Does Brewer's Yeast Eat Sucrose?

Beer is traditionally made from four ingredients: water, barley, hops and yeast. Arguably, yeast is the most important ingredient because it does all the work. It transforms the natural sugars from the malted barley in the wort (not yet alcoholic beer) into alcohol and carbonates it producing a deeply flavored, refreshing beverage. Biologically classified as a fungus, there are different yeasts for different uses. Bread yeast, wine yeast, champagne yeast, and brewers yeast are all different. There are even different yeasts depending on which type of beer you are making.

What is brewers yeast?

Brewers yeast is any one celled fungus, Saccharomyces cerevisiae, used to ferment alcoholic beverages. Rich in vitamin B, it is often dried and used as a nutritional supplement. In brewing beer, there are two types of brewers yeast: top and bottom fermenting yeast. Top fermenting (saccharomyces cerevisiae), or ale, yeasts work best at a slightly higher temperature than bottom fermenting (saccharomyces uvarum), or lager, yeasts and can convert sugars to alcohol at room temperature while lager yeasts must be chilled to work properly. When beer was first made, wild yeast that populated the air fermented the wort naturally. Now wild yeasts are mostly used in fermenting lambics.

What does brewers yeast eat?

According to Charlie Papazian's The Complete Joy of Homebrewing, "the sugars homebrewers encounter most often are dextrose, fructose, glucose, lactose, maltose and sucrose." Easily fermented by brewers yeast, sucrose is naturally occurring in malts and malted barley says Papazian, and is available refined as normal white sugar. Fructose, glucose and maltose are all rapidly fermentable by brewers yeast while lactose (fermentable by some wild yeasts) is not.

Can you use other types of yeast to brew beer?

Normally, only cultivated yeast should be used in brewing. Wild yeasts are unpredictable and may bring with them harmful bacteria that can cloud your beer and cause off flavors.

How does yeast work?

Yeast are single-celled organisms that eat sugar in many forms and produce alcohol and carbon dioxide in the process. According to TheNewCook.com, "one glucose molecule turns into two alcohol and two carbon dioxide molecules." The alcohol is released into the wort and the carbon dioxide is dissolved resulting in carbonation. The fermentation process also produces a variety of subtle flavors depending on the ingredients. When wine drinkers say they taste pear, apple and citrus in white wine and cherries, berries and spice in red wine, those flavors are because of fermentation.

Yeast Fun Fact

Yeast is high in B vitamins, the precise vitamins that alcohol depletes. So drinking unfiltered, homebrewed beer with yeast still in it will greatly reduce the risk of hangovers.

References

• How Does Yeast Work?