A DILUTE solution of honey that stands at room temperature for about eight weeks ferments naturally to become the winelike beverage known as mead. When the drink is made in this way, however, it usually offends the modern palate; it is likely to taste bitter, harsh, yeasty or sour because of slow and faulty fermentation. Even so, mead was a popular alcoholic beverage for thousands of years. It predates wine (a fermentation product of grape juice) and probably the discovery of beer (a fermentation product of grain).

At about the time when mead was fortifying Eric the Red and his fellow Vikings against the rigors of the North Atlantic the art of viniculture spread from the Mediterranean to above the 45th parallel. The grape displaced honey as a popular source of alcohol, and consumption of mead gradually declined. Mead might well have remained in obscurity if it had not attracted the interest in 1950 of Roger A. Morse, then a graduate student of bee culture at Cornell University. Morse designed a series of experiments to investigate the origins of the offensive flavors in mead. Subsequently, in collaboration with Keith H. Steinkraus, professor of bacteriology at Cornell, he developed and patented methods of converting honey into a mead table wine, a mead sauterne and a mead champagne. Morse is confident that mead can be improved even more.

"All wines, including mead," Morse writes, "result from the action of yeast on sugar. The starting materials are a thin syrup, nutrients and yeast. Yeast organisms feed on sugar and nutrients. Waste products of the metabolism include ethyl alcohol and carbon dioxide plus a galaxy of organic compounds, some of which contribute to the flavor of the resulting beverage.

"The rate at which the flavoring compounds are produced depends significantly on the rate at which fermentation proceeds. In general a wine that ferments to completion within two or three weeks is more pleasing than one that requires months. It turns out that the juice of ripe grapes is unique among fruit juices in that it contains sugar in an almost optimum concentration plus nutrients in just the proportions required for the vigorous growth of yeast. Under normal circumstances a new grape wine ferments within one to three weeks. For this reason the ingredients in grape juice can guide the experimenter in adding yeast nutrients to diluted honey and to the juices of other fruits to encourage rapid fermentation and the production of a good wine.

"The quality of a wine varies with the concentration of sugar in the solution from which it is made. Yeasts cannot grow in sugar concentrations of more than 30 percent and cannot live in alcohol concentrations of more than about 15 percent. The natural sugar in grape juice ranges from 15 to 25 percent by volume depending on the variety and condition of the fruit. A 22 percent solution of sugar that contains the essential yeast nutrients can be fully converted by fermentation to an alcohol concentration approaching 14 percent. The resulting wine is said to be dry (not sweet). A 25 percent sugar solution can be similarly fermented into a sweet wine of the same alcohol concentration. The sweetness is imparted by unconverted sugar that remains in solution after the alcohol content rises to about 14 percent and arrests fermentation by killing the yeast. Sugar concentrations of less than 18 percent yield 'thin' wines that are low in alcohol and difficult to keep.

"Bees gather wild yeasts along with nectar. To prevent the mixture from fermenting they fan the honey with their wings to encourage the evaporation of water until the concentration of sugar exceeds the limit at which yeast can grow. Honey contains approximately 82 percent solids, mostly sugar.

"As the initial step in making honey into mead reduce the concentration of sugar to between 20 and 25 percent by adding water to produce a dry or a sweet beverage with an alcohol content ranging from 10 to 14 percent. Honey that contains 82 percent sugar can be diluted to 22 percent by adding to 100 parts of honey enough water to make 373 parts by volume. Unfortunately the amount of sugar in a specific honey may differ from the average by a few percent-just the difference between a dry wine and a sweet one. The actual concentration of sugar in the diluted solution should be measured with a hydrometer that is calibrated in units of the Brix scale through the range of +15 to +25 degrees. For all practical considerations the Brix scale can be interpreted as percentage of sugar.

"The temperature of the solution must be taken into account when the measurement is made. The instrument is calibrated at 68 degrees Fahrenheit. For each three degrees above this temperature add .1 degree Brix to the reading. Conversely, subtract .1 degree for each three degrees by which the solution is cooler than the standard temperature. The hydrometer, together with a cylindrical vessel for holding the specimen and a floating thermometer, can be bought inexpensively from dealers in wine-making supplies.

