Improving Rice Cooker Efficiency

Looking at the plate on the bottom of his electric rice cooker, [AC_Hacker] was surprised to find that it was rated to consume 400 watts. Furthermore when he measured its consumption he found that it consumed 385 watts without even having a cooking cycle initiated. The circuit to keep cooked rice warm was always on – even when the cooking circuit wasn’t engaged.

Something clearly had to be done, so he set about modifying the cooker for better economy. Removing the base revealed that disabling the warming circuit was as simple as disconnecting it. [AC_Hacker] also noticed that the device had no thermal insulation. There was plenty of space between the inner and outer walls, so he packed it with glass wool. The final modification was to reduce the power taken by the heater by installing a half-wave rectifier diode. The cooker still reached the desired temperature, it just used half the power.

You might think that would be the end of it, given that the modifications significantly reduced the cooker’s power consumption without detriment to its rice cooking ability. Rice now took a little longer to cook, so there was still room for improvement. The moment of inspiration came when [AC_Hacker] realized that the cooking time was proportional to the amount of water used in a cooking cycle. He could safely reduce the water without affecting the cooked rice. A 30% water reduction led to a proportional cooking time reduction, and rice cooked using a lot less power.

Surprisingly this seems to have been Hackaday’s first rice cooker hack. Perhaps that’s because you’ve been so busy supplying us with sous vide hacks to write about.

100 thoughts on “Improving Rice Cooker Efficiency

  1. You are better off with a digital pressure cooker (I’ve used both), because it is sealed and takes half the time. Get one of the more expensive ones that have more control over temperature, pressure and time. The sort that also have a yogurt option, but check the exact features to ensure it has adjustable parameters. We cook with it so often we now have two, great for a veg curry and rice for a big family. Over the life of the machine the cost per meal is a few cents, so the power consumption is your primary expense, after food ingredients.

      1. I will not recommend a brand, but I’ll point out that they are all the same in many ways, just the little details and the controllers change. It is the controller function you need to look out for, or hack to your requirements. When you have a short list of models available in your country search their support websites for the instruction booklets as pdf files as these will make it clearer what the units really can do. Some have gaps in their ranges for temperature control, which a hack could remove.

        I did consider adding an ESP8266 to one then controlling the unit via a web page with curves for each parameter and also presets. I’m surprised it has not been done commercially yet as all it would take is less than $10 in parts to have the “most advance unit on the market”. There is no danger in this as the units use physical safety measures that a programming change will not compromise, as far as I can tell. But do think about that carefully if you do mod a unit, ensure all fuses and blowout values are still active and effective.

    1. I have been wanting a rice cooker for quite awhile but just never got one. I recently picked up the Instant Pot Smart cooker when I saw it on a Amazon sale (I think it was under $120) and so far we love it. We used it just for rice and steamed veggies so far but it works perfectly. We have to delve into it more but it is very versatile, has downloadable recipes, and the Bluetooth dashboard monitoring comes in handy.

      Here is a link if anyone is interested:
      https://www.amazon.com/Instant-Pot-Bluetooth-Enabled-Multifunctional-Stainless/dp/B00N310CKG

      1. Hey that even has a wireless option! Not bad, except for the price. Do you have continuous control of all parameters over their full range? I mean how low level are the custom control options?

  2. Hello,although I’d like the idea of improving the efficiency of products… I do would like to make some small comments on the methods used and to the accusations to the original design.

    Adding a diode, in order to only use the top (or bottom) halve of the energy of the sinewave is a very dirty hack. What you are doing will most certainly create net-pollution. Regarding the saving of energy… it depends, because with only halve the amount of energy it will take twice the time to heat up, but here that might not be a problem.

    On the website that shows the hack is stated: “First off, there’s no insulation, not any.”. Well I do not agree, I’m sure that there is a cover on this device to prevent the user from poke into the wiring while the device is plugged in. There must bu such a cover, otherwise it will not have any safety certifications like CE on it. Because of this cover there is some kind of insulation. The air trapped between the cooker and the plastic casing does not move (or at least, not very fast) therefore it is a very good insulator. Perhaps not perfect, it is a form of insulation and a very common one.

