In our last piece we wrote about the parts of a copper kazan and how Serbian rakija is made the traditional way, and concluded that such rakijas have a complex character and suit longer ageing in wood. This time: the instruments, and how the strength of rakija is measured.
Without instruments, making good rakija would be groping in the dark. Even experienced producers do not always manage to judge when to start distilling or exactly when to separate the fractions. Experience is important and irreplaceable, but everything is easier and faster with instruments.
The measuring cylinder
An auxiliary vessel used in the rakija cellar to measure alcohol or sugar: samples of rakija or fermented fruit mash are poured in and the alcoholmeter or must-meter is lowered into it. It carries a scale in millilitres and is made in sizes of 100 to 500 ml.
Well-equipped cellars for resting and ageing rakija also have a thermometer for the air temperature and a hygrometer for the relative humidity. Both matter, because rakija evaporates at different rates depending on them. The ideal temperature in a maturing room is 15–20 degrees; losses are greater when the air is drier, the distillate younger and the alcohol stronger. The best humidity is about 75%: below it evaporation is stronger and losses greater; above it, alcohol and water do not evaporate evenly, which affects quality.
The alcoholmeter
Also called the “grad” or the “rakijaš”: the instrument that measures the percentage of alcohol in rakija.
There is an approximate alcoholmeter without a temperature scale, and one with a temperature scale for precise measurement. It looks like the Oechsle must-meter, is made of glass and narrows at the top, where the scale runs from 0 to 70% vol. It is calibrated for 15 °C; if the rakija is warmer or colder, the reading is corrected using the table supplied with the instrument.
An alcoholmeter measures precisely only in colourless rakija, because it reads the alcohol from the specific gravity of the mixture of alcohol and water. If sugar, colour or an extract is added, it shows less than the real strength: a colourless rakija reading 40% vol will read 37.2% vol after adding 10 g of sucrose per litre. To measure old, coloured rakijas with much extract, the rakija has to be redistilled in a laboratory first.
The must-meter
A glass instrument that shows the sugar in the liquid part of the fruit mash, and so whether fermentation has ended, which matters a great deal: first, to turn as much of the fruit’s sugar as possible into alcohol, and second, because every delay in distilling harms the future rakija.
Half a litre of the liquid part of the mash is filtered off and shaken a few times so that the carbon dioxide escapes and no foam forms. The filtrate goes into a half-litre glass cylinder and the Oechsle must-meter is lowered in carefully; it sinks to a certain level, where the scale shows a reading from 0 to 130 degrees Oechsle.
Like the alcoholmeter, the must-meter is calibrated for 15 °C. If the filtrate is warmer, add 0.2 °Oe for each degree above 15; if it is colder, subtract 0.2 °Oe for each degree below. Filtered samples of fully fermented mash do not show the same value for every fruit.
