What a delicious afternoon tea cake. Lemon, everyone's favourite.
Raising Agents
Raising Agents, known as leaveners, fall into three specific categories – Chemical , Mechanical and Natural. Let’s look at these three separately.
Ingredients for Baking – So many categories, so much information, and skills too
Raising Agents
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Raising Agents: The 'Agents' which gives lift to your Baking!
Chemical Raising Agents
Baking Powder
Baking Powder is a blend of acid, (most commonly, calcium phosphate, sodium aluminium sulphate, or cream of tartar), and alkali – (baking soda/sodium bicarbonate). When combined with liquid and heat, carbon dioxide bubbles are created. These bubbles push up the dough and give lift to your baking.
Commercial baking powder uses several of these compounds which give commercial baking powder a double action. The first, when liquid is added to the mixture, and secondly, when heat is added after you put your baking into an oven.
If you let the scones rest for 30 minutes or so before baking, they will begin to rise. The dough relaxes making it easier for the bubbles to push up the dough.
When the scones go in the oven, the second action, that of heat, will again give the scones lift. The relaxed dough will ensure the scones are light, and soft, and hugely improved.
Do try it and see. This technique of resting baking before it goes into the oven works very well with cookies and cakes too. Do not bang the tray when putting the scones into the oven though, they will collapse down and you will loose the well risen lightness you gained from resting the dough.
Make your own Baking Powder
You can make up your own baking powder. For one teaspoon (equivalent) of baking powder:
Mix 1/2 teaspoon of cream of tart with 1/4 teaspoon of baking soda, and 1/4 teaspoon of cornflour, (This last element acts to round the recipe up to 1 teaspoon. and aids in anti-clogging).
I usually make this in multiples of 4 and store in a clean, dry, and airtight, lidded glass jar. Mix thoroughly. Much easier to measure out! (See the recipe ingredients).
If you decide to mix up your own baking powder, do Be Aware! For the most ‘lift’ using your own baking powder, reduce the resting time by 2/3 rds, as the addition of liquid starts the ‘single’ chemical reaction immediately. If you leave the dough standing too long pre-baking, your ‘home-made’ raising agent will have run out of ‘oomph’ before baking begins. Your scones will have a reduced lift and be more dense. They will still be very tasty though.
Baking Soda (Bicarbonate of Soda)
Baking Soda is used when there is already an acid ingredient in the recipe such as: Applesauce, buttermilk, brown sugar, chocolate, cocoa powder, cream of tartar, honey, lemon juice, molasses, vinegar. When baking soda comes in contact with an acid and liquid is added, carbon dioxide (CO2), water and a neutral salt are produced.
Care must be taken with how much baking soda is used. If too much – a ‘soapy’ aftertaste remains and the product bakes darker. If not enough is used – an acid flavour remains. If you get it right though you will have light and fluffy baking with a much better flavour. Scones made using baking soda and buttermilk/sour cream are really delicious.
Baking soda is much stronger than baking powder. The general rule is to use 1 to 1-1/4 teaspoons baking powder per 100g of flour. Baking soda should be added at 1/4 teaspoon per 100g of flour.
Salt of Harts Horn
Harts Horn was originally made from the ground antlers of reindeer. One of the oldest chemical leaveners, still used in North German, and Scandinavian Countries. It is now made using ammonium carbonate.
It must be used in a particular way as the aroma if not got rid of during baking, will taint the biscuits. However, if used correctly Salt of Harts Horn produces the best ginger bread type biscuit, with a light, crisp texture.
Storage is very important with this raising agent. It should be stored in an airtight container in a cool, dry place as it has a strong flavour, which can be absorbed by other foods
How do these chemical leaveners work?
When liquid is added to the dry ingredients in the recipe the raising agent dissolves, reacts, and carbon dioxide is produced. When heat is added the air bubbles expand and push up against the developed lattice structure. The baking begins to rise.
Towards the end of baking heat fixes the air bubbles and lattice structure, leaving well risen baking.
You will see the tiny air holes when you cut the cake, biscuit, or scone. If you have done this correctly the air bubbles will be evenly distributed throughout.
Nb. At higher altitudes less baking powder/soda is required. Low pressure has an effect on carbon dioxide and makes it expand more. If you do not use less raising agent your baking will end up with a poor texture.
Mechanical Actions as Raising Agents
The physical actions of creaming, kneading, beating, and whisking will incorporate tiny air bubbles which expand when heat is added. The addition of flour gives structure for the air bubbles to work against – you get rise. This structure is fixed in the oven by heat.
