What you need
Milk
White vinegar
Salt
Rennet
A thermometer
A skimmer or slotted spoon
Cheesecloth
Small baskets (to hold curds)
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IT STARTED with bad milk. Thousands of years ago, someone realised that the unsightly blobs in off milk didn’t taste too bad. Then people learned that these curds could be salted and pressed to make a food far more durable and delicious than anyone who drank sour milk could have predicted.
This week, I’m going to show you how to do it yourself. What’s more, you will be able to make two types of cheese from one batch of milk: halloumi (pictured) and ricotta.
Milk contains dozens of proteins, which can be split into curds and whey. When exposed to acid, the curd proteins, or caseins, clump into a solid mass, while the whey stays suspended in liquid.
At some point, people discovered that the curds became more cohesive if the milk was curdled in an animal stomach. That is thanks to the enzyme chymosin, which cleaves caseins in a way that allows them to bond together. Rennet, an extract of calf, lamb or goat stomach containing chymosin, was the first semi-purified enzyme to be used in food-making, an early milestone in biotechnology.
In cooler parts of the world, cheese-makers found they could mature cheese for longer and develop complex flavours using friendly bacteria and moulds. But the simplest cheeses don’t need these. For example, ricotta is made by curdling milk using acid from vinegar or lemon juice.
To make halloumi and other cheeses, you will need rennet, either animal or vegetarian. You can get this in a cheese-making kit, or separately online. You will also need a thermometer and some small baskets to hold the curds while they are pressed.
Heat 7 litres of full fat milk to 32°C, then stir in a teaspoon of rennet. Take the mix off the heat and let it settle for an hour. Then take a knife and slice the curds into 2-centimetre cubes. Leave for 5 minutes to settle, then gently heat the mixture to 38°C, stirring frequently. Use a slotted spoon to scoop the curds into your baskets. Stack them on top of each other to gently press them, and leave in a baking tray to catch draining liquid, then set aside.
You can now make ricotta from the remaining whey protein. This is because chymosin works on only one milk protein, kappa casein, leaving others that can be solidified with acid.
Heat the whey to 90°C, then turn off the heat and add 30 millilitres of white vinegar and 15 grams of salt. After 5 minutes, spoon the curds into a colander lined with cheesecloth. Leave to drain for half an hour, or longer for firmer ricotta.
When the halloumi is firm, cut it into large pieces. Heat the whey again, this time to 85°C, and cook the pieces in it for 20 minutes, or until they rise to the top. Drain, cool and store the cheese in brine until you want to eat it – perhaps fried with pitta bread.
For next week
Cooking oil
Potatoes
Wok or large pan
Thermometer
Skimmer
Next in the series
2 Making cheese
3 Science of crispiness:
Perfect fries every time
4 Tofu and Sichuan pepper
5 Gravlax and curing
6 Tempering chocolate
7 Umami and flavour
8 Perfect pancakes
9 Kimchi and fermentation
10 Sourdough bread
Science of cooking online
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