Keeping leftovers to eat at a later date is an excellent way to save money and reduce waste. It makes eco-friendly common sense to preserve excess food than to send it to the landfill. However, food that is incorrectly stored can become a health hazard and can lead to foodborne illnesses. It's extremely important for commercial kitchens and home cooks to be aware of the methods of proper storage of leftover food.
Proper storage begins with the refrigerator. It should be set to less than 40 degrees Fahrenheit as bacteria grows at temperatures between 40 and 140 degrees.
The refrigerator should be organized to avoid cross-contamination of food as well. Leftovers, like fresh foods, should not be stored underneath raw foods that can leak. Leftovers are also best stored in containers that are labeled as to the date they were stored.
Leftovers should always be placed in the refrigerator within two hours from when they were served. In warm weather this time should be reduced to one hour. Never leave food out to allow it to cool before placing it in the refrigerator. It's not necessary. Using shallow containers will allow the food to cool more quickly.
There are general time frames of how long food should be stored. While cooked meat, seafood and sauces should be used within two days, most others can be consumed safely within three to four days. Any food with mayonnaise should be eaten within a day as this spoils quickly. Some foods can spoil faster, and relying on the smell test is never a safe option. Tasting food for freshness is also not recommended.
If you do not intend to eat leftovers within three to four days maximum, it's best to freeze them immediately. When reheating leftovers an internal temperature of 165 degrees Fahrenheit should be reached to kill any bacteria that may have grown. Slow cookers are not recommended for reheating as they often do not reach the proper temperature. Remember that all food stored in the refrigerator should be properly sealed, either in a container with a tight fitting lid, or in a container covered with plastic wrap to seal the edges.
Most importantly, remember the first rule of leftovers is always 'if in doubt - throw it out'.