Combining Ingredients Flashcards
What is a raising agent?
Increases the volumes of doughs, batters and mixtures by promoting gas release (aeration)
What are the 3 most common raising agents?
Air, steam, carbon dioxide
How does a raising agent work?
- The action of moisture, heat or acidity triggers a reaction with the raising agent to produce a gas
- Gas expands when heated
- Gas gets trapped as it bubbles up through the mixture
- When heated, bubbles form firm structure containing a network of tiny holes left by expanding gases
How is air incorporated by sieving flour?
Air trapped between fine particles e.g. cakes
How is air incorporated by creaming?
Air is trapped in the mixture when sugar and fat are creamed together
How is air incorporated by rubbing fat into flour?
Air is trapped as fat is rubbed into the flour e.g. shortcrust pastry, scones, shortbread
How is air incorporated by whisking and beating?
Egg white is capable of holding up to 7 times its volume of air as the protein stretches e.g. protein, cakes
How is air incorporated by folding and rolling?
Air is trapped between layers e.g. flaky pastry
Steam only works in mixtures that have:
- high amounts of liquid e.g. milk in Yorkshire pudding
- high baking temperatures which allow the liquid to quickly reach boiling point
Steam works during baking when:
- the liquid reaches boiling point + steam released
- steam forces its way up through the mixture to stretch the structure + raise it
- the mixture bakes and sets in the risen shape
- there are large pockets of air where the steam has escaped resulting in an open and uneven texture e.g. Yorkshire pudding
How is carbon dioxide incorporated into mixtures?
- using chemical raising agents e.g. baking powder
- using biological raising agent (from fermentation of yeast)
What are chemical raising agents?
Powders that require liquid + heat to produce carbon dioxide. They must be accurately measured and used in small quantities as they have strong characteristics that can affect the flavour, texture and appearance of a product
What is baking powder?
Made from a combination of bicarbonate of soda (alkaline) and cream of tartar (acid) that react when they come into contact with moisture + warmth to produce carbon dioxide bubbles that expand for a fine delicate-textured result
What is bicarbonate of soda?
It can be used successfully as a raising agent, however it has a yellow appearance + strong, unpleasant taste. It must therefore be combined with other strong flavours to disguise this
What is a biological raising agent?
Yeast is a living organism that needs warmth, liquid, food, and time to release carbon dioxide. This process is called fermentation and aerates the dough during bread making
