Why Leftovers Dry Out When You Reheat Them, and How to Stop It

Heating food from yesterday may be an easy task to do, but many would know for sure that it is not that easy, since it ends up being rubbery, hard, or dried out. Though most people would think that it has to do with their microwave or heating the food too much, food experts would point out that there is a whole lot more to this.
Knowing how food reheats will be essential in preserving its quality and even its safety.

Why does reheated food often taste different

Reheating food may affect its taste due to some chemical reasons.

According to a study carried out by Food Chemistry, the heating of meats, particularly under high heat conditions, may increase what researchers have described as “warmed-over flavor,” which means stale, cardboard, or even somewhat rancid taste of cooked meat when left for some time before being reheated. This is said to occur because of the lipid and protein oxidation, which is when chemicals degrade proteins and lipids, creating substances that make the meat lose its freshness.

The taste of foods containing proteins such as beef and chicken changes more drastically when reheated multiple times or aggressively. It is for that reason that reheating foods on maximum settings makes them drier and less tasty.

Heat doesn’t move through food evenly

The other reason for food becoming tough and rubbery during reheating is non-uniform heating.
Not all parts of the food warm up evenly when reheated. The outer parts get heated faster than the interior, resulting in dried-out edges but cold interiors. This is most common in microwave ovens.
Drying kinetics refers to the movement of moisture inside the food product as the food is heated. Studies reveal that as food gets heated, moisture starts moving from the interior toward the surface. Excessive loss of moisture leads to food developing a tough, dry, chewy, or gritty texture.

Covering food can make a difference

Even something as basic as the choice of container will make a difference for leftovers.
According to research reported by the Processes journal, the choice of container impacts both the evenness of heating and moisture retention. The most effective containers are covered, as their ability to trap some steam but allow it to vent at least to some degree decreases evaporation and prevents the drying of food.
From practical experience, the use of a lid or a moist paper towel will result in steam formation, keeping food moist and ensuring even heating. Another useful measure is the stirring of food halfway through the process of reheating.

High heat is not always better

Most people believe that heat is good since it allows you to warm food quickly. However, science says the opposite.

Although extremely high temperatures allow you to warm food faster, they might be too much for your food, causing it to get overdone and lose its flavor. For meat, some water, broth, or sauce sprinkled on top can improve its condition considerably. As for rice or pasta, even just one spoon of water will make wonders after you warm it with a lid on.

Reheating food in an oven seems effective if it was baked, while a stovetop would be the best choice for warming soups and stews.

Food safety still matters

While quality is essential, safety should always come first. According to the recommendations provided by the U.S. Department of Agriculture, reheated foods should reach an internal temperature of at least 165°F. The use of a food thermometer is highly recommended when dealing with foods rich in meat or other products that require thorough heating.

In addition, the U.S. Department of Agriculture suggests storing leftovers in a refrigerator for two hours after preparation, or within an hour if the temperature exceeds 90°F. The use of shallow containers allows leftover foods to cool faster.
Reheating leftovers in a slow cooker is another common mistake that food safety specialists strongly discourage.

Better leftovers come down to technique

Reheating is not about heating up your food but rather about controlling moisture, heat, and time.
Heat your food using medium heat. Keep food covered to retain steam. Stir as much as possible. Moisturize your food when necessary. Lastly, ensure that you heat up your food completely.
Just because something is leftover does not mean that it will automatically be dry and tasteless. It actually takes just a few science tricks to ensure that the leftovers end up tasting like a whole new meal.