Raising agents… what are they?

Raspberry and Blueberry muffins

In short raising (or leavening) agents make your cakes and breads rise, your mousse and soufflé light and fluffy. There are three main rising agents used in cooking; eggs, baking soda and baking powder. Baking powder is probably the most common of the three. Basically the raising agent is anything that is added to introduce gas to the mixture that lightens and softens the final product.

Baking powder and baking soda both introduce carbon dioxide gas into the mixture when reacted with moisture and temperature (heat from your oven). Both are a white, dry powders that are chemical raising agents. So what’s the difference?

Baking soda (also known as bicarbonate of soda or bicarb soda) is pure sodium bicarbonate (a chemical compound). Baking soda, in the presence of moisture (which most cake batters have) and an acid (like chocolate, fruit and milk) form carbon dioxide. The carbon dioxide gas bubbles get trapped in the mixture as it is cooked and gives the food its light, fluffy texture. Baking soda also produces a slightly tangy taste (although in most foods this is very minimal).

Baking powder is a mix of baking soda, cream of tartar (an acid) and a drying agent (like starch). The combination of the three means that the mixture requires moisture and heat. The same reaction happens, moisture and heat react with the baking powder producing carbon dioxide gas which gets trapped and expands during cooking. Interesting tid bit: self-raising flour contains baking powder, so if you have a recipe that calls for plain flour but don’t have it just use self-raising and omit the baking powder. Equally if you run out of self-raising flour and need it just add 1-2 teaspoons per cup of flour to the flour and mix before using it the recipe as normal.

Oh and no you can’t substitute baking soda with baking powder. If you have to you can use baking soda and cream of tartar instead of baking powder but it will change the taste of the final product.

Eggs are a completely different matter. First off they are a mechanical raising agent (you have to do something to them for them to work as a raising agent) and secondly they don’t produce a gas, they simply introduce air into the mixture. Mechanical raising agents, like eggs, produce similar results to chemical raising agents (like baking powder and baking soda), by trapping gas in the mixture. When you beat eggs with a whisk (the hard way) or an electric mixer (the easy way) you are incorporating air to get into the eggs. It is this air that raising the mixture.

Tangent time… eggs (at least the ones I’m talking about) come from chickens, which makes them an animal bi-product. The parts of animals we eat and animal bi-products, like eggs and milk, are protein based. The protein, beside from being an important mineral is the vital factor of eggs ability to be a raising agent.

Ok back to mechanical raising agents. Beating the eggs incorporates air, which you can see with an increase in volume. The beating also denatures the protein in the eggs, which changes the shape and allows air to be trapped between the protein. This type of raising is especially important in soufflé and mousse where the egg formed shape is very important in the final texture. Egg whites (albumen) are especially good as a mechanical raising agent and for both soufflé and mousse the egg white and air structure formed by beating creates the texture of the product.

So if you want a light, air filled texture then mechanical raising agents (like beaten eggs) are important. If you are going for a moist cake then you want to look more at your chemical raising agents (like baking soda and baking powder).

If you want to put what you have just learnt to good use then check out my chocolate mousse recipe below (on video) or have a look at my recipe page (for the chocolate mousse and many more written recipes).


Posted by on 30/08/2011 in Uncategorized


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Fermenting: how do we use bacteria and fungi in food?


Cheese and wine... what a treat (courtesy of Microsoft Clip Art)

Warning:The reading of this blog may make you to break out a nice bottle of wine and a cheese board and enjoy it in the company of some good friends (or just have it by yourself). You have been warned feel free to continue.

Is there anything better than wine and cheese (well except for maybe chocolate)? It seems that most of our favourite foods and beverages are produced through fermentation. But what is it about fermentation that makes it taste so good?

Lets get technical for just a sec (and then we can go back to discussing food). Fermentation (the process of fermenting something) is basically taking a sugar (carbohydrate) and turning it into an acid or alcohol. This is done using fungus (yeast) or bacteria (but good ones not the ones that make you sick).

Fermentation using yeast makes some of our favourite products including bread and alcohol. Yes that’s right, yeast is placed into sugar sources (like grapes, barley, apples ect) to make different types of alcohol. Yeast is also used to make bread, another fabulous food. The most ancient use of fermentation was, you guessed it, to make alcohol, dating back to Neolithic times (which is really old). How is it that fruit, vegetables and grains mixed with a small microbe produce an amazing treat? Well there are many different ways, each providing a unique flavour but I’ll explain the basics. After the sugar source is collected it is made into a mash. The mash is then mixed with hot water. This is transferred to a fermentation vessel and yeast is added. Yeast, like human cells, works best between 30-37°C, hence the hot water. Fermentation begins, the yeast metabolise (“eat”) the sugar, the by products are alcohol and carbon dioxide gas. After the yeast does its thing, the alcohol is filtered out and prepared for human consumption.

Bread fermentation follows the same principal, activated yeast (warmed up) is added to the dough. The dough is left to rise (which is when fermentation takes place). The carbon dioxide gives bread is fluffy, light texture and the alcohol provides the taste (no you can’t get drunk on bread, the alcohol evaporates during the baking process).

Enough about yeast fermentation, now it’s time to devel into the dairy arena. That’s right some of our favourite dairy products are made by fermentation. Yoghurt, sour cream and cheese are both made by fermenting milk using special bacteria that produce lactic acid. Basically, milk is collected from either cows or goats, and processed (so that the liquid bit goes for drinking and the solid parts are used for other products) and then heated to remove natural microbes that are in the milk (some might be dangerous). After the milk is processed bacterial cultures are added to the warm milk and left to ferment (once again fermentation happens better in heat). The bacteria metabolise the sugar (lactose) found in milk into glucose (another sugar) and then into lactic acid and acetaldehyde (a chemical that gives the distinctive tangy taste). Yes the dairy product we enjoy so much are basically flavoured, curdled, fermented milk. After this a whole bunch of other manufacturing stuff happens to add flavours, age cheese and make these products delicious. Blue cheese (which personally I don’t particularly like) is of special interest to this blog. Blue cheese goes through this process and then a fungus (the mould Penicillium) is added to the cheese. This mould is what provides the distinctive blue-green or blue-grey lines in the cheese.

Other fabulous foods made by fermentation includes chocolate, coffee, tea, soy sauce and vinegar. It seems all the best foods are fermented. So while some bacteria and funguscan be very bad for us, they are also our friends. Although I wouldn’t suggest eating the fermenting fruit or mould food products in your fridges or cupboards. Next time your enjoying a glass of wine with a cheese board, a beer and pie or a yoghurt with cereal remember that it was fungus and bacteria that gave those products the wonderful flavour you are enjoying.


Posted by on 30/08/2011 in Uncategorized


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Welcome to your fridge

So I know most people grow up being told not to play with your food but that’s all cooking is. So as long as you’re not throwing your food around have fun. Your kitchen should not be a scary place, food is your friend. Ok it might be like a friend that you argue with a lot and doesn’t always give you what you were hoping for. But you’re stuck with it, you have to keep going back to it, your life depends on it (literally).

If you want to rekindle your friendship with food and no longer want to be a kitchen nightmare then read on. If your already on good terms with your kitchen and food but want to understand why your fruit draw always smells like your house after a party or you just want to play with your food a bit more then read on. If you want to unravel what I have dubbed the great food debate then definitely read on.

In case you haven’t picked up on it yet, this blog is all about food and the science behind food. I promise some interesting food facts, helpful hints and some tried and tested recipes to impress your friends.

Lets explore the fridge together…


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