How to: Freezing pre-portioned rice

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From the archives: This is a foundation post for anyone interested in Japanese style bentos based around rice. Edited and updated to reflect some safety related questions. Be sure to read the linked bento safety posts too. Originally posted in October 2007.

Rice is the base carbohydrate for most Japanese style bento lunches, but the idea of cooking rice fresh every day may be rather daunting. If you have a rice cooker with a timer that can be set so that the rice is ready when you want to make your bento it is easier (and recommended if you make bentos daily). Of course this does mean that you need to rinse the rice the night before.

While I prefer to wash the rice the night before and set the timer on my rice cooker, I often freeze pre-portioned packets of rice to use on extra busy mornings. Rice freezes very well if you make sure that it’s still warm when you wrap up the portions. This retains the necessary moisture inside the plastic. It’s also a good idea to use sturdy, microwaveable wrap such as Saran Wrap.

I pre-portion the brown rice that I cook 5 cups at a time in a pressure cooker into 1 cup and 1/2 cup portions, using scoop-style cup measures. (I usually do this during the weekend.) After wrapping in the plastic wrap (cling film), I leave them until they have cooled down, then then double-bag them in zip bags and put them in the freezer. (For the environmentally conscious, the zip bags can be reused several times provided you don’t puncture them.) This amount lasts the two of us 2 to 3 weeks. To prepare a bento box, I use a 1 cup portion for myself and 2 cups or 1 1/2 cups for the bigger guy, re-heated in the microwave before stuffing into the box. Pre-portioning rice like this really helps to control portion sizes; when you’re in a hurry in the morning and scooping hot rice out of a cooker, portioning into a cup becomes a hassle.

You may choose to bring the frozen packet as-is, especially if you have a microwave at work. I prefer to re-heat the rice in the morning because I often find that the frozen packet is ice cold at lunchtime, which isn’t very pleasant.

If you do re-heat the frozen rice in the morning, be sure to cool it down again before closing up your bento box. Warm rice leads to condensation. Condensation within a closed bento box is the main cause of spoilage. I usually pack the rice in my bento box first, then leave the box open to cool down while I prep the rest of the contents.

If you want to be extra safe, pack the bento box with a small ice pack, and/or put a single umeboshi (salted pickled plum) in the middle of the rice. The umeboshi in rice is the traditional way of keeping rice fresh. Umeboshi are available at any Japanese grocery store. (You don’t have to eat the umeboshi if you don’t like it - just throw it away.) See also: Keeping your bento lunch safe.

A word about different kinds of rice

The shorter the grain, the moister the rice is and the better it seems to freeze and recover from freezing. So Japanese style ‘sushi’ rice or medium grain rice, round glutionous rice, other medium grain rices like arborio, vialone and ‘pudding’ rice, freeze well. On the other hand long grain rices such as jasmine rice, Carolina rice and basmati rice tend to get hard and dry. If this happens to your frozen rice, you can make it more edible by turning it into fried rice. See also: Looking at rice.

Freezing onigiri

Pre-made onigiri (rice balls), without the nori wrapping, can be frozen successfuly using the guidelines above. Just wrap each warm onigiri securely in plastic wrap and freeze. If you use the cling film method of making onigiri, you can use that to wrap up the onigiri as soon as you make it. Don’t freeze rice balls that have been wrapped in nori seaweed though, unless you like soggy nori!

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frozen noodles?

I know what I’m doing this weekend…making frozen rice. does it work with noodles too?

freezing noodles

I don’t find that freezing noodles goes very well. When you’re freezing something it fares the best when you can retain a lot of moisture in the food, but you don’t want noodles to be that full of moisture! Besides, most noodles do cook quite quickly. So in any case, I don’t freeze noodles (and I don’t use them much in bento either, with a few exceptions). I hope that answers your question!

Re: freezing noodles

Would it be possible to make a bunch of carrot or vegetable flowers and freeze those? Or is there a better way to make them ahead of time?

