Strength and Proof of a Wine or Alcoholic Beverage
Alcoholic strength is something that is not of direct concern to anyone who drinks for enjoyment. It is rather like the skeleton of a human being – it has to be there for health and efficiency but only the specialist needs to bother much about that. Nor can it be exactly determined by tasting – this is a matter for the laboratory to work out. Some wines which people describe as ‘heady’ or ‘heavy’ may in fact be rather light in alcohol; the impression they give and the demands they make can be because of their bouquet and the fascination and complexity of their character. A ‘little’ wine, however, can be what the French rightly term ‘treacherous’ (traitre) and be right up to the limits laid down for table wine. The only way this will be recognised by the drinker is by its effect on his system. The Customs and Excise levy duty on wines and spirits according to their strength, so that all fall into certain main categories; within these they can vary.
There is a belief – often held by peasant producers – that table wines which are right up to the limit of permitted strength are ‘better’ than others. This is not necessarily so. It depends on the wine. Some of the finer Mosels, for example, are comparatively low in strength. Because it directly affects the constitution of a wine, strength does tend to mean that a wine a degree or two higher in alcohol than a similar wine, will stand up to the hazards of travel better. As strength is limited by regulations governing the wines where they are made and by the British Customs and Excise, there is no likelihood of somebody having an extra-strong wine without knowing it. The strength of spirits, however, can vary more, although the strength of each can be checked by the label, where it must be given.
Something that occasionally gives problems is that, in very hot vineyards or in exceptionally hot years, the strength of a table wine can rise up to or even beyond the permitted limits of its class. It is thus brought into the category of heavy or fortified wines, as compared with light or table wines. Apart from the problems with the Customs and local regulations, this kind of thing can throw the wine out of balance, so that it is not necessarily a good thing at all.
Another source of confusion is the argument about ‘Spanish strength’ sherry, which some people take to mean that sherry in Spain is not a fortified wine. But all sherry is fortified, within greater or lesser degrees. What is often done is to increase the fortification slightly before a wine is shipped, so that its delicate constitution is not adversely affected. For example, a delicate fino may become slightly cloudy or throw a deposit, which the ignorant dislike, thinking there is something wrong with the wine. The strength of the principal drinks are shown in the table. At the time of writing, U.K. Duty is levied at 3 strengths of wine: up to 15%, from 15 to 18%, and from 18 to 22%. Some spirits intended for export, such as vodka and Scotch, are of a higher strength.
A measure of the strength of an alcoholic beverage. Proof spirit is a standard solution of pure spirit defined by U.K. Customs. Originally the scheme was evolved by a man named Clark in the 18th century, but his hydrometer (the instrument whereby the density of liquors – and, hence, their strength – could be calculated) was superseded by that of Sikes (or Sykes) in the early 19th century.
The Sikes system is used today to describe proof, but rather confusingly the U.K. And U.S. Standards differ. 100% proof means approximately 57% pure alcohol by volume. The explanation of strength in terms of alcohol by volume is more easily understood according to the system evolved by the Frenchman, Gay Lussac. Thus, in the U.K., proof is about 52% of alcohol by volume, and each 0.5% over or under proof is stated as a degree under or over proof (O.P. Or U.P.). But the U.S. Proof is 50% of alcohol by volume. It is a system which, for obvious reasons, will probably be simplified and internationally standardised in the future, but at the present time it is spirits that tend always to be quoted in terms of proof. Wines, both table and fortified, are more frequently expressed in terms of alcohol by volume (or Gay Lussac) by those familiar with this system and who find proof a complicated way of indicating a fairly simple fact. From 1980, the O.I.M.L. System of determining strength is mandatory in the EEC. This is similar to that of Gay Lussac but, whereas in that the liquid is weighed at 59°F( 15°C), the new system weighs it at 68°F (20°C), so there is a minute difference.