Gregg Wallace is in Gateshead at a cheese factory where they produce 3,000 tonnes of spreadable cheese every year. He follows the production of jalapeno chilli flavour cheese from a 28,000 litre delivery of milk to 5,400 squeezy tubes. The process begins in a traditional way – by making cheddar. He learns about the microbiology responsible for splitting milk into curds and whey and forming this hard cheese. He then chops 344 kilos of cheddar and gouda to make the base for his squeezy cheese, and puts it in a huge blender with whey, water and other ingredients in order to stabilise it and keep it soft and spreadable.Meanwhile, Cherry Healey is finding out how bacteria are responsible for the huge variety in smell, taste and appearance of different types of cheese. She learns that some smelly cheeses contain the same bacteria that are responsible for stinky feet. In cheese the odour is a by-product, a sign that the bacteria are silently changing the internal texture and taste of the product. She also learns the scientific rules for making perfect cheese on toast. It is all about medium sliced white bread, with precisely 50g of grated medium cheddar, set an exact 18 centimetres from the grill.Historian Ruth Goodman is finding out how cheddar, originally just one of hundreds of regional varieties in the UK, became the predominant hard cheese world wide. She discovers that it is down to a Victorian cheesemaker called Joseph Harding who first standardised production methods. She also makes a batch of processed cheese, using Kraft's original 100-year-old patent recipe.