What a useful tip! For some

What a useful tip! For some reason I didn’t think that cooked rice froze very well, so I am glad to hear that it really does work. I’ll be trying your method soon! :)

portioning cooked rice

hey… when you portion the rice for freezing, you do it by measuring cups of cooked rice right? sorry, am a bit confused cos 1 cup of uncooked rice would definitely become more than 1 cup when it is cooked? thanks.

cooked rice

Yes I measure the cooked rice when packing for freezing. (I usually make about 5 cups of uncooked rice at once, which lasts about 2-3 weeks for 2 people depending on how often we have bento or use the rice otherwise.)

Reheating frozen rice

Thanks for the tips! Do you thaw the frozen rice before microwaving to reheat? Do you use the defrost setting on the microwave?

Microwaving frozen rice

Hi! Any tips for microwaving the frozen rice? Do you thaw it first? Do you use the defrost setting? Do you microwave it right in the plastic wrap?

On a side note, I read on a different Bento site (http://lunchinabox.net/) that she often freezes pasta - she butters or oils the noodles prior to freezing. :)

defrosting rice

I don’t defrost the rice (unless I remember to…) - I usually just nuke it from frozen. The packets are small enough that they reheat quite successfully.

I guess I have to disagree with Biggie on the matter of freezing pasta…the only frozen pasta that is ok later to me is something baked in a sauce, like lasagna or mac and cheese, where the pasta can be soft and integrated with the sauce and it’s ok. Maybe because we live very close to Italy and get ‘al dente’ ‘duro’ as the best way for pasta hammered into our heads so much! Actually I rarely use pasta for bento, unless it’s a salad…because the freshly cooked version is so much better (and there are so many other carbs to choose from). It’s a personal preference!

defrosting rice without a microwave

I dont have a microwave at home, and the one at work is icky so I don’t like to use it. If i’m not using a microwave, would putting the frozen rice packet in the fridge the night before defrost it ok? I usually don’t mind cooking rice in the morning, but I do mind washing the rice cooker…and washing a pan where i reheated the rice seems like just as much work. Any ideas?

defrosting rice

Defrosting it by putting it in the fridge the night before should work fine. Be sure it’s well wrapped, so it doesn’t get dried out. Try packing the rice into packets as thinly spread as possible so that it will defrost all the way through (if you have a very cold fridge). You can also try bringing the rice packet as-is, wrapped (in a thin packet) and frozen - it should defrost by lunchtime.

sushi rice

does this technique work just as well for sushi rice?

it should

…if you wrap the sushi rice well while it’s still slightly warm, and defrost to room temperature.

It works!!

I tried this for the first time yesterday, and it worked beautifully! Thanks so much for the tips!

Thanks!

After reading your blog for a while, I finally tried freezing our leftover brown rice, and wow did it taste great after being reheated! So much better than the increasingly dried-out leftover rice we used to have! Thanks for all your bento tips, they’re great!

Microwaving rice in plastic

Not to be a spoil sport, but I would caution you about microwaving rice in plastic. Heated plastic leaches into food. My suggestion would be to purchase wax paper sandwich size bags, add the rice to the bags and then put it in a plastic ziploc in the freezer. I would microwave the rice in wax paper.

Don't be silly

“Heated plastic leaches into food” but wax paper doesn’t? That’s nonsense. Do NOT use wax paper — it is not intended to be heated in food contact. Wax always leaches substances into food if you heat it. Use a plastic wrap that the manufacturer says is safe for heating with food, i.e. a product sold for use in the microwave. Read the package. If there is no mention of heating, buy another brand.

Re: Don't be silly

I have to disagree with your response to this commenter.

Firstly, the term wax paper is often used interchangeably for a number of different types of "non-stick" paper, most of which ARE intended to be heated in direct contact with food. Baking parchment, for instance, is generally coated with silicone and would presumably work well for wrapping this rice (since silicone is pretty inert I doubt there would be leaching issues). And wax paper itself can be produced via a number of different methods, which would result in different likelihoods of leaching unpleasant substances into the food. Traditional waxed paper is often coated with paraffin, but some types are now coated with vegetable-based substances (e.g. soya). And even paraffin wax is actually considered to be an edible substance (it is used in the glazing of certain foods, and for wrapping some cheeses); it is also a fairly inert substance (I don't have time to look up the exact details of the toxicological issues relating to food-grade paraffin, so I couldn't say for certain if it is safer than plastic wrap).

