Yeah, the study said it has no effect on the stickiness of the rice.
Which is bizarre, because I've...seen it. Like repeatedly. And it's not a subtle difference. When I am lazy and don't wash my rice, it comes out MUCH gooier. It's not terrible but it's significantly different than when I wash it well.
Is this going to make me buy a second rice cooker to compare side by side? Ugh.
The popular press report says that washing doesn't make a difference. The actual, paywalled study says they did find a highly significant interaction between washing and type of rice, which is a level of statistical sophistication that a food writer might not grasp. In fact, even the scientific authors seem not to have commented much on the interaction.
In their data, it looks like washing 0-amylose glutinous rice makes it more sticky, while washing medium-grain 21% amylose rice even just 3 times makes it less sticky, and that 13% amylose Jasmine rice is just kind of all over the place or not systematically influenced by washing. They didn't do a big table of adjusted post hocs, so it's difficult to tell which specific groups are different from which others.
They also cooked the rices differently, using 1:1.3 rice:water for the glutinous and 1:1.6 for the medium and Jasmine, which obviously might confound their observations.
I've seen it, too. When I want fluffy individual grains, I rinse the rice first. If I want sticky rice, I don't rinse it. And it works for all different kinds of rice.
There's going to be powdered starch on the outside of the grains of rice. If you rinsed it and then added something like corn starch to the water you'd end up with sticky rice.
But if you read the article you'd have seen that prewashing to remove starch makes no difference. That's literally the point of this article.
"Culinary experts claim pre-washing rice reduces the amount of starch coming from the rice grains. ... Contrary to what chefs will tell you, this study showed the washing process had no effect on the stickiness (or hardness) of the rice."
And traditionally it was washed for cleanliness. The new wash to remove starch is a modern concept some people clearly started to say to sound smart with no evidence or science and it took off.
Read the article
Prefacing this with this is my anecdotal experience, while the results are the same I find it much easier to clean up if I prewash the rice first. I don't bother presoaking most of the time although some recipes call for it. I pretty much only have basmati and jasmine rice on hand so maybe it also depends on the variety?
This was the question in the article. They did a test of unwashed, washed 3 times, and washed 10 times, then compared the rice. The scientists found no difference between the samples. They further speculate that the stickyness level of the rice has to do with the starches that leech from inside the rice.
The article goes on to talk about how, depending on how (and where) the rice is processed, you may want to rinse rice to remove bits of husk, dust, pebbles, and possibly arsenic or microplastics.
Now, having said all of that, take the results of the study with a grain of salt. Washing 3 times isn't going to do much of anything, and 10 times doesn't actually tell us that they washed the rice properly. As soon as the starch is wet, it's sticky. You really have to rinse and agitate the rice, and wash until the water runs clear. Maybe that also leeches some of the more available starch from inside the rice, but the difference is noticeable to anyone who cooks rice on a regular basis. So I'm not going to question the suggested mechanism of action, but I know how to make rice that is and isn't sticky.
Im glad they mentioned the debris. My mom always told me they (family when they were in Vietnam) used to wash rice because of the pebbles, dust and bugs that may get into it. The water makes the bugs move which made it easier to pick out. She does it now because of the dust or whatever that may be on it. Never heard of the starch thing until watching youtube videos.
Still going to wash my rice though. Its better this way.
This is the reason I wash rice. Empty hulls, dirt, and bugs naturally float so it’s easier to take them out. We use brown or red rice so it’s not as “clean” as polished white rice. Also, even if the study says washing doesn’t do anything, the fact that the water turns a different color when rinsing shows that something gets removed when washing.
Only if you're concerned about removing dust, insects, little stones, bits of husk left from the rice hulling process, arsenic, and 20-40% of microplastics. The amount of those things is influenced by the region in which it's produced. Stickiness reduction from washing is nominal due to there being two different types of starch. The kind on the surface is different than the variety inside the grain, which is what affects the stickiness.
I've never bothered rinsing, but probably will now because of microplastics and arsenic. I've never seen impurities like what are listed, but I only buy rice produced in California.