There’s just no getting around it: As soon as you take that lunch box out of the refrigerator and pop it in your satchel or your child’s school bag, the bacteria start to wake up, stretch and multiply. There’s almost always moisture in there, from the condensation and in the food. So there’s food, there’s warmth and rising temperatures. All the three things that stomach-upsetting or food-spoiling microbes love.
Can you stop them? Possibly not. Your child is unlikely to be able to nuke them: Indian schoolrooms don’t usually include a microwave. You can at work, if you work in a well-equipped office, but not all foods like being nuked. And you certainly don’t want to attack edibles or crockery with sterilizing fluids or by pouring boiling water on it all!
What you can do is slow bacterial growth, which might corral them within a low concentration range that your immunity can deal with.
Some like it hot
The best option for a hot meal is to make it too hot for pathogens to handle: close to boiling, above 75 degrees Celsius or so.
Also Read earlier columns on Food Factors
• If it can be heated before you eat, do so.
• If not, pack it in a hot insulated container while it is piping hot. Stand boiling water in the container for a minute to warm it through so that the food doesn’t lose heat to the vessel. Soups, dals and semi-solid foods (such as stews and khichdi) are particularly amenable to this.
Hint: If the food is lukewarm when you eat, you’ve either waited too long or the insulation isn’t good enough.
• To improve insulation, fill the container as much as possible and wrap in a napkin if you can. Or invest in a cooler bag (it works both ways).
Some like it cold
The other option is to keep food chilled, under 4 degrees Celsius ideally, but up to 10 degrees Celsius may be okay for most.
• Pack your lunch box the night before, wrap in a napkin and chill overnight. Remove just before heading out.
• Chill juices, yogurt, lassi, cold soups, most desserts, even fruits. The less time food spends in the danger zone of 4-60 degrees Celsius, the better, and if it has to melt before it can heat up, you’ve minimized that time.
• You can use the low temperature of frozen foods to keep other stuff cold. Alternate frozen and cool foods (a sandwich flanked, say, by frozen grapes and frozen yogurt). Just make sure you wrap up anything dry in plastic so any condensation stays on the outside.
Some you keep dry
Reduce moisture so your meal is less hospitable to germs.
• Biscuits and toast are less likely to spoil or cause problems than salads and creamy sandwich spreads.
• A more tasty trick is making things physiologically “dry” even if they are physically moist. In other words, putting enough sugar or salt to effectively “pickle” them will keep bad bacteria at bay. Examples are jams and pickles. Needless to say, you don’t want your child’s whole meal to be high-salt and high-sugar, but a peanut butter and jelly sandwich is safer than coleslaw.
• Keep wet and dry apart. Pack sandwich fillings and bread separately; the same goes for roti and sabzi.
Some you keep whole
• You can wash foods that come in their own natural wrapper (whole fruits and vegetables) before eating.
• Sterile packages are also a good idea—individual packs of yogurt or juice, sealed packets of nuts or dry fruits.
Don’t let it grow old
If you’ve not eaten it by the end of the day, either heat it through and consume as soon as possible or get rid of it. Do not put it back in the fridge for another day.
Manidipa Mandal is deputy features editor at Mint.