Chemical leavening dates back to the late 18th century, when it was discovered that the reaction between sodium bicarbonate and an acid produces carbon dioxide (CO2). More than 200 years later, chemical leavening manufacturers continue to discover new systems and applications to improve formulation and processing characteristics of bakery food formulas.
Many of these new systems allow bakers to formulate and manufacture products that satisfy increased demands for healthful and convenient bakery foods. Often times, the leavening system’s role in these new product formulations is overshadowed, which creates processing difficulties. For example, trans-fat reformulations are one of the most talked about issues in the baking industry, yet few of these conversations examine how chemical leavening systems affect trans-fat free products.
“If you remove the trans fats from a product, then you no longer have the aerating or enrobing processes that typically occur,” one supplier of chemical leavening systems says. “You need to modify your leavening system and look at the timing of your CO2 release. Predominantly, bakers are adding more leavening and delaying the reaction so you get more pop in the oven.”
Trans-fat free reformulation represents only one of many baking industry issues that impacts leavening systems and their uses. Other issues include sodium reduction, freezer to oven doughs and tortilla processing.
Bakers rely on three forms of leavening to formulate and process bakery foods: yeast, mechanical and chemical. Yeast is the primary leavening system in many bakery food formulas. Yeast ferments sugar in bakery food formulas, which provides CO2 for leavening.
Mechanical leavening occurs when air or gas is mixed into a dough or batter, causing the dough to expand when heated. Chemical leavening systems have various uses in today’s baking industry, and suppliers of these ingredient systems are expanding leaveners’ uses and applications to satisfy consumer trends. Chemical leavening systems spur leavening by the reaction of a soda with an acid. This reaction produces CO2, which causes bakery foods to rise.
Different combinations of baking sodas and acids allow bakers to customize chemical leavening systems’ rates of reaction.
Common baking sodas used in the baking industry include sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate. “Sodium bicarbonate is the workhorse of the baking industry,” one supplier of baking sodas says. “It’s a great source of CO2 and it has wide applications in many baking formulas. It’s also very cost effective.”
Ingredient manufacturers manipulate the size of sodium bicarbonate granulations to influence the rate of CO2 release. “If you have a finer particle size, the sodium bicarbonate will go into the solution more quickly, and therefore be available for reaction quickly, even in the mixing stage,” one ingredient supplier says. “As you go to a coarser granulation, the sodium bicarbonate will go into the solution more slowly.”
A coarse sodium bicarbonate granulation produces CO2 in the early stages of baking, when the ingredient is fully dissolved, hydrated and ready to react. Ingredient suppliers offer many grades of sodium bicarbonate. These grades are used alone or blended with other grades to create customized leavening systems. The three grades commonly used in the baking industry are:
• Grade 1: This powdered form of sodium bicarbonate dissolves rapidly and is ideal for scratch biscuits, cookies, instant or quick breads and most cakes, one ingredient supplier says. This grade also can be treated with tricalcium phosphate to improve flow quality.
• Grade 2: This fine granular sodium bicarbonate is designed for products where minimal leavening during mixing and holding is desired, the ingredient supplier says.
• Grade 4: This granular sodium bicarbonate is used in refrigerated doughs and donut mixes.
To produce CO2, sodium bicarbonate must react with an acid. Acids used in chemical leavening systems include sodium- and calcium-based phosphates and sodium aluminum sulfate. Sodium-based phosphates are the most widely used acids for chemical leavening systems, many ingredient suppliers say.
“The main point of chemical leaveners is to control the rate of the CO2 release,” one chemical leavening supplier says. “Phosphates do that quite well because you can affect solubility and the rate of reaction.”
Popular sodium-based phosphates include sodium aluminum phosphate (SALP) and sodium acid pyrophosphate (SAPP). Bakers use SAPPs for their versatility and ability to offer time-delayed leavening, which allow bakers to delay the rates of reaction until the products are baked.
Timing is essential when formulating any bakery food with chemical leavening systems. “It all boils down to understanding the timing of release of these reactions,” one ingredient supplier says. “You have to know how much CO2 can be released in the mixing bowl, on the line, in the oven or in a post-frozen state.”
The task to improve the health attributes of bakery foods significantly has impacted chemical leavening systems. Popular chemical leavening systems, such as sodium bicarbonate and sodium-based phosphates, contain significant amounts of sodium, which may be a negative for some consumers. “The first thing the medical community will tell someone with cardiovascular problems to do is reduce sodium intake,” one chemical leavening system manufacturer says.
