Pasteurisation is a process during which milk is heated just enough to kill any bacteria that could present a food safety risk. Its use became widespread during the 20thcentury, and today all cow’s milk sold in stores must be pasteurised.
Pasteurisation is a very effective method for ensuring the safety of milk (and other liquids such as juice) that are produced on a large scale or in places far from where they’ll eventually be consumed. Milk for cheese may be pasteurised as well, of course, and this approach makes sense when the milk supply comes from many farms or is located far from the where the cheese is made. Because cheesemaking is a process of farming bacteria, tiny numbers present in the milk at the beginning may grow to high numbers by the end of the process, so there is no room for error.
When milk for cheese is pasteurised, the cheesemaker must replace what has been destroyed by the pasteurisation process by adding starter cultures, commercially-available strains of bacteria that ferment the milk. This process is very efficient and consistent, and if the cheesemaker is skilled, it can result in delicious cheese. But the practice of cheesemaking originated long before starter cultures or pasteurisation had ever been imagined, as the only way of preserving milk on small farms before an era of rapid transport and refrigeration.
Cheesemakers would process their raw milk while it was still fresh, unknowingly propagating the natural bacteria present within the milk as they made the cheese. With a fastidious approach to animal husbandry, and by using milk when it is very fresh, it is still possible today to make cheeses that allow us to taste the impact of these naturally-occurring microorganisms that are unique to each farm. Many of the cheesemakers we work with have started to explore how adapting their farming practices specifically to encourage the presence of interesting and diverse microbes that can make their cheeses taste more unique and interesting.
Some farms that we are working with are now making their raw milk cheeses entirely with microbes that originate on their farms, either by making their own cultures or through using whey (the liquid fraction of the milk that is removed during cheesemaking) as a continuous culture to seed the next batch, akin to a sourdough starter.
Try these amazing cheeses to get a taste of native raw milk microbes at work:
- St James – Holker Farm Dairy
- Innes Log & Innes Brick - Highfields Farm Dairy
- Cardo & Old Ford - Sleight Farm