aluner

A near-synonym of aluminer — to treat something with alum, whether in tanning and dyeing or, more specifically, to firm up fish or meat with alum before cooking or preserving, an old culinary preservation technique.

• Le poissonnier alunait autrefois le poisson pour raffermir sa chair. — Fishmongers used to alum-treat fish to firm up the flesh.
• Ces peaux ont été alunées avant la teinture. — These hides were treated with alum before dyeing.
• La technique consistait à aluner la viande pour la conserver plus longtemps. — The technique involved treating meat with alum to preserve it longer.

There's real overlap with aluminer, and neither comes up outside historical, culinary-history, or specialist-trade contexts — no everyday mistake to correct.

Often confused with aluminer.