I grew up in a house the place rice was on the desk each single evening, and I’ve been cooking rice my total grownup life, typically a number of occasions every week. And every time, I make it the very same method: 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 achieve my first knuckle. This method 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 dimension, proprietor of finger, or dimension 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 method, although she’s unable to supply an evidence 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 fanatics, says her late grandfather taught her the method. “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 realized 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 how one can make rice. I’ve been doing it for therefore 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 method really work? And likewise, 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 frequently cook dinner rice, try and comply with my knuckle-rice directions. I confirmed him the best way 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 incorrect, I questioned, and was it attainable that the knuckle technique wasn’t as foolproof as I believed? I made a decision to search out out.
What Occurs When You Prepare dinner Rice?
In an effort to perceive how the knuckle technique works, we first want to know a pair staple items about what occurs while you cook dinner rice. Because the rice cooks, the grains take up water and the starch inside swells and softens. However there’s solely a lot water rice can take up 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 at least one a part of rice by quantity,” writes Tim Chin in his fundamental white rice recipe.
This will likely strike readers who’ve cooked rice no less than just a few occasions 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 differ, however roughly one-and-a-quarter cups of water per one cup of dried rice is frequent. The rationale for that is evaporation. A 1:1 ratio of rice to water by quantity could also be preferrred, 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 must add just a little further otherwise you’ll find yourself with too little water and grains of crunchy rice.
Hainanese Hen Rice Set
And right here we get to a different difficult element: This further quantity of water that is wanted when cooking rice—let’s name it the evaporation quotient—doesn’t scale proportionally because the batch dimension goes up. Which means, you could 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 comparable pot sizes, the quantity of water that evaporates is kind of the identical regardless of if you happen to’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 fundamental arguments for why the knuckle technique works hinges on the concept that because the rice batch dimension 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 while 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. Which means, the quantity of all of the area between the dry rice grains that’s crammed by the water is roughly equal to the quantity of the dry rice itself. She then goes on to elucidate that by inserting the tip of your index finger in opposition to the floor of the mattress of rice and bringing the water as much as that first knuckle, you’re 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 while 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 dimension, whereas merely multiplying a base ratio doesn’t.
Based on 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 after all her level is just not 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 comparable,” including that if viewers didn’t imagine her, we might 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 further 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 comparable 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 checks, 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.
Check 1: Relying on Fingers
With ruler in hand, I set off across the workplace, asking mates, colleagues, and strangers if I might 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 appropriate time period) of the index fingers of 19 individuals. Even in such a small pattern dimension, I might 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 most important 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 good greater vary. However let’s work with what we have got—for instance six millimeters is how a lot human index fingers differ 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? Properly, that is so simple as calculating the quantity 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 commonest pot dimension 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 a great 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 top? Many readers could also be struggling to recollect their highschool (center college?) geometry formulation, so I will remind you: The amount of a cylinder is calculated by multiplying pi by the sq. of the radius, after which multiplying that end result by the peak.
That is the mathematics:
Let’s simply stroll via 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 end result by the peak: Multiplying 36,651.85 sq. millimeters by 1mm offers 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 last quantity of 36.65mL for each 1mm of top in a typical 3-quart pot.
Translated to teaspoons—as a result of, sure, after the simple mathematical fantastic 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 top.
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 quantity 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 major 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 while you take a look at the messiness of the real-world situation during which one has to stay their finger right into a pot and add water?
I examined that too.
Check 2: You Can Lead a Knuckle to Water…However Can It Make Good Rice?
On this check, I requested a bunch of individuals so as to add water to at least one 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.
Water Quantity (Grams) | Finger Size (CM) |
689 | 2.4 |
639 | 2.5 |
534 | 2.4 |
518 | 2.3 |
448 | 2.7 |
425 | 2.5 |
421 | 2.3 |
405 | 2.4 |
348 | 2.7 |
295 | 2.4 |
259 | 2.5 |
236 | 2.6 |
As you’ll be able to see above, probably the most water added was 689 grams (nearly three cups), and the least quantity of water was 236 grams (about one cup). For comparability’s sake, if we have been working with a ratio of 1 1/4 cups water for 1 cup of rice, the objective could be 295g water right here. Whereas one individual completely nailed it, just a few got here in beneath and lots of extra added an excessive amount of water—shockingly an excessive amount of. However even when we take away probably the most excessive measurements from the highest and backside ends of the vary, we’re nonetheless 639g on the excessive finish and 259g on the low finish, which is a large vary.
Even weirder, the quantities of water added do not appear to correlate with finger size within the methods we might count on. As a substitute of the quantity of water added going up as finger size will increase, my information reveals no clear correlation between finger size and water amount.
What’s up with that? Properly, for starters, my pattern dimension is small. Maybe my information could be higher with 100 information factors as an alternative of the 12 I’ve right here. One other chance is that we did not standardize the method properly sufficient throughout members. I had advised them to put their index finger in opposition to the mattress of rice and pour water as much as the primary knuckle joint, however it’s attainable not everybody interpreted these directions the identical method. Perhaps some allowed their fingers to sink down into the mattress of rice, held their finger at an angle, and/or judged the “first knuckle” inconsistently (there are, in spite of everything, numerous creases on the pores and skin of our knuckles—who’s to say the place the road actually is?).
Even when my information has a excessive diploma of confounding components, the check underscores a essential level: The knuckle rice technique is supposed to be foolproof, and but it may simply be interpreted and utilized in a different way with drastic penalties, and that is not even factoring within the assured variation in water quantity we’d count on to see simply from the variations in finger size.
Is the Knuckle Technique Rubbish?
Although I’ve by no means been let down by the knuckle technique, our check outcomes present that, in actuality, this technique is just not a constant option to make rice. That’s to not say that the knuckle technique doesn’t work; it possible works properly for the people who find themselves acquainted with it, like those that grew up watching their household put together rice this fashion or have completed it so many occasions that they’ve developed an instinct for the correct quantity of water to make use of over time.
One in all our contributors, Vy Tran, tells me that she makes use of the knuckle technique (which she picked up from her mother) every day, however doesn’t assume it’s constant. “As soon as you determine a sure water degree and may eyeball it, it really works properly,” she says. “However often several types of rice will want trial and error of how a lot water.”
It seems that the knuckle technique works not as a result of there’s one thing exact about it, however as a result of the individuals who use it have developed a deep familiarity over time, changing into increasingly more attuned to the nuances of the strategy with out realizing it is not simply the strategy, however their expertise, that makes it work. And so it was for the individuals they realized from, and the individuals the realized from, going again generations.
Although I’m a baker and pastry chef by coaching and swear by the dimensions, I’m nonetheless deeply dedicated to the knuckle technique. The truth that this technique works for therefore many individuals—regardless of the massive variation in knuckle lengths and the quantity of water used—means that apply does, certainly, make good. But it surely’s greater than apply: It’s the embodiment of data and expertise one good points over time within the kitchen. There’s an artwork to creating a fantastic pot of rice, one that’s constructed on an intuitive really feel realized by our arms by doing one thing tons of, if not hundreds, of occasions, typically in methods we’re not even aware of. The knuckle technique might not actually be one of the best ways to cook dinner rice, however it’s additionally undeniably one of the best ways to cook dinner rice.
So does the knuckle technique work? It may—however not for the explanations everybody thinks.