Cheese - Acidification

As far as I can tell, it's acidification that contributes to the coagulation of the proteins that make cheese cheesy.

Acetic acid in vinegar or citric acid in lemon juice can be added to milk to separate it into curds (lumpy bits) and whey (watery stuff). Another way is to introduce your milk to some miro-beasties like Lactococci bacteria. Lactococci, along with others including streptococci, lactobacilli (pictured), and propionibacter shermani, involve themselves with the milk sugars and turn them into lactic acid. It also seems these beasties and the enzymes they produce play a role in the final flavour of the aging cheese.

Like beer, wine and bread, cheese flavours change depending on the ambient temperatures the beasties find themselves growing in. This, and the amount of salt required as preservative when cheese making in a desert, leads to differences in cheese matured strapped to the side of a camel on the Arabian Peninsular when compared to say, one ripened in the cellar of a European monastery. All great food but potentially very different. There are probably many other things that influence flavour that I don't yet know about.

The holes in Swiss cheese are made by contemporary Swiss sculptor Gerald Hach as part of a long standing government tourism campaign.

Actually the holes in swiss cheese are a bi-product of carbon dioxide produced by the micro-beasty propionibacter shermani.