Should You Wash Your Rice? Science is complicated

Rice is a staple food for billions of people in Asia and Africa. It’s also a versatile ingredient in many famous dishes from around the world, including dolmades from Greece, risottos from Italy, paella from Spain and rice pudding from the UK.

Despite its universal appeal, there is a question in every kitchen, whether professional or home, about pre-washing (or rinsing) rice before cooking.

What do chefs and cooks say?

Culinary experts claim that pre-washing rice reduces the amount of starch from the rice grains. You can tell by the cloudy rinse water, which studies show is the free starch (amylose) on the surface of the rice grain that’s created during the milling process.

In culinary circles, washing down some dishes is recommended when a separated grain is desired. Washing is omitted for other dishes such as risotto, paella and rice pudding (where a gooey, creamy effect is required).

Other factors such as rice variety, family tradition, local health warnings, and even perceived time and effort involved affect whether people prewash their rice.

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

A recent study compared the influence of washing on the stickiness and hardness of three different types of rice from the same supplier. The three varieties were sticky rice, medium grain rice, and jasmine rice. These different types of rice were either not washed at all, washed three times with water, or washed with water ten times.

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

Instead, the researchers showed that the stickiness is not due to the surface starch (amylose) but to another starch called amylopectin, which is leached out of the rice grain during the cooking process. The amount leached differed depending on the type of rice grain.

So the type of rice – and not the washing – is decisive for the stickiness. In this study, sticky rice was the most sticky, while medium-grain rice and jasmine rice were less sticky and also harder in the lab test. (Hardness is representative of the textures encountered during biting and chewing.)

However, you may still want to wash your rice

Traditionally, rice was washed to rinse off dust, insects, small stones, and pieces of husk left behind when the rice was husked. This can still be important to some regions of the world where processing is not as meticulous, and a comfort to others.

Recently, due to the heavy use of plastics in the food supply chain, microplastics have been found in our food, including rice. The washing process has been shown to remove up to 20 percent of the plastics from uncooked rice.

The same study found that regardless of the packaging (plastic or paper bags) you buy rice in, it contains the same percentage of microplastics. The researchers also showed that the plastic content in (pre-cooked) instant rice is four times higher than in uncooked rice. If you pre-rinse instant rice, you could reduce plastic usage by 40 percent.

It is also known that rice is relatively high in arsenic because the plant absorbs more arsenic as it grows. Rice washing has been shown to remove about 90 percent of the bioavailable arsenic, but it also scavenges numerous other nutrients important to our health, including copper, iron, zinc and vanadium.

For some people, rice covers a small percentage of their daily intake of these nutrients and therefore has little impact on their health. However, in populations that consume large amounts of heavily washed rice on a daily basis, this could have an impact on overall diets.

In another study, other heavy metals, lead and cadmium were examined in addition to arsenic. It was found that pre-washing reduced the concentration of all of these substances by 7 to 20 percent. The World Health Organization has warned of the danger of arsenic contamination from water and food.

The arsenic content in rice varies depending on the growing area, rice variety and type of preparation. The best advice remains to prewash your rice and make sure you’re consuming a variety of grains. The most recent study from 2005 found that the highest levels of arsenic were in the United States. However, it’s important to remember that arsenic is present in other foods, including products made from rice (cakes, crackers, cookies, and granola), seaweed, seafood, and vegetables.

Can Washing Rice Prevent Bacteria?

In short, no. Rice washing does not affect the bacteria content of the cooked rice as high cooking temperatures kill any bacteria present.

Of even greater concern is how long you store cooked or washed rice at room temperature. Boiling rice does not kill the bacterial spores of a so-called pathogen Bacillus cereus.

If wet rice or cooked rice is kept at room temperature, the bacterial spores can be activated and they begin to grow. These bacteria then produce toxins that cannot be deactivated by boiling or reheating; These toxins can cause serious gastrointestinal disorders. Therefore, be careful not to keep washed or cooked rice at room temperature for too long.

This article was originally published on The conversation by Evangeline Mantzioris at the University of South Australia. Read the original article here.

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