Coolship

Fermentation most typically takes place in an enclosed environment to prohibit the introduction of bacteria or any other nasty objects from contaminating the liquid and producing any unwanted off-flavors and/or aromas. This is the key to style — specific yeast strains fermenting the wort at a specific temperature. But how was this done before refrigeration was invented to cool the water that goes into the heat exchanger? Especially before anyone understood what yeast even was or did, let alone different strains?
As time passed, brewers learned that larger, more shallow vessels shortened the cooling time due to the maximum surface area being exposed to the open air. The industrial revolution then allowed brewers to make these pans of metal (specifically copper) which drew out the heat much more quickly. They also learned to elevate the bottom above the ground to encourage air flow underneath, further enhancing cooling.This large exposed area served as a giant pool for ambient yeasts, bacteria and other floating critters to jump in, naturally inoculating the wort and beginning spontaneous fermentation. These beers typically turned out quite sour by today’s tastes. This, in essence, is beer’s equivalent of “terroir.”