The role of fermentation of carbohydrates in the making of

alcoholic drinks

Lucia Sangenis

Fermentation of Monosaccharides

• ETHANOL IS DERIVED BY FERMENTATION OF GLUCOSE WHICH CAN BE DERIVED BY HYDROLYSIS OF COMPLEX CARBOHYDRATES.

• Yeasts are the main fermentor and alcohol producer in the production of wine, beer and other alcohol drinks.

• The main yeast species used is Saccharomyces cerevisiae. It ferments the sugars, coming from different sources, e.g., grapes for wine, barley for beer, to alcohol and carbon dioxide.

• Both wild and cultivated strains are used. The species or strains used in the fermentation play an important role in giving the final taste properties of the drink.

How is beer made of

The main goal of malting the grains to isolate the enzymes wanted by brewers so that it’s ready for mashing.

This activates enzymes in the grains which causes it to begin to break down and release the sugar inside of it.

The wort is boiled for about an hour during which time hops are added at various points.What are hops? Hops are the small, green cone-like fruit of a vine plant. They provide bitterness to balance out all the sugar in

the wort and provide flavor. They also act as a natural preservative, which is what they were first used for

The brewing is now complete and fermentation begins. The beer is then stored for a couple of weeks at room temperature (in the case of ales) or many many weeks at cold temperatures (in the case of lagers) while the yeast works

Basically the yeast eats up all that sugar from the grains that’s in the wort and spits out CO2 and alcohol as waste products

The flat beer is bottled, at which time it is either artificially

TYPESALES LAGERS →The oldest of the two types of beer, ale production can be traced back more than 5000 years.

→They are fermented and served atwarmer (room)

→Yeast that rises to the surface of the beer during fermentation. This yeast ferments best at temperatures between approximately 55°F and 75°F.

→Lagers have only been around for several hundred years and were not even fully understood until after the invention of the microscope. →They are fermented and served at cooler (cellar) temperatures. This limits the formation of esters and other fermentation by-products, producing a clean flavor.. →Yeasts that ferment at considerably lower temperatures, around 50 degrees Fahrenheit, have the ability to process a chemical compound known as raffinose a complex sugar created during fermentation. These yeasts collect at the bottom of the fermenting beer

ALES LAGERS→top-fermentation yeast” beers, fermented at 15 to 25°C,.→yeast :Cerevisiae saccharomyces

→are mainly brewed in England.

→bottom-fermentation yeast (8 to 12°C)

→yeast :Uvarum saccharomyces

→originated in central Europe

Beer is made from grain – barley is best. Grains contain starch.

• Complex sugars are called POLYSACCHARIDES - Starch Maltose is an example of a disaccharide

• Notice it is two sugar molecules together.• Glucose + Glucose = Maltose• Glucose is a monosaccharide•

(C6H10O5)n

Barley Contains Enzymes to Convert Starch into Fermentable Sugars

• These are released when the grain is soaked in water & allowed to germinate for several days at 18oC.

• This is called BARLEY MALT

• The Sumerians baked this into barley bread.

• Ground barley malt is soaked in water.

This revives the barley enzymes which break polysaccharides into disaccharide.

This reaction is called hydrolysis

H2O

(C6H10O5)n → C12H22O11

FERMENTATIONYeasts are added to the cooled wort

HYDROLYSIS

C12H22O11 + H2O → 2C6H12O6

OVERALL HYDROLYSIS

(C6H10O5)n + nH2O → nC6H12O6

FERMENTATION

C6H12O6 → 2C2H5OH + 2CO2 • Fermentation is an anaerobic process

Wine production

• Wine is made from grapes or other fruit. The fruit is crushed into must that is ready for fermentation. The yeasts used for the fermentation grow on a film on the grapes fruit or in the environment. These wild strains play an important role in the final properties of the drink. However, often cultivated strains of Saccharomyces cerevisiae are added to improve the consistency of the final product. There are hundreds of commercially available yeast strains for wine fermentation

• In the fermentation process, energy that is converted to heat is produced as well. It is important to keep the temperature in the fermentation vessel lower than 40ºC to keep the yeasts alive. To improve yeast growth, sometimes additional nutrients, like diammonium phosphate, are added in the fermentation step.

• When making red wine, there is an additional fermentation step after the alcoholic fermentation Malic acid, naturally present in grape juice, can be converted to lactic acid by lactic acid bacteria naturally found in wineries or added artificially.

Fractional Distillation of Wine to Produce Spirits

Maturation gives rise to new flavour components by many chemical changes and by extraction from oak casks.

• Fractional distillation of wine produces up to 96% ethanol

• Spirits contain 52% – 95% ethanol and these are not attacked by microbes.

• 100% ethanol is called absolute alcohol – an excellent preservative!

Humans have been producing alcoholic beverages for thousands of years. The production of alcohol in these drinks is based primarily on yeast fermentation. Yeasts ferment variety of carbohydrates from different sources into the final products of carbon dioxide and alcohol.