DISTILLATION OF WINE By Walter Scharf and Charles Malerich Natural Sciences/Chemistry Baruch College New York, NY 10010 Introduction One of the oldest chemical reactions utilized by man is fermentation- - the conversation of sugar in fruit juice into alcohol and carbon dioxide by the action of yeast. The fermentation of grape sugar can be depicted by the equation, C6H1206 + Zymase à 2C2H5OH + 2CO2 + Zymase

(1a)

or in words Glucose + Zymase from yeast à grain alcohol + carbon dioxide

(1b).

The reaction will proceed until the alcohol content of the fermentation mixture rises to a toxic level and poisons the yeast. At this point a solution is present which contains sugar, alcohol, and water is commonly called wine. (If the carbon dioxide is not allowed to escape, the solution is called champagne.) By separating the alcohol from the wine, other alcoholic beverages can be prepared which contain a higher alcohol content than wine. This separation is affected by the process known as distillation which is the subject of the next paragraph and this experiment. To complete the making of a quality distilled spirit or beverage, the alcohol obtained from distillation will be aged in a charred wooden barrel. This process removes, by absorption on the wood surface, some bad tasting impurities which are not removed by the distillation process. “Bootlegged” liquor is not aged, and hence retains the unwanted impurities. In separating alcohol from wine, a chemist affects the separation of a liquid from a solution, and, as mentioned previously, this separation can be accomplished by distillation. Distillation is based on the fact that the matter can exist in three phases - - solid, liquid and gas. As the temperature of a pure substance is increased, it passes through these phases, making a transition at a specific temperature from solid to liquid (melting point--mp) and then at a higher temperature from liquid to gas (boiling point--bp). Distillation involves evaporating a liquid into a gas phase, then condensing the gas back into a liquid and collecting the liquid in a clean receiver. Substances that have a higher boiling point than the desired material will not distill at the working temperature, and remain behind in the flask. Applied to the preparation of alcoholic beverages, alcohol has a lower boiling point than water (and sugar) and thus distillation can separate the alcohol from the wine. Some water also evaporates, and the separation is not complete, hence liquors are not pure alcohol and bottles of alcoholic beverages are labeled with the alcohol content. For fermented beverages, like wine and beer, the alcohol content is expressed in percent by volume, while for distilled liquors the alcohol content is usually given in terms of a “proof” rating. Proof is equal to twice the percent by volume of alcohol. Distillation has many other applications. One significant example is the refining of gasoline and other products from crude petroleum.

Procedure In this procedure, wine will be distilled and the alcoholic content of the distillate determined. The distillate from wine is called brandy (short for Brandywine). Distillation 1. Obtain a thermometer distilling flask and condenser from the front of the room. 2. Assemble the distilling apparatus as shown in the figure (See next page). 3. Remove the thermometer and place a boiling chip and about 75ml of wine using a long-stem funnel into the distilling flask. 4. Turn on the cooling water and have the instructor check your setup, then apply the heat to the wine. After boiling begins, reduce the heat so the wine boils at a moderate rate. 5. Watch the temperature closely while distilling and collect the distillate coming from the condenser while the temperature is in the range 80-850C. The temperature should remain nearly constant in this range. 6. When the temperature rises above 85 oC, begins to increase, quickly change collecting flasks then continues distilling until the temperature is between 98 and 100 oC. 7. Record the temperature range over which you collected the alcohol enriched distillate. Determination of alcohol content of the distilled spirit (brandy) 8. Determine the density of the brandies collected by weighing a known volume of each. Brandy (see density experiment). 9. From the table of density versus percent alcohol and the result of step 8, determine the alcohol content of the distilled spirit. Record your result. Proof test 10. Using three watch glasses, pour a small volume of the two brandies and the undistilled wine respectively into a watch glass. Record the contents of each watch glass and then try lighting the liquid with a wooden splint. Record whether the liquid in each watch glass burns or does not burn. Be careful, alcohol burns with a very faint blue flame. Extinguish any burning liquids with cold water before handling.

Density vs. Percent Alcohol of Aqueous Ethanol Solutions at 200C D204 % alcohol by volume D204 % alcohol by volume 0.9973 0.50 0.9504 32.00 0.9963 1.00 0.9468 34.00 0.9954 1.50 0.9431 36.00 0.9945 2.00 0.9392 38.00 0.9936 2.50 0.9352 40.00 0.9927 3.00 0.9311 42.00 0.9918 3.50 0.9269 44.00 0.9910 4.00 0.9227 46.00 0.9902 4.50 0.9183 48.00 0.9893 5.00 0.9139 50.00 0.9885 5.50 0.9095 52.00 0.9878 6.00 0.9049 54.00 0.9870 6.50 0.9004 56.00 0.9862 7.00 0.8958 58.00 0.9855 7.50 0.8911 60.00 0.9847 8.00 0.8865 62.00 0.9840 8.50 0.8818 64.00 0.9833 9.00 0.8771 66.00 0.9826 9.50 0.8724 68.00 0.9819 10.00 0.8676 70.00 0.9805 11.00 0.8629 72.00 0.9792 12.00 0.8581 74.00 0.9778 13.00 0.8533 76.00 0.9765 14.00 0.8485 78.00 0.9752 15.00 0.8436 80.00 0.9739 16.00 0.8387 82.00 0.9726 17.00 0.8335 84.00 0.9713 18.00 0.8284 86.00 0.9700 19.00 0.8232 88.00 0.9687 20.00 0.8180 90.00 0.9660 22.00 0.8125 92.00 0.9632 24.00 0.8070 94.00 0.9602 26.00 0.8013 96.00 0.9571 28.00 0.7954 98.00 0.9539 30.00 0.7893 100.00

Report sheet for distillation of wine Name_____________________Lab section_____________Date_____________

Type of wine used______________________ % Alcohol in wine (see label on bottle)_____________%

Density of distilled spirit (Brandy) a) Via hydrometer reading:___________% b) Via measurement and calculation Weight of graduated cylinder + brandy: ___________g Weight of graduate cylinder:

___________g

Weight of Brandy:

___________g

Volume of brandy in cylinder:

___________ml

Density of brandy

___________g Ml = ___________g/ml

% Alcohol in brandy (from table):

____________%

Proof rating of Brandy:

_____________proof

Proof test Identity of sample __________________

Burns or does not burn

Identity of sample __________________

Burns or does not burn

Identity of sample __________________

Burns or does not burn

Questions 1. Discuss the phenomenon of rain, in terms of vaporization and condensation. Is rain-water distilled water?

2. Port and sherry are called “fortified wines”, because alcohol is added to a fermented wine to prevent it from turning to vinegar when exposed to air. Beginning with squeezed grape-juicewhich contains sugar, water, and yeast- design a procedure for making a fortified wine.

3. What happens to the proof-rating of the brandy, as the distillation process continues? Why?

4. Commercial brandy is brown in color, while your “raw” brandy is colorless. Why the difference? Is brandy simply a water-alcohol mixture?

5. Using four well separated points from the table of density and percent alcohol by volume, make a density vs. percent alcohol by volume graph. Is the relationship between density and percent alcohol by volume a linear one?