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Neat! I was always under the impression that rice cookers worked on a timer basis, but from the article it sounds like it's more of a thing where the appliance

Neat! I was always under the impression that rice cookers worked on a timer basis, but from the article it sounds like it's more of a thing where the appliance will tell you when the rice is cooked - is that right? I'm intrigued to get one now, although it's unclear to me what the difference is between a £40 one and the one mentioned in the post (which looks to be about £100 now on Amazon)

doctoring 3y ago
I love rice cookers! Rice cookers (usually) make clever use of 1) alloys whose magnetism depends on temperature and 2) the fact that boiling water occurs at a fixed temperature. With a "trigger" temperature just above the boiling point of water, the rice cooker automatically turns off the heating element when all the water is gone (and thus the temperature starts to rise above boiling point). More detail here: https://youtu.be/RSTNhvDGbYI https://youtu.be/RSTNhvDGbYI
- SamBam 3y ago
  Those are the older ones. The new ones like the "Fuzzy Logic" line are more akin to a PID controller trying to make the temperature/time graph match a specific curve, where the temperature changes at different points in the cooking, if I understand correctly.
- mauvehaus 3y ago
  I'd like to see a patent that actually confirms this. The Curie temperature of the common ferromagnetic metals is well above the boiling point of water, which raises some questions as to what one would make the alloy out of. Canadian nickels were made of nickel until 1981. Assuming you have a magnet that's heat resistant, you can do a cool demo with a torch or gas stove: pick up the coin with the magnet and dangle it in the flames. You'll know when it hits the Curie temperature. It'll fall off the magnet.
  - ambichook 3y ago
    bimetallic strip doesnt necessarily mean magnetism, i believe in this case it simply deforms to flip a switch
LorenPechtel 3y ago
The fancier rice cookers monitor what's going on inside and turn off when the last of the liquid is gone. At the lower end I do not like them because that ends up somewhat overcooking the rice next to the heating surface--I prefer putting it in the microwave using settings I have determined by experiment to work. Perfect every time. I presume the more expensive ones are better at avoiding overcooking but it seems to me hard to conceive of a conduction-heat system that doesn't suffer this problem to some degree.
- hunter2_ 3y ago
  > putting it in the microwave using settings I have determined by experiment to work. Perfect every time Does that involve a humidity sensor in your microwave? Because if you're just talking about power level and time, then how do you account for variation of water temperature? I guess you could use room temperature water (or a fridge pitcher) which would be plenty stable, but tap temperature varies wildly based on the season, at least where I live.
  - fsckboy 3y ago
    I was taught by a chinese restaurant chef his technique for how to cook chinese rice in a normal pot on the stove at home. The technique consists of (after washing away most of the starch) starting out by submerging the rice under an extra couple of centimeters of water (you use your hand/knuckles to measure, it's not super precise) and high-heat boil uncovered till the water level drops to even with the surface of the rice. Now cover and put heat down very low and let the rest of the water absorb while you make your stir fry. Before serving, turn all the rice over a time or two with a paddle and let it resettle uncovered, this helps the rice dry a little and be less sticky, but keeps it cluster-chop-stick-able. I explained all that to say, I adapted that technique for a microwave and it worked great right away. Microwaves vary a lot in power and timing, so I can't really give a how-many-minutes recipe, but the technique just works.
  - morepork 3y ago
    There are different ways of doing it, but when I microwave rice I boil the water in a kettle first
hunter2_ 3y ago
Right. Before all water at the bottom has evaporated, the temperature is 100C. After all water has evaporated, the temperature rises uncontrolled due to lack of latent heat. So basically it just shuts off when the temperature exceeds 100C, and the classic mechanism is to formulate a magnet that loses its magnetism at that temperature (all permanent magnets have an operating temperature, and it can be tweaked during manufacturing) and at that point it's just a leaf spring switch that the magnet conditionally attracts.
Cyph0n 3y ago
The more expensive fuzzy logic-based rice cookers are more “accurate” in the sense that they have a better idea of when your rice is actually done cooking. This makes your rice cooking more deterministic. As to whether this is worth the extra cost, it depends on your budget and how frequently you cook rice.
- instagib 3y ago
  I got an expensive cooker and can tell the difference. Cheap 3 cup cooker to 10 cup bottom burner to Zojiriushi induction. The same amount of rice cooked would not fit in my rice saver container for stir frying without being smushed down because it was more fluffy. It takes 3 times longer to cook however yet has not burned my rice when sitting on warm yet. I get happy when I smell the fresh cooked rice several times per week so I'm definitely in the worth it category.

