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The rates at which doughs are leavened are important determinants of the quality of baked products. Leavening rates in dough systems are influenced by a variety of factors including the types and concentrations of the leavening agents, temperature, the availability of water, and pressure [8].

Leavening rates may be measured by trapping evolved CO₂ and plotting CO₂ volume versus time. The amount of CO₂ produced is usually expressed as a percentage of the total amount of CO₂ that would be released if all of the sodium bicarbonate were converted to CO₂ and H₂O. When measured in a dough system, leavening rates are called “dough reaction rates.” Typical dough reaction rates for some leavening acids are shown in Figure 2.1.

Figure 2.1 Rates of CO₂ production from mixtures of SALP and MCP‐H₂O, SAPP‐40, or SAS. Evolved CO₂ is expressed as a percentage of “available” CO₂ in the NaHCO₃.

Source: Adapted from [9].

Measurement of leavening rates must be carefully standardized with respect to temperature, time, agitation, and ingredients so that comparisons between laboratories and experiments will be valid [10]. The examples of leavening rates given above serve to illustrate the fact that rates differ considerably among leavening systems. It should be remembered that leavening rates for a given leavening acid can be manipulated by applying coatings and changing particle size. Also, other ingredients in the batter or dough may affect leavening rates. Thus, when purchasing leavening acids from suppliers, it is important to specify the leavening rate needed for a particular application.