Yeast and Alcoholic Beverages: Beer, Wine and Liquor (2024)

Role of Yeast in Production ofAlcoholic Beverages

Introduction

Although there is a distinctionbetween beer, wine and liquor as well as other lesser known alcoholic beverages, theyshare one thing in common. They are the fermentation products of yeasts, mostly Saccharomycescerevisiae or in the case of beers, usually S. carlsburgiensis. Yeasts, as yourecall, are not mycelial. They are unicellular fungi that reproduce asexually by buddingor fission. The reaction by which alcoholic beverages are produced is generally referredto as fermentation and may be summarized as:

Yeast + Glucose èAlcohol (Ethanol) + CO2

This reaction is alsoimportant in baking bread, but the desired product is then the carbon dioxide rather thanalcohol. The production of alcohol occurs best in the absence of oxygen. However, from theyeast's point of view, alcohol and carbon dioxide are waste products, and as the yeastcontinues to grow and metabolize in the sugar solution, the accumulation of alcohol willbecome toxic when it reaches a concentration between 14-18%, thereby killing the yeastcells. This is the reason why the percentage of alcohol in wine and beer can only beapproximately 16%. In order to produce beverages (liquor) with higher concentrations ofalcohol, the fermented products must be distilled.

What's the Difference Between Beer and Wine?

Generally, beverages derived from fermented fruit juice is wine. However, commercially speaking, "wine" is
fermented grape juice from Vitis vinifera. Other wines are specifically referred to by the name of the fruit of thejuices from which they are fermented. For example, elderberry wine, peach wine, etc. Beer on the other hand isusually derived from fermentation of malt derived from the digestion of germinated barleygrains, in western cultures, but other grains may be utilized in other cultures.There is also a difference between processes by which wines and beers are fermented.

There is a perception, perhaps just my own, as to the people that drink beer and the ones that drink wine. Beer
drinkers seem to be "blue-collar." When you get together with friends after you played a softball game or touchfootball game, there is usually lots of beer. When you go to professional baseball and football games, beer isthe beverage most often purchased, not wine. Wine, on the other hand, is a beverage consumed in expensiverestaurants, at formal dinners, social affairs, etc. People that drink only wine seem to be the "white-collarpeople. However, if we compare beer and wine making processes, you might have just the opposite
impression. Beer making is almost a science. Compared to wine making, it is rather complex and there's a
purpose for everything that is done in making beer and the beer makers know just about everything that goes
into beer. Wine making, on the other hand, is relatively simple. It's truly a natural drink and its origin probably
preceded beer making. Anyone can do it. The yeast responsible for fermenting the sugars in the fruits are
usually present in the grape skins, and fermentation will occur whenever there is a break in the skin (take a deepbreath the next time you go hiking and pass a bunch of guava fruits that have fallen to the ground). So whenhuman production of wine began, it involved collecting fruits, crushing them and allowing them to ferment, amuch simpler process than making beer.

History of Beer Making

The making of beer has become apopular hobby and many people now brew beer in their homes. The necessary ingredients anda recipe for beer making, as well as a variety of beer recipes, can be found in the following page.Note, the link for the beer recipe is "framed" so you must click onthe links within to go to the general beer making recipe and the beer recipes,respectively. In addition, knowing the modern process of beer making will helpyou appreciate how beer making has evolved in the many thousands of years sinceits origin.