    1. I agree. Adding the insulation may be a good thing, though. And leaving it on while not in use seems daft anyway, but a switch to turn off could be good if you don’t want to unplug between uses.
      However, halving the power draw only prolongs cooking and uses *more* power, as more heat will be lost. The diode trick can be useful sometimes, but not this time.

    2. @[Jan] and [Mats S]

      The total power (kW/h) you consume to heat something depends on how fast you want to heat it. Halving the instantaneous power Watts does reduce the total power (kW/h) consumption unless you have such a high thermal leakage that the accumulation of lost energy is greater than the saving of time.

      1. “depends on how fast you want to heat it. ”

        No it doesn’t. It still takes a set amount of energy (kWh) to boil a quantity of water no matter if you do it in a minute or in an hour.

        1. Yes! It takes a very fixed amount of energy to boil water. An that amount of energy is defined but the heat leaving the system by way of steam. However prior to that point (100 degrees Celsius) you are simply storing kinetic energy in a comparatively lossless system. These to situations are not comparable.

          1. The cooking of rice takes a certain amount of energy to raise the temperature of the liquid to the point where the conversion of starch starts to happen. Then it needs a certain amount of energy to actually convert the starches.
            Then the rice absorbs most of the water, and the excess is boiled off as steam, which again takes a certain amount of energy.

            If the pot is perfectly insulated, it does not matter whether you do it in an hour or a week. The energy demand is the same. If the pot is not perfectly insulated, you end up using more energy the slower you do it because heat escapes.

            If the pot is well insulated, and you have metered the exact right amount of water, all you need to do is bring it to a boil and then stop heating it. The rice will cook itself.

          2. ok, ok !!!

            I wasn’t going to bother with this thread but since it seems some are still unconvinced …

            Yes, yes, yes it takes a fixed amount of energy to boil water IF it’s homogeneously floating in space and you remotely heat it with a LASER!

            If it’s not floating in space then also have to heat it’s container and deal with thermal losses from the water and it’s container and they are proportional to delta temp and delta temp is going to be much higher when you are heating it faster.

            Guess what – you also have to heat the heating element if it’s not a LASER!

            Other factors are that the intention here is not to simply heat or boil water. The intention is to cook rice by steaming which immediately implies that there are far greater losses then just heating or boiling water.

            You all are raising very valid points about heating water in space with a LASER – now go try some *real world* tests.

          3. ” also have to heat it’s container and deal with thermal losses from the water and it’s container and they are proportional to delta temp and delta temp is going to be much higher when you are heating it faster. ”

            That doesn’t make any sense.

            If you put a heating element, a pot of water and rice, in a nice thick styrofoam box – it’s still going to take you a fixed amount of energy to heat everything that’s inside the box and cook the rice regardless of the speed – and the faster you do it the less energy escapes the box.

            The heat loss from an object is propotional to is temperature relative to the environment, not the speed at which the temperature increases.

      2. Power [W] will halve, but energy [J, kW/h or what ever unit you prefer] will be the same or more, as it will take twice as long or more, because more heat is dissipated over that time (lost) due to imperfect insulation.
        The increase in energy usage is probably negligible in this case, but cooking time is prolonged for no good reason.
        (Re-erading my inital post, I see that I erroneously said more *power*, it should be more *energy*).

      3. For those who are wondering about the kW/h controversy, energy used is instantaneous power integrated over time, which for constant power reduces to power * time. Therefore the correct unit is kW * hr. People just aren’t used to seeing units multiplied, and at least in English we don’t actually have a convention for indicating multiplication (the closest thing is just no symbol at all, which is why when said aloud the term is just “kilowatt hours”), so they try to make it look right by mis-writing it as kW/h or kW-h. It is never correct to say “kilowatts per hour”, which is truly nonsense.

        1. ” It is never correct to say “kilowatts per hour”, which is truly nonsense.”

          It is a valid unit that is used in some contexts, but not here. It’s the ramp rate of power generators on the electric grid, usually expressed in MW/min, but that’s the same unit only in different magnitude.

    3. The goal here isn’t to boil away all the water, it’s to cook the rice. Once the water starts boiling, any power used beyond what it takes to keep it boiling does not contribute to the cooking process.

