The Science of Making Wine, Beer, and Alcohol Through Fermentation

Fermentation is the reaction that takes place when yeast is used to convert sugar to ethanol. During the process, yeast feeds on complex sugars in the order of glucose, maltose, then maltotriose, although sometimes this sequence may not be followed depending on the type of yeast used in the reaction. The yeast converts these sugars into alcohol and carbon dioxide. The sugars provide many flavors to the end product of ethanol, but the yeast’s reaction with other compounds, including amino acids, also contribute flavors.

The equation for the fermentation reaction is written below:

 

C6H12O6 → 2C2H5OH + 2CO2 + Heat

Glucose             Ethanol           Carbon Dioxide

In theory, 10kg of sugar yields 5.1kg of ethanol and 4.9kg of carbon dioxide. Also, about 2.6MJ of heat per kg of ethanol is released.

Yeasts are fungi with a unicellular structure. Those frequently used for fermentation belong to the saccharomyces genus. They can withstand high temperature, high/low pH levels and various concentrations. Yeasts can survive in the presence or absence of oxygen. Ethanol is formed when yeast operates without oxygen.

Equipment

• Container that can be sealed
• Glass jar with 1/2 or 1 gallon measuring capacity
• Plastic bottle measuring up to 2 liters
• Different measurements of jugs.
• Fermentation lock
• Stoppers with size 8 for 1/2 to 1 gal jugs
• Siphon tubes made of vinyl with diameter of 0.5 inch.

Ingredients to Use

• Honey
• Sucrose (sugar)
• Corn syrup or any other kind of glucose. The corn syrup should not contain vanilla.
• Corn sugar or any other kind of dextrose.
• Dried or fresh fruit.
• Fresh juices – they can be concentrates but they should not have any amount of potassium sorbate
• Molasses
• Maple syrup
• Acids- Acids to be obtained include:

- Acid blend (a mixture of tartaric and malic acid).
- Ascorbic acid (these are antioxidants and they include lemon and orange juice)

• Citrus fruits or any other source of citrus.
• Tea, raisins or other sources of tannin.
• Yeast (can be obtained from the market)
• Spices such as cloves, ginger and cinnamon
• Pectic enzyme. You may also use this with fresh fruit, pulp and fruit juices made of pearl and apple.

The Concept of Fermentation and Yeast

Fermentation is simply the process of combining sugars and yeast so that alcohol and carbon dioxide gas are produced. The reaction continues until the whole sugar in the reaction is completely converted or when the yeast has been totally used up. There are different types of yeast for different levels of tolerance. These are highlighted below:

Type of Yeast	Maximum Amount of Alcohol	Ideal Temperature Range (°F)
Ale	9%*	60-80
Lager	9%*	45-55***
Bread/Baking	12.00%	60-80
Wine	14.00%	55-75
Champagne	20.00%	55-75

* If more time is allowed, this value can increase. At this point however, it slows down drastically. ** This can ferment at the same temperature with ale though the results in this case are cloudy.
*** This can be substituted with baking yeast especially when citrus wines are formed. However, baking yeast makes it smell and taste like bread and many people detest it for this reason

Yeast cannot survive on sugar alone. It does better in the presence of organic solvents containing acids, nutrients and minerals, just like other living things. However, they perform much better in an environment that is supplied with oxygen though in this case, they produce only carbon dioxide (with the exception of alcohol).

A lot of requirements for yeast to function well are available in honey. The disadvantage of using honey is that it does not ferment easily. Usually, it takes between three to twelve months for honey to ferment. However, the time can be reduced to one month if acid or some nutrients is added to the yeast.

Fruit juice is a suitable substitute for honey. The most widely used is grape juice because of the acids, tannins, and sugars it has. Apple juice is also another good choice. In addition to helping the yeast, the acids in the fruit juice also helps to improve the flavor.

Sanitization

Yeast can survive in almost any type of environment. Even where bacteria and fungi can hardly survive (such as in acids), yeast tend to thrive well. Yeast can dominate its environment as a result of its fast rate of production. Its presence causes foul smell and makes food taste awful.

To prevent this, cleanliness should be employed when handling beverages. This is more important when the fermenting vessel is being prepared for any given task. Cleaning should be done with a solution of bleach and water that is mixed in the ratio of one capful to five gallon. This works effectively since yeast cannot survive in the presence of chlorine. The bleach must be properly rinsed off so that it does not produce its foul smell. For devices you wish to use immediately, rinsing with hot water will be much better than using the bleach.