Some historians believed thatbeer may have existed before the dawn of civilization while the human specieswas still made up of numerous nomadic tribes. However, most believed that itcame about early in various civilizations. The manufacturing of beer is morecomplex than wine and it has been mastered by many cultures in different ways. Theancient Mesopotamians and Sumerians were brewing as early as 10,000 BC. However,clay tablets, with a recipe for beer, from approximately the year 6,000 B.C., in Babylonia,is the first documented evidence of beer making. This recipe utilized underbaked bread madefrom germinated barley. Being underbaked, the bread serves as a live yeast culture andwhen the bread was cut into small pieces and placed in a large jug with water, malt wouldbe produced. The preinoculated malt when left out will ferment to give you beer. Althoughcrude, the "common" people considered this beverage ready to drink. However,someone with "breeding" would usually filter this mixture before drinking.Dates, herbs and honey were sometimes added for flavoring. Note that early beer did notinclude hops in their recipe, which would not be included until centuries later.Although the recipes for their beer was alsofar different than today’s bottled varieties, it is still recognizable asbeer. In ancient China rice was used to make a rice beer and inpre-Columbian civilizations in the Americas, corn was used instead of barleyand, without knowing it, added theirown enzyme to break down the starch by first chewing the corn before placing it in thefermentation tank. The saliva from their mouths served as the enzyme in the process ofstarch conversion to sugar and gave their beer its improved and distinct flavor.In rural areas of Russia, kvass was made by adding pieces of stale, blackbread to malt, flour, sugar and water, and allowing this mixture to ferment. This resultedin a concoction that was only 1-2% alcohol, but the Russians have maintained production ofkvass for several hundred years.

It is interesting to note that historically, beer production, in many cultures, was considered to be woman's work, along with theproduction of other edible product such as butter and cheese. In fact, the origin of beerin many cultures is attributed to women. The Babyloniansto Siris and in Rome beer was dedicated to Ceres who was the Goddess of the Corn and theirname for beer was cerevisia, which is the derivation for the specific epithet forbrewer's yeast S. cerevisiae. Since women were considered closer to the corngoddess, they were made the priestesses of these goddesses as well as the brewers invarious cultures. In all cases beer was considered a heavenly gift. The Norsebelieved their beer was the drink of Vahalla, their heaven for those who died in battleand in China beer was simply a gift from heaven.

In Western culture, during the Middle Ages, brewing was a household art in which every girl was instructed, along withbaking, since both involved the same ingredients and mysteries. Beer was considered"liquid bread" and a meal would consist of beer, bread and cheese. Therole of women and beer would continue until the Middle Ages, when monasteriesbegan to make beer, and brewing then became a male dominated process. It wasalso at this time that hops was introduced into the process of beer making,which served as a flavoring, but more importantly, a preservative, which gavebeer a longer shelf life. Although early beer was not necessarily verytasteful, one reasonwhy beer was adopted as the beverage of choice, in many early cultures, was because waterwas often of poor quality and contaminated. The Roman armies carried beer with them as they journeyed to conquerdistant lands in order to avoid becoming ill in foreign lands. When an area wasconquered, Roman yeast was introduced by using the wort from previous batches of beer toensure that they would have a decent drink. Skipping ahead in time, Bohemia, historicalregion and former kingdom of present-day western Czech Republic, had established statebreweries, in 1256, in the town of Budweis, and by 1384, Pilsen's breweries were under thecontrol of Charles IV (Holy Emperor of Rome, 1316-78). Beer also had impact onlanguages.In Germany, if the local beer went bad, beer would be imported from another town and soldat cost in the basem*nt of city hall - the ratskeller: Literally councilbasem*nt. Today, a ratskeller is a restaurant or tavern, usually below street level, that features the serving of beer.A custom of medieval marriages, in England, had the bride's family brew aspecial "bride's ale", for the bride. The bride's ale eventuallybecame the present bridal. Even the word ale isderived from the medieval hael, meaning "good health."

Government also used beer as ameans of collecting taxes. Since beer was made at home, it was impossible to impose a taxdirectly. However, taxes were levied on the ingredients that were required to produce beeras well as on alehouses. Churches were exempt from this tax since on the grounds that theyconsumed their own products, but churches often required the community to buy their beers.Because of the resentment of this practice in England, this was but one of the factors thatled to the overthrow of the Roman Catholic Church. However, it would not beuntil after the Reformation and the weakening of the church that brewing becamethe responsibility of commercial brewers who could be taxed for the beer theybrewed.

