This section is from the book "Alcohol, Its Production, Properties, Chemistry, And Industrial Applications", by Charles Simmonds. Also available from Amazon: Alcohol: Its Production, Properties, Chemistry, And Industrial Applications.
Wine, in general terms, is the beverage produced by the fermentation of fresh grapes, or of the juice of fresh grapes. Certain additions are well recognised - e.g., the "fortification " of some wines by the addition of a small proportion of distilled spirit; "chaptalisation' of a poor "must "by the addition of sugar; "plastering" with calcium sulphate, and the use of sulphurous acid or alkali bisulphites as preservatives. These and other additions are made under regulations as to the maximum quantities and other conditions in the chief wine-making countries.
In the United Kingdom, fermented beverages of a somewhat similar type, but made from a variety of materials which may or may not include grape juice, are known as "British Wines." "Sweets," or "made wines," are legal terms for these products, which are described more fully further on.
For fiscal purposes, all wine imported into this country, whether made from fresh grapes or not, is classed as "foreign wine," and pays a duty of customs; whereas British wine is exempt from duty so far as the alcohol is concerned.
The foreign wines usually drunk in this country may be referred to the following principal types: Burgundy, claret, champagne, hock, port, and sherry.
Burgundy and claret are of similar general character, both being dark red, "still "wines, nearly free from sugar, and of low alcoholic strength, ranging from about 12 to 22 per cent. of proof spirit. Burgundy, however, is of different flavour from claret, has rather more "body," and is usually somewhat stronger in alcohol. Champagne is a sparkling white wine containing about 16 to 23 per cent. of proof spirit, with usually a good quantity of sugar - 8 to 16 per cent. or thereabouts - though the "dry" varieties may have very little. Hock is a white Rhine wine, either ' still ' or sparkling, with about the same proportions of alcohol and sugar as are found in Burgundy: Moselle is a similar type of wine, but produced in the Moselle district. Port, a product of north-east Portugal, is a sweet, strongly alcoholic red wine, containing about 26 to 38 per cent. of proof spirit; the sugar may range from about 3 up to 10 or 12 per cent. Sherry is a Spanish wine of characteristic flavour, yellow to brown in colour, and strong in alcohol, containing about 26 to 35 per cent. of proof spirit; Madeira and Marsala are wines of the sherry type, but with their own distinctive bouquet. Sherry may contain sugar in amount ranging from nil up to 5 per cent., according to whether it is dry or sweet.
Portugal sends the largest quantity of wine to the United Kingdom. France and Spain follow closely, and a long way behind come Germany, Australia and Italy. A table showing the quantities imported will be found at the end of this section.
The better-class clarets, "fine growths " and "cms," are named after the place of origin - e.g., St. Julien, Pauillac, Chateau Latour, Chateau Margaux. The French white wines, such as Barsac, Chateau Y'quem, Graves and Sauterne, are produced mainly in the south-west, whilst the champagne area is in the north-east, in the neighbourhood of Rheims and Epernay. Chablis is a white Burgundy wine made in the department of Yonne. Beaune, Macon, and Chambertin are typical red Burgundies. Hermitage is a purplish-coloured wine from the Rhone valley.
Of the sherries, there are two main types - the one, Amontillado, being usually darker coloured and more spirituous than the other, or Manzanilla variety. Alicante and Tarragona are red Spanish wines approximating to the port type. Rota tent is a sweetened red Spanish wine, often used as a communion wine. Malaga is a sweetened, luscious red wine coming from the south-eastern districts of Spain.
The hocks and moselles come chiefly from vineyards in the neighbourhood of the Rhine, Moselle, and Main. Among the more noted Rhine and Moselle wines are Steinberger, Johannisberger, fraumilch. Assmannshauser is a red wine produced near Bingen.
Rudesheimer, Rauenthaler, Berncasteler, Niersteiner, and Lieb.
Asti, Chianti, Montferrat, and Lacryma Christi are Italian wines; Tokay is a noted sweet Hungarian wine; Bual, Tinta and Malmsey or Malvoisie are varieties of Madeira wine.