There is a possibility that even "microwave safe" film may leach something into the food - it is generally recommended to avoid cooking food in direct contact with any kind of plastic wrap, even those that claim to be microwave safe (if you read the packet it will often say not to microwave in direct contact with food). New things are being discovered all the time about the problems with plastics, and it's probably best to assume none of them are completely "safe" (although some are undoubtedly worse than others - polyethylene is probably the safest as as far as we know). Having said that, it's pretty difficult to avoid them altogether, so we need to keep some perspective over it.

If you really want to avoid the risk, use freezable ceramic or glass containers. Of course these will be heavier to carry but then if you're really concerned about your health you could consider the extra exercise a good thing!!

Re: Don't be silly

I know this is an old post, but I wanted to add my comment anyway.

I would be more concerned personally, with microwaving anything - whether it's in plastic, paper, or a glass bowl. I've read a lot of information lately about the dangers of microwaves and are trying to pull our family away from using one in general. It is a definite convenience we will miss, but if you are that concerned about plastic leeching into food when cooked in a microwave - try looking up what a microwave actually does to food instead...

Re: Don't be silly

I've done a fair amount of research into the supposed dangers of microwaving food, and so far as I can tell, very little of that research is reliable. (One of the most widely circulated writings on the subject includes many citations which, upon checking, I found referred to *nonexistent* papers).

Looking up what a microwave "actually does to food"? It cooks it. That's all. There are legitimate concerns about fats in the presence of certain plastics, but that's about it. Japanese rice (basically fat-free) should be fine. Use a glass bowl if you're concerned about plastics.

Bacon cooked in a microwave actually develops fewer carcinogens than fried, if I'm not mistaken.

So please, go back to using your microwave. Don't be misled by poor research.

Filled Onigiri?

Is it okay to freeze onigiri that have a filling? Does it affect the defrosting or not? Do they need to be microwaved longer?

Reheating before use in bento?

I don’t have a microwave, so if I defrosted the frozen rice in the fridge overnight, would I then need to 1) heat it up (with a drop of water in a pan, perhaps?) and then 2) let it cool down again before packing it in a bento box? I’m a bit confused because I understood from the safety info that one needs to reheat cooked food and then let it cool before packing it. Apologies if I’m being dim here!

If you don’t have a

If you don’t have a microwave, you can put the frozen rice in the fridge the night before, and then pack the frozen rice in your bento - it will probably be still cold, but edible by lunchtime (unless you are in a very cold air-conditioned office or something!) Rice is better tasting if you can manage to heat it up in the morning and cool it down, but cold rice would still be okay to eat.

Cooked food that is not frozen needs to be reheated and cooled for safety reasons, but frozen food that is gradually defrosted (and is at room temperature for only a few hours) should be ok.

Refrigerate then freeze?

Good freezing practices typically dictate refrigerating items from their warm state and then freezing them. The theory is it helps to reduce the formation of cell-damaging water crystals (most important for protein products, in particular), reduces the amount of work the freezer does and keeps the food from thawing items stored next to the new addition. It seems that you skip this step: Why? (if there is any reason.)

Good question! The reason

Good question! The reason for this is that for rice (for Japanese type rice in any case), it’s important to keep some moisture on the grains - once the tiny grains dry out (which happens quite fast if they reach room temperature, though much slower than with long-grain rice) they become hard and inedible. With other foods I cool them down as much as possible before freezing, but the method I describe does work best for freezing rice and is also recommended by many Japanese bento books.

White Rice?

Will white rice also work? Since I don’t have any brown rice at home

Aflatoxin

Doesnt rice that is kept overnight or packed away over a few days is most likely to produce aflatoxin - the most toxic, natural-occuring carcinogen?

Re: Aflatoxin

I doubt that this would be an issue if the rice is frozen.

