Are you packing Japanese-style bento for your children or for work? Here are helpful food safety tips on keeping the lunch safe until lunchtime.
Bacteria can grow rapidly in a warm environment, which can cause food poisoning.
Don’t worry, I don’t mean to scare you. I brought homemade bento that my mom prepared every day to middle school, high school, and college, and I never had food poisoning.
To make sure the food is safe for those you pack lunches for, you should follow the following 3 key points: cook/reheat, let cool, and keep it cool till lunchtime.
Why We Reheat Food
Japanese bentos are meant to be eaten at room temperature. The fact is the longer food has been lying around, it gets less fresh, even if you put an ice pack or keep it in the refrigerator.
Therefore, I highly recommend reheating cooked food before packing lunch. Reheating cooked food kills bacteria. It’s better to take extra safety precautions especially if you live in a humid or hot climate.
All you need to do is to reheat the food, let it cool down completely before closing the bento box, and then keep the bento cool with an ice pack the whole time with till lunchtime.
However, if you can keep your bento box in the refrigerator and microwave it at lunchtime (such as in the office), it is okay to pack lunch the previous night and keep it in the refrigerator.
Read more about food poisoning and food spoilage here.
How To Keep Your Bento Safe
Before Packing
- Wash your hands.
- Make sure your bento box is clean and dry.
While Packing
- Use clean utensils (chopsticks etc) or plastic gloves when you touch food. Your hands carry germs so it’s better to avoid handling food with bare hands. If you touch one food to the other with the same utensil, wipe off the utensil in between, or simply use another utensil. If you decide to wash it, then make sure your utensil is completely dry before picking up another food.
- Re-heat pre-cooked/leftover food before packing is highly recommended. If you do so, I also recommend heating up with a pan or toaster oven instead of microwave so that food, especially meat, is heated THOROUGHLY and not partially.
- Before you pack cold/cool food in your typical Japanese bento box, hot/warm rice must be cooled down. It’s dangerous when hot/warm rice heat up other food halfway because bacteria would start growing.
- Remove all liquid from the food which could spoil faster.
After Packing
- To avoid any risk of bacteria growth, you must cool down the food first before closing the bento, especially if the lunch box is going stay at room temperature for a few hours period.
- Use ice packs and an insulated bag to keep food fresh and safe till lunch time.
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[…] Food Safety Tips For Bento […]
Thank you for this information! Just to understand, if I pack my bento the night previously, and it will remain in the fridge at work, the reheating process can be skipped? The only downside is that it would lose freshness?
Hi Meghan! That’s okay as long as the food doesn’t go through different temperature. 🙂
Amazing, thank you! Please keep posting, I’ve tried a couple of recipes with great success!
I’m so glad to hear that. Thank you for your kind feedback, Meghan! xo
Hello! I’m a little confused on what food should be reheated and not reheated. Should spinach namul be reheated before putting in the bento, or can it be put straight from the fridge? What about stir fried onion? For meats and proteins, it is obvious that they should be reheated, but I am unsure about cooked vegetables. Thank you!
Hi Joon! Good question. If the food is cooked (stir fry, steamed, grill, etc), I’d reheat before adding to a lunch box. If it’s chilled salad/vegetables, I would not reheat, like in this Namul case. We don’t eat that dish hot. If the onions were stir-fried before, I’d definitely heat up. If the vegetable is blanched and seasoned (namul, spinach salad, etc), you do not need to reheat as you didn’t cook the dish. You coat the blanched vegetable with sauce. Hope this makes sense. 🙂
[…] In the morning of the day I pack bento, I reheat everything and let cool before I pack each dish into the box (Please read my Food Safety Tips for Bento). […]
Hi, if I were to pack the lunch box into a thermal bag or having a thermal lunchbox and leave it in for 3-4 hrs. Will it help? Thanks!!
Hi Jadie! To keep it warm? Yes, I do that too, but my children say it’s “warm” not hot. To keep it cold, you can also use it too.
After allowing your meal to cool down, can’t you just store your bento in the fridge over night so it stays cool?
Hi Kyle! If you can keep the lunch from refrigerated temperature to your lunch box with ice (similar temperature) to the fridge at work, then yes, you can definitely do that.
Food tend to go bad when the temperature changes, and bacteria loves lukewarm environment. In Japan, we eat bento at room temperature, so we always heat/reheat the food in the morning to kill any bacteria that might have grown overnight, and bring to school/work. 🙂
How can I reheat stuff without microwave? Can I reheat frozen rice with oven or pan?
I honestly don’t know what’s the best way… You can “steam” the rice but it defeats the purpose of convenience. It’s probably faster to cook fresh rice…. But if you can keep the steamer on, you could steam it. Oven or pan don’t work if you want to reheat frozen rice. 🙁 Sorry…
Hi Nami, I just read this and found it very helpful. Just wondering, do you also put ice pack in rice bento? Do you usually eat them cold? My child doesn’t like cold food and it’s quite a hassle for her to take the food out beforehand to let it adjust to room temp – also no space either. I still haven’t found the solution to this, hopefully you can help me 🙂 Thanks before
Hi Maya! I just found your comment when I came to respond to the comment below you. Somehow I didn’t see it until now. I am so sorry for my late response.
If it’s in a cooler place, you don’t have to put ice packs (when I was growing up, we didn’t have ice packs back then and we kept bento box wrapped in cloth etc). I usually pack a small ice pack underneath the fruit box, so fruits stay cool, but bento box has no direct connection to ice pack. Hope this helps!
