A good article on keeping leftovers. Other good advice: Keep hot foods hot and cold foods cold – the rule reads: Don’t let food sit out at room temperature for more than two hours – so store at <40 degrees F. or >140 degrees F. Some bacteria like E. coli can divide quickly. For example, the number of E. coli cells progresses from 1 cell to 2 million cells in a mere 7 hours. Their generation or doubling time is only 20 minutes, i.e., if you ate a hamburger with one pathogenic E. coli cell at 8:00 p.m. this evening, two cells would be present at 8:20 p.m. , 4 cells by 8:40 p.m. and 8 cells by 9:00 p.m. You get the picture – by 3:00 a.m you would have over 2 million cells under optimal conditions. For Staphylococcus aureus, another foodborne pathogen, the generation time is 30 minutes. So it becomes obvious that food storage is of utmost importance. Invest in a refrigerator thermometer – they are inexpensive and reassure you that your refrigerator is keeping the proper 40 degree F. temperature. I’m paranoid so I have two. Source: Jeffrey Pommerville, Alcamo’s Fundamentals of Microbiology, 8th Edition.