By: Thomas Payette, Winemaking Consultant
Ebulliometer: This science principal of testing alcohol has been around for decades it is still widely used by small and large wineries alike. Based on the boiling point of water, calibrated against atmospheric pressure, this test is an excellent tool for most, if not all, dry wines. If attempting to test wine with residual sugar be sure to understand this test has its limits. Other more expensive testing units do exist but typically at a much larger price.
Tools and Chemicals
• Ebulliometer kit complete.
• Distilled water.
• Ethanol for burner lamp (Everclear ™ or equivalent).
• Matches or lighter to light wick.
• Dry wines to test.
• Lab sink or other.
• Ice cold water for condenser.
• Good eyesight and protective eyewear.
• MSDS sheets and other protective gear for handling the unit and reagents.
When: Most winemakers run their alcohols just after fermentation to validate success of their calculated predictions and then once again after blending and/or about three months before bottling to confirm their label printing will be in compliance with all regulatory agencies such as the Tax and Trade Bureau. Obviously testing anytime one suspects a change in their alcohols is recommended.
Calibration With Distilled Water
After you have properly set the unit up you must calibrate the unit using distilled water. Once we have determined the boiling point of distilled water we can start the process of measuring a wines alcohol.
1. Using the supplied glass cylinder fill the small cylinder to the line labeled “eaux: with distilled water. (This is roughly 15 milliliters.)
2. Place this amount in the lower boiling chamber via the opening the thermometer is placed in. Make sure the lower stopcock to the boiling chamber is closed.
3. Replace the thermometer in the appropriate orifice so you may read the markings on the thermometer.
4. Light the wick on the burner and place under the chimney to initiate boiling of the water. {Be careful with the flame positioning to make sure the plastic stopcock does not melt.}
5. Wait about 2 to 4 minutes to hear a steady rumble inside the unit and to watch the mercury rise in the thermometer.
6. Once the thermometer reading has stabilized you may reflect the reading from the thermometer at the zeroing point on the round “slide rule” chart. (This is included in your ebulliometer kit)
7. Double check the readings and double check where you have calibrated the unit chart to.
8. Empty the distilled water from the boiling chamber, by opening the stopcock, (careful this is hot) and flush the chamber out with about 60 milliliters of the upcoming sample of wine about to be tested. (This is the only time the author flushes the chamber due to the fact water, at zero percent alcohol, could cause interference to the first wine sample run).
9. The above may be done without cool water in the condenser chamber but having water in that chamber will cause no harm with this reading
10. Now you are ready to move on to measuring alcohols.
Procedure for Wine
1. We have calibrated the unit and have wines ready to test.
2. Make sure the upper condenser is filled with cool water.
3. Fill the glass cylinder supplied to the line “vin” (roughly 50 milliliters) with the wine you plan to test.
4. Place this amount of wine in the boiling chamber once again through the thermometer orifice.
5. Replace the thermometer in that orifice immediately.
6. Light and place the burner under the chimney to heat the wine sample.
7. Wait about 3 to 5 minutes to hear the similar rumble in the unit as noted previously above in step 5 under the distilled water calibration section.
8. Watch the mercury rise and wait patiently for it to steady on a reading. It will be jumpy at first but allow it to remain on one reading, steady, for about 30 seconds.
9. Record that boiling point.
10. Remove the burner and blow it out.
11. Carefully look on the calibration circular slide rule for that temperature reading.
12. Follow the chart carefully to see what alcohol level that reflects.
13. Record that alcohol reading in the proper places for your records.
14. Carefully dump the boiled wine sample in a lab sink or other container. Recall this is very hot and know that you may need to gently tilt the unit toward the stopcock opening to get the entire sample out.
15. Close the stopcock and repeat steps 3 through 14 above.
16. From experience the operator will easily be able to run about 5 tests with these units before the cool water in the upper condenser needs to be refreshed and the alcohol burner needs to be filled with ethyl alcohol. (Be careful as alcohol is flammable).
Calculation
As you can see there is no real calculation here. Just using the slide rule circular chart and making sure to use a steady hand while making future readings. Make sure not to accidently move the inside circle on the “slide rule” as readings will be affected. If this does happen you will need to relocate the chart to the recorded distilled water boiling point or actually re-establish that data point via the steps under calibration above.
Other Helpful Tips
Residual sugar : The boiling point of a wine is raised if the wine has a perceivable residual sugar. The raising of the boiling point temperature gives a false low alcohol reading for the wine. A wine higher in alcohol will boil at a lower temperature due to the fact alcohol has a low boiling point. Sugar will interfere with the readings
Reproducible results : If this is your first time using one of these units be sure to run several tests on the same wine to make sure you can achieve similar results with each test. If you can’t achieve the same results dig deeper to look for errors.
Spot check your results from time to time with a competent outside lab to see if results are within ranges expected. If not – look for sources of error.
While performing the test make sure to calibrate the unit with distilled water if you notice atmospheric changes taking place outside. At a minimum it may be best to calibrate the unit every three hours or so. Recall to flush the chamber out with upcoming wine sample after calibrating with distilled water to avoid false / water diluted readings.
Typically these units are very foolproof and last for centuries if handled with care. Handle with care and keep clean as you should do with all lab equipment. Most operators find storing them in their box, when not in use, is prudent.
Recall the operator can run about 5 wine sample tests before replacing the chilled cooling water in the upper condenser chamber and take time to refuel the alcohol burner with ethyl alcohol.
In the event you break the supplied glass cylinder the ”eaux” line reading is at 15 milliliters and the “vin” line is at 50 Milliliters.
Summary
These simple units are an excellent investment for most any sized winery that is fermenting their wines dry. To date these units cost near $1000.00 but outside labs charge between $15.00 and $25.00 for samples run. The actual costs to run each test adds up to pennies in terms of burner alcohol, water, ice, matches etc. Certainly a winery testing 20 wines per year will pay for their purchase in 5 years or less.
Short Course:
• Calibrate using distilled water (Be aware of atmospheric changes).
• Make sure the condenser cooling water is refreshed every 5 tests.
• Be gentle with the circular slide rule and thermometer.
• Run tests after alcoholic fermentation and 3 months before bottling.
• Spot check your results with another trusted outside lab.
Tom Payette, Winemaking Consultant, has over 30 years’ experience with winery start-ups and assisting wineries already established in the industry.