However, removing sodium from chemical leavening systems without affecting functionality is difficult. Other acids exist, such as calcium-based phosphates, but their reaction times, which are either fast or
slow, prohibit their use in some formulas.
“Monocalcium phosphate is the primary calcium-based phosphate, and it gives off 60% of the CO2 in a very short period of time,” one ingredient supplier says. “With sodium-based phosphates, the most release you’ll get is 40%.”
One phosphate system supplier recently launched a new product that allows bakers to eliminate sodium-based phosphates without affecting functionality. The product uses a chemical mixture of calcium acid pyrophosphate and monocalcium phosphate to create a 1:1 replacement for SAPP. Besides containing no sodium, this product has 18% calcium, which the supplier says allows bakers to add a “good source” of calcium claim. The ingredient system’s applications include layer cakes, microwave cakes, pound cakes, biscuits, scones, muffins and pancakes.
Bakers further can reduce the sodium levels in their leavening systems by replacing sodium bicarbonate with ammonium or potassium bicarbonate. Ammonium bicarbonate, which does not need an acid to react, commonly is used in cookie and cracker formulations.
Formulations with ammonium bicarbonate require bakers to keep the moisture content of their finished product below 5%. “Otherwise, the ammonium will be retained in the water in the finished product,” one ingredient supplier says. “You want to drive off all of the ammonium, and to do that you have to formulate a low-moisture product.”
Potassium bicarbonate, which functions similar to sodium bicarbonate, also allows bakers to eliminate sodium from leavening systems. When using this ingredient, bakers need to add 19% more potassium bicarbonate to obtain the same CO2 release derived from sodium bicarbonate, one ingredient supplier says. Potassium bicarbonate also helps bakers achieve a health claim for potassium content.
Convenience is key
Although health is the most popular trend in the baking industry today, convenience will continue to dominate future new product formulations. New technologies in leavening systems allow bakers to formulate convenient products that go directly from the freezer to the oven or microwave.
One ingredient supplier’s leavening system consists of a combination of sodium aluminum phosphate, calcium acid pyrophosphate and monocalcium phosphate. This combination of ingredients is ideal for refrigerated and frozen dough products, such as pizzas and small rolls.
Ingredient suppliers also have developed new leavening systems designed to make tortilla production easier for manufacturers. One leavening system supplier produces a granulation of sodium bicarbonate that releases some CO2 up front, but delays most of the reaction for baking.
Another ingredient manufacturer’s tortilla leavening system is a blend of slow acting leavening acids that allows for a 20% reduction in sodium bicarbonate. “The ingredient does not allow the gassing to occur before the tortilla is processed, which makes the dough softer and more pliable,” the supplier of the ingredient says.
Specific application-designed leavening systems represent just one breakthrough in chemical leavening technology. Other breakthroughs have enabled bakers to capitalize on consumer trends for healthful and convenient bakery foods.
Yeast’s profile in the baking industry has expanded as yeast manufacturers continue to find new uses for this ingredient. One new application for yeast allows high-volume bakers to improve the health attributes of their products. Yeast always has been a good source of proteins and B vitamins, and yeast suppliers are fortifying inactive dry yeast to improve mineral and vitamin levels.
“The minerals are absorbed into the yeast protein, and then the yeast is spray dried, which creates an inactive yeast,” one ingredient supplier says. “Bakeries take this product and add it to their formulas. It has no functionality. It’s just vitamins and protein.”
Besides protein and B vitamins, yeast also is fortified with minerals such as selenium. During the fermentation process, yeast absorbs the minerals and often replaces sulfur compounds in the protein structure with the organically bound mineral. The product is added at minimal levels to boost mineral levels to recommended daily values.
Baking powder or soda: What is the difference?
According to a leading supplier of chemical leavening systems, many bakers do not understand the difference between baking powder and baking soda, or interchange the two terms like they are the same product. This confusion leads to countless problems when formulating new products or troubleshooting existing formulas.
Baking powders are defined as complete leavening systems that include
a baking soda (sodium bicarbonate) and phosphates or other leavening acids. Baking powders also contain cornstarch, which separates and improves the flow of the ingredient. Baking sodas are bicarbonates, and do not include leavening acids. Common bicarbonates include sodium, potassium and