How is Rice Made?

Rice is a grain harvested from a grass species called Oryza sativa. It’s the staple food for billions of people around the world and has been cultivated for millennia. Rice is eaten in all manner of dishes, but do you know how they make rice in a factory? Read on to find out.

Engineering How It’s Made
15 October 2022

Rice is the most widely consumed food in the world. It’s the staple dish of over 3.5 billion people – half the world’s population. In 2020, over 750 million tonnes of rice was produced around the world, with China and India accounting for almost half the global output followed by Bangladesh, Indonesia, Vietnam and Thailand.

Rice is nutritious and versatile and the star attraction in some of the world’s most famous dishes. Sushi from Japan, paella from Spain, nasi goreng from Indonesia, risotto from Italy and jollof rice from West Africa are just some of the dishes we know and love. So how is rice manufactured and how is rice produced in factories?

A Short History of Rice

Rice has fed more people over a longer amount of time than any other food. Its cultivation is regarded as one of the most important events in all of human history. Indeed life without rice for much of the world’s population is unthinkable. It’s believed that rice was first cultivated in China’s Yangtze River basin sometime between 13,500 and 8,200 years ago.

Rice is traditionally grown in waterlogged wetlands and the concept of the rice paddy started around 4,000 years ago. Migration and trade spread rice throughout Southeast Asia, then into the Indian subcontinent.

As new trade routes were forged, rice arrived in Europe, America and Africa, where it continues to be grown in huge quantities. Today, there are dozens of different types of rice available on our supermarket shelves – arborio, jasmine, basmati, wholegrain, black, longrain, calasparra and Carolina Gold – to name a few.

Here, we’ll let you know how they make rice in a factory.

How is Rice Produced?

Aerial view of a combine harvester working on a rice field. (Photo: Suriyapong Thongsawang via Getty Images)

In some parts of the world rice is still harvested by hand, but for the most part modern rice production now sees machines do much of the heavy lifting in order to feed the huge demand for the world’s most popular food.

The Harvesting

The question of how is rice made begins with harvesting. After around five months of growth, the rice seed is harvested. A combine harvester strips the rice seeds from the stalks and a troop of trucks takes it to the processing facility.

The Delivery

At the processing plant, the raw rice is unloaded into an underground receiving pit which filters out any stalks and debris. From the pit, a conveyor belt takes the rice to storage silos and into huge warehouses that can hold many thousands of kilograms. In these warehouses, fans blow cool air through the huge rice mountains to lower its moisture content to between 18% – 22%.

The Testing

Next in the process of how rice is made is a moisture test. A probe picks up randomly chosen samples and a technician tests the moisture content. The technician will also sift the grains through a sieve to screen for any foreign objects including tiny bugs that may have fallen through the holes. A single moth or beetle can render the entire batch unusable.

The Filtering

To ensure the rice is completely clean, it’s sent tumbling through small holes in rolling cylinders to screen out any last remaining detritus such as straw, small clumps of mud and weed seed. It will also suction out any empty rice husks.

The Hulling

The clean rice is pushed between two hard rubber or stone rollers to crush the husks and a second machine separates the husks from the grains of rice. In the process of how rice is produced, this is one of the most important elements. Some will inevitably get missed, so the entire batch is put into huge agitator machines to ensure every grain is perfect.

The Milling

At this point, the grains still have their outer layer known as the bran. It’s left on when producing brown rice but, for white rice, the bran is removed. Hulling machines are used to remove the outer layer and the rice is then put into a centrifuge, which rotates it at very high speeds to ensure the entire layer has gone. The brans aren’t discarded, they become an ingredient in cattle feed. The rice is then polished to give it a pearly-white sheen and any broken kernels are caught and separated. We’ve almost answered the question ‘how is rice manufactured’ but there’s still a few things left to do before it ends up on your plate.

The Finishing Touches

To ensure the rice is fit for sale, computerised cameras carefully analyse each batch of thousands or even millions of individual grains checking for discoloured grains. If any are caught, targeted air nozzles blast them out of the mix. Finally, the rice is weighed out and machine-fed into bags which are heat-sealed ready to be sent to supermarkets, wholesalers and commercial food production factories. This is the final step in the process of how rice is produced.

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