The Physics of Fried Rice | Hacker News Reader

The Physics of Fried Rice

arstechnica.com

164 pointscdepman64 comments

The mathematical model Hu and Ko developed isn't just a fun curiosity; it should also prove useful for industrial robotic designs.

I recall seeing somewhere (maybe coverage of CES or another trade show) of automated machines for cooking Chinese dishes that traditionally had to be made by hand. I can't remember if it was for home or industrial use, and I don't remember if fried rice was one of the options.

Fried rice is one of the hardest Chinese dishes to cook at home, especially if you don't have a high-temperature gas range and want to reduce the amount of oil in the recipe. Lots of scraping and hard pushing motions to break up the rice, not to mention the slicing/dicing required for prep.

ETA: Found some articles and clips about the tech:

https://www.scmp.com/tech/innovation/article/1808963/worlds-...

http://www.chinadaily.com.cn/a/201805/17/WS5afd263fa3103f686...

https://www.digitaltrends.com/home/robot-cooking-machine/

I started using lard and stopped wanting restaurant fried rice. Ingredients go a long way in taste.

In fact, lard makes almost everything taste amazing.

We render lard from bacon and chicken fat and refrigerate them in jars for later use. Both work nicely with Chinese dishes, and this reduces the need to buy cooking oil.

True, frybread (which uses lard) is really good but really not healthy for you.

The only non sea creature derived animal product to make the list is Pork fat.

https://www.bbc.com/future/article/20180126-the-100-most-nut...

Not healthy, but likely healthier than many vegetable oils or other unholy substitutes.

Do you use store bought lard or do you render it yourself? I picked up store bought lard one time and felt it was as bland as Crisco. I figured it was just modern processing techniques or low quality sourcing. The stuff I rendered myself was leaf lard from a heritage pig, which was really really good and I'm not sure if it's a fair comparison.

You can often find freshly rendered lard in Mexican markets especially if they sell carnitas. Ask for manteca.

You can also render chicken fat and skin. Pork lard is more versatile, but chicken fat is a delicious substitute for vegetable oils for sautéing or stir frying.

Instead of buying skinned chicken parts get them with skin on. Freeze the skin and extra fat until you have a cup or more. Place fat and skin in a saucepan, cover with water and simmer until all the water is gone. Continue simmering until all the embedded water is also gone and the bubbling stops. The goal is completely dry fat and a pale straw to light gold color. Be careful near the end, once the water is gone the temperature will rise quickly. You now have liquid chicken fat and crispy chicken skin cracklings. Remove cracklings and salt lightly to snack on or use as garnish. Strain fat into container and refrigerate. If you got it completely dry it will keep for months and won’t spatter when cooking.

This procedure works with duck, pork or beef fat as well, except no chicken cracklings.

I like buying a whole duck and trimming the fat and skin off so I get duck fat (lard) and duck cracklings!

In Hungary stores have many different brands of lard one can choose from and one can easily find tasty ones. Meat shops also sell lard.

I recently moved to the UK and I didn't find decent lard yet, typically each store sells a single brand and they are pretty horrible.

Good lard should taste good on its own.

> especially if you don't have a high-temperature gas range

Some people suggest extra effort to accommodate for not having the right heat source: https://www.seriouseats.com/2020/02/hei-now-youre-a-wok-star...

This seems dangerous.

Growing up as an Asian American, my family's gas stove definitely wasn't hot enough, but we also had a separate butane burner that was rated for indoor use. (You could also use it for things like hot pot, so it's not like it was the only thing we used it for.) So long as you have a well ventilated area not very close to a smoke alarm you should be good.

I suspect the separate burner is a better approach.

People use such torches for other things though (e.g. sous vide, but usually with a deflector); I don't know if it's really a risk. I haven't tried it just happened to see the article a few days ago and remembered.

There's nothing particularly dangerous about a blowtorch in the kitchen. They're common for things like creme brulee.

There's also https://www.wokmon.com/, which you can use to modify your stove such that you get a concentrated jet of flame

> Fried rice is one of the hardest Chinese dishes to cook at home, especially if you don't have a high-temperature gas range and want to reduce the amount of oil in the recipe. Lots of scraping and hard pushing motions to break up the rice, not to mention the slicing/dicing required for prep.

