Cheese Please

Cheese Day is on 4 June 2021.

Several years ago, I visited a couple of cheese hoeves (farms) in the Netherlands and here are some fun photos from my travel album. Below you can see the equipment used to make these round cheese blocks. The cheese is completely covered in a wax shell that allows it to keep fresh without refrigeration.

This was in Edam, the town where Edam cheese comes from.

Chemistry + Microbiology of Cheese

Cheese is made from cow, goat, buffalo or sheep milk, which undergoes fermentation with the help of Lactobacillus or Streptococcus bacteria under the right temperature and pH conditions. Under different conditions, different types of cheese can be made. Since lactose is the dominant sugar in milk, it becomes lactic acid upon fermentation. Lactic acid looks like the molecule on the Don't Sweat It Card.

As acidity increases, milk starts coagulating into curds and precipitating out of the solution. Curds, which contain mostly casein protein, are then pressed together and shaped into the cheese blocks. Certain types of cheese are ready to consume at this stage, while others are stored and aged further to develop more complex flavours. Some cheeses undergo a second fermentation with Penicillium moulds or additional bacteria. Can you believe there are over 500 varieties of cheese in the world?

The odour of cheese is also an interesting chemistry. Unique cheeses like blue cheese has a distinctive characteristic smell attributed to nonan-2-one whereas the smell of camembert is because of S-methylthiopropionate. But the smelliest of all pungent cheese smells arises from a molecule called isovaleric acid seen here in The Big Cheese Card.