By the time that the New World wasinvaded by Europeans, beer was already present. Columbus drank corn beer offered to him byNative American Indians. It is said that the dwindling supply of beer, aboard theMayflower, in 1620, was what led to the selection of Plymouth as the end of the voyage for thePilgrim. Beer was considered such a necessity by some of the early settlers,such as George Washington and William Penn, that they started their ownbreweries. The English initially imported beer from England, but by 1629 begantheir own local breweries. The Dutch, on the other hand, started their ownbreweries, immediately. These early beers were all ales and it would be until1840, when German immigrants started breweries that lager beer would beintroduced. Among some of the people that started these German breweries wereFrederick Pabst, Bernard Stroh, Joseph Schlitz, Adolph Coors, Henry Weinhard andTheodore Hamms. Their lager beers soon displaced the ales, in popularity. By the mid 1600's, breweries werewell established in the New World. Beer evencontributed to higher education for women, in 1861, when Matthew Vassar invested hisfortune, earned in beer, in establishing Vassar College.

With the exception ofProhibition, during the 20th. Century beer has been largely mass-produced and automated.There were approximately 4,137 breweries in the United States in 1876 producingquality beer. This number fell to1,100, in 1919, the year before Prohibition. After Prohibition was repealed,only 700 breweries reopened. By the 1970's fewer than 40 breweries remained. Most of these beers were veryuniform and bland. The United States had by this time developed a reputation for havingthe world's worst beer. There were reasons behind this. After WWII, in order to appeal towomen, milder tasting beers were developed. Thus, the origin of "light" beer.However, such beers only sold modestly well. It would not be until 1972 that cigarettemaker, Philip Morris, would change the face of American beer as well as advertising.Philip Morris acquired Meister Brau and its Lite label that year and renamed it Miller Lite.Using a sophisticated and massive advertising campaign, using well known former athletes,Miller moved from seventh tosecond place among U.S. brewers. They were the ones that came out with the slogan:"all you ever wanted in a beer, and less." Thus, business came to realize thatpromotion of the product and not necessarily product quality that determines the successof a product.

The Science of BeerMaking

Today, beer is consumed in vastamounts in this country, and beer making is largely automated as in all mass producedproducts. Despite the sophisticated machinery that is used in brewing beer, it's stillessentially the same procedures that has been used for hundreds of years. We will see avideo on the making of beer on Thursday that will demonstrate the process that we havejust covered. However, beer making has become very sophisticated because of theadvances in knowledge that has resulted from advances in science. Prior to, and evenduring the 1800's, there were many who knew how beer could be made, but noneknew of the science behind each step. It was not until the 19th. century that it wasrealized that during germination, of cereal grains, that enzymes were released that wouldnot break down not only the barley starch and protein into simple sugars and amino acids,but would also do the same for other carbohydrates, such as potato, corn and wheat. Thisrealization cheapened the cost of making beer since germinated barley is a greaterinvestment than the utilization of potato, corn and wheat. It would not be until the 19th.Century that it would be known that yeasts were the organisms that actually wereresponsible for the fermentation process.

Although the process of fermentation had beenused for thousands of years, it was thought to be a magical rather than a materialprocess. As a result, many rituals and superstitions developed to direct and controlfermentation. By the 17th. Century, it was known that yeast was present duringfermentation, but its role was controversial. There were two opposing views onthis subject. One view was that yeast was required for the fermentation process,while the other argued that the process was purely chemical. It was not until Louis Pasteur'swork, in the 1850's and 1860's, was this argument resolved. Pasteur was asked by thedistillers of Lille, where the manufacture of of alcohol, from beet sugar, was animportant local industry, to determine the problem of lactic acid production in theiralcohol. Upon examination of the fermentation product under the microscope, Pasteur wasable to observe the usual yeast cells, but also noted that there were a large number ofsmaller rod- and sphere-shaped cells. When Pasteur placed a small amount of this materialin a sugar solution, a vigorous lactic acid fermentation occurred along with the formationof a grayish deposit in the solution which proved to be the rod- and sphere-shaped cells.Successive transfers of these cells always resulted in production of lactic acidfermentation and an increase in the number of cells. Pasteur argued that the cells were anew "yeast" that specifically converted sugar to lactic acid during its growth.It would be years later before it was understood that the new "yeast" wereactually bacteria. Using a similar method, Pasteur studied a number of organisms and theirfermentative processes. He was able to show that the different fermentation productsproduced were invariably accompanied by specific microorganisms. This discovery,however, had further significance. Just as the different microorganisms causeddifferent fermentation products from sugar, so did different diseases arise as aresult of different microorganisms, and that these microorganisms did not arisespontaneously, as once believed, but that each microorganism was derived frompre-existing cells of the same type. This also led to the concept that bydestroying the microorganisms in food products and beverages or by preventingtheir appearance in sterile products, spoilage could be prevented. This conceptled to the heat treatment of food products and beverages that we now know aspasteurization.

