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What is yeast and how is it made?

Yeasts consist of one cell, and belong to the taxonomic group called fungi, which also contains moulds.

There are many species of yeasts. The most common yeast known is Saccharomyces cerevisiae, which is used in the baking- and brewing industry. Yeasts also play an important role in the production of wine, kefir and some other products. Most yeasts used in the food industry are round and divide themselves through budding. This budding is a characteristic used to recognize them through a microscope. During budding the cells appear in 8-shaped forms.

Yeast cells

Yeasts need sugar to grow. They produce alcohol and carbon dioxide from sugar. This reaction makes yeast so important for the food industry. Yeasts also produce pleasant aroma components. These aroma compounds play a very important role for the flavour of the end product. In beer the yeast is needed to produce the alcohol and the carbon dioxide for the brim. In the bread industry, both alcohol and carbon dioxide are formed; the alcohol evaporates during baking.

Yeasts can be found everywhere in nature, especially on plants and fruits. After fruits fall off the tree, fruits become rotten through the activity of moulds, which form alcohol and carbon dioxide from the sugars in it. Sometimes drunk animals appear in the news because they have eaten these spoiled fruits.

Yeasts are grown in the industry in big tanks with sugary water in the presence of oxygen. When the desired amount of yeast is reached the liquid is pumped out, and the yeast is then dried. Nothing else is added in the production of yeast.