Re: Aflatoxin

Only if it's not cooled properly. Aflatoxin is the other (and perhaps, most important) reason to freeze rice while it's still warm. Aflatoxins reproduce best at room temperatures, so freezing (or refrigerating) while it's still very warm means it passes through this temperature very quickly, thus making it safe to keep.

Never keep rice at room temperature for too long.

Re: Aflatoxin

Karla wrote:

Only if it's not cooled properly. Aflatoxin is the other (and perhaps, most important) reason to freeze rice while it's still warm. Aflatoxins reproduce best at room temperatures, so freezing (or refrigerating) while it's still very warm means it passes through this temperature very quickly, thus making it safe to keep.

Never keep rice at room temperature for too long.

I think this falls under the category of "a little knowledge can be a dangerous thing." People hear about some substance and immediately blow it out of proportion. The fact is that Chinese and Japanese have been eating rice that's been cooked and left in the pot up to a week for centuries. They do it for convenience, since it's easier to cook a big batch and use it over several days than to cook a small pot every day. If aflatoxin in rice was that dangerous, they would have been dropping like flies, considering they eat more rice in a week than most westerners eat in a year.

Re: Aflatoxin

do NOT keep your rice at room temp (any temp above 41 F) for more than 2 hours. period. less is much better.

Dont leave your rice in the rice cooker on warm for very long either. not safe. people do it but this doesnt make it safe.

Remember that the generation time of your average bacteria is 20 minutes. Geometric progression thereafter leads to trillions of bacteria in very short order. If you WANT fermented rice you need to innoculate it with known beneficial species that will outcompete the pathogenic species.

If you pop open that rice cooker, the moment it is opened it is grossly contaminated by fungal spores from the ambient environment. The moment you stick something in the rice or you hover over it, breath on it - bacteria take up residence. At that point the clock is ticking. As the unopened rice cooker cools and is no longer venting hot steam it begins to pull back in air from the contaminated environment = more contamination.

Make rice on demand or make and fridge/freeze. dont thaw at RT overnight.

Just because there are hearsay reports of rice pots kept at RT for a week (gag - not only would aspergillus be blooming well before the end of that week but plenty of other nasties - the rice would be entering a slimy level of decomposition) doesnt make it safe, in any way at all.

If your rice is slightly thawed but still very chilly when you put it in the bento you are ensuring 1) the rice will be safer and the bento will be chilled 2) you and your kid wont be praying to the porcelain goddess all night long

After reading your blog for

After reading your blog for a while, I finally tried freezing our leftover brown rice, and wow did it taste great after being reheated! So much better than the increasingly dried-out leftover rice we used to have! Thanks for all your bento tips, they’re great!

Re: How to: Freezing pre-portioned rice

I tried this at the weekend, bagging a week's worth of rice for work lunches. I just ate the first, and I think I must have done something wrong! The rice was very flavourless and dry, and had lost all its glutinous quality, separating out into individual soft little grains. Maybe it was because I let it defrost overnight? It was perfectly edible, just not very interesting.

Re: How to: Freezing pre-portioned rice

Did you wrap it up tightly while it was still a little warm? That traps some moisture which helps to keep the rice grains plump. If you let it cool down completely before wrapping it, the grains will dry out. You can still use that dried out rice for fried rice or put it into soup and things though.

Re: How to: Freezing pre-portioned rice

I think it mustn't have been wrapped tight enough! I'll have to make sure I don't get distracted next time - though today I brought in another bag, and found a microwave to heat it with a little extra water added just in case. It came back to its original state, hurray! Thanks for the advice :-)

Freezing prepared sushi?

Hello, I have in the past few months started to prepare my own rice, bentos, and sushi. I was wondering if and how you should freeze prepared sushi/maki rolls. I include maki rolls in my bento every day of the week. And if I leave them in the refrigerator, after a few days they start to get hard. Is there a proper method involved when freezing them? Or is it just not recommended? If not, then what is a better option other than making rolls a couple of times a week. Thanks!

