Sodium Hydroxide
The short version
Caustic soda — a strong base used for pH adjustment, pretzel browning, and olive curing.
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Where it comes from
Manufactured industrially by electrolysis of sodium chloride brine (chlor-alkali process). One of the highest-tonnage industrial chemicals; food-grade material meets strict heavy-metal purity criteria.
How it's used
Used as a processing aid for pretzel and bagel browning (a brief dip in dilute lye solution before baking creates the characteristic dark crust), in lye-cured olives (removes oleuropein bitterness), in Dutch-processed cocoa (alkalinizes the beans), and in some Asian noodles (kansui). Functions as a pH adjuster across many product categories at low residual levels.
Safety profile
ADI not specified — neutralized to harmless sodium salts during food processing. The pure material is highly corrosive (strong base) so it is a workplace-safety hazard, not a consumer hazard. Final food products contain only trace residual.
Physical & chemical properties
White solid (pellets or flakes), extremely hygroscopic and deliquescent. Dissolves exothermically in water. Strong base (pH 14 in 1 M solution).
Regulation worldwide
Permitted globally as a processing aid and pH regulator. Residual must be neutralized in the final product.
Educational information only. Not medical or dietary advice.