How Does Yeast Work As a Raising Agent?

How does yeast work? You see, making your own cake, bread, and rolls at home is very satisfying.  It saves quite a lot of money and using the quick modern methods given here it does not take long.  Provided you follow the instructions exactly, it is easy to achieve good results.

The Flour To Use

Choosing the right flour is important when you are baking.  It makes all the difference between getting good and poor results. For bread-making, you should use strong flour, which is marked strong or bread flour on the packet. However, for cake making go for the one written cake flour.

Strong flour is made from hard wheat.  It contains more of a substance called gluten than does the soft wheat grown locally.  When the gluten is mixed with water and kneaded it becomes stretchy, elastic, and strong.  It will rise effortlessly and hold the bubbles of carbon dioxide gas which the yeast yields.  In this manner, it forms a solid framework for the bread and offers a well-shaped loaf with a good feel.  It is hard to attain good results with regular soft plain flour.

Wholemeal flour and brown or wheat meal flour is too appropriate for bread making, as they are made from hard wheat.

What Is Yeast and How Does It Work?

Yeast is a living, unicellular plant.  If it is destroyed by excess heat it will not work and make the bread grow, so it should be cautiously treated.

How Yeast Works

In the correct conditions, the yeast cells will breed and increase in number.  As they do this, alcohol and carbon dioxide gas is formed.  The bubbles of gas are detained in the stretchy framework of the bread and so the bread increases in size.  Once it has grown in size adequately to give a light, well-risen loaf, it is put into a hot oven, the yeast is destroyed and the dough does not rise any more.

Yeast needs moisture and food in order to grow.  When you make bread, moisture is provided by the water or milk in the dough.  The food is provided by sugars in the flour.  Warmth encourages the yeast to grow more quickly, but it is not essential.  Bread dough will rise in a refrigerator overnight and this cool rise produces a good, well-shaped loaf.

A lot of warmth or heat will destroy the yeast cells so you need to be careful to avoid mixing the yeast with hot water or allowing it to rise in too hot a place.

The Type of Yeast To Use

Quick-acting dried yeast is now very widely available.  It is the simplest kind of yeast to use as it can be stirred straight into the flour.  This type of yeast often has vitamin C added to it to help it work more quickly.  As it is easy to buy, cheap, simple, and quick to use it has been in all the following recipes.

Fresh yeast:  you can use fresh yeast instead if you can obtain it.  It is easy and quick to use but is not available in so many shops.  You would use 15g(1/2 oz) in each of these recipes.  Measure the right amount of water or milk for your recipe and make sure that the temperature is correct.  And the yeast and stir until it is dissolved.  Then use this liquid according to the recipe.  When you do find a shop where you can buy fresh yeast it is useful to buy a fairly large amount, perhaps 8oz/250g.  Divide it into ½ oz/15g portions, wrap each in greaseproof paper or foil, and put it in a plastic box.  You can store this in the freezer for several months, or in the freezing compartment of a refrigerator for up to a month.  It keeps very well and this enables you to keep a store of fresh yeast in useful-sized portions.  It does not need to be unfrozen before usage.  Just put the frozen piece of yeast into the warm water and it will dissolve easily.

Ordinary dried yeast: this has to be mixed with water and left until it is frothy (about 15 minutes) before you can use it and so it is not so quick and convenient to use. To use this kind of dried yeast in any of these recipes, prepare the yeast and water mix before you do anything else, so that it will be ready to use by the time you have weighed out the other ingredients and prepared the tin and oven.  Measure out the water as in the recipe so that it is just warm.  Add 2 level teaspoons of dried yeast and a good pinch of sugar.  Stir well, then leave until frothy.

The Water Temperature

It is essential that you use water which is at the correct temperature.  It must be just lukewarm or at blood heat.  If you dip your finger into the water it must feel neither warmer nor cooler than your finger.  If the water is excessively hot, the yeast may be destroyed and the bread dough will not increase.  If the water is too cold, it will increase much more slowly.

When you add the water to the flour the mixture must be fairly soft and sticky at first. If it is too dry and hard it will be hard to knead and the bread may be heavy.  As flours vary in the amount of water they absorb, you may have to add a little more than the recipes states.  Wholemeal and brown flours mainly may need a little more water to make certain a soft pliable dough.


This is an important part of bread making.  It makes the gluten stretchy and strong so that the dough can both rise easily and hold its risen shape.  Knead the bread as strongly as you can, pulling and stretching it to grow the gluten.  If you have a big electric mixer you can use a bread hook attachment.

Leaving the Dough to Rise

The dough can be left to rise in the tins in a warm place or on the kitchen bench or table or in the refrigerator for a slower rise.  In a warmer place, the dough will rise more quickly, but too hot a temperature may kill the yeast.  The dough should be covered loosely during rising to prevent hard skin forming on the surface.  Wrap the tin loosely in a polythene bag or cover it with a slightly damp tea-towel.


Bread should be baked in a hot oven, Gas 8, 230 degrees Celsius.  The heat will cause the bread to rise a little more at first, then the yeast cells will be killed and the bread will be baked and set in its risen shape.  Test the bread to see if it is cooked by turning it out of the tin and tapping it underneath.  If it is cooked it will sound crisp and hollow.  Leave it to cool on a wire tray.

It is not necessary to brush bread before baking, but to give it a particularly attractive appearance you can brush bread rolls or round loaves with beaten egg and milk and sprinkle them with poppy seeds.

How To Work With Yeast

General instructions for making bread using quick-acting dried yeast

  1. Mix the flour, salt, yeast, and fat
  2. Mix the flour and water, knead well
  3. Shape into loaf or rolls
  4. Cover and leave to rise
  5. Bake in a hot oven

What else did I miss about how does yeast work? Let us know in the comments and don’t forget to share this article with friends and family.

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