-
Once Upon a Time ...30 / 03 / 2022
The precursors of oenological analyzes were Baumé, Gay-Lussac, and later Pasteur, who, in the 18th and 19th centuries, laid the theoretical foundations of fermentation.
In their illustrious wake, Jules Salleron (1829-1897) specialized in precision instrumentation and invented the still, the acetimeter and above all the ebulliometer. Joined by Jules Dujardin (1857-1947), the pair continued to innovate to become pioneers in the development of must and wine analysis instruments. Indeed, as a pupil of Pasteur, Jules Salleron was particularly interested in fermentation and the determination of alcohol. The first laboratory stills were designed around this time, in the middle of the 19th century. They were already used by tax offices. The ebulliometer was designed around 1870 by Jules Salleron, who also manufactured and distributed it. His young collaborator, Jules Dujardin improved this ebulliometer to give it the form we know today.
With simple equipment and quick implementation, ebulliometry makes it possible, mainly during blending operations, to determine the acquired alcoholic strength by volume (TAV) of dry wines and to give an immediate result.
Measuring principle
The boiling point is one of the characteristics of a liquid: at the pressure of 1 atmosphere, water boils at 100°C and ethanol at 78.4°C. Since wine is a mixture composed mainly of water and alcohol, its boiling point depends on its alcohol content. The lower the boiling point of a wine, the higher its alcohol content. Atmospheric pressure and altitude influence the boiling point. A calibration is therefore necessary to determine the environmental conditions at the time of the measurement. Thus, the first step is to measure the boiling point of water or a standard wine to adjust the "boiling point/alcoholic degree" correspondence table. The boiling point of the sample can then be measured and reported on the correspondence table to know the alcoholic degree. The sugars in solution have an influence on the boiling point. Below 2 g/l, this influence is not significant enough to reduce accuracy. Beyond this threshold, a correction must be applied or another method used.
With simple equipment and quick implementation, ebulliometry makes it possible, mainly during blending operations, to determine the acquired alcoholic strength by volume (TAV) of dry wines and to give an immediate result.
Measuring principle
The boiling point is one of the characteristics of a liquid: at the pressure of 1 atmosphere, water boils at 100°C and ethanol at 78.4°C. Since wine is a mixture composed mainly of water and alcohol, its boiling point depends on its alcohol content. The lower the boiling point of a wine, the higher its alcohol content. Atmospheric pressure and altitude influence the boiling point. A calibration is therefore necessary to determine the environmental conditions at the time of the measurement. Thus, the first step is to measure the boiling point of water or a standard wine to adjust the "boiling point/alcoholic degree" correspondence table. The boiling point of the sample can then be measured and reported on the correspondence table to know the alcoholic degree. The sugars in solution have an influence on the boiling point. Below 2 g/l, this influence is not significant enough to reduce accuracy. Beyond this threshold, a correction must be applied or another method used.
Recommendations
Boiling point measurement requires the use of an ebulliometer, either traditional or electric. In all cases, a measurement (excluding calibration) lasts approximately 7-8 minutes.
The method is valid for dry wines below 20% Vol., with an accuracy of approximately ±0.1% Vol. In order to obtain precise results, it is necessary to take precautions for use:
• use the same thermometer or the same probe for calibration and measurement; • scrupulously respect the volumes of standard solution and sample provided;
• work with liquids and an ebulliometer at room temperature;
• do not pour the sample into a hot boiler; • ensure that the refrigeration is efficient to avoid loss of alcohol vapor during heating;
• ensure the absence of sugars in the sample;
• renew the calibration regularly if the ebulliometer is not fitted with an atmospheric pressure sensor.
Thanks to its simplicity of use, more than a century after its development, the ebulliometer remains an instrument widely used in the world by winegrowers. Available in its traditional form with heating by alcohol lamp or in more contemporary forms with electric heating and electronic temperature acquisition, its use now extends to other activities in the food industry (breweries, cider houses, rum , vinegar factories, etc.) and industrial (production of bioethanol).
The method is valid for dry wines below 20% Vol., with an accuracy of approximately ±0.1% Vol. In order to obtain precise results, it is necessary to take precautions for use:
• use the same thermometer or the same probe for calibration and measurement; • scrupulously respect the volumes of standard solution and sample provided;
• work with liquids and an ebulliometer at room temperature;
• do not pour the sample into a hot boiler; • ensure that the refrigeration is efficient to avoid loss of alcohol vapor during heating;
• ensure the absence of sugars in the sample;
• renew the calibration regularly if the ebulliometer is not fitted with an atmospheric pressure sensor.
Thanks to its simplicity of use, more than a century after its development, the ebulliometer remains an instrument widely used in the world by winegrowers. Available in its traditional form with heating by alcohol lamp or in more contemporary forms with electric heating and electronic temperature acquisition, its use now extends to other activities in the food industry (breweries, cider houses, rum , vinegar factories, etc.) and industrial (production of bioethanol).
