Billions Use This Technique for Cooking Rice—However Does It Work? We Examined to Discover Out

I grew up in a house the place rice was on the desk each single night time, and I’ve been cooking rice my complete grownup life, usually a number of instances every week. And every time, I make it the very same approach: I wash the grains in water till it runs clear, pressure the rice, then place it in a pot. I contact the highest of the rice utilizing my pointer finger and add simply sufficient water to succeed in my first knuckle. This system is broadly known as the “knuckle technique,” which many house cooks—significantly these of Asian descent, together with myself—swear will yield the right ratio of water to rice, no matter batch measurement, proprietor of finger, or measurement of pot. Each time.

“The knuckle technique has all the time been foolproof,” meals author Jess Eng tells me. “I picked it up from my mother who picked it up from her mother.” Eng grew up watching her dad and mom make rice utilizing the knuckle technique, and as we speak she prepares rice the very same approach, although she’s unable to supply a proof of why she thinks it really works. Meredith Wong, a Chicago-based house cook dinner whom I related with over social media after placing out a request searching for knuckle-rice lovers, says her late grandfather taught her the approach. “I can’t bear in mind when he confirmed me, however I’ve used it as a information since,” she says. 

Like Eng and Wong, I discovered to make rice by watching my dad and mom and grandparents. I don’t bear in mind when, precisely, they taught me, nor do I bear in mind a time in my life after I didn’t know tips on how to make rice. I’ve been doing it for thus lengthy that it feels deeply intuitive. With the knuckle technique, I could make fluffy, tender grains in any pot and in any kitchen. However how does the approach truly work? And in addition, extra critically: Does it work?

These questions first popped into my head after I watched my husband, who grew up in a family the place his Scottish and Ashkenazi Jewish dad and mom didn’t recurrently cook dinner rice, try and comply with my knuckle-rice directions. I confirmed him the way in which my dad and mom taught me, assured his rice would come out as good as mine. He adopted my instructions to a T, however his grains got here out mushy and overcooked. What had gone fallacious, I questioned, and was it potential that the knuckle technique wasn’t as foolproof as I believed? I made a decision to seek out out.

What Occurs When You Cook dinner Rice?

With the intention to perceive how the knuckle technique works, we first want to know a pair basic items about what occurs whenever you cook dinner rice. Because the rice cooks, the grains take in water and the starch inside swells and softens. However there’s solely a lot water rice can take in earlier than it reaches optimum gelatinization—any extra and the rice blows out and turns to mush. “That ratio sits at round one a part of water to 1 a part of rice by quantity,” writes Tim Chin in his fundamental white rice recipe.

This will strike readers who’ve cooked rice no less than a number of instances of their lives as odd: Most recipes do not name for equal volumes of rice and water, they name for barely extra water than rice. Ratios fluctuate, however roughly one-and-a-quarter cups of water per one cup of dried rice is frequent. The explanation for that is evaporation. A 1:1 ratio of rice to water by quantity could also be superb, however that is solely true if not one of the water escapes as steam. In the true world, since some quantity of water boils off in a cloud of vapor, you need to add a bit of additional otherwise you’ll find yourself with too little water and grains of crunchy rice.

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And right here we get to a different difficult element: This additional quantity of water that is wanted when cooking rice—let’s name it the evaporation quotient—doesn’t scale proportionally because the batch measurement goes up. That means, chances are you’ll want one-and-a-quarter cups of water to cook dinner one cup of rice, however you do not want two-and-a-half cups of water to cook dinner two cups of rice. That is as a result of, given roughly related pot sizes, the quantity of water that evaporates is kind of the identical regardless of should you’re cooking one, two, or three cups of rice; you may all the time lose about one-quarter cup of water as steam.

Understanding the logic behind the knuckle technique requires first understanding these fundamental info of absorption and evaporation in the course of the cooking of rice.

How Does the Knuckle Technique Work?

One of many foremost arguments for why the knuckle technique works hinges on the concept because the rice batch measurement goes up, the water scales up with it in a ratio of 1:1 by quantity, however the evaporation quotient doesn’t—it simply will get added on high.

In a YouTube video, Julie Yu, a scientist on the San Francisco museum Exploratorium, tells viewers that whenever you put dry rice in a pot and add solely sufficient water to simply submerge the rice, you’ve got roughly arrived at that fundamental, good 1:1 ratio of water to rice by quantity. That means, the amount of all of the area between the dry rice grains that’s crammed by the water is roughly equal to the amount of the dry rice itself. She then goes on to clarify that by inserting the tip of your index finger towards the floor of the mattress of rice and bringing the water as much as that first knuckle, you might be efficiently measuring the evaporation quotient.

“As a result of the quantity that you just want for absorption scales [with] the quantity of rice, however the quantity that escapes by evaporation doesn’t, a ratio technique goes to trigger you bother whenever you get into bigger and bigger portions of rice,” she says. And that, my mates, is why the knuckle technique can work whatever the batch measurement, whereas merely multiplying a base ratio doesn’t.

