Stilton is made using pasteurised milk, starter cultures, rennet and blue mould spores.
Once the curds have formed and the whey is removed the curds are allowed to drain overnight.
The next morning the curd is cut into blocks to allow further drainage before being milled and salted.
Each cheese requires approximately 11 kg of salted curd to be placed into cylindrical moulds (hoops).
The hoops are then placed on boards and turned daily to allow natural drainage for 5 or 6 days. This ensures an even distribution of moisture throughout the cheese. The cheese is never pressed. After 5 or 6 days the cylinders/hoops are removed and the coat of each cheese is sealed by smoothing or wrapping (binding) to prevent any air entering the inside of the cheese.
The cheese is then moved to the maturation store where the temperature and humidity are carefully controlled. Each cheese is turned regularly during this maturation/ripening period.
At about 5 weeks of age the cheese is ready for piercing with stainless steel needles. This allows air to enter the body of the cheese and start forming the distinctive blue veining associated with Stilton. At about 9 weeks of age when each cheese weighs around 8kg the cheese is ready to be sold. Before this can happen, however, every cheese must be graded using a cheese iron.
The iron is used to bore into the cheese and extract a small plug of cheese. Using sight and smell the grader will decide whether the cheese is up to standard and can be sold as Stilton. At this young age Stilton is still quite crumbly and has a slightly acidic taste. Some customers like a more mature cheese and if left for a few more weeks it will start to develop a smooth, buttery texture, with a more rounded mellow taste.