If the germ theory is relatively new, how do they think fermentation was happening (like wine, ale, yogurt etc.) thousands of years ago?

Question

If the germ theory is relatively new, how do they think fermentation was happening (like wine, ale, yogurt etc.) thousands of years ago?

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Answer 1

So there is a difference between doing something and understanding what you are doing.

Germ theory is new – it is an understanding that germs exist, and beyond that the whole understanding of microscopic life and the role they play in things like fermentation.

Before that, all these things like wine, ale, yoghurt etc came about through trial and error, and passing on that knowledge to the next generation.

Cheese is a good example – one theory is someone in ancient times tried to store milk within a container made out of an animal stomach; this accidentally exposed the milk to the enzymes in the stomach and separated the milk into curds and whey. This is one method of making curds. Tasting the curds you’d realise it’s something new; the next step is separating out the solid curds from the liquid whey to make your cheese. There are over 1000 different cheeses as there are so many different ways of both making curds and what you can do with curds afterwards, and so many different milks to use. All of this is from trial and error, with totally different methods and so different cheeses from all over the world. But the first step is thought to have happened in 5,000 BC and spread from there.

But the science of cheese – actually understanding how curds form or the other steps that go into making cheese work – is modern. Until then it was simply – if you do this, you will get this cheese.

This applies to wine, ale, yoghurt and so on. Some are easier to understand how they might be accidentally discovered – making wine by accidentally leaving grapes to ferment for example. Others are a bit more mind boggling – yoghurt is made by heating then cooling then culturing. However each step still produces something useful that may have allowed the next step, which may explain how complex processes for some yoghurts came about. For yogurt, the first step is called scalding – scalded milk is used directly in some recipes, scalded then cooled milk is used to make some breads and so on.

So while it seems impossible to do these things without understanding how it works, a lot of these things have been around for 1000s of a years and likely came about by accidents, and people trying new things and sharing those new recipes and methods. Then once we developed microscopes we started to understand how these things actually work.