      One improvement on the hack is to reconnect the keep warm thermostat across the diode so it starts at full power.

      1. I have had rice cookers for 40 years. In fact, my simple small one was bought at a little shop of Japanese household items in Mento Park, CA and I used it last night (Chinese pork slices with leeks and Calrose). The cooker turns off when the water has boiled away and the temperature starts to rise. That is how they work. Therefore the rate of boiling determines the cooking time. If you turn down the boiling rate – as with the diode – you will overcook the rice. It isn’t rocket science but it does confuse a lot of people. Heat flow is not deterministic and is not intuitive like classical mechanics. Well, thermodynamics in general is not intuitive.

        1. Most of the water doesn’t actually boil away, but gets absorbed by the rice.

          The rice isn’t overcooked by how long it is cooked, but by how much water is absorbed because at some point the rice starch start to dissolve into the water and make a paste/porridge. If you have the exact right amount of water, you can cook it fast or slow, doesn’t matter – the rice comes out the same.

          Of course it takes some temperature-dependent time for the rice starches to convert and absorb the water, so that’s your minimum cooking time.

          1. This is correct and proven by the fact that we can cook perfect rice in a pressure cooker and let it cool so that even when opened there is no significant escape of steam, however you do need to get the water to grain (yeah we do other types the same way and they are all different) ratios just right or the results is drier or wetter than is desirable. This highlights the one small benefit of a rice cooker, they will continue to boil away excess water until the temperature rises and the control circuit activates to lower the heating power. Nothing will stop rice from being dry if you don’t have enough water in the first place so the rule people use actually add a little bit more than is needed.

  3. Be careful of sweating and moisture build up in the bottom. The terminals to the hot-rod will go to pot. No way to solder.
    These “crock pots” are already efficient, versus a stove top. This is further improvement.

      1. ehh, No. The involved currents are not a problem for soldered connections and the higher voltage do not affect anything, in fact with a higher voltage, the voltage drop at the connection is more acceptable than in a low-voltage circuit. The connections of the heating elements getting above the melting temperature of solder is really to only thing to watch. My water cooker has electronic control and has the mains wires and wires from the 230V 3kW heating element soldered to the PCB.

        1. @[jaap]

          Quote: “The terminals to the hot-rod will go to pot. No way to solder.”

          The rise in temperature that results from a current going through a resistance is a “rise FROM the already existing temperature”

          If you are starting from 100 degrees Celsius then that is 100 degrees Celsius that the resistive junction has under it belt before it begins to make a difference.

          The resistance of solder increases with temperature so you can quickly reach thermal runaway with a 100 degree head start.

          Any connection that is directly exposed to a heating device of any power and current should NOT be soldered. Instead is should have a connection like crushed copper in brass where the expansion of the copper due to increased temperature reduces resistance.

          1. It’s not about solder resistance (which is negligible.) It’s because 1) solder doesn’t usually bond to Nichrome or other heater element materials, and 2) the temperature usually locally exceeds the melting point of solder.

            You crimp because a solder joint will fail, not because it’s lower resistance.

          2. @[pelrun] I agree …

            At 1800 – 2400 Watts that is pretty obvious. The heater mentioned here is 400 Watts and in non-fault condition only self heated to 100 degrees Celsius so it is less obvious.

            Also, even with some nichrome elements you have spot welded spade clips. It is possible to solder a wire to the matching connector and that is equally a bad idea.

          3. The fact that the resistance increases with temperature means that the current will decrease with temperature. Most metals (including the nichrome alloy used in most heating appliances) have positive temperature coefficients of resistance, but we don’t see nichrome heaters going into thermal runaway.

            I can see where the confusion might come from, since power = current squared * resistance, which means that in a circuit that for a given current, any component whose resistance increases will exhibit increased heat dissipation, with the risk of thermal runaway. But here we don’t have a constant current. More to the point, in a mains-powered circuit, we have pretty close to constant voltage applied, so another expression for power, voltage squared / resistance, applies. This means that for a given voltage, increasing resistance will cause power to decrease.

            Yes, it’s still a bad idea to use solder in heating appliances, but thermal runaway has nothing to do with it.

