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11 Foods You Should Never Buy At Costco

From diamond rings to frozen pizzas to a year's supply of toilet paper, there's something for everyone at Costco. But that doesn't mean you should buy everything that's for sale.
11 Foods You Should Never Buy At Costco

Costco is one of America’s most beloved stores, and for good reason. Where else can you make a whole lunch out of free samples, purchase a diamond ring, and buy a rotisserie chicken for just $5?

Mainly, Costco is known for its bulk items: vats of mayonnaise, gallons of olive oil, a 16-pack of tuna cans. But as much as people love shopping at this members-only store, you shouldn’t buy everything in bulk. Even if you think you’re saving money at the moment—after all, those low prices can be pretty enticing—you’re actually losing it in the long run.

That’s because a lot of those bulk foods go uneaten and wind up being thrown away. A study in the International Journal of Consumer Studies found that low-income households waste more food than middle-income homes, due in part to bulk buying. It typically goes like this: We see something that’s a better value when bought in bulk, we get bored stiff of it and by the time we can stomach the idea of digging back into the pile, it’s either gone bad or lost its flavor or nutritional potency.

Make sure you avoid these common items bought in bulk. And to save even more money at the grocery store, don’t miss our essential list of the 46 Best Supermarket Shopping Tips Ever.

1 & 2

Nuts and Seeds

Nuts seem like one of those foods that never go bad, but that’s actually not the case. Even if they don’t grow mold or get freezer burn, they can still spoil. Both seeds and nuts contain a lot of oil, which comes from healthy unsaturated fats. Fats, healthy or otherwise, tend to go rancid rather quickly. Even if you store your seeds and nuts in an airtight container and keep them in a cool, dark spot (as you should), they’ll only keep for a couple of months. If you’re stuck with a mountain of macadamias or a hefty bag of hazelnuts, put them in airtight containers and store them in the fridge or freezer. This may extend their life to up to a year, which would be ideal since they’re one of the 29 Best-Ever Proteins for Weight Loss.



Even if spices don’t actually go bad, they do go stale rather quickly. Which is a huge bummer, since the whole point of spices is to, you know, be flavorful; and the more refined the spice, the more rapidly it will lose potency. Ground spices will start to get dull after just six months while spices purchased in a whole form—cumin seeds for example—have about a year. Although buying in bulk seems tempting for the price, people typically only use a pinch here and there, so buying large amounts isn’t necessary; they’ll go bad before you get to enjoy them all.



Eating lots of flour isn’t great for your waistline—getting rid of empty carbs is one of the 40 Things You Must Do for a Flat Belly—and it’s bad for your wallet, too. Flour, be it all-purpose, whole wheat, or another variety, attracts water. Although that makes it a great ingredient for thickening soups, stews, and sauces, it also means it soaks up moisture in the air. And the longer you have it, the more time it has to soak up moisture, and the closer it is to turning rancid. White all-purpose flour actually keeps longer than whole grain or nut flour—about a year versus a couple months—but unless you are cooking and baking with flour every day, you probably won’t go through a bulk size within the year. You can extend the life of flour by putting it in your fridge, but if you keep buying everything on this list in bulk, your icebox is going to get pretty crowded.



Coffee beans

Coffee is pretty cheap as it is, so there’s no real need to buy it in bulk. Plus, real coffee aficionados know that’s not the freshest way to enjoy a hot cup of joe. The freshest, best tasting cup of coffee is made from beans that have been roasted within two weeks of the cup being brought to your lips. If you value what your coffee tastes like you’re best off doing two things: choose a bag that contains as much coffee as you could get through in a week (or two), and avoid those giant barrels or bins of coffee altogether. We simply don’t know how long the coffee’s aroma and flavor have been sucked out of the beans and into the surrounding air.

6 & 7

Baking Powder & Yeast

While baking soda can last for a long time, baking powder is prone to attracting moisture — the same reason why flour goes rancid. Unless you are baking up a storm every day, it’s unlikely that you’ll go through your big tub of baking powder before it goes bad. Baking powder can only stay fresh and active for about six months to a year when stored in a cool, dry place. Dried yeast may still do the trick after six months, but the fresh variety will lose its mojo months sooner. Store fresh yeast in the fridge and dry yeast in the freezer for maximum shelf life.


Whole Grains

Did you realize whole grains contain oils? They’re found in the grain’s bran and germ and can cause them to go rancid quickly, just like nuts and seeds. Although the oils are removed during the processing (like white rice), they do remain attached to the grain and can cause them to go bad.



Your favorite condiments like ketchup, mayo, and mustard tend to be loaded with sugar, salt, and other preservatives. Despite this, they can still go bad. Even if they are “shelf stable,” they are slowly going bad. Family finance and frugal living expert Jordan Page advises you forgo buying an economy-sized vat of ketchup. “It almost always will go bad before you can go through it,” she says.



Since beef jerky is preserved with salt and other spices, you’d think it would stay fresh for a long time, right? Not quite. Jerky, whether it be chicken, beef, or turkey, needs to be refrigerated after opening. In fact, most jerky packages state to eat within three days of opening and store it in the fridge after that. But even in the refrigerator, jerky only lasts about a week or two. Unless you want to get fancy and vacuum seal it (in which case it can last up to two months), you’re better off sticking to the smaller packs.



Even if you’re someone who frequently cooks with oils and uses it as a base for sauces and dressings, it’s unlikely you’ll go through one of the bulk-sized vats in the 3-6 month timeframe that experts recommended you enjoy oil once it’s opened. And it doesn’t matter which type of oil you use: olive, sesame, canola, and peanut all start to go rancid at around a few months, even when unopened. Once a bottle is open, it only lasts between 1 and 3 months. Since, according to Bertolli, Americans only go through about one and a half 750-milliliter bottles of extra virgin olive oil a year, you likely won’t have to buy that much oil. Looking for inspiration to use your bottle of oil before it goes bad? Check out our 14 Popular Cooking Oils and How to Use Them.

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