To dr refer study food goes bad. Toss or not to toss: Exactly when leftovers become trash has fueled arguments of couples, roommates and co-workers since the dawn of the refrigeration.Does moldy bread go in the trash, or just get a trim around the green spot? Can Sunday's leftovers be Friday's meal? What about that day-old ground beef? Bread Ever wonder why that wonderful fresh loaf you bought at the bakery grows mold in a matter of days, while the grocery store variety can last for several weeks? The difference is preservatives, which can greatly extend the shelf life of mass-produced bread. But you also play a role in how long bread survives in your kitchen. In order to lengthen the shelf-life of bread it should be stored in a reasonably air-tight container,recommends Ira Allen, a spokesperson for the Food and Drug Administration (FDA). Humidity will also create a prime environment for bread to mold, so try to store bread in a dry place if possible. Cheese When it comes to...