Cheesy Challenge

Cheesy Challenge Activity Card Cosmic and Gem are having a picnic. They are tucking into glasses of cool milk and tasty cheese sandwiches. “Isn’t it amazing that they can turn a white runny liquid into cheese?” Cosmic wonders out loud. Gem stops chewing and looks at the cheese and then at the milk. She has a puzzled look on her face. “How do they do that?” Gem asks. “It’s fascinating! We need to do some investigating. I think a little bit of chemistry might help.” Your challenge Can you help Cosmic and Gem find out how milk is turned into cheese? Discuss Take a look at some cheese and milk. Talk about what you already know about it.

Getting started Ingredients A cup of semi skimmed or skimmed milk Lemon juice A spoon, a bowl (for heating in the microwave) or a small pan (for heating on the cooker) A sieve, a bowl and a piece of very clean, thin cloth to strain the milk Salt and other flavourings (optional) Clean hands, equipment and table Cheese Recipe Method 1. Pour 1 cup of milk into a bowl or small pan. Heat it in the microwave or on the cooker until the milk just begins to boil. If it is on the cooker, keep stirring to stop it burning. 2. Remove from the heat. Add lemon juice a few drops at a time and keep stirring gently. 3. Keeping adding lemon juice until the milk starts to go very lumpy (curdle). Let it cool. 4. Put a sieve on top of a bowl and put a cloth in the sieve. 5. Pour the milk into the sieve and let all the liquid (the whey) run through into the bowl. The lumps (called curds) will stay in the cloth. 6. Lift up the cloth and gently squeeze out more of the liquid. You have now made some cheese! Add a little salt and any other flavours that you like. Test your ideas Is cheese only made from cow’s milk? What different types of cheese are there? Are they all made in the same way? Do people eat cheese everywhere around the world? When was cheese first made? Can the whey be used for anything? Share your ideas What kind of cheese have you made? Does it look like any of the cheese that you buy in the shops? What does it taste like? Make a poster showing how a little chemistry helps to turn milk into cheese. Put it on display. Extra things to do Here are some other milk products. Can you find out how they are made and what they are used for? Not all milk comes from animals. Can you spot which ones do not and find out more about them? Yoghurt Sour cream Lassi Ghee Cream Smetana Butter Clotted cream Condensed milk Creme fraiche Kaymak Buttermilk British Science Association Registered Charity No. 212479 and SC039236