Food waste is a huge problem in the developed world. Rich nations throw away perfectly good, nutritious food all the time-and by the millions of pounds. At home, it's important for us to do our part in stemming the tide of this type of waste.

Knowing how to store leftovers safely is one way we can reduce what we throw away.

Cookbook author Norene Gilletz is a big believer in saving food. She says a good rule of thumb for keeping leftovers is three to four days, maximum. And that's if the food has been cooked properly, cooled rapidly, not left on the counter for hours, not cross-contaminated and covered.

How to get the most from your leftovers
• Put food in the fridge or freezer as soon as it's cool enough not to cause condensation in the container.

• Use clean utensils for each dish and every time you take one last bite (because, the last bite is never really the last one, is it?). The enzymes in our saliva that get into the container will start breaking down the food -- literally digesting it -- in the fridge.

• Keep things airtight. Use lidded containers, tightly sealed plastic wrap or clean food-storage bags.

• Transfer leftovers from their serving dish or cooking vessel to a clean storage container. Why? Because while that serving dish sat on the table, it was exposed to microscopic bacteria growing at an exponential rate.

• Store different kinds of food in separate containers. For example, don't spoon the last of the potato salad beside the meatloaf. The salad is going to be eaten cold, so if any harmful microorganisms have jumped from the meat to the mayo, it may cause tummy upset. Pack meats together, dairy together, raw veggies together and so on.

• Dairy and meat tend to go bad faster than veggies, and fish goes bad even faster. If you don't think leftovers are going to be eaten as a midnight snack or in the next two or three days, pop them in the freezer.

Photography, iStockphoto.com.