"A few precautions reduce the probability that the mead will be invaded by organisms that destroy the desired flavor or that the product will sour. The safest container in which to conduct fermentation is glass. Five-gallon carboys are excellent fermentation vessels. They are easy to clean and enable the experimenter to observe the fermentation and the clarity of the mixture.

"The traditional belief that wines cannot be made and aged in glass has come into question during recent decades. Excellent wines have been made commercially in glass-lined vats both here and abroad. Wood barrels of 25 to 50 gallons capacity are also popular containers. Secondhand whiskey barrels can be obtained at reasonable prices. Barrels that have been recently emptied can be used after they have been rinsed with clean water.

"Some of the traditional recipes for making mead specify that the diluted honey should be boiled for 30 minutes. At one time I questioned the practice. Boiling alters the flavor and destroys some of the vitamins that are required for the growth of yeast. On the other hand, some meads tend to be cloudy. The product does not become clear even when it is allowed to stand undisturbed for many months.

"Honey water that has been boiled and skimmed yields a mead that clears readily and has a long shelf life. Whether or not boiling affects the flavor adversely is a question of personal preference. It is one of the variables that the amateur may wish to experiment with. Transfer the diluted honey solution to the clean fermentation vessel. The fluid should occupy not more than two-thirds of the volume to leave space for the froth that accumulates on the surface of the mead during fermentation.

"Prominent among the variables that determine the quality of a wine is the kind of yeast that mediates the fermentation. The wild yeasts in honey may or may not produce a good mead. At the turn of the century vintners learned that the addition of sulfur dioxide to grape juice inhibits the growth of certain yeasts, molds and bacteria but not the yeast that makes the best wine.

"Sulfur dioxide, which is a gas at ordinary temperatures, is liberated when either potassium metabisulfite or sodium bisulfite reacts with a sugar solution. The chemicals are available as powders. They can also be bought from dealers in wine-making supplies in the form of pellets known as Campden tablets. The amount to be used is indicated on the bottle in which the tablets are sold. They are added to the diluted honey just prior to fermentation and again as a preservative when the mead is bottled. The biochemical mechanism through which sulfur dioxide inhibits the growth of organisms selectively is not fully understood. Sulfuring does not impart an undesirable flavor to wine if the directions for adding it are followed precisely.

"Although hundreds of yeasts have been described, only a few make good wine. Most of them have been identified during the past century. Some such yeasts are known as general-purpose wine yeasts. Others carry the name of the wine that is commonly made with them: Madeira, Chablis, Pommard, Bordeaux, champagne and so on.

"The yeast that we used to make mead by our patented procedure is Steinberg 618. A pleasant mead can be made, however, with any good wine yeast. Most dealers in wine-making supplies carry the cultures. The amateur is urged to experiment with several kinds.

"Usually yeast is packaged either as a growing culture on nutrient agar or dormant in the form of a dry cake. The live culture ordinarily comes in a test tube that has been partially filled with agar, plugged with sterile gauze and inclined almost on its side until the agar hardens to expose a surface of maximum area for the growth of yeast. The test tube is known as an 'agar slant.' Dried yeast is typically sealed in an airtight envelope filled with nitrogen. Cultures can be perpetuated by inoculating slants of fresh nutrient agar under sterile conditions every 90 days.

"Before inoculating the diluted honey with yeast the experimenter should add a number of growth stimulants. The kind of stimulants and the amount required vary with the kind of nectar from which the honey was made. Our investigations have been confined primarily to the honeys produced in New York State. The varieties include clover, buckwheat, fall flower (mostly goldenrod) and wild thyme. We made a major effort to use clover as being representative of the light honeys and buckwheat as being representative of the dark honeys. The flavor of honey increases with its color and carries over into the mead.

"Light clover honey consists principally of sugars and water. It is deficient in nitrogen, phosphate and vitamins that stimulate the growth of yeast. In the absence of sufficient nitrogen and phosphate fermentation may require two months or more.

"The absence of vitamins is less serious, particularly if the honey water contains adequate nitrogen. Most yeasts can synthesize their own vitamin requirements, but they do so at some cost in terms of their rate of growth. We found by experiment that fermentation can be accelerated by adding growth stimulants to the diluted honey in two forms.

