Yeasts are a form of fungus, and most are single-celled microorganisms which reproduce asexually by forming buds. The most familiar yeast in food production, Saccharomyces cerevisiae, has been used in brewing and baking for thousands of years – the ancient Egyptians are known to have made bread using yeast 4,000 years ago. While yeasts were first identified by the Dutch scientist van Leeuwenhoek in 1680, it wasn’t until 1857 that Louis Pasteur showed that they are responsible for the fermentation process used to make alcoholic drinks. Discover more about the use of yeasts in food by following this link>>

Unlike plants, yeasts don’t need sunlight to grow. Instead, they ferment sugars. These can be simple sugars like glucose or fructose, or more complex ones such as sucrose and maltose. They grow best in warm conditions – the ideal temperature for a fermentation using S. cerivisiae is 30 to 40 °C – but if they become too hot they cease reproducing and the fermentation stops.

In nature, yeasts are commonly found in sugar-rich environments, such as on fruit skins and in plant saps.

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