There is instructions below how we use a rice cooker for cooking.
More water = more cooking.
Rice cookers generally work by boiling the rice and monitoring the temperature. When all the water has boiled away, the temperature starts to rise, which tells the rice cooker to shut off because the rice is done. Obviously, what this means is that how long the rice cooks depends entirely on how much water there is in the cooker. If you don't put in enough water, the rice will come out underdone; if you put in too much, overdone. With practice, it is even possible to very precisely adjust the qualities of your cooked rice by adjusting the water ratio.
Occasionally you can find rice which has rice-cooker instructions on the back of the package, but a good starting point for most rice in most rice cookers is:
1 cup rice = 1 cup water
..or, in other words, equal parts rice and water. If you are cooking smaller quantities of rice you will need to add a bit of extra water to make it come out right, but for larger amounts of rice, the 1:1 ratio is just about spot-on.
Note that if you're using completely dry rice, you will also need to add a bit more water. The 1:1 ratio is based on the assumption that some water will be retained by the rice as a result of the rinsing process.
Keep in mind, however, that this is only a guideline. Different rice cookers can vary somewhat, and different kinds of rice require different amounts of water as well. Take the time to familiarize yourself with your cooker and your rice, and do some test runs of rice batches to see what really is the right ratio for you.
Rinse your rice before cooking.
Before cooking rice in a rice cooker, you should rinse it thoroughly. Place the rice in a large container and fill the container with water, swirling the rice as you fill. Pour out the cloudy water and repeat. Do this until the water "runs clear". When done, drain the rice as well as you can, then place it in the cooker, add the right amount of water, and start cooking.
Once upon a time, rice was coated with a fine dust of talc to keep it from sticking together during storage. The original purpose of rinsing rice was to remove this talc coating, which obviously was not particularly tasty. Nowadays, however, a starch-based anti-caking agent is used instead, which is completely edible and tastes pretty much like the rice itself, so many people have come to the conclusion that rinsing is now unnecessary. In a rice cooker, however, rinsing the rice has another purpose: It makes the rice cook better.
I know from personal experience that this is the case, but I do not know exactly why. My current theory goes along the following lines: The anti-caking agent in modern rice actually absorbs and binds some of the water in the pot into a thin film around each grain as the rice cooks. This prevents the water from being absorbed into the inner portions of the grain as quickly as it should, and also uses up some of the water so the cooker detects the end of the cooking cyle earlier, which means by the time the cooker has finished cooking, the insides of the grains are still slightly underdone. One could try to compensate for this by adding a bit more water, to cause the rice cooker to cook it longer, and thus get the rice properly done on the inside, but this has the result of making the outside of the rice slightly overdone as well. In fact, it appears that the best one can get this way is both overdone and underdone at the same time, which isn't really the same as done-right-all-the-way-through.
If the anti-caking agent is removed before cooking, I have found that rice will typically come out of the cooker with a more consistent texture, and when cooked right will have a perfect soft-but-not-mushy texture all the way through every grain. This is, admittedly, a subtle difference, and many people will not even notice it consciously. It's surprising what people can pick up on subconsciously, however, particularly when it comes to food, and it's almost guaranteed that this difference will result in a more enjoyable and appetizing rice, even for those who can't really explain why. In any case, it only takes a couple of seconds, so why not do things right?
One other advantage of rinsing your rice is that it retains a bit of water from the rinsing process, which makes the 1:1 water-to-rice rule above come out just about exactly right in the end.
Some sources recommend letting your rice drain in a collander for as much as 30 minutes after rinsing before cooking it. Personally, I have been able to detect no discernable difference in the resulting rice when doing this, and frankly adding an extra half-hour to cooking my rice for a benefit I can't even detect seems silly to me. As far as I can tell there's no reason to let your rice drain before cooking, so once it's rinsed, feel free to just throw it into the cooker and go.
Do not rinse jasmine or basmati rice.
I know I just said rinse your rice, but there's an exception to this rule. Jasmine rice (because it is a "fragrant" rice) contains a lot of subtle flavor, and much of it can be washed right down the drain by the rinsing process. The disadvantages of not washing the rice also seem to be less pronounced with this variety anyway (I suspect partly because of its longer grain). In this particular case I personally prefer to forgo the texture benefits of washing and instead opt for the flavor benefits of not washing, as its wonderful flavor is, after all, the main reason for using jasmine rice in the first place. The reasoning for basmati rice is the same.