"The first preparation consists mainly of inorganic salts and citric acid: ammonium sulfate, one gram; potassium orthophosphate, .5 gram; magnesium chloride, .2 gram; sodium hydrogen sulfate, .05 gram, and citric acid, five grams. The total weight of the additives is O.75 grams. This quantity is added to each liter of diluted honey.

"The second preparation includes selected vitamins plus small amounts of organic and inorganic nitrogen. It consists of biotin, .05 gram; pyridoxine, one gram; meso-inositol, 7.5 grams; calcium pantothenate, 10 grams; thiamine, 20 grams; peptone (Roche), 100 grams, and ammonium sulfate, 861.45 grams. The total weight is 1,000 grams. This preparation is added to the honey solution at the rate of .25 gram per liter.

"The influence of these preparations on the rate of fermentation was studied separately and in combination, as will be discussed below. Honey water that contains both preparations simulates natural grape juice as a medium for supporting the growth of yeast, but the formulas can doubtless be improved by further work. The vitamins are available from distributors of pharmaceuticals.

"The time required for fermentation is also influenced by the technique employed for inoculating the honey solution with yeast. Even a few yeast cells can eventually multiply enough to complete the fermentation, but the interval can be reduced substantially by a massive infusion of yeast [see illustration at right]. Three days before the inoculation is to be made we transfer about 10 percent of the solution that has been fortified with nutrients to a clean container. By means of a small loop of wire that has been sterilized in a flame we pick up a bit of yeast from the culture and stir it into the transferred solution After the mixture has incubated for 72 hours at room temperature we pour it into the honey solution. It acts as a massive inoculation. Vigorous fermentation begins at once.

"We close the opening of the fermentation vessel with a tuft of cotton or gauze for three or four days. During that time an appreciable volume of carbon dioxide is liberated. After the rate of fermentation subsides we replace the tuft of cotton with a fermentation valve. This device can be a stopper that contains a single hole into which one arm of a U-shaped glass tube is inserted. The other arm of the U dips into a small container of water. Carbon dioxide from the fermenting mead escapes by bubbling through the water. The valve seals the mead from the atmosphere and thus inhibits the growth of aerobic organisms that ferment alcohol into vinegar.

"Inexpensive fermentation valves that are somewhat more convenient to use are available commercially. They consist of glass tubing bent into a loop that has a blown bulb on each side [see illustration at left]. Enough water is placed in the device to fill the bulbs halfway. Carbon dioxide escapes from the valve by bubbling through the water.

"The stopper should make an airtight fit with the fermentation vessel, and the glass tube must make a similar fit with the hole in the stopper. The progress of the fermentation can be estimated by observing the rate at which the diluted honey bubbles and froths. If the vessel is small (a one-gallon jug, for example), the rate of fermentation can be measured by weighing the vessel periodically. A vessel that contains 85 fluid ounces of fermenting liquid can lose 10 to 12 ounces of weight in the form of escaping carbon dioxide within one to three weeks.

"As I have mentioned, we learned that honeys vary considerably in their fermentability. Light honey, represented by clover, was the most difficult to ferment and required more additives in the form of vitamins, minerals and nitrogen than dark honey, represented by buckwheat or goldenrod. Not all batches of clover honey reacted the same way, however; some fermented slowly and others little if any in the absence of supplementary growth factors.

"With the addition of growth stimulants all honeys that we tested fermented rapidly. Each honey yielded a distinctive mead. All the meads were free of the unpleasant flavor that results, in our opinion, from the typically long fermentations that occur in the absence of supplemental yeast nutrients. Clover honey yields a mild-flavored, sauterne-like mead that is acceptable to most people. It carries only a hint of honey flavor. Mead that is made from buckwheat honey is characterized by a heavy flavor that is less acceptable to the average taster.

"The addition of both nutrient preparations to clover honey stimulated the most rapid fermentation. A honey solution diluted to 25 percent sugar and inoculated with .4 percent by volume of yeast culture (instead of 10 percent) reached an alcohol concentration of 12 percent in two weeks. With all other variables fixed, the use of only the first preparation resulted in somewhat slower fermentation, but even so the fermentation was significantly more rapid than it was in the untreated solution. The addition of ammonium sulfate and potassium phosphate alone (the two most important yeast foods m the first preparation) worked about as well as the complete formula in the absence of the second preparation.

