The UK gets through two thousand tonnes of baked beans every year - and Gregg Wallace and Cherry Healey went behind the factory that produces the popular food. The 54 acre factory in Wigan, is the largest food processing plant in Europe, and they make an average of three million cans in 24 hours. As well as baked beans, the factory produces 199 other products, with 1200 staff employed to oversee the production. Baked beans are made using haricot beans, which are grown in the summer and left to dry on the plant before being shipped to the UK from North America.

Gregg followed the journey of the beans from arrival at the factory to the finished product - it takes an average of two hours from the arrival of the beans to them being in a tin. The beans arrive in two tonne bags (which hold nine and a half million individual beans or 20,000 cans worth) which are lifted over a funnel where they then go to the blanching area, travelling at five miles an hour on an inclosed conveyer. The beans are then rehydrated with water, passing through two 85 degree chambers, soaking the beans for ten minutes each. This blanching in steam quickly softens the outside of the dry beans and lets in water - by the end of this process they have taken in 65 per cent more water.

BBC2 Gregg Wallace took a look behind the scenes at the Heinz baked bean factory

The beans then move along the factory to be rehydrated in warm water to get rid of excess skins. Then a laser looks for discoloured beans and fires an air jet to knock any they find off the production line - previously this would have been done by hand. The next step is the very secret part - the addition of the secret spices. The recipe has been the same since 1896 and the spices are delivered to the factory in three separate bags to further ensure the recipe is kept secret.

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One bag of the spice mixture goes into a tomato sauce which then makes 20,000 cans worth of the sauce we recognise as Heinz. Tomato puree, made using Californian tomatoes, is added, with one tonne bags squeezed out by two rollers. Starch is then added to thicken the sauce, followed by sugar and spice to sweeten the mixture. Finally vinegar - although it is a secret as to how much.