by Glen Thompson, chief editor

As consumers continue to seek out baked goods with the appearance, taste and mouthfeel of home-baked products, commercial bakers constantly are experimenting with new formulations to meet customers’ appeals for a culinary connection to memories of fresh-from-the-oven bakery foods. Leaveners are among the most basic ingredients in every bakery, and by understanding their potential uses, bakers today are able to create formulations that not only satisfy, but surpass the expectations of their nostalgia-driven customers.

Biological leavening technology has been traced back roughly 5,000 years to Ancient Egypt and chemical leavening has been around for at least two centuries. Of course, there have been modifications, refinements, taste changes, etc., but when you get down to brass tacks, the three basic methodologies remain the same: Yeast remains the primary leavening system for breads, rolls, many sweet goods and other dough products; chemical leaveners, which consists of acid and alkali blends, otherwise known as baking powder, are widely used for batter formulations; and mechanical leavening, which simply is aerating batter or dough by mixing or beating and then exposing it to steam or heated air. Popovers and cream puffs are primary mechanical leavening applications.

Yeast
Chief among organic leaveners, yeast is a living organism known as a fungi. It feeds on sugar. The main byproduct is carbon dioxide (CO₂), which forms the gas bubbles that cause dough to rise. Additional byproducts include alcohol and other organic acids. (The beloved aroma of bread baking largely is a result of alcohol evaporation in combination with the organic acids.) The technical name for the types of yeast used in baking is Saccharomyces cerevisiae. It can be purchased in active dried, compressed or bulk forms, all of which share the same basic manufacturing characteristics except for the final processing and packaging steps.

While all baking yeasts are variations on the abovementioned species, different strains of yeast require different handling and produce different results. The open-crumb bread loaves that currently are enjoying such popularity as the artisan baking movement continues to expand require different yeast strains than frozen doughs, high-fiber products, whole grain breads and rolls, pizza doughs, etc.

Sugar & Salt
Yeast’s most basic function, the production of carbon dioxide, is grounded in the organisms’ readiness to ferment added sugars as well as the natural sugars found in flour. The choice of sugars in a dough formulation is equally important as the strain of yeast that is used. The most commonly used sugar in baking applications is sucrose, which, in turn, is composed of two simple sugars: glucose and fructose. The reaction of sucrose on yeast is a two-tiered process. The glucose ferments first and, once it is spent, fructose fermentation takes place. Different sugars ferment at different rates, making the selection of sugars in baked goods formulations a critical factor in achieving the desired leavening effect.

Another important consideration when leavening with yeast is salt, a certain amount of which is required to regulate the growth and fermentation of yeast. According to one ingredient manufacturer, “too much salt, any amount greater than 1.5%, will begin to inhibit yeast activity.”

Health benefits
In addition to its leavening proper ties, yeast is an excellent source of B vitamins and protein, and manufacturers also fortify their yeast with minerals such as silenium.

High-volume bakers are improving their products’ healthfulness by deactivating yeast through spray drying after fortifying it to improve mineral and vitamin levels. The inactive yeast is added to formulations for baked goods.

Chemical leavening
According to one ingredient manufacturer, “bakers are moving away from a one-size-fits-all approach, and are fitting the baking powder system to fit the application, which improves processing and end-bake quality.”

Most cake formulations utilize chemical leavening systems. Sodium bicarbonate—common baking soda—combined with any number of acidic agents remains the favorite source of CO₂ because it is inexpensive, easy to use and nontoxic. By mixing sodium bicarbonate with one of the acids and adding water, CO₂ is released. The amount of gas and the rate at which it is produced is dependent on the choice of acidic agents in the mixture.

Ammonium bicarbonate is another source of CO₂ that can be used as a leavening agent. When heated, it releases ammonia in addition to car bon dioxide. Ammonium bicarbonate’s primary applications are dry cookies and crackers. When used in products that contain moisture, the ammonia is retained, rendering the final product inedible. Potassium bicarbonate is also a widely used baking soda.

“In the development process, bakery scientists monitor tolerance for gas sing or rate of reaction, baked-product volume, crumb structure and the flavor profile, so that a custom leavening agent can meet the needs of the specific application,” says one ingredient manufacturer

Ingredient manufacturers produce baking sodas in various size granulations to influence carbon dioxide release. “The finer the granules, the quicker the reaction,” one supplier says. There are three common grades used in the baking industry:

Grade 1: This powder dissolves quickly and is the common choice for biscuits, cookies, quick breads and most cakes.

Grade 2: Consisting of fine granules, this is designed for products where minimal leavening during mixing and holding is desired.

Grade 4: Another granular sodium bicarbonate, this grade is used in doughs and donut mixes. While the various leavening acids are available for bakers to create their own formulations, premixed baking powders, while some what restrictive in their applications, remain a highly convenient option for commercial baked goods formulations. Baking powders are available in three basic types: fast acting, slow acting and double acting.

The differences among the three types are straightforward: Fast acting baking powders release the lion’s share of their CO₂ immediately upon contact with water, slow acting powders require heat—they don’t release any gas until they hit the oven, and double acting powders react partially when mixed with water and continue to release CO₂ during the baking process.

Of the three, double acting baking powder is the favorite among commercial cake bakers. This is largely owing to the inert ingredients that are added to double acting powders. Corn starch, calcium sulfate, calcium lactate are a few of the compounds found in double acting baking powders.

Their purpose is to prevent the leavening agent to react too soon and to standardize its strength throughout the mixing and baking processes.

The key to formulating bakery goods using chemical leavening systems is timing “There’s no way around it,” says one ingredient supplier. “Bakers have to have a good grasp on the release times for chemical leaveners.”

Leavening trends that are on the horizon include organics and healthier solutions. And, healthier alternatives, such as lower sodium quantities in leaveners are allowing bakers to offer healthy product claims.

Leavening acids glossary Many bakers eschew premixed baking powder systems in favor of customized combinations of baking soda and the leavening acids described below: Sodium aluminum sulfate (SAS) was used in combination with other fast leavening acids to produce the first double-acting baking powder. It is commonly used in chocolate cake and English muffins, Sodium aluminum phosphate (SALP) releases carbon dioxide fast during the baking stage. It is one of the most commonly used leavening acids in double acting systems, largely because it does not contribute to flavor changes, provides fine close texture, and reduces tunnel formation in cakes. Monocalcium phosphate (MCP) is used in viscous, high-volume batters. It is a very fast reacting leavening acid that releases most carbon dioxide by the end of the mixing stage with remaining being released during baking. Gluconodeltalactone (GDL) slowly releases gluconic acid, which in turn reacts with baking soda to release carbon dioxide. It is used to retard fat absorption in donuts. Sodium acid pyrophosphate (SAPP) is a slow to very slow reacting agent. Very slow grades are used in cake donuts because in order to achieve buoyancy without full expansion. The slow acting grades of SAPPs are also used in canned refrigerated biscuit doughs. Anhydrous monocalcium phosphate (AMCP) is considered a stable ingredient that is fairly slow reacting with only about 15% of carbon dioxide released at the mixing stage. Dicalcium phosphate dehydrate (DCP) has a very slow reactive rate and it only reacts with sodium bicarbonate at batter temperatures above 60 degrees. Potassium acid tartrate, commonly known as cream of tartar, is one of the fastest reacting leavening acids with about 70% released within the first two minutes. Source: Guelph Food Technology Centre