Though reheating food might seem to be the most convenient way to devour your leftovers, not everything is meant to be reheated and consumed. This is due to the fact that some foods change their composition, lose their nutritional properties and even become toxic when reheated. However, it’s not just the reheating process that causes the problem but the way the food has been stored before it was reheated is equally important.
Harmful microorganisms which can cause various illnesses can grow exponentially and spread in perishable foods within two hours unless the food is refrigerated. If the temperature of the food is 90 ˚F or higher, it may take less than an hour for the microorganisms to grow at dangerous levels. Bacteria can spread dramatically faster at temperatures between 40 °F and 140 °F, so chilling food safely and following proper food storage methods becomes imperative to reduce the risk of foodborne illnesses.1
What Happens To Food When You Reheat It?
Foods should not be reheated for varying reasons. What happens to the food while reheating depends on the kind of food. Reheating foods high in protein will actually change the composition of the protein in the food. This can change the flavor of the ingredient, destroy the health benefits of the food and can even cause severe digestive problems. Foods can lose their nutritional value and can also become toxic when reheated. 2
Reheating food can assist in the growth of the toxin producing/food poisoning bacteria. These microorganisms can multiply rapidly when chilled food is reheated to temperatures above 5ºC. They will stop multiplying when the food reaches 60ºC. The longer it takes for food to reheat to 60ºC the greater the number of bacteria that may be in the food.3
What Does Ayurveda Say About Reheating Food?
Ayurveda doesn’t approve of reheating food because the energy and the good properties of the food are lessened and the oils are affected. People with mucus congestion, the kapha type, are particularly cautioned not to reheat food.
Foods That Should Not Be Reheated
Chicken/Mushrooms
Reheating chicken and mushrooms will actually change the composition of the protein which can lead to severe digestive problems on consumption.
Rice
Rice is a common leftover item, but you can get food poisoning after re-heating it.4
Spinach, Beets, And Celery
These vegetables possess high levels of nitrates. When these vegetables are reheated, these nitrates can become harmful to the human body. If you have leftovers with any of these three ingredients, either eat it cold or remove the nitrate offenders prior to reheating.
Potatoes
Potatoes can become toxic and they lose their nutritional value on reheating.
Tips To Reheat Leftovers Safely
Ideally, cooking only so much that one can eat is the perfect suggestion but most of the time you can’t estimate how much you will eat and thus the leftovers. Therefore, here are some tips that can help you keep your family safe from food poisoning at home.
Cool Food Rapidly
To prevent bacterial growth, it’s important to cool food rapidly so it reaches as fast as possible the safe refrigerator-storage temperature of 40° F or below. To do this, divide large amounts of food into shallow containers. Hot food can be placed directly in the refrigerator or be rapidly chilled in an ice or cold water bath before refrigerating.
Wrap Leftovers Well
Cover leftovers, wrap them in airtight packaging or seal them in storage containers for storage in the refrigerator. Immediately refrigerate or freeze the wrapped leftovers for rapid cooling.
Store Leftovers Safely
Leftovers can be kept in the refrigerator for 3 to 4 days or frozen (0° F or below) for 3 to 4 months. Although safe indefinitely, frozen leftovers can lose moisture and flavor when stored for longer times in the freezer. Find out how long to store leftovers by checking out this Safe Storage Times chart.5
Reheat Leftovers Thoroughly
When reheating leftovers, be sure they reach 165° F. Always use a food thermometer to check the internal temperature of the food.
Cover Leftovers to Reheat
This retains moisture and ensures that food will heat all the way through.6
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