"In the case of the purest clover honey, in which yeasts grow slowly if at all, fermentation was stimulated by the addition of the second preparation. In other batches of clover honey the second preparation alone had no apparent effect. A solution of clover honey without nutrient additives served as the experimental control. No fermentation was observed in the control for 18 days. It reached an alcohol concentration of 6 percent in 54 days.

"Buckwheat honey without additives fermented much more rapidly than clover honey. This suggests that dark honeys contain more natural yeast nutrients than light honeys. In the case of buckwheat honey the use of both preparations produced the most rapid fermentation. The use of the first preparation alone resulted in more rapid fermentation than the use of the second preparation alone did.

"The acidity of the honey solution differed with the types of honey and, indeed, with individual batches of the same type. With the addition of the first preparation, which contains citric acid, the pH often dropped below 3. A clover honey at pH 2.9 fermented much more slowly than one at pH 3.7. We found that a pH in the range from 3.7 to 4.6 is desirable. The pH can be controlled by the addition of more or less citric acid. A pH of 3.7 proved to be high enough to encourage rapid fermentation but low enough to discourage the growth of undesirable bacteria.

"The rate of fermentation is significantly influenced by temperature. Generally the higher the temperature, the faster the fermentation. The rate declines slightly at 98.6 degrees F. At about 89 degrees and above the fermentation stops before the sugar is fully converted to alcohol. With the yeast that we used and at an inoculum of .4 percent by volume, fermentation proceeded at a sufficient rate at 75.2 degrees to convert all the sugar into alcohol in approximately two and a half weeks. At 86.6 degrees fermentation was complete in two weeks.

"The experiments demonstrate that with added growth factors, a selected yeast, proper pH and a temperature in the range from 75.2 to 80.6 degrees F. even light-colored honey such as clover can be fermented to an alcohol concentration of 12 to 13 percent by volume in approximately two weeks without agitation. Although more rapid fermentations can be achieved at higher temperatures, some vintners believe lower temperatures and longer fermentation intervals result in wine of better flavor. Our experiments do not support this opinion in the case of the clover meads. On the other hand, some of our experiments that did not require the maximum rate of fermentation were made at 64.4 degrees F.

"To make mead champagne we used clover honey base diluted to about 18 or 19 percent sugar at the beginning of fermentation. Both nutrient preparations were added to the diluted honey. This yielded a cuvée (a wine from which champagne is made) with an alcohol content of about 10 percent by volume.

"Granulated sugar in the amount of 2 percent by weight was added to the cuvée along with the following yeast nutrients (per gallon): peptone, .1 gram; thiamine, .02 gram; calcium pantothenate, .01 gram; inositol, .075 gram; ammonium sulfate, .00086 gram; pyridoxine, .001 gram, and biotin, .00005 gram. The cuvée can be fermented with a 7 percent (by volume) inoculum of any good champagne yeast.

"Immediately following inoculation the cuvée was transferred to champagne bottles, sealed with metal caps and incubated at 64.4 degrees F. Within 21 days the alcohol content increased to 11.9 percent (by volume). The pressure of carbon dioxide trapped in the bottles increased to 4.6 atmospheres at room temperature. The conventional procedures of champagne making were employed for disgorging yeast cells from the bottle. Mead champagne produced from clover honey has a pleasant flavor and retains its carbonation quite well. The beverage has a greater tendency to form a head than grape champagne.

"Clover honey was made into a light sherry by refermentation with flor sherry yeast (Saccharomyces oviformis, Strain 31). The concentration of acetaldehyde was increased from 48 to 190 milligrams per liter in 48 hours by passing the mead through a glass column filled with pieces of ceramic tile that were inoculated with the yeast. The initial alcohol content of the mead was 10.4 percent. This was increased to 13 percent by adding alcohol before initiating fermentation. Many people preferred the flavor of the resulting sherry to that of mead. As a matter of fact, because of its low acidity mead is an excellent base for the production of sherry.

"Like all wine, mead should be aged. Transfer it from the fermentation vessel to an aging vessel by means of a siphon. Keep both ends of the siphon below the surface of the liquid to avoid trapping air. Fill the aging vessel to the neck to minimize the area of the interface between the mead and the air. Seal the vessel with an airtight stopper to exclude bacteria and inhibit the growth of aerobic organisms. Store the vessel in a place where it can remain undisturbed, preferably at a temperature of between 55 and 65 degrees F.

