Baking leaveners are other indispensable baking ingredients that are extensively used within the baking and pastry industry by retail and commercial bakeries, pastry chefs, and home bakers. Almost all kinds of baked goods including yeast bread, cakes, quick bread, cookies and other pastries are reliant on these ingredients for successful baking. So what are they and how do they work?
Baking leaveners (or leavening agents) are ground substances used in pastry dough and batters, causing chemical or biological reactions in the presence of heat, moisture, and/or acidity. As a result of this reaction, carbon dioxide and other gases are released, forming air cells or bubbles right through the dough or batter. While being baked, the gasses expand furthermore and protein in the dough or batter sets around these air cells, giving the baked product its rise and light, soft texture.
If we are to classify baking leavening agents, we can briefly divide them into three types:
Organic Baking Leaveners:
- Yeast: is a living organism called fungus, used primarily to leaven bread and sweet pastries like doughnuts, croissant, cinnamon buns, danish and others. In an organic process called fermentation, yeast converts starch found in flour into sugar, and as it feeds, it releases carbon dioxide and ethanol. Gluten developed in a bread or pastry dough then traps carbon dioxide, forming air cells or bubbles throughout the dough and forcing it to rise and double in size. Ethanol on the other hand, evaporates immediately when baked. For yeast to grow and function properly, the following conditions must be taken into consideration:
- Moisture: is necessary for yeast to dissolve in, react to, and thus grow rapidly. More often that not, bread and pastry recipes call for dough to be as moist and workable as possible...not too dry and not too sticky. A dry dough takes longer time to rise because when using insufficient amount of liquid in a dough, yeast reacts weakly, expelling insufficient amount of carbon dioxide and resulting in heavy-lifting dough.
- Food: yeast feeds on sugar for growth. For this to happen, it converts starch found in flour into sugar for food. Without this ability, yeast wont' be able to grow and thrive as rapidly, especially in sugar-free bread.
- Amount of salt used: unlike sugar, salt has the ability to retard yeast growth significantly, especially when the amount of salt used is not in-balance with the amount of yeast being used. Using extra salt than necessary in a recipe, is likely to increase the amount of time needed for a dough to rise.
- Temperature: is a key factor in determining how fast yeast can multiply. Although yeast is a living organism, it is dormant unless we create the right environment for it to flourish. At 40 F, yeast is inactive and will not grow. At 55 F, yeast begins to grow, yet very slowly. An environment of 78 F to 80 F is perfect for yeast to thrive. At 140 F, yeast dies immediately. Therefore, it is recommend not to use hot water or liquid in your bread or pastry dough; make your liquid warm instead. To work out the right temperature, use baking thermometer. It helps a great deal in measuring the temperature of:1) water or liquid used for mixing, 2) dough, and 3) baked product when almost finished. Because yeast is alive and react significantly to warm temperatures, it is recommended that it be kept in cool places like a refrigerator or a freezer so as to stay in- good shape till next-time use. Make sure your yeast is not expired too, otherwise you won't have successful baking results.
Available in grocery stores, and commonly used among pastry chefs, commercial bakeries and home bakers are two forms of baker's yeast:
- Dry Yeast: is dehydrated granules of fresh yeast that has been compressed and dried with only 8% moisture remaining. It has a very small bead shape-like, sandy color-like, and a relatively longer shelf life compared to fresh yeast. This is why it is commonly used by noncommercial and home bakers. Baker dry yeast are divided into two types:
- Active Dry Yeast: usually needs to hydrate first in warm water, allowing it to grow and become foamy, then it can be added to the dry baking ingredients of a recipe. However, this step may be skipped nowadays because dry yeast has become quite reliable and very small to a point where it can be dissolved in the dry ingredient of a recipe so easily. Bread or pastry dough made with active dry yeast needs a slightly longer time to rise and needs two risings in order to develop the yeasty flavor we cherish in bread.
- Instant Active Dry Yeast: has smaller granules than active dry yeast and since it is porous, it can absorb water easily, and thus doesn't need to be hydrated in water first. It can be mixed with the dry ingredients immediately. Bread and pastry dough using instant active dry yeast needs half of rising time and only one rising compared to that of active dry yeast.
- Baking Soda: also called sodium bicarbonates; an alkaline compound used mainly to leaven batters and dough that contain acidic ingredients such as sour cream, yogurt, buttermilk, lemon and orange juices, citrus fruits, cocoa, honey and/or molasses. Muffins, cakes, quick bread and cookies are example of baked products whose recipes depend on the use of baking soda. Recipes that don't include acidic ingredients, don't require use of baking soda because in such a case no chemical reaction will take place anyway. So how does it work...? In the presence of moisture, baking soda reacts immediately as soon as it comes in contact with acids in a batter. This chemical reaction results in releasing carbon dioxide gas needed to leaven the batter or dough, and meanwhile neutralizing acids contained within, so no longer yogurt or buttermilk for example, have their acidic tang in the final product. Usually, for each cup of flour, 1/4 tsp of baking soda is needed. Using too much baking soda is likely to result in a bitter, soapy aftertaste. However, in preparing heavy/thick batters as in peanut butter chocolate chip cookies and/or very acidic batters as in red velvet cupcakes, you may need to use slightly more than the usual amount of baking soda per each cup of flour in order to obtain successful baking results. Finally, batters/dough made with baking soda need to be baked immediately, otherwise the carbon dioxide needed to leaven the batter may escape, and the end product will be ruined.
- Baking Powder: a neutral alkaline-acid compound made of starch, baking soda and one or more acids. While baking soda needs an acid to create a chemical reaction, baking powder already contains acids within its mixture, and thus react with itself in the presence of moisture like milk, eggs, water, etc. Just like baking soda, the chemical reaction results in producing carbon dioxide needed to leaven a pastry batter or dough. Available in grocery stores are two types of baking powder: single-acting vs. double acting, with the latter being commonly used in almost all baking and pastry recipes. Whereas single acting reacts at a room temperature when moisture is applied, double acting reacts twice; it releases a small amount of carbon dioxide when it comes in contact with moisture, and another strong release of this gas happens when a batter or dough is subjected to heat (while baking). Unlike baking soda, a recipe made with double acting baking powder doesn't need to be baked immediately. It can be left unbaked for a short period of time without loosing its leavening ability.
Alongside with the previously mentioned leaveners, bakers can entrain air cells within batters or dough, and thereby lighten and lift the finished baked products through:
- Creaming method: in which sugar is beaten with fat, usually butter.
- Beating egg whites: in which air cells are captured and product is lightened.
- Steam: while baking.
