DCPD is a type of orthophosphate, a single phosphate group with two calcium atoms and two water molecules. This compound is a very stable acid salt which can be stored under suboptimal conditions without adverse effects on its leavening performance.
Incorporation into aqueous systems and hydration is the key to DCPD functionality in bakery batters. Especially, when heated to temperatures above 150°F (65°C). With these two conditions met, DCPD breaks down into phosphorus-containing acids and tricalcium phosphate. The acids formed then react with the bicarbonate and produce CO2.1
Leavening reaction of DCPD with baking soda:
CaHPO4·2H2O + NaHCO3 → Ca3(PO4)2 + Na2HPO4 + 8 H2O + 2CO2
During baking, a portion of DCPD decomposes into tricalcium phosphate and phosphoric acid, thus the basis for its good leavening acid characteristics. The chemical equation for this reaction is as follows:1
3CaHPO4 + Moisture + Heat → Ca3(PO4)2 + H3PO4 + 6H2O
DCPD is also used to adjust pH level of finished products (if no residual soda is present). Lowering pH of the product may affect crust and crumb color, however, it can also be beneficial in terms of shelf-life extension.
DCPD is synthetically produced from the reaction between calcium carbonate (hydrated lime) and phosphoric acid. The reaction requires carefully controlled reactants’ ratios and reaction conditions mainly pressure, pH and temperature, among others.
The neutralizing value (NV) of DCPD is 33, indicating that 100 grams of DCPD require 33 grams of sodium bicarbonate to achieve perfect neutralization and optimum CO2 release.1
Considerations when formulating DCPD in sweet baked goods:
- DCPD should be used in conjunction with faster acting leavening acids. If additional acid is needed to fully neutralize sodium bicarbonate in a product, DCPD can be used.
- It can be part of double-acting baking powders in cases where a cracked surface on the baked good is desired. This is possible since DCPD produces gas after starch gelatinization and protein denaturation have initiated i.e. setting of crumb structure.
- DCPD is extremely slow to react, only releasing CO2 in the last stages of baking, when the product reaches approximately 150°F (65°C). This would require a fairly long bake time. Dicalcium phosphate dihydrate may be useful for dense and large products (e.g. pound cakes).
- DCPD may also be used as a calcium source for fortified flour/grain products. Due to its slow-acting rates, it is great for frozen and refrigerated doughs.
DCPD holds a GRAS (generally recognized as safe) status in the United States.2
- Book, S., Livvix, N. “Acid Sources.” Chemical Leavening Basics, AACC International, Inc., 2018, pp. 25–48.
- CFR – Code of Federal Regulations Title 21, Part 182—Substances Generally Recognized as Safe, The information on this page is current as of April 1 2019. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182, Accessed 29 June 2020.