Aluminium Sulfate
The short version
Alum — historically used to firm pickles and egg whites, now restricted in EU food use.
It's permitted and generally considered safe, but there are a few reasons to be mindful — like sensitivities in some people, debated studies, or intake limits. The Safety section below explains the specifics.
Where it comes from
Manufactured by reaction of aluminium hydroxide with sulfuric acid. Common industrial chemical (water-treatment flocculant); food-grade material more rigorously purified.
How it's used
Historic firming agent for pickles and cucumber slices (gave the crisp crunch), egg-white whipping aid, and a clarifier for some sugar refining. EU restricted to firming agent for egg-white wares since 2014 (aluminium intake re-evaluation). Largely displaced by calcium chloride (E509) and calcium hydroxide (E526) for pickling.
Safety profile
ADI of 0–1 mg/kg body weight (combined aluminium, EFSA 2008). Aluminium absorption from soluble forms (sulfates, lakes) is higher than from metallic or insoluble forms — drives the more restrictive limits.
Physical & chemical properties
Colorless to white crystalline solid. Soluble in water with mildly acidic solution.
Regulation worldwide
Permitted in the EU restricted to egg-white whipping. Permitted in the US for food and water-treatment use with stricter purity criteria for food-grade.
Educational information only. Not medical or dietary advice.