I make bentos for lunch at school (because I don’t trust my family to make my lunch anymore) and our classroom is airconditioned most of the time so we get to keep our lunch there. I pack my bento in plastic inside a insulated lunch bag with an ice pack but I would like to keep my food warm for a change. Can I pack food hot in my bento?
Hi Avery! I pack hot food in a thermos jar.
http://amzn.to/2mPPr3m
I pour boiling water in the empty jar twice to make sure inside is super hot when I place hot food in it. My kids say it’s “warm” enough at lunch time. You won’t be able to keep the food hot in the regular bento. 🙂
Hi Nami,
Like to ask a question about use of cheese in bento. Can I use it straight out of the package onto bread? Or should I bake it after assembly to prevent it getting spoiled? I usually use Kraft slice cheese.
Many thanks,
Dawn
Hi Dawn! I recommend keeping your bento cool until you eat at lunch time. As you know, cheese “should be” kept in refrigerator. I think a few hours of “cool” place should be safe to consume, but I don’t recommend room temperature for a long time. Hope this helps! 🙂
Hi Nami! Thank you so much for posting all this info about making bento! I’ve been wanting to try making bentos, but the problem is the waiting time to let all the reheated food to cool down. I’m not much of a morning person, and I’d rather not have to wake up 2 or more hours earlier before classes just to make sure the food has cooled down enough so that I can pack it. So how long does it take usually for the food to cool down, and do you have any tips on making them cool down faster? Also, should I let the food cool down on a separate plate first before putting them inside a bento box, or should I just pack them all in the bento box while still warm, and just let it cool down without the lid on? Thank you in advance!
Hi April! I totally understand and I feel the same way. I use ice packs – place the bento box on top of ice packs and it cools faster. And It’s much faster if you cool down on a plate, then pack in silicone cup, then put inside bento box (while you put rice in the bento box and let it cool first). Bento box has “sides” that will retain heat, so if you are short on time, use plate to cool down. You can also prepare at night time too, as long as you can keep it safe till lunch time. 🙂
Before you pack cold/cool food in your bento box, hot/warm rice must be cooled down. It’s dangerous when hot/warm rice heat up other food halfway because bad bacteria would start growing.
Just wondering, to what temperature should the rice be cooled down to? Slight condensation in bento box pose any health risks? Thanks.
Hi Michelle! The bacteria loves the temperature 86-39F (30-40C) so you will need to cool down to below 50F (10C) to be safe with ice pack etc.
I would like to know if it ok to take a bento box to work frozen and then by lunch time it should be thawed to eat?
Hi Tasha! Does your work have an microwave or do you plan to eat just out of the box after begin thawed. Some foods works great like that. In Japanese bento menu, Tamagoyaki for example can be frozen and put it directly into lunch box and thaw to enjoy. However, some foods are not good without reheating. So as long as you pack foods that are good at frozen-thaw-eat process, it should be okay.
Hi! You must be tired of so many questions, but I have to ask: which are those foods that can be thawed to eat? I suffered a gastritis recently due to an infection of h. Pilory. I’m avoiding eating food from the street,and the only way I could carry my bento to the university would be freezing the food in the night and carrying out in the morning (I’ve been cooking my lunch in the morning, but it’s too much time consuming,and I’m afraid it won’t cool down completely before I close the lid)
Could you recommend some options for me? I mainly eat chicken breast, fish, eggs, rice (with vegs or plain), pasta and cooked vegs, and I’m really afraid of getting another bacterial infection 🙁
Ups! I forgot to add:
-I live in a tropical country
-I can’t get a proper bento box, but I have a lot of BPA-free plastic containers with air tight lids
-I don’t care about eating cool or room temperature food,as long as it’s safe
-I don’t have access to a microwave to reheat the food before lunch time
Thank in advance!
Hi Angie! No worries. I try my best to respond to questions when I have time. Since you live in a tropical country and the temp is relatively high (germs like warmer environment), I would really recommend re-heating your meal. BUT if you can keep your lunch cold till lunch time, you can pack at night, keep in the fridge, then bring to school. I can’t recommend homemade frozen food directly put inside bento and bring. In Japan we have some frozen food that you can pack in bento,etc. But those are flash frozen in a special freezer not home freezer (too slow). So bacteria might have grown. I mean you always want to take safe side, especially with your recent health condition. The best choice would be prepare at night, keep your lunch cold all times till your lunch time with ice pack etc. 🙂
Thanx! I’ll search for some recipes that I can eat cold.
Would a bottle of freezed water work as an ice pack?
Hi Angie! In general, gel-pack lasts longer time than own ice (and it gets wet around the bottle).
http://amzn.to/1rmo5TM
Hi Nami,
I like your blog and had try some of your recipes. thanks ya. Next I may want to try your bento recipes for my son in school, but before that wanted to ask if I prepared my bento in the morning say like 7am then only eat at 3pm, will it be too long? At here temperature is around 33 Celsius and it is humid. Thanks for your advise in advance.
Hi Michelle! Thank you for reading my blog! 33C with humidity, I’ll make sure to pack ice packs and it keeps the food safe. Ask your son if his lunch was “cool” when he opens. You can definitely bring lunch box, but you need to make sure it’s stored safely. 🙂
Hi Nami,
Thanks a lot for your advise and reply…
Why must the bento be interesting?
Hi Yaya! What do you mean?