Re: How to: Freezing pre-portioned rice

I want to freeze brown rice with my vegetables,can anyone tell me what kind of freezer bags I need?Also I want to put the frozen rice straight into the microwave and reheat when needed???REGARDS

Re: How to: Freezing pre-portioned rice

It may sound as a stupid question (and probably it is), but at what point one unwraps the rice, before putting it in microwave, or re-heating it in a plastic wrap and then unwrapping it into a bento box.
Thank you

Re: How to: Freezing pre-portioned rice

Thanks! I tried it this morning. If you read my 'recipe sprucing!' post ( Trust me I'm not asking you to!!:P) I needed help with cutting down the time it takes to make stuff. So I made a couple onigiri, wrapped them, froze them, and now tomorrow I'm going to defrost them! I really hope this works!!

Defrosting frozen rice in the microwave

I've successfully frozen rice and onigiri warm but have problem is defrosting it in the microwave. Mine turn dry and hard. The onigiri suffer the most. Do I need to add a bit of water? What setting for how long do I need to use? I realise microwaves are different but I think need a staring point to experiment with.

Re: Defrosting frozen rice in the microwave

Make sure that the rice you are defrosting is covered in plastic wrap. Also, you may want to try defrosting on the HIGH setting, not the DEFROST setting, for a shorter time (try about 3 minutes for a standard single onigiri start, and see if your microwave needs a bit longer). The onigiri or rice will come out piping hot but steamy and moist, just as if it were freshly made.

Re: How to: Freezing pre-portioned rice

So let's see if I have it right:
1) Make rice. Wrap in plastic and freeze while still warm.
2) Remove from freezer to use. Heat on high ~3 min. for onigiri. Comes out moist and steamy.
3) Cool quickly (again in freezer?) for use in that day's bento

Right?

I don't want to put my family's health at risk!

Re: How to: Freezing pre-portioned rice

I use this method quite frequently - and in my experience you don't have to heat the rice back up to hot - I usually nuke the frozen rice for about 1:30-1:45 on high - it's at most warm at that point - some bits are still kind of cold but they come to temperature soon enough, and it's never so warm as to really form any noticeable condensation.

I don't freeze onigiri though, so I don't know. I just freeze the plain rice and then do what I want with it once it's room temperature again. and my times are based on a cup of frozen rice, with a splash of water added to the bag to help it reconstitute.

Re: How to: Freezing pre-portioned rice

This is probably one of the most useful things on the site, Maki. I have done this over and over again, and it works so, so well. It's really convenient to have cooked rice in the freezer, and much better (and cheaper!) than the microwave-and-eat stuff.

Re: How to: Freezing pre-portioned rice

Love this tip. How long should you microwave it and when you reheat it, do you take off the wrapping? I tried it both ways and I don't know which one's better.

Re: How to: Freezing pre-portioned rice

Thanks for the tip!

I'd be interested in the answer to freezing sushi myself (comment by Suzy) as well - I made a couple rolls for the first time this week and freezing would be nice.

Re: How to: Freezing pre-portioned rice

Yay! Nice to see the foundational posts being reposted! ;)

Re: How to: Freezing pre-portioned rice

I like to heat up my frozen rice in a corningware dish. I remove the plastic wrap and usually add a splash of water just to make sure that there is enough moisture, then I pop the lid on before placing it in the microwave. Just a couple of minutes and the rice is as good as new, without microwaving the plastic wrap.

Re: How to: Freezing pre-portioned rice

See, I would have never thought of that because ever time I try and keep rice it drys out.
But I suppose if you store it while it is still hot it preserves moisture.

I think I am going to make some extra rice next time I cook and give this a try.

Re: How to: Freezing pre-portioned rice

We don't have a microwave so I reheat rice (and plain pasta) from the fridge by pouring in some boiled water from our Zojirushi Hot Pot. I leave the water in with the lid on for a few minutes and then drain it. Then I fluff the rice and it's ready to eat or season. If you leave it for too long it can get a bit too wet but it's not bad if you watch it. I've also "re-steamed" rice in a pot with a little water on the bottom. Both of these work well especially if the rice is a longer grain but I haven't tried it on frozen rice. I'm guessing they would work but with maybe more water in the pan or a change of hot water from the hot pot.

I'm sure neither of these will win a culinary awards but they get the job done without a microwave.

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