Categories: Accidental discoveries | 1 Comment
Guest post by Rowena Fletcher-Wood
Was brandy first created as a tax dodge?
During the 15th and 16th century, alcoholic drinks were taxed by volume, since methods for assessing percentage of alcohol were relatively crude. This gave rise to a clever little corner-cutting idea: distil down wines for export, pay less tax, then add the water back in after delivery.
The process of distillation had been long known. It was usually performed in an alembic, or alchemists still apparatus, made of glass. Led by the Dutch, merchants started using these to boil down wine to between 35% and 60% abv, at which concentration they made an inferior-flavoured, very boozy concentrate.
Like all forms of preservation, the process left behind its own unique flavour, even after the concentrated drink was watered back down. The merchants accounted for this by calling the reconstituted wine brandewijn, or burnt wine to describe what they thought had happened to it. They might better have called it burning wine, for this was how they tested the concentrate – taking a portion and setting it alight, deeming the distillation adequate when their sample was entirely flammable . Often, several distillations were required, the first distillate being called the spirit of wine, and the improved distillate the spirit of wine rectified.
We know now that it is congeners – other molecules from the fruit or fermentation that are present in the drink – that produce the characteristic flavours in alcoholic drinks. These include esters and aldehydes, acids, oils, and small amounts of minerals and other solids – a playground of chemical complexity. The esters are highly volatile and contribute much of the aroma. Acids often contribute the bulk of congeners, but are not necessarily the dominant flavours: we pick up different chemicals at very different thresholds, so that, for example, the cis and trans isomers of oak lactones are perceived at very different concentrations. Most wines are very different from each other, and may only have a few congeners in common.
However, it’s not just the loss of volatile compounds that leads to the strange flavour of distilled wine, but also the decomposition of some congeners under heating. New volatile compounds are created in chemical reactions between contents and with the distillation vessel, such as the hydrolysis of esters.
During modern distillation processes in copper stills, brandy is made from a base wine that contains fewer sulfites which can react to make unpleasant copper sulfate. The distillate is collected in three steps, first the ‘heads’, then the ‘heart’, then the ‘tails’. The head contains highly volatile compounds, such as methanol, butane and hydrazine, many of which are harmful in high concentrations. The tail is filled with gritty solids that sediment at the bottom of the still. By keeping just the heart, distillers minimise the concentrations of harmful portions. Often, the head and the tails are distilled again and again, until every part that could come out as the heart has been extracted.
But distilled wine is not yet brandy. To make brandy, the distilled wine needs to be aged in wooden casks, such as on a long sea voyage – something the medieval merchants had failed to account for. When they tasted the brandewijn at the end of their travels, many of them were amazed to observe that the alcoholic burn had been softened, and new, smooth flavours introduced during maturation. The resulting liquid was also darker in colour. This was the accidental discovery of brandy.
Ageing is a complex and unique chemical process that takes place best in wooden barrels, such as those the merchants had designed for easy transportation.
The constitution of the distillate does not remain constant, with come congeners remaining stable while others degrade. The rate of degradation may vary, but eventually everything will be decomposed (probably, say the experts, who use sine wave mathematics on this kind of thing, after 15 years – so older brandies are unlikely to be any way improved).
Although compounds in the distilled wine can react together, most of the character of brandy comes from gradual oxidation through the porous wood, or reactions with the wood itself.
Oxidation reactions are affected by climate. In hotter places, evaporation is more rapid, and fast aging produces harsher brandies. Humidity affects the balance between ethanol and water evaporation. More water evaporates if it’s dry, and more ethanol if it’s humid, making up what distillers call ‘the angels’ share’. Since different compounds are dissolved in the water and ethanol fractions, the evaporation rate affects the flavour. Water houses rich sugars and colourants, whilst ethanol holds the aromatic derivatives from wood: lignins, vanillins and tannins.
Wood derivative flavours are also affected by pre-treatment, such as exposure to other alcoholic beverages, or charring, which was traditionally used to soften the wood for bending into barrels. Charring incidentally breaks down some lignins and tannins in the wood, and caramalises hemi-cellulose plant sugars.
Numerous scientists have explored the flavour and colorant molecules in brandy using techniques such as chromatography, UV absorption and mass spectroscopy. However, in the everlasting trend of corner-cutting, today many brandies are coloured to imitate aging, as storing the spirit for years, with the angels constantly taking their share, is expensive. There is even such a thing as counterfeit brandy. Therefore, some of these techniques are used to test for the characteristic spectra of compounds including sinapaldehyde, syringaldehyde, and coniferyl aldehyde that appear in real brandy, but not its imitation.
So while brandy itself came about as a means to reduce costs, in the modern drink we rely on chemists to sniff out the counterfeits and cut corners.