When do food items really go bad?

How do you know when something in cupboard or refrigerator has gone bad --or on the flip side --may look a little weird but is perfectly fine to eat?

It can be easy to know when dairy and meat products go bad because of “use by” and expiration dates. Also our nose knows when those foods go bad. It can be harder, though, with everyday items that many of us keep stocked in our homes.

There’s also the issue of flavor. While some products may not go bad per se, they may start to develop an odd taste.

Jay Weinstein, a culinary professor, at The Natural Gourmet Institute in New York City walks us through what to look for with some of the most popular items we have around our kitchens. Some of the answers may surprise you.

Oh, and get a garbage bag handy, you may be dumping a lot of things. The last thing anyone wants is to get food poisoning, especially when it can be prevented.

Butter

Salted butter has a longer shelf life than unsalted. After unwrapping, salted butter should last ten days in the refrigerator before its flavor is compromised. Within two weeks, a translucent layer develops indicating the start of rancidity. It could also have a cheese-like smell.

Eggs

While the Food and Drug Administration recommends refrigerating eggs, Weinstein points out bakers usually leave them out, and they can last up to a month that way. As for the FDA’s recommendation, the organization say fresh eggs are good in the refrigerator for up to five weeks.

Juice

Non-pasteurized fruit juice starts to spoil within a week of opening, even if it’s refrigerated. Consumers wouldn’t notice much at first, since it doesn’t take on the sour smell that milk or meat products do when they spoil. Eventually though, it will start to cause a tingle on the tongue, like soda. There’s nothing harmful about drinking it this way, it’s just starting to ferment. Most people don’t like that taste and discard it.

Coffee

Coffee starts to lose nuance of flavor from the moment the beans are ground. Coffee’s essential oils are air soluble, and dissipate quickly. Spoilage? That takes months. It’s only spoiled when its remaining natural oils go rancid.

Brown sugar

Despite the fact that brown sugar goes rock hard within a week no matter how many layers of zipper-seal bags you pack it in, the stuff will keep for years in that petrified state. If you own a microwave you can pop it in there for about 30 seconds to loosen it up or put an apple peal in there to keep it moist.

White sugar

Weinstein, author of The Ethical Gourmet jokes that “white sugar is so highly refined, it may have longer shelf-life than petroleum. I’ve never known white sugar to become spoiled, even stuff I’ve found in camping supplies from previous decades.”

Maple syrup

Maple syrup that’s been opened is susceptible to a mold spore that causes a powdery film to develop on its surface. The mold looks like cinnamon, and can give a mushroom-like undertone to the syrup. This may occur within three weeks of opening it, or might not appear for months.

Vinegar

Vinegar starts to let off sediments which settle to the bottom of the bottle within three months of opening. The problem is most pronounced with red wine and cider vinegars, but will happen with most natural vinegars eventually. Distilled vinegar won’t develop this problem. While the sediment clouds the vinegar and makes it unsightly, the taste isn’t affected. You can keep most vinegar for up to a year.

Olive oil

Most people use rancid olive oil most of the time. Even filtered olive oil starts to develop a rancid, cardboard-like smell after just four weeks of opening. Plenty of people open a bottle of olive oil and leave it in a cabinet for months, using it a teaspoon at a time. A lot of consumers think it’s supposed to smell dusty. Ideally it should smell like artichokes and freshly ground black pepper, or if it’s lighter stuff like the French, Tunisian or California varieties, it should smell like butter and tree fruit.

Vegetable oil

Processed vegetables oils keep for a long time before rancidity sets in. You could keep an opened bottle of canola oil for almost a year before you’d detect that dusty, cardboard-like odor of spoilt oil.

Peanut butter

Packaged peanut butter has plenty of preservatives to keep it shelf stable for over a year. Natural peanut butter starts to go rancid within three months. Putting it in the refrigerator slows but doesn't prevent the peanut oil from going bad.

Salad dressing

Mayonnaise-based dressings like freshly-made Caesar should be consumed within a week. Vinaigrettes hold quite well for up to two weeks, assuming that there are no fresh herbs in them.

Ketchup & Mustard

Both are heavily seasoned with vinegar and salt and keep well for about a year.

Flour

This one could be a shocking to a lot of people. Weinstein says “flour is rancid so often that most people don’t even know what fresh flour smells and tastes like.” The chef trained at the Culinary Institute of America says “it should be used within three or four weeks of opening, but most people keep it in their cupboard for years and still use it. Fresh flour smells sweet. Rancid flour smells like cardboard and dust.”

Honey

Here's one you can keep in your cupboard. While honey may crystallize it should last forever with the same great flavor and sweetness.

Jelly & Jam

Natural jellies and jams are perishable. Despite the preservative effects of sugar, open jams will start to grow mould or rot in about six months.

Dry pasta

Like beans, dry pasta contains a tiny bit of water content that helps it hydrate properly when it cooks. This ultimately can make the pasta go bad overtime, but it is likely that bugs would get to it first. It should be used within two years of purchase.

Rice

Wholegrain (brown) rice is more perishable than polished (white) rice. Brown rice should be used within two years of purchase.