 

Methods

• Start by making the yeast. Use old yeast first before opening another pack. When opening a new pack of yeast, you may decide rehydrate it. Rehydrating can be done by adding the quantity of yeast you wish to use into a cup of juice or a mixture of water and sugar. Rehydration takes about 15 minutes.
• Yeast culture may also be prepared. This can be done by transferring a little quantity of yeast from a fermentor into a sugary solution so that more yeast can be formed. This helps to save money from purchasing yeast though it has some health risks.
• Culturing can be done in a couple of hours but better results are achieved when done overnight. The container should have a very tight cover to prevent the entry of air. Fermentation lock and stopper can be used to actualize this purpose.
• Next is the preparation of must (or wort for brewers). The must is a mixture of sugars, acids, juices and nutrients that has not fermented. This can be done by heating honey and pouring hot water over fruits for easy extraction of the juice. A solution of about two pounds of honey per gallon will ferment to yield 10%-11% alcohol. This percentage is the required composition for wine production. Fruit juice can ferment to yield up to 11% alcohol. Adding a little quantity of honey can boost the reaction. The juices, honey, tannins, nutrients and acids should be mixed in a fermenting vessel.

• After these, the yeast and must are mixed together for fermentation to take place. The vessel should not be filled so that there will be enough space for the liquid to occupy when it foams.
• The fermentation vessel should be covered with the fermentation lock after making the mixtures.
• Fermentation will start after one or two days. Fermentation begins faster with the use of packaged yeast. Fermentation can last between seven days and one month, depending on the strength of beverage you want.
• During the fermentation, racking should be done once in a while. Racking is the process of removing some liquid from the vessel to prevent the loss of both yeast and the liquid.
• After fermentation, the yeast falls out to make the solution clear. If the solution does not clear after a long time, it could be due to the presence of some by-products of fermentation or fruit pectin. To make it clearer, pectic enzyme, bentonite or gelatin may be added.
• The next step after these is to siphon the fermented solution into clean bottles. You can use plastic pop bottles or wine bottles with corks.
• If there is need to carbonate the drink, the bottle you choose should be able to withstand the pressure. In this case, the plastic pop bottles work well.
• To carbonate, simply add sugar or juice to the beverage before bottling. Half cup of white sugar should be enough for five gallons. Carbonation should take between one and two weeks.
• You can decide to leave the beverage for a long time (normally between one and six months) to improve the quality. This should be done in bottles and kept away from sunlight.
• If these steps are taken carefully, the final product will be a unique beverage that is ready to be used.

Additional Reading:

• Yeast and the Production of Alcoholic Beverages: The page is a good resource for learning about yeast, the history of beer making, the science of beer making, the history of wine and how to make wine.
• Types of Yeast: The types of yeast include brewer’s yeast, nutritional yeast and brewer’s yeast. Each of these has their specific importance.
• Yeast as Fungus: The page shows a diagrammatic representation f what yeast looks like. More about the structure of yeast can also be obtained here.
• Home Made Wines: This PDF file contains step by step procedures on how to make domestic wine; apparatus needed for the procedure also listed on the page.
• The Fermentation of Ethanol: In discussing the fermentation of ethanol, the page highlights the properties of ethanol, ethanol fermentation with yeast, ethanol fermentation with bacteria and a comparison of the effects of yeast and bacteria in the fermentation of ethanol. There are other very educative subheadings on this subject.

• The Chemistry of Beer: Topics discussed include the history of beer, how to manufacture beer and the chemical reactions involved in the process.

• Famous Wine Drinkers: The art of drinking wine can be traced back to time of the Roman Empire when wine was used on almost every occasion. This art was also imbibed by some wine enthusiasts in the 20^th century. Some of them include Roald Dahl and William F. Buckley.
• Red Wine: The page discusses the advantages and disadvantages of drinking red wine.
• Making Root Beer at Home: Instructions for making root beer (with a negligible amount of alcohol) through fermentation at home.
• Fun Facts About Fungi: Information on the yeast that is used to make different foods and beverages including beer, bread, yogurt, cheese, and wine.
• Beer Brewing: The Art and Science: Information on the ingredients of beer, the fermentation process, and many other facts about the science of brewing this popular beverage.

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