Benefiting from chemical leavening Part 1
February 10, 2016
by Laurie Gorton
Bakers using chemical leavening can take advantage of these ingredients’ ability to functionally affect color, flavor and texture of the finished product. Baking & Snack asked Kim Powell, commercial development specialist, bakery, at Innophos, Inc. to explain these additional benefits. Here’s what she said.
Baking & Snack: What are the functional powers of the bicarbonates, leavening acids and baking powders outside of their ability to aerate baked foods?
Kim Powell: Baking powders, which are made up of bicarbonates and leavening acids, are generally known to help make a baked product rise in the oven. However, the choice of acid and bicarbonate can also add to various other properties, such as color, flavor, texture, mouth feel, appearance and nutritional profile of the final product. In terms of manufacturing, these ingredients can also attribute to shelf-life of dry mixes, process tolerance, and overall bake performance.
Color is largely based on the final pH, to which leavening acids and bicarbonates contribute. Each leavening acid will buffer slightly differently, resulting in color differences. The lower the pH, the less color development in terms of brown notes will be observed. The higher the pH, the more browning will occur.
In general, the bicarbonate level is selected to deliver the required amount of leavening gas. The acid salts that are used in the leavening system are selected for the timing of release of the gas. 1) The ratio of acid to bicarb, if excess acid is used, the pH will be lower; 2) the type of acid and is buffering capacity. The relative pH/buffering of each acid goes from organic acid > sodium aluminum sulfate (SAS) > monocalcium phosphate monohydrate (MCP) > sodium aluminum phosphate (SALP) > sodium acid pyrophosphate (SAPP) > dicalcium phosphate dehydrate (DCPD) where organic acids buffer to the lowest pH and SAPP/DCPD buffer to higher pH in the 7.4 to 7.6 range.
Additionally the degree of color in the final product can go from white / pale brown to golden brown to dark brown. Salts which contain aluminum may also cause the color to be less bright.
Adjustments in the ratio can help to target the final pH. For devil’s food and chocolate systems, excess sodium bicarbonate is often used to help deliver the color of the chocolate. As much as 25% excess bicarb may be added just to adjust the pH. The color of the chocolate can go from red to black brown.
Beyond crust color, the crumb color will also be impacted by the pH of the final product. At lower pH the crumb will be white, at higher pH the color will be more creamy, yellow in appearance.
Some leavening agents can also have an impact on flavor – sometimes related to pH, sometimes inherent to the component. Potassium bicarbonate can provide a sweeter, nuttier flavor than sodium bicarbonate. Ammonium bicarbonate may leave behind residual ammonia if not formulated and handled correctly. Sodium bicarbonate can provide the flavor notes associated with browning, think of the flavor associated with pretzels.
On the acid side, SAPP and SAS are known to have an aftertaste, astringency, associated with the pyrophosphate and sulfate anions. Not all consumers are sensitive to the flavor. In some cases, the flavor can be limited or controlled by assuring proper use of the acid so that it is full reacted or fully neutralized by the bicarb. Sugar can also be used to mask the flavor. Glucono-delta-lactone (GLD) is known to have a flavor like yeast when the product is warm; however it has an off flavor when the product is cool. Calcium- and other sodium-based ingredients, such as monocalcium phosphate (MCP), calcium acid pyrophosphate (CAPP), SALP and DCPD tend to be flavor neutral.
The final texture of a product can be influenced by the leavening ingredients. SAPP will give a softer, moister texture, with more open cell structure, whereas CAPP or SALP will add some resiliency and a finer air cell structure. SALP will give the most resilient, springy texture. Texture and mouth-feel can also be influenced by the amount of aeration in the product and the overall grain structure and air cell size. MCP addition helps to create a fine air cell distribution whereas SAPP tends to give a more open structure. The air cell size and distribution also will affect the appearance of the grain. When finer cells are present, there is more surface area and less shadowing, creating a brighter appearance, whiter in a white product, more yellow in a yellow products. Larger air cells tend to impact the appearance to be grayer, less white.
Reaction timing, which varies by acid, is also important for overall aeration, air cell size, distribution and structure. Appropriate timing of a reaction can also result in a flat or domed top, cracks on the surface, or holes and tunnels in the crumb of the product. In high-ratio, high-sugar baked goods, cakes and muffins, DCPD may be selected to assure late leavening and suspension of the structure during the end of baking. DCPD or slow SAPP may also be used to deliver a dome or a crack, for instance, in a muffin. When a flat surface is desired, SAPP provides an even rise, creating uniform lift and a flat structure. In a product such as a cookie or tortilla, the leavening system can contribute to the product’s spread — therefore affecting the texture and appearance as well. This is often due to the pH of the system, which can be managed largely with the amount of bicarbonate added and the acid selection. In cookies selection of the bicarbonate can impact the color, spread and cracking. In general, the more bicarbonate the more color. The use of ABC in general delivers greater cracking and less spread. The use of KBC delivers great spread. An increase in the leavening will increase the height, and thereby decrease the spread. For tortilla, there are several appearance factors of interest including: color, transparency/opacity, spread, height.
