In this article, you will learn about the types of yeast. Yeast is a plant that grows and reproduces itself by the fermentation process. This is another process by which carbon dioxide gas is given off and used to raise flour mixtures and make them light in mass. The raising agent suitable for this process to take place in yeast as used in bread making.
- Suitable temperature (warm conditions) are needed. High temperatures cause the plant cells to die while low temperatures retard the growth of yeast cells.
- Moisture-milk, water, milk + water can be used
- Food-usually sugar is used.
Yeast + warmth + moisture + sugar =carbon dioxide
Types of yeast
There are 4 types of yeast used for baking:
- Compressed yeast
- This is yeast in its fresh form
- Usually sold in blocks
- Has a pleasant smell
- Crumbles easily
- Is light brown in colour
- Dried yeast
- Obtainable in two forms: sold in granules or in powder. The powdered yeast is very easy to mix and quick to use in flour mixtures.
- Is cream in colour
- More concentrated than the fresh yeast.
- Brewer’s yeast
This type of yeast is used when brewing beer.
- Home-made yeast
Mixtures that are prepared at home and are capable of producing carbon dioxide gas by fermentation process can be used in bread making to substitute for yeast. Fermentation will have taken place when the:
- Bubbles form on top of the liquid
- Liquid tastes more like vinegar
Examples of mixtures that produce froth are:
- Traditional brew i.e fermented beers
- Cooked and fermented potatoes specifically to use for bread making. Remember that in the fermented potato mixture, a little yeast is added to speed up the process.
- Keep compressed yeast in a cool place for several days
- Compressed yeast can be frozen for short periods of time.
- Divide compressed yeast into smaller portions and wrap individually before freezing.
- If during storage yeast becomes soft and sticky or develops dark brown stains, it should be discarded.
- Store dried yeast in tightly closed containers in a cool place.
- If the container is opened, dried yeast can be kept for up to 6 months but for up to one year if not opened.
- Check for expiry dates on the containers
Quantities of Yeast Used
Use the correct amount of yeast. The amount may depend on:
- The type of flour
- e.g for 500g plain flour use 10 g yeast
- The type of flour and yeast
- g for 1200g white flour use 25g fresh yeast
- for 1200g white flour use 15g dried yeast
- for 1200g wholemeal flour use 50g fresh yeast
- for 1200g wholemeal flour use 25g dried yeast
- for 1 kg flour use 125ml home-made yeast.
Enriched yeast mixtures (where extra fat, sugar, eggs or fruit are used) slow down the action of yeast. Additional yeast should be used in these cases.
Methods of Making Yeast Mixture
- Dissolving the yeast
- blend fresh yeast in the liquid and add to the flour to make dough
- Dissolve sugar in the warm liquid. Sprinkle dried yeast on top. Leave in a warm place for around 10 minutes or till frothy. Add to flour to make dough.
- Sponge batter method
Mix one-third of the flour in the recipe, yeast (fresh or dried) and sugar with liquid. Leave the mixture for about 5-20 minutes or until foamy in a warm place. Add the rest of the ingredients to make the dough. Salt should not be added in the sponge mixture. The sponge batter method is suitable for enriched yeast recipes.
- Rubbing-in method
Rub the yeast into flour. Add liquid and make the dough. This method is only appropriate when using fresh yeast. It is suitable for soft dough, quick bread, and sweet dough.
Variations In Yeast Dough
- Plain yeast dough uses flour, yeast, water and salt. Fat is an optional ingredient.
- Milk dough is where milk is used instead of water. Fat is an optional ingredient.
- The enriched dough is where fat, egg, and sugar are added to the basic ingredients. The fruit is an optional ingredient.
Tips for success
- All the ingredients including yeast must be in good condition
- Correct proportions of yeast to flour must be used
- The suitable temperature throughout is important
- Through kneading of the dough at appropriate stages is necessary to incorporate the yeast and develop good texture.
- Give yeast mixture and yeast dough sufficient time for fermentation to take place
- Correct temperature for baking should be used-must be hot to kill the yeast and prevent further fermentation. Reduce the heat to avoid hardening the bread.
Which types of yeast do you know? Share and comment below…
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