          4. @[BrightBlueJim]

            While what you have said is loosely true – in this particular case your analogy couldn’t further from the truth.

            The resistance of a solder joint isn’t on the same scale as the resistance of a heater or you have a serious problem on your hands.

            Power is V squared on R. So while the current may reduce as the solder increases in resistance the power dissipated increases at a near to exponential rate due to the increased proportion of voltage across the solder joint.

            Where I live it is mandated that you CAN’T solder joints that carry higher currents in mains systems even if they are no where near a heating element. I was taught this in the first year of EE.

          5. “Power is V squared on R. So while the current may reduce as the solder increases in resistance the power dissipated increases at a near to exponential rate due to the increased proportion of voltage across the solder joint. ”

            Suppose we have some arbitrary voltage input and two resistors, R and r connected in series where r remains a constant. Therefore the V that applies to R is proportional to R / (r + R) and the result in terms of power becomes proportional to R/(r+R)^2 which for small values of R is roughly equal to R/r or linear increase in power, not exponential, and for larger values or R it becomes proportional to R/R^2 which is a diminishing result because R^2 grows faster than R.

            That isn’t to say the solder joint can’t melt – that depends on how much power exactly gets applied to it and how much heat can escape, but it does not trip up “exponentially”. If that wasn’t the case, just about any solder joint in any device with more than say 10 Watts of power would eventually desolder itself if left on, and that’s just not happening.

            While the EE professors’ advice was good for a variety of reasons, it always pays to double-check your assumptions.

            On the concept of it, this problem is actually identical to putting two incandecent lightbulbs in series. They behave the same: as you add more power to one, its temperature increases, which increases its resistance, which puts a higher proportion of voltage to it – which on the face of it should cause an exponential runoff and always pop the hotter bulb nearly instantly – but it doesn’t happen and here’s why.

          6. In fact, the peak power for R in the R + r system occurs when R = r and then it starts to diminish, which is why two roughly similiar lightbulbs in series always balance to one another instead of one running off exponentially.

            For the rice cooker with a constant r heating element, this would mean the solder connection that starts to heat up – assuming no heat loss from the solder – would increase in resistance until the power of the device is halved and R is recieving half of it. For a 400 Watt device, that would be 100 Watts acting at the dodgy connection. That would be cause for concern.

            However, since the heat loss is directly proportional to the temperature, while the heat increase is always less than directly proportional to R which tracks the temperature, the system must be stable. As long as there’s not enough current running through to melt the solder via I^2R losses alone, it can’t start into a thermal runaway. Obviously – otherwise lightbulbs too would always blow up instantly upon switching them on.

            The real problem comes when the heating element resistance r drops significantly such as in a short-circuit. Maybe the heating coil has a fault, burns and touches the metal shield – that’s when the soldered joint actually becomes dangerous.

      2. The real reason you don’t solder mains power wirings is because in the event of a short to the chassis or other grounded piece of the device, the solder will melt and the connection will break, and the fuse at the breaker box may not.

        That means there’s now a potential fire hazard in the device because there’s free dangling wires with live voltages on them that can spark and arc and set fire to dust or grease etc. It’s especially bad if the -ground- wire is the one that was soldered on, because now the device has a live chassis and will kill upon touch.

    1. I agree.

      I bought one of these and used it a couple of times before putting it in the cupboard permanently. Most of the reason was that I don’t want to learn how to cook rice all over again. I do fine just with a pot.

      There is room for a better rice cooker though. It is just science after all. A cooker that weighs the rice (by type) and then calculates the amount of water and then heats for the correct amount of energy (time) would be great.

      With rice, the amount of water you put in is the variable that has the greatest influence on the outcome (burnt rice on the bottom of the pot NOT included here).

        1. one part … well that would be by weight or volume and neither of those work for me because I rinse rice thoroughly before I cook (steam) it.

          Then I put it in a lager pot an add water till its about 7mm above the rice. Then in the fridge overnight if I have that luxury.

          But probably more importantly I add oil, salt and butter along the way.

          1. With a digital pressure cooker you really can just rinse the rice and throw everything in together, hit go and walk away. The better units even have a delay so you can have the food ready when you get home or come in from the workshop etc. YouTube is full of howto videos.

