Why Thomas Keller Recommends Buying Olive Oil In Small Quantities

Savvy grocery shoppers the world over know that when it comes to snagging a great deal, it's almost always a good idea to buy pantry staples in bulk. That is, instead of buying small bags of rice, it's usually cheaper to choose a large one and simply store the rice correctly in order to preserve its lifespan — instead of reaching for the eight-ounce bottle of apple cider vinegar, you'll get more bang for your buck from the gallon size. Bulk products, after all, are the main attraction at buying clubs such as Costco and Sam's Club.

As explained by U.S. News, bulk items are usually cheaper in the long run — in spite of the larger upfront costs — because the items you'll get are less expensive per unit. If you buy a 12-pack of tuna cans, let's say, the cents saved on each can could add up to a few dollars worth of savings. And since bulk items utilize fewer packaging materials, it's also a more eco-friendly strategy. But when it comes to food items, not everything should be bought in larger sizes, something The French Laundry chef Thomas Keller knows all too well.

Olive oil needs to be used up quickly once it's opened

Have you ever gone to use one of your bottles of oil and noticed that it smells or tastes different than it did when it was fresh? That's because over time, as the oil is exposed to light, heat, and air, it goes rancid, tasting and smelling sour and musty, according to Live Science. While some oils have longer shelf lives than others — think peanut and palm (via Primal Survivor) — others go bad more quickly.

Delicate extra-virgin olive oil is one of them, per olive oil producer Brightland. Though an unopened bottle stored in a cool, dark place can last up to two years, once it's opened and starts to get exposed to air, that shelf life goes down to six months. That's why it really doesn't make too much financial sense to buy huge bottles of olive oil because you'll risk having to toss the product before you get through it.

Buying olive oil in small bottles is a tip chef Keller agrees with. "I encourage you to buy whatever you're buying in terms of extra-virgin olive oil in as small a container as possible," he told MasterClass. "This will help maintain the quality of the oil."