Introduction

Although there is a distinction between beer, wine and liquor as well as other lesser known alcoholic beverages, they share one thing in common. They are the fermentation products of yeasts, mostly Saccharomyces cerevisiae or in the case of beers, usually S. carlsburgiensis. Yeasts, as you recall, are not mycelial. They are unicellular fungi that reproduce asexually by budding or fission. The reaction by which alcoholic beverages are produced is generally referred to as fermentation and may be summarized as:

Yeast + Glucose è Alcohol (Ethanol) + CO2

This reaction is also important in baking bread, but the desired product is then the carbon dioxide rather than alcohol. The production of alcohol occurs best in the absence of oxygen. However, from the yeast's point of view, alcohol and carbon dioxide are waste products, and as the yeast continues to grow and metabolize in the sugar solution, the accumulation of alcohol will become toxic when it reaches a concentration between 14-18%, thereby killing the yeast cells. This is the reason why the percentage of alcohol in wine and beer can only be approximately 16%. In order to produce beverages (liquor) with higher concentrations of alcohol, 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 the juices from which they are fermented. For example, elderberry wine, peach wine, etc. Beer on the other hand is usually derived from fermentation of malt derived from the digestion of germinated barley grains, 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 touch football game, there is usually lots of beer. When you go to professional baseball and football games, beer is the beverage most often purchased, not wine. Wine, on the other hand, is a beverage consumed in expensive restaurants, at formal dinners, social affairs, etc. People that drink only wine seem to be the "white-collar people. 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 deep breath the next time you go hiking and pass a bunch of guava fruits that have fallen to the ground). So when human production of wine began, it involved collecting fruits, crushing them and allowing them to ferment, a much simpler process than making beer.

The Science of Beer Making

Today, beer is consumed in vast amounts in this country, and beer making is largely automated as in all mass produced products. Despite the sophisticated machinery that is used in brewing beer, it's still essentially the same procedures that has been used for hundreds of years. We will see a video on the making of beer on Thursday that will demonstrate the process that we have just covered. However, beer making has become very sophisticated because of the advances in knowledge that has resulted from advances in science. Prior to, and even during the 1800's, there were many who knew how beer could be made, but none knew of the science behind each step. It was not until the 19th. century that it was realized that during germination, of cereal grains, that enzymes were released that would not 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. This realization cheapened the cost of making beer since germinated barley is a greater investment 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 were responsible for the fermentation process.

Although the process of fermentation had been used for thousands of years, it was thought to be a magical rather than a material process. As a result, many rituals and superstitions developed to direct and control fermentation. By the 17th. Century, it was known that yeast was present during fermentation, but its role was controversial. There were two opposing views on this 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's work, in the 1850's and 1860's, was this argument resolved. Pasteur was asked by the distillers of Lille, where the manufacture of of alcohol, from beet sugar, was an important local industry, to determine the problem of lactic acid production in their alcohol. Upon examination of the fermentation product under the microscope, Pasteur was able to observe the usual yeast cells, but also noted that there were a large number of smaller rod- and sphere-shaped cells. When Pasteur placed a small amount of this material in a sugar solution, a vigorous lactic acid fermentation occurred along with the formation of 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 acid fermentation and an increase in the number of cells. Pasteur argued that the cells were a new "yeast" that specifically converted sugar to lactic acid during its growth. It would be years later before it was understood that the new "yeast" were actually bacteria. Using a similar method, Pasteur studied a number of organisms and their fermentative processes. He was able to show that the different fermentation products produced were invariably accompanied by specific microorganisms. This discovery, however, had further significance. Just as the different microorganisms caused different fermentation products from sugar, so did different diseases arise as a result of different microorganisms, and that these microorganisms did not arise spontaneously, as once believed, but that each microorganism was derived from pre-existing cells of the same type. This also led to the concept that by destroying the microorganisms in food products and beverages or by preventing their appearance in sterile products, spoilage could be prevented. This concept led to the heat treatment of food products and beverages that we now know as pasteurization.

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

With the genetic manipulation of yeasts, numerous varietal strains have been bred. This, along with modifications in the brewing process have led to different types of beers. Those most often 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.

Making Wine

Wine is made today much the same way that it was centuries ago. However, unlike beer, there is still a great deal that cannot be controlled in the production of wine. You will see this as we discuss the process.

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

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

Once the juice is in the fermentation tank, preferred strains of yeast are often added, but are not needed. The skin 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 grapes vary in different vineyard, especially if they are in different countries, the quality of the finished wine will also vary (this is probably the basis for the claim that one country's wine is superior to another). The addition of the preferred yeast gives some measure of control to the end product. Sulfur dioxide is normally introduced into the juice at this time to kill bacterial growth that may spoil the taste of the final product. Fermentation is allowed to continue for about eight to ten days, after which the initial wine is drawn off of the skin, if it is still present. Any liquid obtained from the skins that remained during the fermentation is considered to be of 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 second fermentation, the dead yeast cells as well as other particulate matter settle to the bottom. When this process is complete, the wine is separated from the sediment and transferred 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 is known as racking. If the final tank is a wooden cask, this also adds another uncontrolled quantity into the final product. Because wooden cask cannot be cleaned, they provide a unique character to the wine some of which are said to make the wine "superior." However, the use of stainless steel vats have removed this uncertainty.

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

White wines can benefit from aging for up to five years, after which they will tend to deteriorate. Red wines, on the other hand, 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 gaseous carbon dioxide. If fermentation stops before the sugars have all been metabolized by the yeast, 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 content will be 14-18%. However, in fruit wines, the percentage is lower because the amount of sugars in other fruits are generally lower. Even with the addition of sugar, fruit wines are generally 5 to 7% alcohol.