Yeast is a useful ingredient in cookery. Yeast is used as a raising agent to make a dough mixture light with an 'open texture'. Yeast is a biological raising agent. It is a single cell living organism called 'bakers yeast' or saccharomyces cereviciae.
Yeast cells need the right conditions of warmth, moisture, food and time to ferment. Yeast produces a gas during this process called carbon dioxide. The gas aerates the dough mixture and makes it rise. During baking in a hot oven the yeast cells are inactivated and the dough is set into the risen shape.
Yeast likes a temperature of around 35ºC to produce gas bubbles. It uses the flour and some sugar as a food source. The proving process takes time. It needs to happen before the baking when you put the shaped dough to rise in a warm place and wait. You can tell if the yeast has done its work when the dough has doubled in size.
Flat breads do not use yeast and that is why they are flat and less voluminous that leavened breads. Soda bread uses another raising agent, bicarbonate of soda.
Yeast can be bought in the following forms as shown on the photo:
Left: Instant, easy-blend yeast Centre :Fresh bakers yeast Right: Dried yeast - rehydrate to use
15g of fresh yeast can be replaced by 7g (a satchet) of fast action or easy blend yeast.
See how yeast ferments to produce gas bubbles after 5 minutes.
Start with white bread rolls, pizza bases, cottage loaves, plaits and move on to sweeter mixtures for teacakes, hot-cross buns and then try enriched doughs, with added butter and eggs such as the brioche, stollen and Danish pastries. You will find all the recipes on the website.