Gypsum, for those who are not in the know, is CaSO4 – calcium sulfate (we can thank dear Lavoisier for his nice nomenclature). It’s in your water, to varying degrees, depending on where you live. Locations with ‘hard water’ typically have much higher concentrations of it that Sydney, which has quite soft water.
Why the interest in the chemical composition? Well, it all starts with a beer called pacific ale. Or more specifically, various attempts to replicate it. From dry hopping, to last minute of the boil and rapid chilling, to proposing various bits of complex machinery, no one that I know has yet managed to replicate the delicious Galaxy (passionfruit) hop aroma of Pacific ale. So how do they do it?