rinsing water of rinsing rice

Should You Rinse Rice? – The Science of Cooking Rice

Once you’ve decided which of the many rice dishes you want to cook and once you’ve decided which specific rice variety to use, you’ve got another decision to make. How to cook your rice? And, just as importantly, should you rinse your rice before you cook it?

Of course, the method you choose may already be determined by the dish you chose to make, or by the equipment you have at hand. But whether you rinse tends to be more of a free choice, which do you choose?

Unfortunately, as with just about anything food related, the answer isn’t straightforward and simple. It depends…

A quick recap on where rice comes from

As we discussed before, rice is a grain that grows on a grass. After the grass stalks are harvested, the grains are removed through a process called threshing. In the case of parboiled rice, the rice is cooked, in other cases, producers head straight into the next step: removing the inedible husk through milling.

At this point, your brown rice is ready to go, whereas white rice needs to undergo an additional milling and polishing step to become what the name says it is: white rice. In some countries white rice is enriched with vitamins and minerals that would have been present in the outer bran layer that is removed during milling.

Cooking rice

Whereas you likely won’t have any control over the process up to this point, from here on onwards you definitely do. How you cook and prepare your rice will influence how your final rice turns out and for which dishes it is most suited.

There are a lot of different ways to cook your rice. Which one you use will depend on what you’re used to, what you’ve been taught, the equipment you have on hand, and the texture you’re after. We’ll be highlighting a few methods, but, before doing so, let’s have a look at what actually happens when cooking rice!

What happens when cooking rice

A rice kernel sold on the market is a dry kernel with a moisture content lower than 14%. This low moisture content is essential for ensuring the rice can be kept for long periods of time without spoiling because of the growth of microorganisms. Rice in its dried form consists of about 80% carbohydrates, which are mostly starch, and a smaller amount of protein.

When you’re cooking rice, you’re mostly concerned about the starch and protein in the starch. These are the two that will change significantly while cooking your rice. Starch is a mixture of two major molecule types: amylose & amylopectin. These each behave slightly differently and will impact the final rice structure as we discussed before for risotto rice. The ratio of these two molecules depends on the rice you’ve decided to cook with.

In a raw uncooked rice kernel, the starch in rice is in a glassy state. It’s why a rice kernel is hard and firm and pretty much inedible. In order to get that soft rice kernel, you need to increase the moisture content of the rice and transform the starch into a softer texture.

When you place rice in water it will start to hydrate, absorbing water into the kernel. At higher temperatures the starch can absorb more water. Once it’s hot enough, most rice cooking methods bring water to the boil, that starch starts to gelatinize. The starch has absorbed a lot of water into its granules and these granules start to burst.

All the while, the proteins also absorb significant amounts of water into the rice kernel, softening the structure as a whole.

Cooking method for rice

The main goal of cooking rice is to get the kernel to absorb water and as a result soften. There are a lot of ways to do so.

Cook in just enough water

First of all, you can cook rice in just enough water for it to cook. In this method all of the water that you add to your rice will be absorbed by the rice. It’s important you choose the correct amount of water for your rice variety. The more water you use, the softer and potentially stickier it becomes. However, if you don’t use enough you might still have crunchy rice left that hasn’t yet had a chance to absorb enough water.

Common mentioned ratios for water: rice when using this method are anywhere between 1.5 – 3 : 1 (by volume!). In all cases, you’ll need more water than rice, just how much you will need depends a lot on the rice you use and whichever cooking method you use. Also, you’ll likely need a little more water if you’re cooking just a little rice in a big pot since more of the moisture will evaporate.

rice pudding made with risotto and basmati rice
Rice pudding tends to be made using the ‘just enough water’ method, be it that we used milk instead of water.
Electric rice cooker

An invention from the 1950’s in Asia that revolutionized rice cooking for a lot of people is the electric rice cooker. The cooker will cook your rice for you, all you have to do is to add the right amount of water and rice and it will do its job. Instead of (often women) having to get up early to start cooking and regularly stirring the rice, this cooker could do it all with far less attention.

The electric cooker is actually quite a simple system. The cooker brings and keeps the water boiling in the cooker. As long as there is water in the cooker, the temperature will remain at the boiling point of water (100C/212F). However, once the water has been absorbed, the temperature of the remaining steam can go up. The cooker measures this and it is at this point that it turns off, knowing that all the moisture has been absorbed so the rice should be cooked!

Microwave

Instead of cooking rice on the stovetop, there are ample of smart accessories for you to cook your rice in the microwave. Again, the concept is the same, but here it’s micro waves that bring the water to the boil instead of a stovetop.

Oven

And yes, you can also cook your rice using this method in the oven. Add the correct amounts of water + rice to an oven dish, cover and cook until all the moisture has been absorbed!

Cook in excess water

Instead of ensuring that all the water gets absorbed, you can also cook the rice in an excess of water, just like you would pasta or potatoes. Since the rice will continue to cook and soften as long as there is water left in the pot, it is important to drain the water from the rice to prevent over-cooking.

A big disadvantage of this cooking method is that you can lose valuable nutrients from your rice. If you use enriched rice, which sprayed on vitamins and minerals, then these will disappear with your water when pouring it off.

