Think that flour in your pantry is good after a year? Think again. Flour's lifespan is closer to half a year. It can go rancid or get infested by insects, and you don't want any of that in your baked goods. Make sure to store flour in a cool, dry place, as humidity exacerbates spoiling. Here's a tip: you can keep flour in the fridge or freezer to protect if from humidity!2
This is a biggy. People tend to assume spices last forever -- or if not forever, at least a few years. According to Karen Page, who wrote The Flavor Bible, spices only last between six and 12 months. While expired spices may not be harmful, they'll lose their strength and won't have the same impact on your dishes.3
You might assume that brown rice lasts indefinitely, but you'd be wrong. Brown rice only lasts between six and eight months. White rice has a longer lifespan, four to five years according to Eat By Date, and indefinitely, if stored properly, according to Good Housekeeping. Brown rice, however, can go rancid.4
Depending on the nut, you could be looking at a very short lifespan. Unopened nuts will last longer, depending on the kind. It varies from nut to nut, and if you're worried you're not going to get through all your nuts fast enough, store them in the freezer!
Buying cereal in bulk? Not so fast. Most likely your cereal will just go stale and not be harmful to eat, but it can go bad if stored in a humid climate and exposed to moisture.
You might want to toss that bottle of ketchup that's been in your fridge for years. It may still be safe to consume, but if the liquid separates from the solid matter, it's not going to taste great. Save your hot dogs and burgers!7
Certain Cooking Oils
Not all cooking oils are alike. While olive oil lasts up to two to three years, grape seed oil only lasts three months! Eat By Date has a complete list of different oils with their different expiration dates, according to where they're stored and if they're open or unopened.