doctoring 3y ago

I love rice cookers! Rice cookers (usually) make clever use of 1) alloys whose magnetism depends on temperature and 2) the fact that boiling water occurs at a fixed temperature. With a "trigger" temperature just above the boiling point of water, the rice cooker automatically turns off the heating element when all the water is gone (and thus the temperature starts to rise above boiling point). More detail here: https://youtu.be/RSTNhvDGbYI https://youtu.be/RSTNhvDGbYI

SamBam 3y ago
Those are the older ones. The new ones like the "Fuzzy Logic" line are more akin to a PID controller trying to make the temperature/time graph match a specific curve, where the temperature changes at different points in the cooking, if I understand correctly.
mauvehaus 3y ago
I'd like to see a patent that actually confirms this. The Curie temperature of the common ferromagnetic metals is well above the boiling point of water, which raises some questions as to what one would make the alloy out of. Canadian nickels were made of nickel until 1981. Assuming you have a magnet that's heat resistant, you can do a cool demo with a torch or gas stove: pick up the coin with the magnet and dangle it in the flames. You'll know when it hits the Curie temperature. It'll fall off the magnet.
- ambichook 3y ago
  bimetallic strip doesnt necessarily mean magnetism, i believe in this case it simply deforms to flip a switch

LorenPechtel 3y ago

The fancier rice cookers monitor what's going on inside and turn off when the last of the liquid is gone. At the lower end I do not like them because that ends up somewhat overcooking the rice next to the heating surface--I prefer putting it in the microwave using settings I have determined by experiment to work. Perfect every time. I presume the more expensive ones are better at avoiding overcooking but it seems to me hard to conceive of a conduction-heat system that doesn't suffer this problem to some degree.

hunter2_ 3y ago
> putting it in the microwave using settings I have determined by experiment to work. Perfect every time Does that involve a humidity sensor in your microwave? Because if you're just talking about power level and time, then how do you account for variation of water temperature? I guess you could use room temperature water (or a fridge pitcher) which would be plenty stable, but tap temperature varies wildly based on the season, at least where I live.
- fsckboy 3y ago
  I was taught by a chinese restaurant chef his technique for how to cook chinese rice in a normal pot on the stove at home. The technique consists of (after washing away most of the starch) starting out by submerging the rice under an extra couple of centimeters of water (you use your hand/knuckles to measure, it's not super precise) and high-heat boil uncovered till the water level drops to even with the surface of the rice. Now cover and put heat down very low and let the rest of the water absorb while you make your stir fry. Before serving, turn all the rice over a time or two with a paddle and let it resettle uncovered, this helps the rice dry a little and be less sticky, but keeps it cluster-chop-stick-able. I explained all that to say, I adapted that technique for a microwave and it worked great right away. Microwaves vary a lot in power and timing, so I can't really give a how-many-minutes recipe, but the technique just works.
- morepork 3y ago
  There are different ways of doing it, but when I microwave rice I boil the water in a kettle first

hunter2_ 3y ago

Right. Before all water at the bottom has evaporated, the temperature is 100C. After all water has evaporated, the temperature rises uncontrolled due to lack of latent heat. So basically it just shuts off when the temperature exceeds 100C, and the classic mechanism is to formulate a magnet that loses its magnetism at that temperature (all permanent magnets have an operating temperature, and it can be tweaked during manufacturing) and at that point it's just a leaf spring switch that the magnet conditionally attracts.

Cyph0n 3y ago

The more expensive fuzzy logic-based rice cookers are more “accurate” in the sense that they have a better idea of when your rice is actually done cooking. This makes your rice cooking more deterministic. As to whether this is worth the extra cost, it depends on your budget and how frequently you cook rice.

instagib 3y ago
I got an expensive cooker and can tell the difference. Cheap 3 cup cooker to 10 cup bottom burner to Zojiriushi induction. The same amount of rice cooked would not fit in my rice saver container for stir frying without being smushed down because it was more fluffy. It takes 3 times longer to cook however yet has not burned my rice when sitting on warm yet. I get happy when I smell the fresh cooked rice several times per week so I'm definitely in the worth it category.