Just Bento

In most cases, your bento lunch would have been sitting around for several hours by the time you open it. There are some precautions to take if you don’t want to get sick from eating it, which is not fun to say the least.

Thoroughly re-heat then cool any cooked food before packing

Using leftover and pre-cooked food reduces the time needed to assemble your bento in the morning. But the longer food has been lying around, even in the refrigerator, it gets less fresh and edible. Re-heating cooked food helps to kill off any micro-organisms that may have started to grow.

The best way to re-heat things in my opinion is in a pan, rather than the microwave, because the surface is where the microorganisms are likely to have formed, and the high heat of a pan will kill those off immediately. This is particularly important with meat.

I know that it may seem like a bother to re-heat already cold food, but I believe it to be a necessary step. Japanese bento books recommend this also.

Don’t use raw or undercooked fish or meat

You’re probably not going to be carrying a steak tartare to work for lunch. But you might think about sushi. Don’t. Raw fish is not safe unless it’s eaten immediately. If you have leftover sushi from the night before, throw it out or cook the fish if you must. (Yes you might have been ok eating leftover sushi, but you were lucky.)

Sushi that uses cooked or preserved foods (egg, boiled shrimp, broiled eel (unagi), vegetables like kanpyou (dried gourd strips), pickles) is ok, though always use caution. Futomaki, the colorful big pinwheel sushi, usually only uses cooked items so is usually ok. There are also special sushi varieties that are meant to be long-keeping, such as saba zushi (marinated horse mackerel that is pressed onto a log of rice), but you rarely see these outside of Japan. Sushi rice itself keeps fairly well, due to the vinegar and salt that flavors it.

Some meats, like beef, may be tastier when they are undercooked in the middle, but for bento purposes you must cook them through thoroughly.

Avoid very moist or undercooked proteins in hot weather

Undercooked meat is not safe, and neither is undercooked or raw fish. But undercooked or moist protein of any kind should be avoided when the weather is hot. Plain tofu, for example, that hasn’t been cooked through thoroughly, can be unsafe, and should be reserved for the cooler months. Or, use an icepack or other cooling device for safety. (Most tofu recipes on Just Bento will be totally cooked through, so are safe. For simple stir-fries and so on, I prefer using fried tofu over plain tofu because of the lower initial moisture content.)

Conversely, don’t use bad tofu that is bad in the first place. I have tasted so much bad tofu at various restaurants, and even in people’s homes. If the tofu smells or tastes sour or rotten or ‘off’ in any way, it should be tossed. To keep tofu that’s been opened fresh, totally immerse in fresh water and seal completely. Change the water at least once a day.

Tamagoyaki, the slightly sweet Japanese omelette, is a bento staple. But to be really good it has to be slightly moist or undercooked in the middle. So, be sure to use fresh eggs, and to cool it down before packing into the bento box.

Home made mayonnaise is delicious, but should be used with caution, in foods like tuna salad. Commercial mayo has all kinds of preservatives in it that we’d rather not think about, but do keep our tummies happy. (See freezing tuna salad.)

Keep cool foods separate from hot

Remember the McDLT? The gimmick with that burger was the two-part styrofoam container, with one side for the lettuce and tomato, and the other for the burger and bun. (Here’s an old commercial for the McDLT featuring Jason Alexander, who played George Costanza on Seinfeld.) There was logic behind this rather environmentally unfriendly packaging. Any foods that should be kept cool, such as raw fruits and vegetables, should be kept in a separate container from the cooked foods, even if the cooked foods have had a chance to cool down. This will keep veggies fresh and crisp.

In hot weather, pack an ice pack with the cool food.

Try to only use freshly cooked or frozen rice

Plain rice can actually go bad pretty fast, since it’s so moist. It can also become inedible quite fast if it goes a bit dry and hard, especially in the desert-like atmosphere of a typical refrigerator. This is why a rice cooker with a timer function is a very useful thing to have.

If you do cook rice the day before, make sure it’s wrapped up completely before storing in the refrigerator. If you want to keep rice longer, it’s best to freeze it. You can carry the frozen rice as-is in a block (especially in hot weather), or heat it through completely in the microwave or by steaming, and cool down completely.

If you live in a very warm and humid climate, you may want to consider carrying rice in the form of sushi rice or as well-salted onigiri only in the summer - or with umeboshi (see below).

Certain foods that help keep things fresher

Traditionally, umeboshi (pickled plum) has been used in bentos and as onigiri filling. The traditional hinomaru bento, a bento box filled with white rice sporting one, lone umeboshi in the middle, is a very good keeper. (Incidentally, the logo and favicon for Just Bento are inspired by the hinomaru bento.) Umeboshi may have antimicrobial qualities, as do (supposedly) shiso leaves.

Wasabi and ginger may also help to keep things fresher. Try using wasabi to flavor vegetables (example: broccoli with wasabi sauce), or tucking some pickled ginger in the corner of your bento.

Salt is a time tested preserver, so the salt you put on the surface of onigiri is not just for flavor - it’s to keep the rice fresher longer.

Vinegar is also a preserver. Salty or vinegary foods keep longer than foods with little seasoning. Sushi rice keeps better than plain rice because of the vinegar, salt and sugar.

Wash your used bento containers and implements completely

A no brainer perhaps. But don’t try to re-use an unwashed bento box or Mr. Bento dish! Wash and dry everything thoroughly before you use them again. The same goes for any eating utensils, such as chopsticks, forks and spoons, and picks, and all the cooking implements you use to prepare your bento.

Be careful of tasting while cooking

Did you know that you can contaminate food by tasting it? Example: if you dip a spoon into a pot of soup, taste from that spoon, then put the spoon back in to the pot, you’ve added whatever germs are in your mouth to the soup. This may not be a big deal if you’re eating the food right away, but if you’re going to be carrying it around for a few hours you want to be extra cautious. If you do need to taste while cooking, don’t use the utensil you put into your mouth back into the food.

Don’t forget about your hands either! Don’t use your fingers to pick up food and put it in your mouth while you’re making onigiri for example. And of course, you should wash your hands thoroughly before handling any food.

Try not to overhandle the food

If you are a budding cute bento charaben artist, be careful of overhandling food that you are bringing for bento, especially in hot weather. Try to avoid using your hands as much as possible. (If you need to practice your decorative bento skills, you may want to consider eating the results immediately. There’s no rule that says rice shaped like Totoro has to be only be eaten for bento!)

Conclusion: Be safe, not sorry!

My aim is not to scare you off of making bento lunches by any means. But it’s better to take just a few commonsense precautions. Bentos should make you healthier, not sick!