Cook in too little water

This is the method that a lot of cooks use when making a risotto. You don’t necessarily add too little water, however, you do add it in several portions, to have the rice slowly absorb all the liquids. Overall, you still add enough water, but you definitely start off with too little water in the pan for it all to cook.

rinsing water of rinsing rice

What happens when rinsing rice?

It may surprise you, whereas there’s a lot of research done on milling rice, processing rice and cooking rice, there is barely any done on rinsing rice. So what would we say happens when rinsing your rice?

First of all, of course, any dirt or dust on the rice gets rinsed off. Whether this is relevant for your rice really depends on the quality and packaging of your rice. Most rice we buy doesn’t need to be rinsed for this reason, it’s clean enough to use as is.

Apart from this, not much happens when rinsing your rice. You will likely rinse off some powdery rice and possibly some starches sitting on the surface. As you can see on the photo above, the rinsing water from the first few rinses was clearly the least clear. It likely contains starches and powdered rice. After a few rinses, this gets all rinsed off. It’s important to realize that every rice variety will be different here, another rice variety we tested only needed one or two rinses to give completely clear water.

Soaking is not rinsing

Keep in mind that soaking and rinsing are not the same thing. If you rinse rice all you do is wet the rice with an excess of water and you poor it off immediately. The rice won’t have a lot of time to absorb any of this water. However, when you’re soaking you’re rice, you’re already starting to soften the rice by it absorbing more water.

Soaking rice can help you soften rice for making a rice drink such as horchata or if you want to reduce the amount of energy required to cook your rice.

So, should you rinse rice?

It depends….

There are several possible scenarios that all depend on how your rice was processed before you got it, the rice variety you chose to use, but is also depends on how you’re planning to use your rice!

NOT, if it’s enriched

A first clear ‘no’ to rinsing your rice is if you’re using enriched rice. You know whether you’re using this rice variety by checking the ingredients on your pack. If it lists both rice as well as a list of nutrients, you know the manufacturer has enriched the rice.

Since in most cases those nutrients are just sprayed on top of the rice kernels, you wash them away very easily by rinsing your rice!

MAYBE, depends on your rice

We’ve rinsed several types of rice and for one variety, pre-rinsing the rice seemed to help the rice cook. The non-rinsed rice was just a little drier.

3x rinsing rice experiment

MAYBE, depends on what you’re used to

Every dish is different and every rice is different. If you need a very dry fluffy rice and your type of rice seems to turn out best if you rinse it, do so. However, it might always be worthwhile to experiment and see if rinsing really makes a difference!

YES, if your rice is dirty

Various sources online state that rinsing rice was done in a lot of countries out of necessity. Milling processes weren’t as clean in the past and some contaminations might have ended up in the rice. Rinsing the rice would have been a good way to get rid of some of these.

To what extent rinsing was only done for cleaning purposes, no one knows for sure. Also, the practice probably differed by region and their own customs.

So, do I rinse my rice?

In our experiments with a few rice varieties, the difference between rinsed and unrinsed rice, or 2 vs 7x rinsed rice where virtually non-existent. It was almost impossible to distinguish them with the exception of that one sample that seemed to be cooked just a little less.

Rinsing rice uses quite some water though. So, seeing as how the benefit was minor for us, I won’t continue to rinse my rice. It’s not worth all the extra water!

Sources

Rosa Paula Cuevas, Melissa Fitzgerald, Linking starch structure to rice cooking quality, IREC Farmers’ Newsletter, No. 177, Summer 2007-08, link

Juthamas Tangsantikul, Nigel Power, Cooking Rice, Rediscovering Design, Cumulus Kyoto, 2008, link

Kushwaha, U.K.S. Black Rice: Research, History and Development. Germany, Springer International Publishing, 2016., p.69, link

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3 comments

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  • Thanks for another interesting article! Just one thing though – and this is from someone who, in the past, never rinse rice either (for fear of losing control of the ratios and ending up with gluggy rice) – but, more recently, I’ve read scientific reports about levels of arsenic in rice (‘brown’ or ‘silver’, in particular) with the recommendation to rinse & even soak overnight so as not to poison oneself. What say you?

    • Hi Marian,

      Great question and one that I came across during my research. I didn’t include it since I’m not an expert in the impact of arsenic on health and since arsenic content of rice can vary considerably between origins, types of rice, etc. Also, rice is not the only contributor of arsenic and for large portions of the population, other foods contribute more than rice does. If you’re interested, EFSA did a study on this, though of course this was very much Europe focused so results might not be directly translatable to other countries with different diets and origins of food.

      In any case, when it comes to rinsing rice and its impact on arsenic in rice, that effect actually seems to be quite limited. For some rice varieties you can remove up to 10% of the arsenic, but for most rice varieties, just rinsing does very little. If you’re worried about arsenic in your rice, the best method is to change to cooking method to the excess water method. Tests where rice was cooked in 6x its volume in water, of which the excess was poured off, showed reductions of approx. 50% in arsenic content, so that seems to be your best move (sources: study 1, study 2).

      Hope that helps!

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