In the beginning of beer making,beer was an alcoholic beverage with the flavor of malt and grain. It was flat, slightlysweet and would spoil quickly. It would not be until the 8th. Century, that brewers incentral Europe found that the addition of Hops flowers preserved the beer and gave it theslightly bitter taste that made it more palatable. However, Hops was not the only bitteradditive used. Various cultures used other bitters; tannins from Oak and Ash trees wereused in Scandinavia; cinnamon in southern Europe and in America sweet fennel, licorice orsassafras was used. Nevertheless, by the end of the 15th. Century, it was Hops that becamethe standard bitter and preservative added to beer. Only in England was there resistanceto the use of Hops, but they, too, accepted it by the end of the 16th. Century.

With the geneticmanipulation of yeasts, numerous varietal strains have been bred. This, along withmodifications in the brewing process have led to different types of beers. Those mostoften seen in North America include:

• Lager. Beers made with yeast that settle on the bottom (Saccharomyces carlsbergensis) of the container used. Thus, all the yeast and other material settles on the bottom which results in a clear beer. Most American beers are lagers.
  • Pilsner. A colorless lager beer originally brewed in the city of Pilsen. Water used for this style of beer tend to be harder, with a higher calcium and magnesium content than water used for lager. The color of pilsner is also lighter than that of lager beer.
• Ale. Beers made with yeast that floats (Saccharomyces cerevisiae) to the top of the brewing vats, resulting in a cloudier beer. They tend to have a higher alcohol content than lagers.
  • Stout. A very dark, almost black ale. The dark color and roasted flavor is derived from the roasted
    barley, and/or roasted malt. Beer historians consider it to be the descendant of the Porter ale.
  • Porter. A very dark ale. The darker color and special flavor comes from toasting the malt before brewing. This usually results in a stronger taste and higher alcohol content. Considered by beer historians to have evolved into the Stout ale.

History of Wine

As in the case of beer, the placeand time of origin of wine is uncertain. Because of the number of different types of winethat are produced, we will restrict our discussion to grape wine. The species of grapesused in most wines is Vitis vinifera and is known to have been"domesticated" before 4,000 B.C. Wine made before this time probably would haveused wild grapes. Unlike beer, women were not associated with wine. In ancient Greece,Dionysus gave wine to man and his Roman counterpart, Bacchus, was the God of Wine. InHebrew folklore, it was Adam who planted the first grapevine.

Around 600 B.C., wine grapecultivation spread from the Mediterranean region to France and later to Spain, Portugaland Algeria. Until recently Europe and North Africa were the world's leader in quality andquantity of wines produced. Now the United States, Argentina and Russia rank among the top10 wine producing countries of the world.

In the United States, thequality of wine produced were poor to begin with because the New England area, which wasthe part of North America that was settled first, was not favorable for growing Europeangrapes. However, there were other areas where growth would be better. Although not part ofthe United States at this time, California began cultivating grapes around 1769 and by themiddle of the 19th. Century, California had a small but respectable wine industry.

Making Wine

Wine is made today much the sameway that it was centuries ago. However, unlike beer, there is still a great deal thatcannot be controlled in the production of wine. You will see this as we discuss theprocess.

The grapes from which the wine is to bemade is first separated from the stem (stemmed) and then crushed in orderto release the juice. The combination of the skin, juice and seeds is called themust. Grapes may be crushed by various means, from stomping on them withbare feet to the use of sophisticated electric presses.

