Grape must

Determination of Volatile Acidity in Wine and Must (Grape Juice)... 

Gay-Lussac found that must (grape-juice) did not begin to ferment in absence of air in a tube over mercury, but fermented when air was admitted. O. Dopping and H. W. Struve could not confirm this. Traube (who mentions van den Broek, see p. 306) found that juice squeezed from grapes did... 

If for every liter of must (grape juice) there are approximately 450 g of glucose (sugar formula C6H12O6) per liter, what is the volume of CO2 produced under normal conditions from 100,000 L of must ... 

Acid content calculated as tartaric acid is about 6—7 g/L for best flavor and stabiUty. It is higher for tart low Brix musts and less important for sweet high Brix musts. High acid levels coiacide with a higher level of the second acid of grapes, malic acid. 

Fermentation. Today (ca 1997) it is almost universal to inoculate the must with a selected yeast strain. Yeasts are chosen for conducting predictable, prompt, and complete fermentations under the conditions appHcable for the particular wine. It is tme, at least in most wineries, that grapes will ferment with the yeasts naturally present. At one time it was argued that part of the special regional character of wines was the result of the local yeasts. 

Regulations specify a considerable Hst of additives and treatments which may be permitted under controlled limits and conditions. It is important to note that no wine receives mote than a few of these treatments, and many have none. For example, most grape musts ferment readily without additions, but some extra nitrogen source for the yeasts is occasionally beneficial. If some is requited, ammonium phosphate is the most commonly used. 

Careful records must be kept to enable verification of compHance. Each lot of wine must be traceable back to the grapes and vineyard. Tanks must be carefully gauged and the capacities recorded on them. If the wine is to be labeled "estate botded," not only must the wine be fermented, processed, and bottled by the state winery at thein Hsted address, but the vineyard must also be owned or controlled by that winery. Other label terrninology, subject to some further intricacies, are "produced," ie, fermented 75% or made into a different class of wine "prepared," "vinted," or "cellared," ie, subjected to ceUar processing or aging without changing the class of wine "blended," ie, combined at the stated address, wines (probably purchased) of the same class and type and "botded" or "packed" by the stated winery. 

Wine. The earliest known wines were made in Iran about 5400—5000 BC (25). The species of grape used is unknown and may have been either the wild grape Fitis viniferus sylvestris or a cultivated precursor of the modem wine grape V. viniferus viniferus. The source of the yeast used, and the procedures used are completely unknown. In modem times, grapes (about 21—23% sugar) are pressed the liquid must is either separated and allowed to settle for 1—2 days (for white wines) before inoculation with yeast, or the whole mass is dkectly inoculated with yeast (for red wines). In either case, while the initial fermentation takes place, the carbon dioxide formed by fermentation excludes ak and prevents oxidation. White wines are transferred to a second fermentor (racked) near the end of fermentation and kept isolated from the ak while solids, including yeast, settle out, a process that requkes about six... 

Addition of up to 200 ppm sulfur dioxide to grape musts is customary. Strains of S. cerevisiae and S. bayanus grown in the presence of sulfite, become tolerant of fairly high concentrations of SO2. Cultures propagated in the winery are added in Hquid suspension, usually at 1—2% of the must volume. Many strains are available in pure culture. Factors such as flocculence, lack of foaming, fast fermentation, lack of H2S and SO2 formation, resistance to sulfur dioxide and other inhibitors, and flavor production will affect strain choice. No strain possesses all the desired properties. 

Brandy. Brandy is a distikate from fermented juice, mash, fmit wine, or fmit residues. It is distiked at less than 190° proof in such a manner as to produce the taste, aroma, and characteristics generaky attributed to brandy. Fmit brandy is distiked solely from the fermented juice or mash of whole, ripe fmit or from standard grape, citms, or other fmit wine. Brandy distiked exclusively from one variety of fmit must be so designated, except grape brandy which can be identified by the term brandy. Brandy must be matured a minimum of two years in oak barrels, otherwise it must be labeled immature. 

In the United States about 95% of the brandy comes from California. The first brandy was made in 1837 though it was not produced in quantity until 1867. Ak California brandy must be made from grapes grown and distiked in the state and aged a minimum of two years in oak barrels. 

Maische, /. mash grape juice, grape must (Sugar) pulp. — weingare —, (Distilling) wash. — zweite —, aftermash, maischen, v.t. mash. 

Meiran, m. marjoram. -81, n. marjoram oil. Meisch, m. mash (unfermented)-grape juice, grape must. 

Certain fruits, notably grapes and dates, may have some surface contamination or infestation when first picked, and they are fumigated with sulphur dioxide or some other gas. They must, of course, then be thoroughly ventilated before going into storage. 

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