Sodium Bicarbonate — Frequently Asked Questions

Use the acid's neutralising value, the weight of sodium bicarbonate neutralised by 100 parts of the acid. For example, a sodium acid pyrophosphate with a value of about 72 needs roughly 72 parts of bicarbonate per 100 parts of acid, and monocalcium phosphate at about 80 needs 80 parts. Check the value on the acid's specification, then fine-tune by measuring crumb pH and tasting the product.

That is the classic sign of excess sodium bicarbonate. Unreacted bicarbonate and the sodium carbonate left after heating make the product alkaline, which gives a soapy or metallic taste, yellowish crumb and stronger browning. Reduce the bicarbonate, increase the leavening acid, or check that the acid has not lost strength. Uneven distribution can cause the same fault in patches, so check the particle size and the mixing.

Yes. Fine powder dissolves and reacts quickly and distributes evenly in batters and doughs, which suits most bakery uses. Coarser granular grades react more slowly and flow better, which suits dry mixes and effervescent tablets and reduces premature reaction in storage. Very coarse particles in a soft dough can leave brown alkaline specks. Agree the particle-size distribution in the specification.

Ammonium bicarbonate decomposes completely on heating into gas and water vapour and needs no acid, which gives strong lift and spread in thin, dry biscuits and crackers. The ammonia must escape during baking, so it is unsuitable for thick or moist products. Sodium bicarbonate needs an acid, leaves a sodium salt behind and works in any product. Many biscuit recipes use both.

Keep it in sealed bags in a cool, dry store away from acids and acidic ingredients. Above about 50 °C it slowly loses carbon dioxide and turns partly into sodium carbonate, which weakens leavening and increases alkalinity. Moisture makes it cake and can start reactions in pre-mixed baking powders. Rotate stock and avoid storing it near ovens or in hot warehouses.

Potassium bicarbonate, E501(ii), releases carbon dioxide in the same way and can replace sodium bicarbonate partly or completely in reduced-sodium bakery products. It is slightly heavier, so about 1.19 kg replaces 1 kg of sodium bicarbonate, and it is more hygroscopic. At high replacement levels some tasters detect a bitter note, so trial the substitution in the finished product.