            I really wish guys in particular would master these devices as not only do they save a lot of time and money they will have you living a longer healthier life because you will improve your diets. Not saying anyone in particular needs to do this, just a lot of single guys and there are clearly a lot of them amongst the HAD readers. Hack your diets!

        2. Don’t get complicated. One handful of rice per person (2 if you have been splitting wood all day). Water depth is one finger joint greater than rice depth. Plain rice or with chicken/pork and veggies added. Throw switch and go away. When the switch pops open, done. (Brown rice two joints or you will do a LOT of chewing.) Can’t do that on a stove top.

        3. That ratio actually doesn’t hold up, especially in a rice cooker, and it gets even less intuitive the more rice you are making. For example, you might only use 2.5 cups of water with 2 cups of uncooked rice, even less if you are using a rice cooker. For perfect white long grain rice it’s a 2:2.2 rice:water ratio in a cooker but if you are using, say 8 cups of rice then it’s closer to 8:8.2 rice:water. The ratios vary the same way but not by the same numbers if you’re cooking on the stove but I haven’t cooked rice on a stove in over 25 years. It’s much easier to concentrate on cooking your food and let the rice do its thing. I’ve never had rice in a rice cooker burn but it only takes one well timed distraction to burn rice on the stove.

          It’s also prudent to note that you’re supposed to rinse your rice several times(preferably with hot water) until the rinse water runs clear. Then for the last rinse use cold water, drain fully and then use cold water to put in the cooker. This will keep lots of the starches from making the rice sticky and gummy.(though this is desired for sushi of course but you use a different rice, different method, etc…)

          Full disclosure, I made rice “professionally” for a good number of years when I worked for a Vietnamese restaurant in my early 20’s. The owner(a really good friend of mine) gave me the rice cooker I use to this day.

          1. I learned it from an old Japanese woman. By one finger joint deeper than the rice, I mean the rice should be covered by 1 finger joint of water. If there is a small amount of rice, this extends the cooking time enough. If there is a lot of rice then it makes little difference. In an automatic (thermostat type) cooker, the cook time and the amount that steams off is determined by the amount of water and the size of the little hole and I have no idea what else. But someone figured out that about 2cm of water over the rice gives good results no matter how much you are cooking if the thing is built right. A good one is very forgiving. I run it a little dryer if I’m making sushi rice and need it firm and hot so rice vinegar and sugar will evaporate off quickly while stirring (in front of a fan if you don’t have an assistant. I wash rice for sushi but usually not for regular cooking. The packages often say do not wash to retains vitamins. I think there is no talc on US rices.

          2. The reason for the varying ratios is that with smaller amounts of rice to cook, a larger portion of the water simply evaporates by boiling rather than getting absorbed into the rice. With larger amounts of rice in a bigger pot, the ratio of water to rice approaches the amout of water that the rice will absorb which is roughly 1:1 by volume, give or take depending on the variety of rice.

            Cooking on the stove requires more water because the temperature control is worse and the pot boils. Ideally you should need only the water that the rice absorbs to achieve the consistency you like, and no more.

          3. ” The packages often say do not wash to retains vitamins.”

            The rice is fortified with niacin, which prevents you from developing pellegra if you’re subsisting on a diet that consists heavily of polished rice, cornmeal, white flour, etc. staples that do not contain it because it’s been removed. Reason being that in polished rice and processed flours, the germ is removed from the seed in order to remove the oils that would go rancid in storage and spoil the product – but it contains all the vitamins. You end up eating pretty much plain starch with no nutrients in it.

        4. pretty much what i do. i do this thing where i boil the water and when you dump in the rice it kills the boil, and then immediately set it on the lowest setting and put the lid on at that point. it shouldnt boil up with the rice in the pot. run it till the rice is tender or run it longer if you want sticky rice. if the results are too sticky consider rinsing the rice. i dont.

          i have to draw the line at kitchen gadgets somewhere. you got to consider cleanup time as well as cook time. if cleaning a rice cooker is more complicated and takes more time than cleaning a pot, im going to use a pot. im not going to start a rice cooker in the morning, leave a device with a heater unattended and waste power all day for a 15 minute job, no thanks. its like automatic can openers, ive yet to see one that can do a better, faster job of opening a can than i could do.

