 g of sample is added to its own volume of a solution at pH 3.2. Both samples are stirred manually and left for 4 h. The samples are then ﬁltered
vatting (Volume 1, Section 12.5.3) and increases again later in some cases. During the ﬁrst phase, corresponding to extraction of coloring matter from the grapes, the anthocyanins are copigmented to a certain extent with simple phenols. Color intensity may increase again in the third phase, due to the formation of new tannin– anthocyanin complexes as well as new anthocyanin–tannin copigments, if these substances are present in large enough quantities. The alcohol produced in the second phase
odor, and when diluted they are reminiscent of oaky wines. Concentrations in wine are on the order of a few tens of mg/l, considerably higher than the perception threshold (a few tens of µg/l). Fig. 2.13. β-methyl-γ -octalactone REFERENCES also come from grapes, as is the case in Riesling, where they contribute to the varietal aroma. Infection of grapes by Botrytis cinerea probably produces sotolon (4.5-dimethyl-3-hydroxy-2furanone) (Figure 2.12), involved in the toasty aroma characteristic of
countries. 4.6.3 Citric Acid and Gum Arabic Treatment Citric acid solubilizes iron, forming soluble iron citrate. Citric acid is an authorized additive at doses up to 0.5 g/l. The total concentration must never exceed 1 g/l. This treatment may only be envisaged for wines that have been sufﬁciently sulfured to protect them from bacterial activity that would otherwise break down the citric acid, producing volatile acidity. In practice, this treatment is used exclusively for white wines that are
authorized for white and ros´e wines, including sparkling wines, in 1962. It is also permitted for vins doux naturels. In France, winemakers who decide to use potassium ferrocyanide must declare their intention to the authorities at least eight days beforehand. Each treatment must be supervised by a qualiﬁed enologist. The enologist must carry out an analysis of each vat or barrel to be treated, including preliminary tests to determine the doses required. The winemaker is then issued with a