FERMENTATION Introduction Fermentation is an energy producing process

FERMENTATION

Introduction �Fermentation is an energy producing process that does not require oxygen to take place. �That means that living things can use the process of fermentation to get energy, without having to have air (situations without air are called anaerobic).

Fermentation �Bacteria, yeast, and even humans use fermentation to make energy. �Human bodies normally use sugar (glucose) to get energy through a process called cellular respiration, where oxygen helps break down sugar to get energy. �Fermentation occurs in the human body when there is not enough oxygen in the body.

Fermentation �Some organisms, like the microbes that cause botulism (a severe form of food poisoning) and tetanus (lockjaw), only live in anaerobic conditions and so they only ever use fermentation to get energy.

Fermentation �During fermentation, cells use glucose and break it down into pyruvate. �Pyruvate normally will either do one of two things-change to lactic acid or change to alcohol and carbon dioxide. �Pyruvate can change to lactic acid (during what is called lactic acid fermentation), as seen in humans and in the bacteria that make yogurt.

Fermentation �Pyruvate can also change to alcohol and carbon dioxide (during what is called alcoholic fermentation). �Alcoholic fermentation is used when yeast is put into bread dough, so that the carbon dioxide bubbles from fermentation help the bread to rise. �The small amount of alcohol produced burns off during cooking.

�This same type of fermentation can be used to make drinks that are carbonated (they are fizzy because they contain carbon dioxide bubbles produced during fermentation).

�Alcoholic beverages are also made using alcoholic fermentation, but they have a much higher concentration of alcohol than carbonated drinks because of different methods of production that affect how much alcohol is made during fermentation.

�Next is a diagram that shows glucose being broken down into pyruvic acid (for our purposes this is the same as pyruvate). �It then shows five things that pyruvate can change into-five types of fermentation. �Each type of fermentation is done by a different microbe(s), and produces products different from the other types of fermentation. �Those products can be used-for example, acetone is used in nail polish remover.

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