If the desired product is a whitewine, the free juice is transferred to a fermentation tank and the peels and stems areremoved and pressed again. The juice of the second press can be added to the original juice or used tomake another lower grade wine. If red wine is the desired product, the skins of thegrape go into the fermentation tank with the juice. The red color of this wine isfrom the red pigment in the epidermis of the grape skin. Various vessels may beused as the fermentation tank. The most inexpensive and commonly used vessel isa 32 gallon, plastic garbage can.

Once the juice is in thefermentation tank, preferred strains of yeast are often added, but are not needed. Theskin of the grapes already have adequate yeasts on them that this step could be omitted.This is one of the uncontrolled quality of wines. Since the yeasts that grow on the grapesvary in different vineyard, especially if they are in different countries, the quality ofthe finished wine will also vary (this is probably the basis for the claim thatone country's wine is superior to another). The addition of the preferred yeast gives some measureof control to the end product.Sulfur dioxide is normally introduced into the juice at this time to killbacterial growth that may spoil the taste of the final product. Fermentation is allowed to continue for about eight to tendays, after which the initial wine is drawn off of the skin, if it is still present. Anyliquid obtained from the skins that remained during the fermentation is considered to beof a poor quality and is used in poorer quality wines or for vinegar.

After the initial fermentation,the liquid is allowed to ferment for 20 days to about a month. During this secondfermentation, the dead yeast cells as well as other particulate matter settle to thebottom. When this process is complete, the wine is separated from the sediment andtransferred to an aging tank. As the aging process continues, more sedimentation occurs,and the wine is often transferred across a series of tanks during aging. This process isknown as racking. If the final tank is a wooden cask, this also addsanother uncontrolled quantity into the final product. Because wooden cask cannot becleaned, they provide a unique character to the wine some of which are said to make thewine "superior." However, the use of stainless steel vats have removed thisuncertainty.

The aging of wine is variable. Forwhite wines, usually one year to eighteen months, but red wines can age for as long asfive years. At stages during aging, the wine is sampled and judged by a wine master. Thefate of the wine is dependent upon the decision of the wine master. The wine may bebottled after aging is complete or used only as a blend to make an inferior wine. Thebottled wine, again, based on the decision of the wine master, may be aged longer in thebottles or sold immediately after bottling. Thus, is the variability of the finished wineproduct.

White wines can benefit from agingfor up to five years, after which they will tend to deteriorate. Red wines, on the otherhand, can continue to improve for thirty or even up to forty years.

The above wines are"still" wines because they are fermented in open tanks and contain no gaseouscarbon dioxide. If fermentation stops before the sugars have all been metabolized by theyeast, the finish product is a sweet wine. If all the sugars have been metabolized,the wine is said to be dry. As in the case of beer, the percent alcohol contentwill be 14-18%. However, in fruit wines, the percentage is lower because the amount ofsugars in other fruits are generally lower. Even with the addition of sugar, fruit winesare generally 5 to 7% alcohol.

A detailed recipe for red and white winescan be downloaded from the Viticultureand Enology Department at the University of California at Davis. They have anice web page on making wine at home, with wine making recipes in pdf files.

Champagne and OtherSparkling Wines

In order to obtaincarbonation, extra sugar is added to yeast while the yeast is still actively fermentingand then tightly cap. The build up of carbon dioxide will carbonate the beverage to giveyou the bubbly effect. This is somewhat tricky since if too much fermentation occurs, thetightly sealed bottle can explode from the built up pressure. What about really cheapchampagne? The price of the champagne does not necessarily mean that quality is lacking.Some champagnes are cheap because they are mass produced in large vats rather than handledas individual bottles.