          1. Ir cooks in an aluminum or staineless pot that you take out when it is done. Nothing special. Easy cleanup. Some have a nice glass lit, some a metal lid that you can use with the pot till served, etc. And you don’t have to pay any attention to it when cooking.

      1. Because of the specially designed switch in the rice cooker, it automatically turns off once the water has boiled off. My 30-year-old National/Panasonic rice cooked has *never* burnt any rice. Perfect rice, every time.

        1. Exactly. I’ve never once burned rice in a rice cooker, and, as I note above, I worked in a Vietnamese restaurant for many years. I know my rice cookers. That said, I do like the idea of the insulation. I’ll have to see if mine has some, if not, I’m definitely adding)

    2. It’s actually more efficient to heat the water to boiling in a kettle, and use the stove to just simmer it while the rice cooks. Stoves are very inefficient at heating because the exposed metal pot is basically a radiator, and gas stoves even more so because half the heat from the fire escapes out the flue.

    3. You are clearly thinking of the most mundane versions of rice cookers. There is something to be said for comfort: Even slightly more advanced ones will save you the hassle of watching your pot, prevent overcooking, keep it warm if you don’t need it right away … not to mention the bells and whistles of really advanced ones. It becomes more apparant if rice is on your daily diet, if you’re eating rice once or twice a month you can be forgiven to not see the difference.

      Or to put it another way: In a typical Japanese household the rice cooker is easily the most expensive and advanced technical item (with the Captain’s Chair toilet seat in a close second).

    4. Automatic iice cookers are very popular in cultures where rice is a staple. Are the people in those cultures stupid? I don’t think so. You could as easily say that having a machine to cook bread to make toast instead of just doing it on a hotplate is stupid. And yet, most of us who eat toast own automatic toasters.

      Indeed, the doing of mundane tasks is where machines excel.

      1. Hey Dan#1438459043. Is there something wrong with your hackaday comment wordpress login? You seem to be switching back and forth between this account and your usual Dan#1438459043 account.

        I know the comment system here is a bit of a mess, but there might be something we can do. Let me know if you need anything.

          1. Oh so you have homoerotic fantasies about me do you? Keep them to yourself or it is sexual harassment and I’m sure the directors of SupplyFrame will not be happy to be associated with such conduct.

          2. No I have not, I’m still here kido, doing what I have always done. Talking to turds/trolls so people can quickly search HAD and know who you are. You talk to me and to each other far more than any other posting type. The patterns are clear as a bell, and there are others too, but I’m not letting you know how much is really visible, because that would be helping you to brigade against and harass people.

          1. Your fantasies are irrelevant, all of the following are from the same character set !@#$%^&*(),./[]{} but the function each is unique. {notarealemail} Dooo yooou undeeeer staaaaand meeeee noooow?

        1. Many of the readers here have seen Dan (Dan#8582394734, Dan#1438459043, Dan#9445376854, PurpleTurdBracket) attack us with verbal abuse and juvenile behavior. Readers have noted Dan on many occasions calling people names like – pervert, sexual deviant, and pedophile. Dan appears to have an inflated sense of self worth and it is not uncommon for Dan to call someone a stalker, or claim that they are obsessed with him. Dan’s use of an alias simply to belittle and troll people is disconcerting.
          Myself and many readers here have seen behavior that causes us to question Dan’s mental stability.

          1. Don’t wast your time I am sure anyone who cares to check your claims understands the following very clearly.

            I’m still here kido, doing what I have always done. Only talking to turds/trolls so people can quickly search HAD and know who you are. You talk to me and to each other far more than any other posting type. The patterns are as clear as a bell, and there are others too, but I’m not letting you know how much is really visible, because that would be helping you to brigade against and harass people.

            PurpleTurdBracket is like running a yellow highlighter pen over your posts and nobody (who matters) has told me that it is against the rules. So that makes you shitty, bad luck, you caused the problem, the PurpleTurdBracket is the solution.

          2. Yeah, I have seen that guy around. He is one of those people that won’t allow anyone to get their alternate opinion in, and if you try he calls you a troll.

