Why Some Leftovers Taste Better Than Others

Eating leftover food is a point of contention for many of us. On one hand, some claim excess food is no longer as tasty as its fresh version. On the other hand, some insist leftovers taste way better. Celebrity cookbook author Ina Garten doesn't like eating leftovers, but that doesn't mean you won't find her repurposing food surpluses at her home. Turning any excess into something different, like using leftover Chinese takeout to make fusion burritos, is a smart way to reduce food waste, and it prevents flavor fatigue, too. 

Interestingly, some dishes seem to taste decidedly better the next day, even if you don't repurpose them into a new dish. A good example is saucy curry, which tends to taste richer after a night in the fridge. If you are wondering why this is so, it all boils down to some nifty food science.

According to Dr. Kantha Shelke, a spokesperson for the Institute of Food Technologists and founder of food science and research firm Corvus Blue LLC, foods that taste better after staying in the fridge overnight commonly contain loads of aromatics, such as chiles, alliums, herbs, and spices. "Aromatic ingredients tend to undergo a larger number of reactions that produce flavor and aroma compounds, which in turn react with the proteins and the starches," Shelke explained (via Forbes). "In general, as the food cools and is left to sit in the fridge and then reheated, some of these reactions continue to take place, resulting in improved flavor."

Fresh ingredients contain volatile compounds, such as essential oils, sugars, and acids. Cooking causes their flavors to be in flux, as heat prompts different reactions, like the Maillard reaction and caramelization. However, once the dish starts to cool, another phase, which often gets overlooked, begins, and it involves resting and integration. As food sits either outside or inside the fridge, components responsible for flavors and aromas continue to move and interact. A good example is how resting ensures perfectly cooked steaks – the juices are given enough time to spread and penetrate every fiber of the meat.

Similarly, some foods taste better than others the next day because the spices, herbs, fats, and acids they contain have enough time to slowly break down and distribute more evenly throughout the dish. This is particularly evident in dishes with broths and sauces. After resting, the sauce tastes more well-rounded, and the aromatics can fully penetrate the meat and vegetables. 

It is worth noting that certain starchy components, like rice, pasta, and potatoes, can significantly change in consistency once they soak up more liquid from the broth and sauce. Foods with crispy textures, such as french fries, schnitzels, samosas, or tempura-fried vegetables, will also lose their crunch after a stint in the fridge.

At the top of our list of best leftovers are curries, stews, soups, and braised dishes because these foods have layered flavors. Overnight refrigeration will allow their spices, seasonings, and aromatics to combine thoroughly, giving you a richer taste the following day. Dishes with tomato-based sauces, like Bolognese and chili, come next, since the tomato flavor deepens. Casseroles and lasagna also tend to improve flavor- and texture-wise after a while. The same is true for grain- or bean-based salads that have had enough time to soak in all of the dressing.

However, there are some caveats since there are so many mistakes you can make with leftover food. Not putting them away fast enough is one common misstep that can be very risky to your health. The U.S. Department of Agriculture (USDA) recommends stowing away leftovers within two hours of cooking to prevent bacterial growth. Another mistake to avoid is waiting too long to eat your leftovers. The idea that the longer you leave them be, the better they will taste can be easily misconstrued. Leftovers only last three to four days in the fridge. If you can't consume them within the period, it's better to toss them in the freezer, where they can last for up to four months. Just don't expect them to taste the same or better at that point.