Kombucha

A beverage that is non-alcoholic that came to theattention about ten years ago is commonly known as Kombucha, but has manycommon names.It is also known as the "Tea Fungus","Manchurian Mushroom", and "Fungus Japonicus", just to namea few. However, these names, as is the case with many common names, are misleading. The "fungus" in this caseis actually a composite organism, composed of bacteria and fungi, none of whichare mushrooms. The organisms involved are:

• Acetobacter xylinum
• Acetobacter xylinoides
• Saccharomycodes ludwigii
• Schizosaccharomyces pombe
• Saccaromyces cerevisiae

The first two are bacteria and the last three areyeasts. When put together, they have an interesting appearance. They have thecolor and consistency of a fillet of sole and looks somewhat like "fishcake". However, do not try to eat it, apparently when consumed inthis matter, it is somewhat toxic! The Kombucha fungus is picturedbelow:

Physical appearance of Kombucha "Fungus"

The first record of its appearance was in 221B.C., during the Tsing Dynasty, in China. Thus, like the alcoholic beverages, itis also an old beverage. It was used as a herbal remedy and currently is popularfor that reason. The tea that is made from Kombucha is said to a remedy for manyailments, arthritis, high cholesterol, high blood pressure, cancer, AIDs, andmany many more. However, there has been little scientific research done on thevirtues of this beverage, but it is probably safe to say that many of the claimsmade of this beverage are "exaggerated".

The recipe for making the tea from Kombucha (40fluid ounces) that I was given is:

• Boil 40 fluid ounces of water in metal container, with a lid.
• After boiling, add one third to one half cup of sugar.
• Add two regular size tea bag or an equivalent amount of tea to water.
• Allow tea to steep for 10 to 15 minutes and then remove tea bag.
• Cover tea and allow to cool to room temperature.
• Pour tea into a 64 fluid ounce glass container.
• Pour 8 to 12 fluid ounces of previously made tea or a piece of Kombucha fungus into container.
• Cover tea with unbleached filter paper held in place with a rubber band.
• Allow to incubate for about a week before drinking. You should see the beginning of a new Kombucha fungus growing at the top of the tea at this time.

Guenther's Web site, in Germany,also gives a variation of the above recipe, but has pictures. If you havedifficulty visualizing what is done in the above recipe, you may want to visitthat site.

Mycological Terms

There are a large number of brewing and winemaking terms. I have only included a few, below. If you are interested inlooking up more terms, I have included links to glossary for brewingand winemaking.

Beer:Any alcoholic beverage produced by the fermentation of sugars obtained fromgrain. In western culture, barley is the grain generally used.

Ethanol:Alcohol that is the metabolic product of yeast in the wine and beer making.Specifically, it is produced by the yeast during fermentation.

Fermentation:The process by which yeast converts sugars into alcohol and CO₂.

Hops:Flower of hops added as ingredient to beer that gives it a bitter taste.However, it also serves as a preservative that gives it a longer shelf life.

Kombucha:A tea that is brewed with several species of bacteria and yeast and said to beof medicinal value. Also known as Manchurian Mushroom Tea, Fungus Japonicus andTea Fungus.

Wine:Usually fermentation of grape juice, but may also be other fruit juices as well,e.g., elderberry, peach, apple, etc.

Yeast:In wine and beer making, the "ingredient" that converts the simplesugars into ethanol. The most common species used are Saccharomycescerevisiae and S. carlsburgiensis. However, otherspecies are also used.

Questionsto Think About

1. In the strict sense, how would you distinguish beer and wine?

2. In either case, why is it that you cannot produce a beverage that is more than 18% alcohol? That being the case, how is hard liquor, which has a much higher alcohol content, produced?

3. Early beer was flat, not very palatable and also spoiled quickly. Yet, people continued to drink it. Other than for the obvious reason, what was another reason for continuing to drink beer?

4. It was a long time before the early spoilage of beer was remedied. How did brewers finally keep beer from quickly spoiling?

5. Various cultures developed beer making, independently. Although the process by which they made beer was similar, one obvious difference was in the grain that was used for malting. Name some cultures that used grains other than barley for making beer.

6. Which is older, beer or wine? Why do you believe this to be the case?

7. Why is production of a standard quality wine more difficult to achieve than a standard quality beer?

8. What is the composition of the Kombucha "fungus", in terms of the organisms involved?

9. There are various reasons for drinking Kombucha. Is there any evidence to believe that this usage is justified? Why or why not?

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