Raising Agents

Textbook and spec not used

Why do we use a raising agent?

Raising agents produce a risen, light and airy texture in the food

Unleavened produce…?

Do not use a raising agent

What do raising agents do?

bubbles of gas are introduced into the mixture

heating causes the gas to expand and the mixture to rise

What are the types of raising agents

Mechanical, Physical, Chemical, Biological

Yeast

Is a Biological raising agent grown commercially

Yeast be brought either fresh or dried

Yeast equation

Yeast+ Moisture + oxygen food + time = masses of carbon dioxide gas bubbles

Why is yeast used in bread making

Bread needs lots of bubbles to raise the dough, particularly in a large loaf.

Proving

yeast is added to the dough warm place for a period of time

What happens during proving

The yeast beings to respire using sugar in the mixture as its fuel; this produces carbon dioxide gas as a waste product

once the yeast run out of oxygen they will anaerobically respire, producing alcohol as well- fermentation

Final stages of yeast in bread making

The carbon dioxide gas causes the dough to rise

Heat during the baking causes the gas to expand further.

Heat kills the yeast and any alcohol produced.

Mechanical Raising Agents

Trap air within a mixture, air expands during cooking

Whisking eggs

When whisking, air will be trapped causing the egg to turn into a foam.

The mixture must be cooked immediately to set and stabilize the foam

Can be stabilized with lemon juice or sugar

Why is foam formed

Due to unravelling and stretching of the protien, ovalbumin, creating the increase volume

Rubbing in

Fat and flour are rubbed in together, this process traps air between the flour particles

Creaming

Fat and sugar are beat together, trapping air within the mixture. The fat become pale and creamy

Lamination

Air is trapped each time flaky and rough puff pastry dough is rolled and folded to create layers.

Sieving

A sieve is used to add flour or icing sugar to a mixture, breaking up the particles and trapping air in between

What is a foam

A foam is made when a food is aerated

It is called and air in liquid foam.

Creating a foam denatures the egg white protein. The strands unravel and change shape and allow the egg to trap the air bubble and become light and airy .

Physical Raising Agents

Steam is created in products such as choux pastry which contains large quantities of water

Process of physical raising agent

The high temperature of the oven turns the water into steam, forcing it through the mixture

The heat in the oven then sets the and flour creating a hollow, risen food

What should u not do in with physical raising agents

The oven must be hot for the steam to be created quickly before the flour and egg set

Opening the oven repeatedly or removing the food too early will cause the food to collapse

Chemical Raising Agents

React to proudce the co2

Bicarbonate of soda

Can give food a slight soapy taste, so it needs to be used in food with str