I found this funny. That's a fair call on the slicing/dicing, except I'm pretty sure the traditional way to make fried rice is to throw in whatever leftovers you already have to hand.

So if you're already cooking other Chinese food, fried rice is just a mostly-free leftovers dish. It works as part of the entire Chinese-food cultural complex; it's harder to slot in to a schedule of foreign food, where every element of it has to be prepared specially.

(Of course it's popular in restaurants now, and they must make it in a consistent way. But you don't need to.)

Doing a mushy, sad fried rice at home is easy. But I think op was referring to the difficult of making -good- fried rice.

It's not the ingredients or prep that is hard, it's that you need a carbon steel wok and enough BTUs to keep that wok around 500F even while dropping cold ingredients into it.

Without a carbon steel or cast iron pan and enough constant temp, you won't get the "wok hei" which really affects flavor and texture.

J Kenji Lopez has a great write up on the difficulties of good fried rice at home. https://www.seriouseats.com/2012/06/the-food-lab-for-the-bes...

>was referring to the difficult of making -good- fried rice.

I don't really understand, just fry your ingredients at high heat and don't stop stirring. Make sure the pan is hot before you add oil, make sure the oil's hot before you add the ingredients. Start with the meat/protein, when that's browned, if you really want it all nice and cooked well, take the meat out and put it aside then do the onions, theb mushrooms, peppers, veggies etc. Garlic and ginger and stuff last, re-add the meat, add your cooked rice, maybe an egg at that point and keep stirring until it's nice and golden brown.

Did you read the parent article? There’s a distinct smoky, rich flavor and lack of mush that great fried rice has that only occurs under those conditions.

Sure, homemade fried rice can be good (with some more work than you said) but that’s not what the parent was saying.

Is it common to throw the egg in at the end? I was always taught to fry and scramble the egg in the oil first.

I'm a fan of mixing a couple of egg yolks with the cold unfried rice at the beginning, gives you a texture and flavour that's very unique compared to normal fried rice.

There seem to be a few schools of thought - one is to mix some egg through the cold rice before frying, one is to add egg mixture near the end, one is to fry the egg and like an omelette and chop it up and add.

> one is to fry the egg like an omelette and chop it up and add

That's the one I would consider normal.

I live in Japan and have only ever seen people putting the egg first, then rice, then seasonings and toppings

I like my eggs less well done. Eggs cook fast, especially on high heat.

Oil has a smoke point of about 200 C. The author wrote:

The trick is to ensure that the rice constantly leaves the wok, allowing it to cool a little, since the wok temperature can reach up to 1,200 degrees Celsius.

I am pretty sure that it’s a typo, it would basically melt your wok at that temperature. But also someone else here was speaking about constant temperatures of 500F that is still well over the oil smoke point. So I think that I’m missing something here.

> But also someone else here was speaking about constant temperatures of 500F that is still well over the oil smoke point.

Not “well over” for many refined oils (smoke points of 450°F+ are not uncommon for refined oils), and not even “over” for a few (e.g., avocado, safflower.)

Fried rice is usually made with rice leftovers which have somewhat dried out. It's a way to make those leftovers more palatable. If it's mushy it means that the rice was too moist.

It's simple to make with your standard (deep) frying pan, on your standard cooker.

>It's simple to make with your standard (deep) frying pan, on your standard cooker.

If you believe that, my friend, then you have not had really good fried rice. Give the article I posted a read of you want more info on why.

Great write up from J Kenji Lopez! Thanks for sharing link.

Can’t speak for Chinese, but Thai fried rice is a very specific dish that doesn’t have much variation, other than the choice of protein source.

Chinese fried rice isn't like that at all.

I am Thai and pretty sure this is not true.

Yeah I varies quite a bit is texture and flavor between provinces too

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The ingredients aren't the hard part - it's the technique and equipment involved. There's lot's of other "simple" dishes like this where it's all about technique and not just getting the right ingredients: french omelettes, bread, carbonara etc

Bread is definitely a part about getting good flour, you can get everything else right, but a poorly stored flour can make it end up bad.

Lifehack for rice friers: Use leftover rice or make sure the rice is dryer than fresh out the pot.
I boil it, then throw it in the oven or microwave it, stir a few times so there's less moisture. If the rice grain is too moist the outside of it wants to stick to the pan instead of itself.
A lot to be said about automation (or anything sort of skilled work) and making sure your inputs are consistent.

