???? Should you wash rice before cooking it? Here’s what the science says

2023-11-10 12:00:07

Rice is an essential food for billions of people in Asia and Africa. It is also a versatile ingredient found in many iconic dishes around the world, such as dolmades in Greece, risottos in Italy, paella in Spain and rice puddings in the United Kingdom.
Image d’illustration Pixabay

Despite its universal appeal, the question that gets asked in every kitchen, whether professional or personal, is whether to pre-wash (or rinse) rice before cooking.

What do chefs and cooks think?

Culinary experts say that pre-washing rice reduces the amount of starch from rice grains. Some studies have confirmed that it is indeed the free starch (amylose) on the surface of the rice grain, resulting from the milling process, which disturbs the rinse water.

In the culinary world, washing is recommended for certain dishes that require a separate grain. On the other hand, for other dishes such as risottos, paella and rice puddings (in which a sticky and creamy effect is sought), washing should be avoided.

Other factors, such as the type of rice, family tradition, local health advisories, and even the time and effort required, influence the choice of pre-washing rice.

For risotto, traditionally cooked with arborio rice, it is not recommended to rinse the rice, in order to promote the creamy texture of the dish. (Shutterstock)

Is there any evidence that washing rice makes it less sticky?

A recent study compared the effect of washing on the adhesiveness and hardness of three different types of rice from the same supplier. The three types were glutinous rice (sticky rice), medium grain rice and jasmine rice. These different rices were either unwashed, washed three times with water, or washed ten times with water.

Contrary to what chefs will tell you, this study indicated that the washing process had no effect on the stickiness (or hardness) of the rice.

Instead, the scientists demonstrated that the stickiness was not due to the surface starch (amylose), but rather to another starch called amylopectin, which is extracted from the rice grain during the cooking process. The amount of amylopectin that is leached differs from one type of rice grain to another.

So it is the variety of rice, rather than the act of washing the rice, that gives it its sticky characteristic. In this study, glutinous rice was the stickiest, while medium-grain rice and jasmine rice were less sticky and also harder (crunchy) in laboratory tests (hardness is representative of textures associated with chewing).

Fried rice dishes, like nasi goreng, are made from less sticky varieties of rice. (Shutterstock)

It is still useful to wash the rice

Traditionally, rice was washed to remove dust, insects (Insectes is a French-speaking ecology and entomology journal intended for a wide…), small pebbles and pieces of bark (The bark is the outer covering of the trunk, branches and roots of trees, and more…) left by the rice husking process. This can still be important in some parts of the world where the processing process is not as meticulous, and can provide some peace of mind.

More recently, with the abundant use of plastics in the food supply chain, microplastics have been found in our foods, including rice. The washing process has been shown to rinse up to 20% of plastics uncooked rice.

This same study found that rice contains the same amount of microplastics no matter what packaging (plastic or paper bags) you buy it in. Researchers also showed that plastics in instant (pre-cooked) rice were four times higher than in uncooked rice. By pre-rinsing instant rice, you can reduce the amount of plastic it contains by 40%.

Rice is also known to contain relatively high levels of arsenic, due to the absorption of arsenic a greater quantity of arsenic during plant growth. It has been demonstrated that the rice washing removes not only nearly 90% of bioaccessible arsenic, but also a large amount of other nutrients important to our health, including copper, iron, zinc and vanadium (Vanadium is a chemical element, with symbol V and of atomic number 23.).

For people who consume little rice and who meet their daily intake of these nutrients otherwise, washing rice will have only a small impact on their health. However, for populations who consume large quantities of heavily washed rice daily, this might impact their overall nutrition.

Another study examined the presence of other heavy metals, namely lead and cadmium (Cadmium is a chemical element with the symbol Cd and atomic number 48.), in addition to arsenic. According to this study, pre-washing reduced the levels of all of these metals by 7 to 20 percent. L’World Health Organization has warned the population once morest the risk of exposure to arsenic contained in water and food.

Arsenic levels in rice vary depending on where it is grown, rice cultivars, and how it is cooked. The best advice is to pre-wash your rice and make sure to eat a variety of grains. The most recent study, carried out in 2005, revealed that arsenic levels are highest in the United States. However, it is important to keep in mind that arsenic is present in other foodsincluding in rice products (cakes, crackers, cookies and cereals), seaweed, seafood and vegetables.

Can washing rice remove bacteria?

In short, no. Washing the rice will have no effect on the bacteria content of the cooked rice, as the high cooking temperatures will kill any bacteria present.

Of more concern, however, is the shelf life of cooked or washed rice at room temperature. Cooking rice does not kill the bacterial spores of a pathogen (The term pathogen (from the Greek παθογ?νεια!…) called Bacillus cereus.

If wet rice or cooked rice is stored at room temperature, bacterial spores may be activated and begin to grow. These bacteria then produce toxins which cannot be neutralized by cooking or reheating; these toxins can cause serious gastrointestinal illness. So be careful not to keep washed or cooked rice at room temperature for too long.

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