Sodium hydroxide

Sodium hydroxide (lye) is a strong base used widely in food processing for pH adjustment and alkaline treatment. Its most visible food applications include the distinctive shiny, chewy crust of German pretzels and lye bagels (briefly dipped in dilute sodium hydroxide solution before baking), the curing of olives to remove bitter compounds, the alkalization of cocoa in Dutch-process cocoa powder, and the processing of hominy corn.

JECFA's ADI is "not specified," evaluated in 1965. In food, sodium hydroxide is fully neutralised by the natural acids and buffers present in food during processing, producing sodium salts that are indistinguishable from any other sodium compound in the diet. No free sodium hydroxide remains in properly processed final food products. The sodium contribution from residual neutralisation products is nutritionally equivalent to other sodium sources.

Sodium hydroxide is approved in the EU, US (GRAS), UK, Australia, and globally. It is a fundamental food processing chemical encountered in many traditional foods including pretzels, bagels, olives, and Dutch-process cocoa. For consumers there are no safety concerns from its approved food use — the distinctive flavour it imparts (particularly to pretzels) comes from the Maillard reaction products formed during baking of the alkaline surface, not from residual lye.