It’s fair to say that flour is a superstar ingredient which boasts incredible versatility. In the UK alone we produce around five million tons of flour each year.
There are in fact many different types of flour, including self-raising flour, bread flour, gluten-free flour and rice flour. All have particular properties that make them suitable for different types of cooking and baking.
However, before we answer the question ‘how is flour manufactured’, we’ll take a trip back in time. A long, long way back in time.
Flour - A Short History
Flour in its most basic form stretches far back into prehistory and has been made for thousands of years. The first evidence of flour production comes from ancient Egypt, where archaeologists have found wall paintings of women grinding grain into flour. Around 500 BC, the Greeks developed the first flour mill but it was the Romans who super-charged the process with the creation of watermills that could grind wheat into flour on an industrial scale.
This method of making flour quickly spread all over Europe and by the eleventh century, the Domesday Book recorded over 6,000 watermills in England. This historic flour-making process wasn’t as refined as modern techniques and the wheat, barley and rye weren’t broken down as much – resulting in coarse, gritty flour and dark bread. The process of how flour is made today is far more precise.
Fast-forward to the eighteenth century and the automated flour mill was invented in the USA. A century later, steam mills were developed that could mass-produce flour in vast quantities. Today, flour is made in factories with over 400 million tonnes of flour produced every year.
How Flour is Made
The process of making flour is fairly simple – in its most basic form a selected grain is ground up and the resulting powder is sifted to remove any impurities. The type of grain used to make flour depends on the type of flour being made. For example, wheat flour is made from wheat grain, while rice flour is made from rice grain. But there’s more to it than this simple explanation, and here you’ll find out the step-by-step process of how flour is made using a modern production process.
Types of Flour
As we’ve mentioned, there are many different types of flour produced in modern flour mills. High protein or hard wheat varieties are used to make bread flour, while lower protein or soft wheat varieties are used to produce flour used for cakes and pastry. Medium protein all-purpose flour sits somewhere in the middle. To make white flour, only the wheat kernel’s soft inner part – the endosperm – is ground. This requires removing the kernel’s hard skin known as bran, and its seed, called the germ.
Harvesting, Testing and Separation
The wheat is harvested and as soon as it arrives at the processing plant, a probe vacuums up randomly selected samples for testing. If the samples pass the stringent quality control tests, the wheat is sent to an underground conveyor. The wheat kernels are then passed through rollers that remove the bran and germ and crush the endosperm into small pieces called semolina.
Sifting the semolina removes the germ and any remaining larger bran pieces. Much of it is still covered in tiny bran particles so between each milling station is a purifier. This is a machine that uses controlled air currents to essentially ‘float’ the lighter bran above the heavier semolina which in turn enables sieves to separate the two.
The protein content of wheat varies by species so the first step is to blend together the correct wheat for the type of flour being produced. From the blender the wheat goes through an intensive cleaning system that removes the tiniest of impurities such as seeds and dust.
The milling is the most important element of the flour production process. The wheat is passed through a succession of progressively smaller milling machines. Each one grinds the grain between steel rollers. Particles too large to pass through continue to the next milling machine. By the final machine, whatever is still not completely processed gets vacuumed up to begin the cycle again. The finely ground semolina is sieved to make sure it doesn’t leave the final milling machine until it’s been ground to the perfect fineness.
At the end of the production process, the mill ends up with three distinct products. The bran is used for animal feed and baking; the wheat germ is sold into the health food market and the white wheat flour is the star of the show. Any leftover by-products go into livestock feed. Just before the flour is packed, it is enriched with vitamins and minerals which were lost when the bran and germ were removed.
The bags of flour in various sizes from 500g upwards are shaken to settle the product and then they’re boxed up and sent off to supermarkets, restaurants, commercial bakeries and food producers. Tanker trucks which can hold as much as 20 tonnes transport bulk flour to huge industrial bakeries. This is the final step in the process of how flour is produced.