Creaming Method
Fat and sugar are creamed together until the sugar crystals melt. The whole mass takes on the consistency of whipped cream. Use castor sugar which has a small crystal size, it will combine with the fat far easier than granulated sugar which has a larger crystal. This is not absolutely necessary though, as long as you cream the mixture properly, granulated sugar works just as well.
The creaming method incorporates air into the mixture which is held in place by the semi-solid fat. These bubbles expand during baking allowing the batter to rise. Care must be taken once flour is added. This should be folded in carefully to avoid development of the gluten lattice structure.
If you over mix the cake mixture after adding the flour, once baked you will get a very firm crumb and a prominent point in the centre of your cake. The cake will still be edible, though dense!
You will get a cake with a better texture and more rise by using cake flour to bake with as it is lower in lattice forming gluten. If you cannot purchase cake flour you can easily make it. Substitute 20% corn starch (cornflour) for 20% of the flour called for in the recipe. Sieve the two together well. You will have reduced the gluten content of ordinary plain flour.
Kneading Method
Kneading is a process used in bread making. Yeast liquid is dispersed into high gluten flour to make a dough. The mechanical action of kneading the dough, either by hand or machine, develops the gluten strands which form into a lattice structure.
As gentle warmth is applied, carbon dioxide is released by the yeast and is trapped in the developed lattice pockets. The yeast continues to work and give off carbon dioxide, which pushes up the lattice structure, until heat is applied during baking.
Heat kills the yeast, and fixes the gluten’s lattice structure in place. You have a well-risen loaf, light in texture with a lovely crunchy outer.
Beating
Certain procedures in baking require you to use a ‘beating’ method – generally where heat is involved.
If you are making hot water crust pastry you would bring water and butter to the simmer stage in a pan. Flour is added and the mixture is beaten until combined. Use as the pastry for ‘Raised’ Pies. This pastry has a much stronger structure allowing pies to be cooked without a tin.
The same principal applies when making choux pastry. Flour is added to a hot water/butter mixture. Raw egg is then beaten in. The egg gives the rise with this pastry
Whisking
When volume has to be added then the whisking method is used. Meringues are made by whisking egg whites with sugar until the volume is six to eight times more than you began with.
Gentle heat applied over several hours dries out the meringue and leaves a crisp, sweet confection.
Fatless sponge cakes require whole egg and sugar to be whisked together to achieve a high volume. Cake flour is gently folded in. Air incorporated into the eggs and sugar give volume and lightness to the cake.
Natural Leaveners as Raising Agents
Yeast
Yeast is a natural leavener. Give it food, moisture, warmth, and air, and it will grow.
During this ‘fermentation’ process the carbon dioxide gas released by it is trapped in tiny air cells. These continue to expand and push up against the latticed gluten structure and you have rise! The lattice structure is formed and developed when water is added to the flour, and both then kneaded together to form a dough.
It takes about 2 hours using fresh, active dry, or, instant active dry, yeasts, for the bread to reach this stage.
The baking process stops the action of yeast cells by killing them through heat. The lattice structure of the wheat protein (gluten) is now fixed in place.
Sourdough – a natural process using air borne yeast cells can take up to 24 hours to reach the same stage. This lengthy process produces bread with a wonderful aroma and flavour.
Eggs
Eggs are another natural raising agent. The white of egg (albumen) is whisked up with sugar until it is six to eight times its volume. Again, the addition of heat causes the albumen to coagulate and fixes the structure in place.
With a whisked sponge like Genoese, the yolk of the egg when whisked with sugar again expands in volume by air being incorporated into it. The addition of flour gives the structure which holds the air bubbles in place.
Eggs have many uses in baking.
They make things rise such as in soufflés and sponge cakes.
They can thicken as in custards and sauces.
They can be used to add a lovely finishing colour to pastries.
They emulsify and soften texture.
With frostings, eggs stop the sugar from crystallising.
In general, eggs add colour, flavour, richness, and they lighten the mixture.
Eggs come in different sizes though most recipes call for a large egg to be used – which is 2ozs (50g) in weight. The yolk is 1/3rd of the egg, the white 2/3rds.
The yolk contains all of the fat and most of the nutrients while the white contains albumen.
Care must be taken in using fresh eggs due to a problem with Salmonella. Raw egg should not be eaten, especially if pregnant. If raw egg is to be used for eating without cooking, it should be pasteurised.
In Baking, this is not usually a problem as significant heat is usually applied.