Food Grade Lye - Sodium Hydroxide (Food Grade) Extensive use in the food industry this chemical is used among other for: Pretzels and German lye rolls, which are glazed with a sodium hydroxide solution before baking to make them crisp and contributing to their unique crust. Sodium hydroxide is also the chemical that causes gelling of egg whites in the production of Century eggs. Black olives result from the bathing of green olives in a lye-based chemical mix.