Back in 1987, I had 33 beer—Ba Mu’o’i Ba in Vietnamese—from France at a Vietnamese restaurant. Later, I found some from Vietnam in a specialty store. But it didn’t taste like it was brewed with formaldehyde, which is said to have been used in the 33 beer brewed in Vietnam so that it would not quickly go sour in Vietnam’s tropical climate.
Beer going sour? That’s what hops are for.