Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/640

Rh 602 WINE Vinous fermen tation. Pro- fully explained under FERMENTATION (vol. ix. p. 92 sq.). From what is said there it will be readily understood that wine-making is an easy art where there is a sufficient supply of perfectly ripe grapes. In Italy, Spain, Greece, and other countries of southern Europe nature takes care of this ; in the more northern of the wine-producing dis tricts of France, and especially on the Rhine in Germany, the culture of the vine means hard work from one end of the year to the other, which only exceptionally finds its full reward. And yet it is in those naturally less favoured districts that the most generous wines are produced. Southern wines excel in body and strength ; but even the best of them lack the beautiful aroma (Bhime or bouquet) characteristic of high-class Rhine Avine. The large propor tion of sugar in southern grape juice would appear to be inimical to the development of that superior flavour. Yet in Missouri, for instance, where wine is produced in pretty much the Rhenish way, from Rhenish kinds of grapes, which there ripen far more readily than they do at home, no wine equal in flavour to real Rhine wine has as yet been made. It seems that the hard struggle for existence which the vine-plant has to fight on the Rhine is essential for the development of the peculiar flavour of the wine. To secure the highest attainable degree of maturity in or the grapes, the vintage on the Rhine is postponed until wine. the g ra P es almost begin to wither, and the white grapes on the sunny side of the bunches exhibit a yellowish brown (instead of a green) colour and show signs of flac- cidity. In the best vineyards (where it is worth the trouble) the bunches are carefully sorted, the ripest being put aside and pressed by themselves. In some places even the individual bunches are analysed and the best berries cut out with a pair of scissors, to be used by themselves. The processes concerned in the extraction of the juice are described below (p. 605). If the production of red wine is intended, the juice is allowed to ferment over the stalks and skins until enough of alcohol has been produced to enable the juice to extract the pigment from the skins. After that juice and residue are separated. The alcohol, however, extracts other things besides the pigment, especi ally tannin, which imparts to red wines their characteristic astringency. The must (or magma of crushed grapes) is immediately conveyed to a cool cellar, the temperature of which should lie between 9 and 12 C., and is placed in large tubs or vats or open casks, and is then left to itself. Although no yeast is added from without, vinous fermenta tion sets in sooner or later, and after some four to five days is in full swing. On the seventh day, as a rule, the pro cess has passed its climax, and after ten to fourteen days the yeast-scum on the surface disappears and the liquid clears up. It now constitutes what is called Jungivein, which still contains a considerable remnant of unfermented sugar. This young wine is drawn off into large casks and placed in cellars having a temperature of 9 to 12 C. ; there it is left for some months, generally until the following March. The casks are filled almost to the bung-hole and kept full by the occasional addition of wine, the small bung-hole being covered so as to provide an outlet for the carbonic acid, without giving any greater access to the air than is absolutely unavoidable, to prevent acetous fer mentation. During this period the small remnant of sugar in the young wine gradually ferments away, while the percentage of alcohol undergoes a corresponding gradual in crease. As this after-fermentation progresses very slowly, there is no perceptible increase of temperature in the liquid, and even the newly- formed yeast cells remain deposited at the bottom as a precipitate. On it certain components of the must, being less soluble in (alcoholic) wine than in the must, separate out, as, for instance, the albumenoids and, most markedly, the bitartrate of potash; this last Neroberg Riesling. Steinberger Ausle.se. Sugar 18 06 24-24 Free acid ... 42 43 Al bumenoids 0-22 0-18 Combined organic acids and extracts 4-11 3 92 Mineral matter 0-47 0-45 Total solids 23 &quot;28 29-22 Water (by diff.) 76 72 7078 100 100 separates out conjointly with tartrate of lime and colour ing-matters, as a coherent crust known as argol. The finished young wine is drawn off clear into smaller casks, bunged up, and allowed to mature. It is during this period that the &quot;bloom&quot; of the wine develops, probably through the very slow formation of ethers from the alcohol and the acids previously produced, or from traces of higher alcohols by oxidation. How long a wine should be allowed to mature depends on its richness. With relatively poor wines a year s maturing may be amply sufficient; rich wines continue improving for years. To give an idea of the composition of grape juice, we quote two analyses of high-class musts of 1868, by Neubauer : Supposing such musts to ferment, the albumenoids are partly precipitated as components of the yeast or other wise, or decomposed, with formation of ammonia salt ; part of the phosphates go into the yeast likewise ; the greater part of the bitartrate of potash of the juice is pre cipitated as argol; and the greater part, if not all, of the sugar is decomposed, with formation from every 100 parts of sugar destroyed of alcohol 48 5, carbonic acid 46 9, succinic acid 7, glycerin 3 - 0, matter passing into the yeast - 9 as principal products. Besides the predominating process of vinous fermenta- Minor tion proper, certain minor fermentations and other bye- ^men- reactions take place, which lead to the formation of free tatlons - acetic and other fatty acids, ethers, and traces of higher alcohols. Of these last, however, which play such an important part in whisky-brewing, only very little is formed in grape-juice fermentation. Of the bye-products the ethers are undoubtedly the most important, because it is they that constitute the bloom ; but our knowledge regard ing them is very limited. The flavour of a wine is due to two sets of volatile bodies, namely (i.) cenanthic ether (see CENANTHIC ACID, vol. xvii. p. 731), to which is due the smell common to all wines (which remains in an empty wine cask after the bloom proper has gone), and (ii.) a set of ethers (are they ethers 1) which constitute the Blume. Geiger distilled a bottle of good wine and then re-mixed residue and distillate. But the mixture was not drink able ; yet, after having been bottled up for a long time, it gradually regained its original virtues. These remarks apply only to white Rhenish wines. Red wines, in addi tion to the components named, contain chiefly colouring and astringent matters. The wines of Hungary, France, &c., as is well known, have a different character from those of the Rhine region ; but the scientific analysis of the relations is of comparatively little importance. In all rich musts part of the sugar escapes fermentation and imparts to the wine a higher or lower degree of sweet ness ; southern wines (port, sherry, &c.), even in their natural condition, contain relatively large percentages of sugar. In their case it is chiefly this sugar, in Rhine wine the glycerin and what there may be of unchanged sugar, which constitute the &quot; body &quot; of the wine. Spanish and Portuguese wines, however, especially those intended