Rice is the staple food for billions of people in Asia and Africa. It is also a versatile ingredient in many popular dishes from around the world.

Despite its universal appeal, the question that is asked of the chef in every kitchen, whether professional or home, is whether rice should be washed (or rinsed) before cooking.

Cooks claim that pre-washed rice reduces the amount of starch in the grain of rice. And you can see it in its cloudy wash water, which studies have shown to be free starch (amylose) on the surface of the rice grain, from the milling process.

In culinary circles, it is recommended to wash the dishes when you want to cook rice with individual grains. However, for other dishes such as risotto, paella, and rice pudding (where you want a sticky, creamy effect), washing should be avoided.

Other factors, such as the type of rice, family traditions, local health warnings, and even the perceived cost of time and effort, will influence whether people should pre-wash rice.

A recent study compared the effect of washing on the viscosity and firmness of three different varieties of rice from the same supplier. Three types: glutinous rice, medium-grain rice, and jasmine rice. These different types of rice are not washed at all, either washed with water 3 times or washed with water 10 times.

Contrary to what chefs will tell you, this study found that the rinsing process did not affect the stickiness (or firmness) of the rice.

Instead, the researchers showed that the stickiness was not caused by surface starch (amylose), but rather by another starch called amylopectin, which is leached out of rice grains during the cooking process. The number of leaks varied depending on the type of rice grains.

Thus, the grade of rice, not the rinsing, is critical for grain sticking together. In this study, glutinous rice was the stickiest, while medium-grain and jasmine rice were the least sticky. (Hardness is the texture associated with biting and chewing.)

Traditionally, rice was washed to wash away dust, insects, small stones, and bits of husk left over from the rice husking process. This may still be important in some regions of the world where data processing is not as accurate and may provide peace of mind for others.

Recently, with the massive use of plastic in the food supply chain, microplastics have been found in our products, including rice. The washing process has been shown to wash out up to 20% of the plastic from uncooked rice.

And the same study showed that rice, no matter what packaging (plastic or paper bags) you buy it, contains the same percentage of microplastics. The researchers also showed that the plastic content of instant (precooked) rice was four times higher than that of uncooked rice. And if you pre-wash your instant rice, you can reduce the amount of plastic by up to 40%.

Rice is also known to contain relatively high levels of arsenic due to the crop absorbing more arsenic as it grows. Washing rice has been shown to remove about 90% of bioavailable arsenic, but also leaches out a large amount of other nutrients important to our health, including copper, iron, zinc, and vanadium.

For some people, rice provides a small percentage of their daily intake of these nutrients and therefore has little effect on their health. But for a population that consumes large amounts of heavily washed rice daily, it can affect overall nutrition.

Another study looked at other heavy metals such as lead and cadmium in addition to arsenic. And I found that prewash reduces all these percentages by 7-20%. The World Health Organization has warned of the dangers of exposure to arsenic from water and food.

Arsenic levels in rice vary depending on where it is grown, the variety of rice, and how it is cooked. The best advice is to rinse the rice beforehand and make sure it eats different grains.

Can rinsing rice prevent bacteria?

In short, no. Rinsing the rice will not affect the bacteria content of the cooked rice because the high cooking temperature kills any bacteria present. Of more concern is how long cooked rice or washed rice can be stored at room temperature. Cooking rice does not kill the bacterial pathogen Bacillus cereus.

If wet or cooked rice is stored at room temperature, it can activate bacterial spores and start their growth. These bacteria then produce toxins that cannot be deactivated by cooking or reheating; These toxins can cause severe gastrointestinal illness.

Therefore, do not store washed or cooked rice at room temperature for too long.

The report was prepared by Evangeline Manziuris, Director of the Nutrition and Food Science Program, a registered dietitian at the University of South Australia.

Source: Science Alert