The leavening acid and bicarbonates are also ingredients which influence the nutritional profile and potential claims for a baked good. Sodium bicarbonate and SAPP are significant contributors of sodium in baked goods, but potassium bicarbonate or calcium based leaving acids such as CAPP, MCP, or DCPD can be substituted in order to fortify with calcium and/or potassium while at the same time reducing sodium. Sodium bicarbonate, MCP, DCPD and SAPP can be used as leavening in baked goods that are labeled as “made with organic.”
Selecting the appropriate leavening acid can also have impacts on attributes besides the finished product. In a dry mix, the acid and bicarb will have a tendency to react in the presence of residual moisture during storage. By using more stable leavening acids (that is, those with less potential for immediate reaction), the shelf-life of a dry mix can be controlled. Examples would be a coated anhydrous monocalcium phosphate, a slow SAPP or a SALP (which needs heat to fully react). Encapsulation of the bicarbonate source is also an option.
During processing, the leavening ingredients’ reaction timing needs to match the process timing. For batters with long hold times, slower reactions are needed so that lift will still happen during baking. SAPP and SAS generally can tolerate longer bench times. For refrigerated batters and dough, very stable reactions are also needed and can be accomplished with slow SAPP, SALP or DCPD. The latter won’t react at all until reaching baking temperatures. During processing, batter viscosity is also an important factor to consider. Reactions that happen quickly and during mixing, such as MCP, will help build batter viscosity. Viscosity is important for flow-ability, batter density, and ability to fill pans.
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?
These factors are extremely important when designing the leavening system. Don’t be confused: Rate of reaction and neutralizing strength are the primary selection factors; however, when different characteristics are needed in the final product, these other functionalities become important and allow the formulator to deliver the target product.
During formulating new products or reformulating existing products, there are many factors that the leavening system can influence. For example: What texture does your consumer expect? Are you looking for an open grain with large air-cells or a tighter, finer grain? Should it look “home-made” or very consistent like a commercial bakery? Do you want your product to be softer or springier? Should the crumb dissipate/melt in the mouth or have more chew / coalescence? Is there a potential for the leavening flavor to come through? Is your system balanced or unbalanced? What is the desired finished pH of your product? Do you need a lower pH for shelf life of a baked product? What is the desired color of your product? Do you want your baked good to spread or be taller? How large of a dome or muffin top is desired? Does your consumer want a product with less sodium? Do you need to meet other claims such as calcium claims or organic or trans-fat free? How long will your batter or dough be held during processing? Does the batter or dough have a potential for rework? What is the shelf-life of your dry mix? What are the storage conditions of your finished product, dry-mix, frozen, refrigerated, shelf-stable? What is your bake temperature, how long is your bake time and how fast of a reaction do you need to optimize volume before set? How much overall aeration is desired in the final product? Leavening can be used to manipulate and deliver the target baked good.
What research have you done to shows off these additional powers? What do bakers think of these aspects?
We use various analytical methodologies to characterize products baked in our labs. We have standard formulations for everything from scones, to pancakes, to tortillas, to donuts, to biscuits to various types of cakes and muffins that we use for research. We can measure texture differences with a TA.XT2 texture analyzer. This instrument gives a profile of softness, springiness, adhesiveness, chewiness and other texture attributes. We also measure height and volume with traditional methods, such as rapeseed, or with a Volscan laser scanner that gives detailed information, including a drawing of the final product. We monitor the pH to determine reaction completeness and well as to understand expected color development and ability to support preservative performance during supply chain distribution and retail sales. We also look at sensory properties such as mouth feel, taste and aftertastes. Standardized slicing methods also show differences in crumbliness and fragility that can correlate to texture measurements.
We also can measure the rate of reaction of our leaving systems; either single ingredients or blends, in order to determine what may work best for the formulator’s needs. We can characterize raw ingredients analytically to determine chemical composition as well as impurities that may be affecting performance. We also can monitor the shelf-life of dry mixes by measuring CO2 potential, caking tendencies, and chemical and analytical changes in the product over time.
Overall, baking evaluations have been more sensory orientated and less analytical. We are striving to provide more standardized, analytical characterization of our ingredients as well as the characteristics of the finished products. This is extremely helpful to bakers in order to see the direct impact of the leavening components on the final product and to understand the functionalities that can be provide through leavening ingredients.