It's not always obvious when food has gone bad.When it comes to fish, a strong "fishy" smell, surprisingly, is a sign it might not be good to eat.It's important to also be on the lookout for a shiny or slimy film covering your food.With more and more evidence revealing that expiration dates are not always correct, causing many of us to throw out perfectly safe food just because it has expired, it can be confusing to know if those frozen leftovers or that can of tomatoes is actually still safe to eat, regardless of a printed date or common misconceptions about eating expired food.There are plenty of obvious signs that an item in your pantry or fridge has gone badif it's stale, moldy, or smells sour or rancid, you know to toss it in the trash. But there are several subtle signs your food has expired that you might not even notice, but definitely should because it could unknowingly be dangerous to consume.INSIDER spoke with two chefs and a registered dietitian who gave us the scoop on the super subtle signs those kitchen staples have already begun to go bad, and some of them might surprise you.Check potatoes for a greenish tint.Potatoes are one of the most versatile veggies out there, and their sturdiness might have you believing that they last much longer than other items in the produce aisles. But once your potato takes on a slight color change, you might want to toss it."The green tint in potatoes is not from age," said Isabel Maples, MEd, RDN, a Virginia-based registered dietitian nutritionist and volunteer spokesperson for the Academy of Nutrition and Dietetics. "It comes from them being near the surface of the earth and being exposed to sunlight, causing a buildup of a compound called solanine."The greenish hue means your potato is beginning to go bad, but Maples said it can still be safe to eat. "Just peel off the green before eating the potatoIt can taste bitter and can cause illness if eaten in large amounts. As potatoes get older, their texture becomes less firm, sometimes wrinkly. They start growing sprouts at the eyes. Just cut the eyes out before cooking to eat. Eventually, potatoes do develop soft spots, rot and stink," at which point, they're past the point of no return.Vegetables will begin "sprouting."If your potatoes, peppers, or onions begin sprouting, it's time to toss them, according to Alisa Rosa, an executive chef, who notes that a good rule of thumb is: "If they have sprouted, they have gone too far.""Thin-skinned" fruits and vegetables will look slightly wrinkled or begin peeling.Those fresh fruits and veggieslike tomatoes, peppers, and berriesaren't so fresh anymore if they've developed wrinkled or peeling skin or have started to go soft and shrivel, according to Rosa."Natural foods are very good at letting us know when they are fresh and when they are beginning to start to decompose," she told INSIDER. "Decomposition is a natural process by which the product starts to literally go back to the earth. The tomato's job is to reproduce and it does this by decomposing and releasing its seeds back into the earth so that a new fruit may be produced. Though sometimes a little smelly and pretty gross to look at, if you think about it, it really is a perfect, beautiful processThe literal circle of life."If they've begun to "weep some moisture," they will need to be tossed promptly, according to Rosa, because this marks the beginning stages of mold growth.See the rest of the story at Business Insider Click here to read full news..