  4. ” The cooker still reached the desired temperature, it just used half the power.”
    And double the time to cook… So no solution.

    “He could safely reduce the water without affecting the cooked rice. ”
    Uhm, no you can not. You’re supposed to exactly measure the rice and water you put in. If you do it right, no water is left when it’s done. So two options here, or he now end up with uncooked rice, or he didn’t read the instructions and just used tons of water before…

      1. I wish I’d seen this before I commented above. We always used a simple ratio. Put in ever how much (rinsed) rice you are going to use and then put enough water to go up to the first joint on your index finger above that. But that said, the link you provided is pretty much spot on.

  5. On the topic of rice cookers, many have a porridge setting. Mine does not. Does anyone know the temperature difference between this setting and the regular rice setting? I have an old rice cooker I’d like to convert for steel cut oats.

          1. Water in a pressure cooker can boil at a lower temperature than in a rice cooker or a stove. This is why vitamins are retained by that form of cooking. All fresh plant based foods are full of enzymes, thery are denatured at different temperature-pressure points.

            I don’t eat meat but I do know that papaya helps to break down meat into a more digestible form. Cooking is as much an art as it is a science.

            http://biotechlearn.org.nz/themes/biotech_at_home/fruit_enzymes_tenderise_meat

            As for dog food, well if you knew what goes into dog food you’d probably want to run it through a nuclear reactor. ;-)

          2. “Water in a pressure cooker can boil at a lower temperature than in a rice cooker or a stove.”

            It can, but only if you attach a vacuum pump to the pressure outlet.

  6. IIRC the majority of the power for cooking really does go into the food itself. Probably was meaningful to use insulation rather than add a keep warm circuit, but I’d imagine the efficiency improvement for cooking itself wasn’t terribly great.

    Cooking is remarkably energy-inefficient – after all most techniques were developed, well, pretty much before scientific understanding. Cooking pasta is typically done by heating many more times the mass of water as there is pasta – and then most of that water is poured down the drain. It’s pretty unclear why so much water is necessary (other than due to stupid pot geometries – you fill up the whole thing so that the water covers all of your spaghetti, or something), and there’s quite likely much better ways of doing it. There’s some nonsense about starches in water, but I’d like to see an actual scientific explanation / analysis of why you could possibly need that much water, because I’ve never seen any real sources on that. Anywho, I recall calculating that the cost of cooking pasta can actually be a non-negligible fraction of the cost of the pasta itself if you were really using as much water as is traditionally called for.

    1. You can cook spaghetti in a skillet, starting with cold water, faster than you can get a pot of water boiling, and it won’t stick together since the starch isn’t being activated by the heat immediately. You can choose to keep the leftover starchy water to make a sauce if you like.. I’ve actually made this several times and it’s amazingly quick.

      http://lifehacker.com/5860015/cook-pasta-with-cold-water-and-a-frying-pan-for-a-quick-dinner-and-an-easy-sauce

      1. I just use angle hair for everything. It cooks in a couple minutes and I use water from an electric kettle so as not to wait for a pot to boil. Oh, and break it up short first. I never saw the point of the long strands. It looks like it is still on the bush.

        Amazing number of comments rice cooking has generated.

        1. Yeah, angel hair is great and all but if you’re cooking actual spaghetti or linguine, you will need another method and the skillet method is one to keep in mind. It would have your angel hair done before your kettle was done heating the water.

  7. Back to that sweaty corroding terminals. I meant to say, you won’t be able to solder or do any repair at all if things “go to pot”. Often water on the countertop gets into the base or drips down the side when lifting the lid off. Always lift any lid towards the inside of the pot, not like a hinge on the rim so water etc. drips back into the pot.
    I had a friends coffee maker go bad, rusty as hell it reveled a chocolate drop sized and shaped hunk of aluminum created like corium when a nuke melts down. The thermal fuse was still good.
    Keep it clean and dry, countertop too.

  8. “The cooker still reached the desired temperature, it just used half the power.”

    My intuition on this is that it takes longer with the net same or more energy consumption, plus heating filaments draw more power when cool. Though the cool-down between cycles is probably negligible…

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