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​12 Carbon Dioxide Methods​

12-10.01 Residual Carbon Dioxide in Baking Powder

To determine residual carbon dioxide in baking powders resulting from sodium and calcium carbonates or unreacted sodium bicarbonate. Calcium carbonate is used as a diluent, to keep sodium bicarbonate and leavening acid separated. Generally used in combination with starch, calcium carbonate is also a source of calcium for nutritional fortification. A strong acid, e.g., sulfuric acid, is required to neutralize carbonate sources. This method can be used for single- or double-acting baking powders that contain various leavening ingredients such as sodium aluminum sulfate, sodium acid pyrophosphate, sodium aluminum phosphate, monocalcium phosphate, dimagnesium phosphate, or organic acids. In this method, baking powder is heated to cause most of the sodium bicarbonate to react with the leavening acids. Residual carbon dioxide, released by sulfuric acid, is generally associated with other carbonate sources. Therefore, excessive sodium bicarbonate, not neutralized by the leavening acids, will also contribute to the residual carbon dioxide.

12-20.01 Total (Gasometric) Carbon Dioxide in Baking Powder

To determine total carbon dioxide in baking powders. Carbon dioxide may be released from various carbonate sources including sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, calcium carbonate, and sodium carbonate. A strong acid, e.g. sulfuric acid, is required to neutralize carbonate sources. Bicarbonates are added to baking powders to provide carbon dioxide for leavening, and calcium carbonate is added as a diluent, to keep sodium bicarbonate and leavening acid separated. Generally used in combination with starch, calcium carbonate is also a source of calcium for nutritional fortification. This method can be used for single- or double-acting baking powders that contain various leavening ingredients such as sodium aluminum sulfate, sodium acid pyrophosphate, sodium aluminum phosphate, monocalcium phosphate, dimagnesium phosphate, or organic acids.

12-21.01 Total Carbon Dioxide in Prepared Mixes and Self-Rising Flours​

To determine total carbon dioxide in prepared bakery mixes and self-rising flours. Bakery mixes may include cake, biscuit, pancake, cookie, muffin, or other chemically leavened mixes. Carbon dioxide may be released from sodium, potassium, and ammonium bicarbonates (as sources of leavening gas) or calcium and sodium carbonates. Calcium carbonate is also used as a source of calcium for nutritional fortification. A strong acid, e.g. sulfuric acid, is required to neutralize carbonate sources. This method can be used for systems that contain various leavening ingredients such as sodium aluminum sulfate, sodium acid pyrophosphate, sodium aluminum phosphate, monocalcium phosphate, dimagnesium phosphate, or organic acids. A large sample of the bakery mix and self-rising flour is used to provide sufficient carbon dioxide to be detected by the Chittick apparatus.

12-29.01 Table: Correction Factors for Gasometric Determination of Carbon Dioxide