"When the mead is clear, after perhaps four to 12 months, it should be bottled. Corking machines and wine-bottle corks are available, but crown caps are equally satisfactory if they fit the bottles. I once thought that aging mead for one or two years was satisfactory, but I now believe meads five to six years old are superior. Wine less than one year old should not be consumed, but how much longer it should be stored is a matter of personal opinion.

"The experimenter should be prepared to make at least four tests: for sugar, alcohol, acidity and sulfur dioxide. I have already described the tests for sugar concentration. Two techniques are commonly employed to determine alcohol concentration. One consists in measuring the temperature of the vapor immediately above the boiling solution. Close a 100-milliliter flask with a two-hole stopper. Put about 30 milliliters of solution in the flask. Insert a thermometer in one of the holes of the stopper to suspend the bulb of the thermometer above the surface of the liquid. Boil the solution and measure the temperature of the vapor to within .1 degree Celsius. Subtract the temperature of the vapor from the temperature at which water boils. To find the percentage of alcohol (by volume) multiply the temperature difference in degrees C. by 1.78 and subtract 3.2 from the resulting product. For example, a temperature difference of six degrees indicates an alcoholic concentration of 7.48 percent (1.78 x 6 - 3.2).

"The second technique involves a distillation apparatus that can process 100 milliliters of liquid. The apparatus can be an Erlenmeyer flask with a Liebig condenser. Place 100 milliliters of the fluid to be tested in the flask and distill until 80 milliliters has condensed in the receiver. Add sufficient water to the distillate to make exactly 100 milliliters. Place the solution in the refrigerator and cool it to 60 degrees F. Transfer the solution to a hydrometer jar and measure the alcohol concentration with a Tralles hydrometer calibrated from 0 to 100 percent.

"The acidity of honey solutions can be measured with sufficient accuracy by means of test paper that changes color with pH. A set of papers manufactured by Micro Essential Laboratory, Inc. (4224 Avenue H, Brooklyn, N.Y. 11210), is particularly suitable; the papers span the range from pH 2 to pH 5.

"Finally, an apparatus for measuring the concentration of sulfur dioxide is useful. The test is made by transferring exactly 20 milliliters of specimen solution to a 50-milliliter beaker and adding five drops each of a 25 percent sulfuric acid solution and a 1 percent starch solution. With a burette add to the mixture drop by drop an N/40 solution of iodine and potassium iodide. Stop adding solution when the mixture turns black. Multiply by 40 the number of milliliters of iodine solution required to achieve the change in color in order to determine the concentration of free sulfur dioxide in parts per million. A dry mead should contain about 30 parts per million of free sulfur dioxide at the time it is bottled.

"Distributors of wine-making supplies can be found in many communities by referring to the classified pages of the telephone directory. Typical of the long established firms are The Winemaker's Shop (Bully Hill Road, Hammondsport, N.Y. 14840); Continental Products, Inc. (Box 26034, Indianapolis, Ind. 46226); I. F. Schnier Company, Inc. (683 Bryant Street, San Francisco, Calif. 94107); Presque Isle Wine Cellars (West Main Road, North East, Pa. 16428), and WineArt Sales, Ltd. (3417 West Broadway, Vancouver, British Columbia). In addition the experimenter will find it helpful to obtain a copy of Home Winemakers Handbook by Walter S. Taylor and Richard P. Vine (Harper & Row, New York, 1968). This book explains in detail the techniques of making conventional wines.

"At least five days before the experiments are undertaken a copy of U.S. Treasury Form 1541 must be executed and filed with the Regional Office of the Bureau of Alcohol, Tobacco and Fire Arms to conform with Article 240.540, Part 240 (Wine), Title 26, of the Code of Federal Regulations, which states: 'A duly registered head of any family may produce annually for family use, and not for sale, not in excess of 200 gallons of wine without payment of tax. This exemption does not authorize the production of wine for such use contrary to state law.' The permit is issued without charge."

Bibliography

MEAD. Brother Adam in Bee World, Vol. 34, No. 8, pages 149-156; August, 1953.

METHOD OF MAKING WINE FROM HONEY. Roger A. Morse and Keith H. Steinkraus. United States Patent Office No. 3,598,607, August 10, 1971.

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