Yeasts are a group of single-celled fungi and about 160 different species are known. It is one species, in particular, Saccharomyces cerevisiae or “brewer’s sugar fungus”, that is good for brewing and baking. Yeast gives off a characteristic flavour and smell; it leavens bread and converts the grain carbohydrates into alcohol and carbon dioxide. When we buy yeast it is live but inactive. With a little warmth and the addition of some water it is activated and releases the gas, carbon dioxide, that will raise the dough. The activity ceases only when the dough is placed in the oven and the yeast is killed by extreme heat.
Fresh yeast – this should be putty-like in colour and texture; it should look firm and moist and feel cool to the touch. If it is dry, dark and crumbly it may be stale or not live. Fresh yeast can be bought for a pittance from many supermarkets that have a bakery on site or from your local bakery. Keep fresh yeast in an airtight container in the fridge for up to 3 days. Alternatively, divide the yeast into 15-g or 30-g (1/2-oz or 1 -oz) portions and freeze for up to 3 months. Always defrost your yeast thoroughly at room temperature or in the fridge before use.
To use: using a spoon, crumble the fresh yeast into a small glass bowl and add about a quarter of the required amount of water as specified in the recipe to it. Use the back of the spoon to cream the yeast until it dissolves in the water and forms a smooth blended paste. Stir in the remaining water. The yeast mixture is now ready to be added to the flour.
Dried granular yeast – usually bought in jars or tins from the supermarket. Dried yeast can be reconstituted with a little lukewarm water and will give exactly the same result as fresh yeast. It must be stored in an airtight container and always keep an eye on the date stamp. If it doesn’t produce a frothy head when reconstituted with water it is not fresh.
To use: sprinkle dried granular yeast into a small glass bowl containing the quantity of lukewarm water as specified in the recipe. Leave to dissolve for 5-10 minutes. Once the yeast has dissolved, stir the mixture with a wooden spoon. The yeast mixture is now ready to be added to the flour. Continue as instructed in the recipe.
Dried easy-blend yeast – the easiest of yeasts to use as it is just added to the flour, with the water added separately. Again, the end product will be just as superior as using fresh or granular yeast. Always check the date stamp to ensure freshness.
To use: sprinkle dried easy-blend yeast directly onto the flour. The yeast will activate once the liquid has been added. Continue as instructed in the recipe. Easy-blend yeast cannot be used for the “sponge” method (see page 36).
NOTES • 15g fresh yeast = 2 tsp dried granular yeast = 2 tsp dried powdered yeast
• In the recipes, we have used dried granular yeast and the method has been written to reflect this. If you want to use other types of yeast when making the recipes, refer back to these pages.