Leaveners

Flaky biscuits, fluffy pancakes, pillowy sandwich bread, chewy French loaves, ethereal angel food cake, tender devil’s food, soft oatmeal cookies, and cloudlike soufflé…mmmmm. All of these little lovelies share a common trait – they have all been leavened. Leavening is the means by which lift is introduced to baked goods, giving them their characteristic textures, and in some cases, much of the flavor as well.

Leaveners are the means by which this happens, and for the home cook, leavening is going to fall into one of three categories; biological, chemical or mechanical. Yes – this makes it all sound like the introduction to a science class you didn’t really want to take. But knowing what they are and how they work will give you culinary superpowers. The neato-keen part is that it’s not nearly as esoteric as it sounds at first; you’ve even heard of all these things.



Yeast, baking soda, baking powder and the creaming method are the leavening agents with which this article will be concerned, since they are the methods and ingredients with which the home cook will be working. There are others – but unless you’re heading into the world of commercial baking or brewing beer, you probably won’t encounter them. So here we go…




Yeast


The biological and chemical leaveners share the characteristic of releasing gas bubbles when activated, which provides the lift and therefore the texture of baked goods. Carbon dioxide gas is released into a dough or batter, which then creates the volume which is characteristic. There are mulitple types of each, but most people will be using one of three: yeast, baking soda, and baking powder.



Yeast is the biological leavener that is most used by the home cook. It is a single celled microorganism which grows, multiplies and works on it's little food supply. As it does each of these things, it produces lovely stuff which the cook can use. During food production, alcohol and carbon dioxide gas are produced, which do two things. The alcohol, during fermentation, is what gives us the 'yeasty' flavor and aroma so fabulous with bread. (Brewers and vintners love it for this alone). The carbon dioxide which is released in this process is released into the dough, where it is trapped by the matrix developed during the kneading process. Baking sets this matrix, so breads that are risen correctly retain their shape.



Yeasts are everywhere. Saccharomyces cerevisiae. It literally floats around wild - and you can set a trap for it if you wish to make Sourdough Bread. However, you can also run down to your Piggly-Wiggly and grab it if you're making any other type of bread. There are three types easily used at home. They're all basically the same - the difference is in how they processed and packaged.



Active dry yeast - probably the most common, this comes in either little packets for 'single use' or in jars at the grocery. Bulk warehouse stores carry it in larger one pound containers. Keep it in a cool, dry place, and once opened, store it in the fridge, tightly covered. Bring it to room temperature before using.

Fast rising active dry yeast - this can be used interchangeably with active dry yeast, it just works more quickly. Older recipes will need to have thier rise times adjusted. A benefit to this is that often a second rise in bread baking is not necessary - a downfall is that the second rise allows more flavor to develop. This one is often used in single rise bread machines, and the grains are smaller than active dry. This one can be mixed with the dry ingredients, skipping the proofing process.

Compressed fresh yeast - this one contains much more moisture than the dry yeasts, and must be stored in the fridge. It's also rather perishable - you'll need to use it within a couple weeks of purchase, or it will die. You can freeze it, but then you need to use it immediately upon defrosting. Compressed yeast comes in little cakes - so I've heard. It's hard to find in the United States because active dry yeast is so convenient. So I've never actually used it. In theory for recipe conversion the exchange is one cake of compressed yeast to a scant tablespoon of dry yeast.

Yeast doesn't ask much of us in order to produce incredible results. It needs food and warmth - just like we all do! Love it a little bit and you'll be well rewarded. In order to activate yeast, put it warm water, and give it a little food in the form of sugar. Yeast needs warm - not hot - water. Remember that this is a living organism. You don't want your own bath water over 120F - so when activating (also called 'blooming' or 'proofing') your yeast, think of the same bath water in which you'd bathe a baby, and you'll be good. The ideal temperature is 105-115F for proofing yeast, but I honestly never measure. I run the water over the inside of my forearm, and it it would make a baby happy, it'll make the yeast happy.



Much of the time bread recipes will call for two ingredients - sugar and salt. You won't need much of either, but both have an important part to play. Yeast uses sugar as a food source - so sugar in a dough allows for the fermentation process to work. Yeast can also use starch - in flour - so it's not absolutely necessary. But it also provides a little mellow flavor and a nice complexity.