Note that since you'll be starting with completely dry rice, you'll need to add a little bit more water when cooking it.
Let the rice rest after cooking.
When you fire up a rice cooker, it will burble happily along to itself for a little while cooking the rice, and then, equally happily, shut off with a click, and go into "warming mode". The uninitated might well assume at this point that the rice is now done, and it's time to dig in. However, this is not the case. After cooking rice in a rice cooker, the rice should be allowed to rest for at least five, preferably ten, minutes afterward, to fully complete the cooking process and allow the water level to stabilize. During this time, do not open the rice cooker. Just let it be. Ten minutes. Trust me, the wait is worthwhile.
As with any other form of cooking, with rice there is always some degree of "carry-over" after the heat has been removed, during which time the rice continues cooking. In addition to this, when the rice cooker initially stops, there is still a lot of extra moisture present in the rice. If you try to eat it now, you will get a very mushy, somewhat gummy consistency to the rice which is not particularly appetizing. If, on the other hand, you wait a few minutes, the excess water will slowly steam its way out of the rice, and the doneness of the rice will equalize between the inside and the outside of the grains, leading to a perfect texture all the way through.
Do not open the rice cooker.
Well, ok, I know, you need to open the cooker to actually eat the rice, and what's the point of cooking it if you can't eat it? What I mean is, try to open the rice cooker only as much as is absolutely necessary. Do not leave the lid open for long periods of time. When you close it, be sure to close it firmly. Every second you leave the lid open is a second of water vapor running away from home, never to be seen again, and you will find your rice drying out with amazing speed.
The other part of this, of course, is that you should leave the rice in your cooker up until you're actually about to use it. If you immediately dump it all out into a bowl or something and leave it out to the open air, then keeping your cooker closed really won't help the rice any, will it?
Keep the rice cooker plugged in when there's rice in it.
Even if you're done cooking the rice, keep the cooker plugged in. Rice cookers are designed to maintain the moist, warm environment of the rice such that it's always at its best for serving, even hours after it's finished. While nothing can quite equal that first time you open the cooker ten minutes after the click, a good rice cooker, which has had its lid kept properly closed, and has remained plugged in, can keep rice remarkably fresh and tasty even, believe it or not, as much as days after being cooked.
Do not use metal utensils to serve the rice.
Most rice cookers have a non-stick surface which, like lots of non-stick surfaces, can be scratched reasonably easily by metal forks, spoons, etc. Whenever possible, use plastic utensils to dig the rice out of the cooker.
For easy cleanup, leave the cooker on and open for a bit.
If you need to hand-clean your rice cooker bowl, here's a tip which can make things a lot easier: Empty out any large amounts of leftover rice, and then put the bowl back in the rice cooker and leave it turned on, with the lid open, for a few minutes. The heat and air circulation will quickly dry out any remaining rice and other residue, making it simple to remove. After a few minutes, you should be able to just reach your hand in and run it around the surface of the bowl and all the rice and residue should just fall right off. You will still want to give the bowl a quick rinse after this, but it will be a lot quicker than trying to scrub the wet stuff out would have been.
Clean your whole cooker periodically.
Most cookers have dishwasher-safe removable bowls, and obviously you'll want to clean these after each use like any other cookware. However, it's also important to clean the rest of your cooker periodically too, as the gummy residue from the cooked rice can find itself on some unexpected surfaces. More importantly, over time mold spores and other contaminants can find their way onto those surfaces, and they can find the rice residue and the damp conditions of the rice cooker to be perfect breeding ground. You will want to periodically wash all accessible surfaces to make sure they're clean. It's also important to note that some rice cookers have a removable inside lid so you can get behind it and clean properly. Make sure you know what portions of your cooker are intended to be dismantled for proper cleaning, so you don't leave things lurking in unknown crannies.
Ironically, this is actually more important the less you use your rice cooker. If you use your cooker all the time, the heat of cooking and the regular airflow of using it will prevent most molds and such from taking hold and growing, but if you use it only intermittently, the pauses between uses can give things an opportunity to take hold, and you'll need to be more careful.
If you let it go too long and you discover things growing that shouldn't be growing, it's not the end of the world. Just be sure to clean all the surfaces thoroughly, and wipe them down with a mild bleach solution to sterilize everything, let it all dry thoroughly, and you should be good to go again.
