So, Birdgirl & I were eating some leftover Indian last night but we needed some new white rice. As per usual, our rice cooker comes to the rescue and the lids pops up when the rice is done. Then we start thinking: if we put in the same amount of brown rice as white rice, it takes longer and somehow the rice cooker just knows. Since $10 didn’t buy me Artificial Intelligence, I got to wondering: how does a rice cooker know how long to cook different kinds of rice.
And no, ours does not have a timer.
Wikipedia says: “Whereas less expensive and older models use simple electronics and mechanical and thermal sensors…” then goes on to talk about super-rice-cookers with microprocessors. Needless to say, I don’t have one of these.
I need a little more information. What mechanical sensors? Why is my rice cooker a better chef than I am?
When the rice is sitting in a puddle of water, the temperature never gets over 212 degrees F. When the puddle of water goes away (into the rice), the temperature on the surface of the pot goes over 212 degrees and trips a switch.
Sort of like how the electric percolating coffee pots work. It boils full blast until the temperature of the horribly burnt and bitter coffee gets up to X, then it goes into warm mode.
Yup. That’s how mine works. This question bothered me too, and my first hypothesis was that it went by weight. I.e. when the cooker no longer detected the weight of the water, it shut off. But then I realized that my hypothesis was completely dumb. So I looked into it and, as Cheesesteak suggested of yours, mine has a thermal sensor that looks for 213 degrees F.
Clever, eh? One of my favorite kitchen devices. Just beautifully simple, an elegant application of basic principles. And it makes pretty good rice, too.
(Rice cooker trick— Make basmati rice according to the directions, with the following adjustments: substitute chicken broth for water; before making rice, warm the broth a bit and add a pinch of saffron, and let steep 15 minutes; then proceed with making rice in rice cooker as usual. But when the rice is a few minutes from being done, i.e. a lot of the broth has boiled off but the rice is still stirrable, mix in a generous handful of frozen green peas; and presto! Indian-restaurant-style saffron rice.)
I’ve tried doing that with regular jasmine rice, and in all cases, the rice wound up having an odd mealy texture. I wonder if that was due to the variety of rice – I should try that with basmati sometime.
This is similar to how, when doing laundry, you’re not supposed to over-dry your clothes. When they’re wet, the temp is limited to 100C, but as soon as they’re dry, the temp can get very high, and it’s the high temperature that’s damaging to your clothes.
In every dryer I’ve ever worked on, the temperature was limited by one or more thermostats and always to below 100 C, and always included overheat protection, in the form of a thermal circuit breaker. Newer dryers also may include humidity sensors to control the amount of drying more accurately.
I think I’d heard of the heat-detection method (we have a lower-end Zojirushi that uses that method) but the website doesn’t discuss this: What about using a rice cooker at higher altitudes, where the water boils off at < 212F (100C)? Would one have to adjust the amount of water? do something else to get it to work properly? The website was silent on that point!
