Benefiting from chemical leavening Part 3
March 15, 2016
by Laurie Gorton
When working with chemically leavened baked goods, to get things right you must select the optimum leavening system. Sharon Book, PhD, bakery technologist for ICL Food Specialties, offers advice for making such choices. More than leavening power is involved.
Here’s what she said.
Dr. Book’s work focuses on learning and sharing information about chemical leavening and baked goods. She has extensive experience working in chemical leavening and with customers in a variety of bakery applications. She has also conducted research to more fully understand the impact of leavening acids on the properties of tortillas, cakes and other baked products.
Baking & Snack: What are the functional powers of the bicarbonates, leavening acids and baking powders outside of their ability to aerate baked foods?
Sharon Book: Based on the legal definition for food additives, they are added for a specific purpose, or function. The additional influences they have on product characteristics are not “functions.”
Direct food additives are those that are added to a food for a specific purpose in that food. For example, xanthan gum — used in salad dressings, chocolate milk, bakery fillings, puddings and other foods to add texture — is a direct additive. Most direct additives are identified on the ingredient label of foods. See the FDA website for more details.
That being said, the function of baking powders and their components is to provide gas to aerate the baked good. This will improve sensory characteristics (visual appeal, mouth feel, bite, etc.). Cakes without leavening are dense, gummy and small.
Attaining the characteristics of the final product is the challenge to food formulators, along with optimizing all the ingredients since they work together. Leavening, like all ingredients, will have an impact on appearance, color, texture, cell structure and volume as well as the critical attribute of flavor.
Leavening acids differ in the timing of their reaction with the soda. This can be crucial for some processing situations. There are acids that are fast reacting for nucleation to provide gas bubbles in the system if there is not a great deal of mixing to aerate. Other acids will be slower to release the gas — often during baking, before set, when the gas can be trapped in the matrix to provide volume.
A specific example of a product that requires a precise reaction by the leavening acid is refrigerated dough. There is only one kind of slow-reacting sodium acid pyrophosphate (SAPP) that allows the dough to proof in the can. Often, an additional acid is added to provide leavening during baking to give adequate final product characteristics.
A different example is in foodservice applications, which gain value from a leavening acid that is stable over time. Pancake batter that will be in a restaurant refrigerator for a few hours creates a larger, better-quality cooked pancake if a heat-activated leavening, like sodium aluminum phosphate (SALP), is used. Cracking of a muffin crust can be achieved with dicalcium phosphate dehydrate (DCPD) due to its late reaction and production of carbon dioxide.
There are many types of SAPP available. The timing of the release of the gas with SAPP is critical for donut formulations. The unique fast cooking in oil, along with the flip to cook both sides, means that gas production must be timed well.
There are other reasons to adjust a leavening system. The color of a chocolate cake can be an important sensory parameter. A darker color can be achieved with a dark cocoa or using a lighter cocoa and optimizing the acid-base balance to give a higher pH. With non-chocolate products, the color can also be due to the leavening system. A more alkaline pH will be slightly more yellow in tone, and acidic pHs tend to be brighter and more white.
Calcium phosphates will act as a dough conditioner — monocalcium phosphate monohydrate (MCP) can be the acid of choice in lower-moisture systems, like biscuits, to enhance the handling properties of the dough.
Research has shown that not all leavening acids are the same in how they influence the size and textural characteristics of cakes (CFW 2015 60(2):71) mentioned that calcium pyrophosphate (CAPP) provided the largest cake with the most cohesive texture. The color of the crust can also be leavening acid dependent. In many products (biscuits, muffins, cakes), we have observed a more brown crust with CAPP.
Translucency in wheat flour tortillas is a critical characteristic; consumers like the opaque appearance caused by the presence of gas bubbles within the dough. Published data shows SALP consistently provides higher opacity than sodium aluminum sulfate (SAS) or SAPP (“Tortillas — wheat flour and corn products,” 2015 AACC). This is a bigger issue with whole wheat tortillas. Research has demonstrated SALP minimizes translucency and produces a more opaque tortilla as compared to SAS and SAPP-28 (Liu, T. et al; 2015 AACCI annual meeting presentation). Besides the visual properties of the tortilla, SALP also improved the physical characteristics as resulted in larger diameter product than SAS or SAPP-28.
Besides the type of acid, the amount of total leavening system used is critical. When formulating, the first step with leavening is to pick the amount of baking soda. Then the acid is calculated based on this level. With yellow cakes, the article in CFW demonstrated that there is an optimum level of soda. If there is not enough, the cake is small. If there is too much, the gas appears to destabilize the system and result in a smaller cake. Getting the amount just right provides maximum volume.
Similar results were found with tortillas. Optimizing the level for a system allows the thickest and largest diameter.
The sodium bicarbonate is responsible for the gas, but more carbon dioxide in a system does not mean it will have a greater volume or size. Optimizing with the complete formulation and preparation methods is important to achieve final product characteristics.
How important are these other functionalities when selecting a leavening system? Why should they be considered when formulating a new product or reformulating an existing one?
The influence of the type of leavening system and amount of leavening is crucial. The final product characteristics must meet the goals (i.e., consumer expectations) and all ingredients and levels need to be optimized.