Salt is a little trickier. It will have the opposite effect as sugar does - it will retard the fermentation process. I think almost everything needs a touch of salt - and in breads it helps with a finer crumb and better crust. Too much though will prevent the yeast from doing it's job, and result in bread that is salty, vs. flavorful. So be judicious.



Baking Soda


I actually have an early memory of baking soda. I'm not sure what that says about the early development of my obsession with food. In the first grade, at age six, a story teller gave a performance at my elementary school. One of the stories was called "Sody Saluratus" - and told a tale of an old woman trying to get her biscuits to rise. I don't remember what happened to her or her baked goods, but it did give me an easy way to remember the difference between baking soda and baking powder. Baking soda is older (hence the folktale), and is an ingredient in baking powder. So just remember that baking soda comes first.



The tale's title came from the name of the first commercially marketed bicarbonate of soda. Soda saleratus was the name given to the product when Arm & Hammer packaged it back in 1867 (from the Latin sal and aeratus for salt and aerated respectively). Of course it had been around before then, but American marketing made it widely available. Double acting baking powder came along in the late 1880's, and the first name brand - Calumet - is still found in millions of American homes.



Baking soda is alkaline, and requires an acid in order to work. In baked goods, the acid often comes in the form of lactic acid, via buttermilk or yogurt. The soda, when combined with acid, releases carbon dioxide, much like yeast does in the fermentation process. This is why it is often used in quicker recipes - it works immediately instead of over a 'rise' process. It will also react immediatly in the presence of water - for this reason it is mixed with the dry ingredients, and any batters or doughs in which it is used should be baked immediately. They will lose their lift if left too long.



Baking Powder


Baking powder is one step ahead of baking soda - primarily. There's a trick you need to know. Commercial baking powder, such as what you find in most grocery stores, is a type known as double acting - meaning it releases carbon dioxide twice. The first is on contact with moisture, and the second on heating - such as the in the oven. This type of baking powder already contains an acid - usually cream of tarter - so is used when no additional acids are used in a recipe. For this reason you can NOT substitue baking soda for baking powder in recipes.



You also need to keep in mind that soured milk products - yogurt, sour cream, and buttermilk - have a higher acid content than sweet dairy products such as milk or cream. For this reason, you'll need to keep in mind that acids in these ingredients will 'unbalance' your recipe if you don't adjust your baking powder, and you'll have less lift than you need to acheive a good result.



Single acting baking powders are harder to find - tartrate and phosphate - but can be purchased online through a little diligent searching. They are single acting because they have one release of carbon dioxide - when they contact liquid. Like double acting baking powder - the carbon dixoide is released upon contact so goods baked with these should be baked off immediately. They are worth hunting down though - especially if you have heirloom recipes or antique or vintage cookbooks. Just buy small amounts because baking powders lose their potency and freshness relatively quickly. The most you're going to get wtih cool, dry storage is a few months of active leavening power.



Mechanical Leavening


Mechanical leaveners are perhaps the simplest - you're using one of a number of methods to get air into a dough or batter. The creaming method is when fat and sugar are whipped together. The edges of the sugar crystals literally cut the particles of fat down, which allows for air to be trapped in the resulting mix. This is the first step to creating tender crumb and texture to many cookies and cakes, although sometimes an additional chemical leavener is used for additional lift.



Whipping egg whites or cream will also create the pockets of air that are necessary for lift. Egg whites are whipped for thousands of applications - from sauces to souffles, and when the resulting product is baked, the pockets are set - trapping the rise in place. Whipped cream will create rise, and is often used initially in a baking process, although there must be another element before baking, as the butterfat content in cream is rather high, and it will melt when baked.



The final mechanical method of leavening a dough is through steam. This is one of the tricks to great flaky biscuits- although a chemical leavener is used, much of the characteristic texture comes when the moisture in the dough encounters heat high enough to immediately vaporize to steam - create the pockets or holes you'll see on the interior. Any dough cooked at a temperature high enough to flash moisture to steam uses this method - including some deep fried batters.



For the complete article, including how-to videos and photographs, check the link above!