Teposnyaki make some good fried rice. They have high heat but they don’t have the luxury of tossing with the wok.
Their technique is different, but I don’t think it comes out worse for it.
In order for the rice to have a chance, it has to be kinda dried out (day old in the fridge) and clumpy.

Oh god this brings back traumatic memories: When I was getting my degree in culinary arts at Bristol (Boston, MA) in the mid-80's I had "Professor Wong", not a professor but a chef who taught a segment on Chinese cuisine. I had to make ~5lbs of fried rice every day for two weeks and he would say in a thick over-emphasized (phony) chinese accent, "You burn rice, you fail!" every day -- with a big smile, of course, but meaning it. And holy HELL was I sore every day during that period. The industrial woks are very heavy and you do need to keep it in constant motion.

Lol what a delightful story :)

Huh. This whole thing appears to be about how the motion of the wok affects the fried rice.
But at the only restaurant I've watched fried rice prepared at (a college cafeteria in Shanghai), it was done on a flat iron surface, teppanyaki-style. And that was considered the good cafeteria.
"The physics of fried rice" seems to overestimate the scope of the study a bit.

I think “cafeteria” is the key word in here. They most likely do not have the time & resources to do it how they would do it in a high end restaurant.

That makes no sense; iron cooking counters everywhere and different chefs at different stands to prepare your food on demand are a much bigger investment of time and resources than preparing food in bulk in the back on a single stove/counter.

Happy to see my school getting mentioned on HN. Dr. Hu has a TEDx talk called "Confessions of a Wasteful Scientist" (https://www.ted.com/talks/david_hu_confessions_of_a_wasteful...) that talks a bit more about research he has done in this vein.

Grandpa bfung said (paraphrased from translated Cantonese): “if your fried rice is the color of soy sauce, you’re doing it wrong - that’s the color of poop”.
Just wanted to share some fried rice wisdom.

All of a sudden I got super excited and wanted to go buy a wok, something I've wanted to do for a while, even started looking on Target... then I realized I have an electric range.
I could get an outdoor propane stove, can't wait for it to get warmer.

Chicken Fried Rice used to be my favorite go-to Chinese restaurant dish, but too many places loaded up the dish with tons of rice and veggies and skimped hard on the chicken, presumably to save on meat costs.

You should try a Vietnamese place if there’s one near by you. The ones around here at least don’t seem to skimp on the meat as much

The comments of this article are where the meat lies. There’s no way anyone is flipping rice in a 1200-degree steel wok.

When physics and food meet.. It's a dinner made in geometrical heaven, and shoulder pain evidently.

I usually cheat and use parboiled rice, it won't become a sad mush.

Why in the hell is this considered...technical?

If it is not, why would it matter? Hacker news always has non technical post on its front page.

While that may be true this is a new level information i dont care about...

then don't read it

...and if you can't stand to see it, "hide" it.

If you don't care about it, can you even imagine how much other people don't care about you not caring about it? Seriously. And if you think it's silly to point that out, you're the one posting in a thread about how you don't care about the thing that the thread is about.

Apparently enough of us care about it to make it to the front page... go figure

That's perfectly fine if you don't care about it, but there are plenty of us that do.

It is physics. Have a look at their published physics paper, it's quite technical.
https://royalsocietypublishing.org/doi/10.1098/rsif.2019.062...

I would hazzard a guess that quite a lot of engineers are into cooking because it can be a highly technical and scientific process that involves chemistry, physics, and engineering with delicious results.
And the highly technical paper in this post attests to that.

What the Discovery channel, I mean ArsTechnica, calls "science" shall not be questioned! ;)
Also it has "Royal Society" in the paper so it has carte blanche to pick seemingly frivolous topics if they have merit. Furthermore, very good cooking is mostly scientific with some art. French Guy Cooking's Alex has more of a lab/workshop than a kitchen because he's so fanatical to improve the art and science of food.

I personally find it pretty amazing that, as they mention, no one has succeeded in making a robot that can do it effectively. That is certainly a technical issue. It seems to me something that is highly automatable.
The fact that it is something that physicists are studying and it is published on Ars Technica seems to me to be enough to justify it being technical enough for Hacker News (which generally doesn't have to be technical per se, but just intellectually interesting to technically oriented people)

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