Raising (or leavening) agents
When we want to make a dough or batter rise when baking, either in patisserie or bread-making
, we need to use a raising agent or leavening agent, one of which is called leaven
In the context of baking, a raising agent is simply what "makes something rise". It is a substance which, when added to the dough or batter makes it swell up by creating thousands of tiny bubbles of carbon dioxide within it.
As there are 2 kinds of yeast, 2 kinds of leaven and baking powder as well, this can be confusing, so here is a summary of the different types and how they act.
This is the yeast used by bakers to make bread, brioches, etc. It is basically the same kind that brewers use to make beer, so it is sometimes also known as brewer's yeast.
Yeast is a living organism, a microscopic fungus, which reacts with the sugars in flour to form carbon dioxide. It is this fermentation process that makes the dough rise. Yeast is available in 2 forms:
This is the classic baker's yeast which is normally sold as a small, beige-coloured block. It should be kept in the fridge and not for too long.
This is exactly the same yeast, but completely dehydrated. It comes as a beige powder and keeps very well.
This white powder is a mixture of bicarbonate of soda and cream of tartar. It reacts on contact with the water in the dough or batter to form the carbon dioxide which makes it rise. There is no fermentation.
Baking powder is used mostly for cakes
Leaven is a natural raising agent, like yeast. It is made from a mixture of water and flour that begins to ferment when exposed to the naturel yeasts present in the air.
It is a living substance and reacts with the sugars in flour to form carbon dioxide by fermentation, which makes the dough rise. Two different forms can be made:
This is a leaven made with equal parts of water and flour. As the name suggests, it is liquid, rather like pancake batter.
This is a leaven made with one part water to two parts flour. It has a consistency similar to bread dough.
Whether the leaven is liquid or stiff makes very little practical difference. It is just a question of what you are used to.
It is worth noting in passing that when making leavened bread
, it is usual to combine a large amount of leaven with a little yeast. This improves the bread's appearance especially the crust.
We can say that yeast and leaven work by fermentation, whereas baking powder uses a chemical reaction.
Back to top of page
The 3 essential knives
You must have heard a chef or cook say: "There’s no good cooking without good ingredients". This is very true, of course, but for any amateur or beginner it is equipment that really counts to start with. What I mean is that you should not skimp on [Read more...]
Using stretch food film effectively
Maybe you use food film in your own kitchen. You know, the very thin, clear plastic stuff that you can stretch, often used to cover food and protect it from the air. It’s become so widely used that it’s now an essential item for pros. They even [Read more...]
The mock CAP baker's certificate exam
The next instalment in my life as an apprentice baker at the French INBP professional school. I’m now halfway through training and it’s still as exciting as ever, and exhausting – but maybe I’m just getting old, or both… Anyway, a few days [Read more...]
Rosemary in recipes
Rosemary, as I’m sure you know, is a culinary herb:
It is one of the famous French "herbes de Provence", and is very effective in bringing a real taste of the Mediterranean to any dish.
The classic way to use it in a recipe is to add a [Read more...]
The Holy Grail of French bakers
While browsing through the recipes on this site, you may have noticed that while I adore cooking (everything, in fact, to do with eating and drinking), I am particularly drawn to bakery: bread, viennoiseries and all that goes with them – it’s a [Read more...]
Is it really necessary to cream egg yolks?
Let’s try and answer a question that crops up in cookery and patisserie, even if it verges on the existential: do the egg yolks in a custard recipe really need to be beaten until pale, or not?
You might already have noticed in many recipes [Read more...]
Egg yolks and caster sugar
We often come across recipes where we need to mix egg yolks with caster sugar. This would appear to be a very ordinary and simple thing to do but, be warned, these two ingredients can behave oddly together.
Let’s take confectioner's custard [Read more...]
The golden-brown finish on puff pastry
Let's take a look at the tricky matter of producing puff pastry with an attractive, golden-brown finish. French pastry chefs call this "dorure" (literally, "gilding").
Behind this quirky term there lurks a real problem (and the solution): when [Read more...]