In keeping with Yu, the strategy is so reliable as a result of the size of your index finger from tip to first knuckle simply occurs to be spot-on for measuring the evaporation quotient. However in fact her level shouldn’t be solely that your finger is the right size for measuring the water to be evaporated, however that everybody’s finger is the right size for this. She claims, fairly confidently, that the “first phase of adult-sized fingers are remarkably related,” including that if viewers didn’t imagine her, we may measure for ourselves—which is strictly what I did.

The Testing

The idea behind the knuckle technique is sensible: Volumes of water and rice scale in a 1:1 ratio, however the additional water wanted to account for steam doesn’t. However after watching my husband, I had doubts about how “foolproof” the strategy actually was in apply. Are our fingers actually related sufficient in size to ensure such constant outcomes? The excellent news is that that is simply measured with a ruler and calculated utilizing fundamental geometry.

I made a decision to run two assessments, one based mostly solely on finger measurements and quantity calculations, the second a extra real-world examination of the knuckle rice technique put into apply.

Take a look at 1: Relying on Fingers

With ruler in hand, I set off across the workplace, asking mates, colleagues, and strangers if I may measure their index fingers. (This elicited some unusual appears—you’d be amazed how uncomfortable this could make some individuals.) 

Quickly, I had the measurements of the primary phalanx (to make use of the anatomically right time period) of the index fingers of 19 individuals. Even in such a small pattern measurement, I may see that not everybody’s finger was the identical size. In my survey, I documented a six millimeter vary between the smallest finger phase (2.3 centimeters) and the biggest phase (2.9 centimeters, belonging to our very personal editorial director Daniel Gritzer). Since this was a survey of solely 19 index fingers, one can safely assume {that a} bigger variety of measurements would have uncovered a fair greater vary. However let’s work with what we have—for example six millimeters is how a lot human index fingers fluctuate when measured from the tip to the highest to the knuckle (which I outlined as probably the most pronounced crease on the palm-side of the finger).

The subsequent query is: How a lot of a distinction in water quantity can a six millimeter distinction in phalanx size make? Effectively, that is so simple as calculating the amount of a cylinder, as a result of what’s a pot if not a cylinder that is closed on one finish and open on the opposite? I figured the most typical pot measurement for many at-home batches of rice could be about three quarts. After numerous 3-quart pots on-line I settled on 8 1/2 inches as common diameter, which any sane individual would instantly convert to metric (216mm) earlier than doing any math.

The query then turns into: What is the quantity of a 216mm-wide pot for each one millimeter of peak? Many readers could also be struggling to recollect their highschool (center faculty?) geometry formulation, so I am going to remind you: The amount of a cylinder is calculated by multiplying pi by the sq. of the radius, after which multiplying that consequence by the peak.

That is the mathematics:

Let’s simply stroll by way of the above in case it is inflicting the math-phobic amongst us psychological paralysis.

• First we calculate the radius: The radius is half the size of diameter. The pot’s diameter is 216mm, so the radius is half that at 108mm.
• Then we multiply pi by the sq. of the radius: 108mm squared is 11,664 sq. millimeters, and we multiply that by 3.1416, getting 36,651.85 sq. millimeters.
• We multiply this consequence by the peak: Multiplying 36,651.85 sq. millimeters by 1mm provides us a quantity of 36,651.85 cubed millimeters.
• As a final step, let’s convert these cubed millimeters into milliliters: This will get us a remaining quantity of 36.65mL for each 1mm of peak in a typical 3-quart pot.

Translated to teaspoons—as a result of, sure, after the plain mathematical great thing about the metric system, we’re gonna change again to the inane (but acquainted!) chaos of US customary—that is about 7 teaspoons for each 1mm of pot peak.

Now let’s return to the 6mm vary I would documented when measuring index finger segments: If each millimeter of water in a 3-quart pot holds about 7 teaspoons, then a 6mm vary in finger phase size can alter the amount of water in a rice recipe by 42 teaspoons. That is greater than 3/4 cup!

Let me spell that out: The pure variation in a human finger can change the quantity of water added to the rice by greater than 3/4 cup, which is a big quantity contemplating we solely need about 1/4 cup of additional “evaporation quotient” water when cooking rice.

This isn’t excellent news for the declare that knuckle rice is a foolproof technique. However that is additionally simply based mostly on finger measurements and calculations on paper. What occurs whenever you have a look at the messiness of the real-world state of affairs wherein one has to stay their finger right into a pot and add water?

I examined that too.

Take a look at 2: You Can Lead a Knuckle to Water…However Can It Make Good Rice?

On this take a look at, I requested a bunch of individuals so as to add water to 1 cup (200 grams) of dry jasmine rice in a 3-quart pot utilizing the knuckle technique, weighing how a lot water was added every time.