The complete analysis of wine requires a large number of determinations and tests to be made - some 20 are specified in the French regulations, and 28 in the German. A fairly full ordinary analysis would usually include determinations of: Specific gravity; alcohol; extract; acids - total, fixed, and volatile; tartaric acid; polarisation; sugars; glycerol; ash; phosphates; sulphates; and tests for artificial colouring matters, together with the organoleptic tests of taste and smell. In addition to these, the French requirements include a microscopic examination, tests for saccharin and dextrin, determination of potassium, sulphurous acid, chlorides and citric acid; and examination for free mineral acids and for antiseptics. The German regulations include, besides most of those mentioned above, tests for commercial glucose; nitric acid; barium, strontium, and copper; tannin; tartaric acid present in the free state, as cream of tartar, and as tartrates of the alkaline earths. It will, of course, be understood that certain of these data are only obtained in special cases.
Beyond a certain point, chemical analysis is only of limited value in appraising wine. The finer shades of flavour, the "bouquet" and the aroma, which so largely determine the quality and value of the more expensive wines, are matters for the expert palate, not for the analyst qua analyst. In his province lie the recognition of the wine as wine - i.e., as a product of the fermentation of fresh grape juice; the determination of its general character or type; the estimation of its main constituents; the ascertainment of its freedom from adulterants; and the formation of a judgment upon its soundness, condition, and general quality. But even if he is not an expert wine-taster, the wine-analyst will find his practised senses of taste and smell very useful to him in dealing with wines.
The chief forms of sophistication to which wine is subject may be divided into two classes: (1) those involving the addition of foreign substances such as preservatives, coal tar colours, and artificial sweetenings; and (2) those in which substances of like nature to those already present in the wine are added to the wine. The second class includes the dilution of the wine with water; the addition of ordinary alcohol; the strengthening of the must with sugar in order to augment the eventual alcoholic strength; the admixture of fermented liquors such as raisin wine, gooseberry wine, or cider, not derived from the juice of fresh grapes; and the addition of glycerine or of cream of tartar, to mask some of the other sophistications.
Since the substances in the second class are normal constituents of wine, or contain such constituents, and since some of the additions, as already mentioned, are tolerated within certain limits in wine. producing countries, it is necessary in the analysis to determine the proportions of such ingredients quantitatively, and to compare the results with recorded statistics, before conclusions can be drawn as to the probability of adulteration, so far as those ingredients are concerned. Statistics of the chemical composition of French wines have been published by Gayon and Laborde,1 and of German and other wines there are many in Konig's well-known compilation. A few typical analyses are included on pp. 489.490) in illustration of the principal types.
Apart, however, from the question of general agreement of the analytical data with those of recorded analyses, each determination has its own special importance. It may be well, therefore, briefly to indicate the significance of the chief determinations before proceeding to describe them in detail.
The importance of this constituent scarcely needs pointing out. It shows, in the first place, whether the sample dealt with is the ordinary type of wine, or a "non.alcoholic ' product; and if the former, whether it is a normal or a "fortified ' wine. It is important per se, as the stimulant and intoxicant constituent of the wine; its amount may help to show whether the wine agrees with an alleged description; and in conjunction with other constituents it may assist the analyst in forming a judgment as to whether the wine has been diluted with water.
An unusually low extract may indicate that the wine has been diluted or fortified, or that it has been mixed with "marc" wine, which is poor in extract. On the other hand, a high extract is characteristic of "concentrated" sweet wines such as those of the Tokay type, which have been prepared by evaporation of the must, as distinct from wines which have been sweetened by the simple addition of sugar.
This is one of the products of alcoholic fermentation, and therefore must be present in genuine wine. The ratio of glycerol to alcohol is reduced by the addition of distilled alcohol to the wine. Also sweet wines obtained by adding alcohol to must which has been but slightly fermented are naturally poor in glycerol, whereas those which are prepared by sweetening normally fermented wines contain the normal proportion. Hence the determination of this ingredient may assist in distinguishing between these kinds of wine. Again, the ratio of glycerol to alcohol has a tendency to be high in old wines, because some of the alcohol originally present has been lost by evaporation. Unfortunately, however, there is a considerable variation in the ratio of glycerol to alcohol produced in genuine wine, so that the estimation is less helpful than it might appear to be at first sight. The usual range is from 6 to 10 grams of glycerol per 100 grams of alcohol in red wines, but in white wines the maximum may be much higher, reaching 15 or 16, and, exceptionally, even greater values. This variation is traceable to the activities of different micro-organisms in the must. Hence deductions drawn from the proportion of glycerol should be made with circumspection.
1 " Vins," Appendix.