Choosing the right olive oil can be a daunting task. Going to the olive oil section at your local grocery store can seem like shoe shopping at the sporting goods store — an entire wall of goods, all similar looking, and all advertised to be the best. But unlike shoes, you can't usually try out the olive oils before you buy them. And even if you could, what should you look for?
In this article I will provide you with a crash course on olive oil so you can reign supreme in the salad arena and be an envied oil know-it-all at your next dinner party.
A marketing mistake
Almost all olive oil you find nowadays come in clear plastic or glass bottles. The manufacturers have figured out that the average consumer is more likely to buy their bottle if they can see the product. But those beautiful amber and green lipids can be deceiving.
Let's go back to chemistry class for a moment — assuming that you took chemistry (if you didn't, just smile and nod) – olive oil is liquid vegetable fat from olives. A much closer look would reveal chains of fatty acids, and an even closer look would reveal chains of carbon and hydrogen molecules.
The problem is, that unlike water, these fat chains break up into smaller chains in the presence of oxygen – they oxidize. So when olive oil (or any oil) is exposed to oxygen, it begins to go bad and eventually becomes rancid.
Another problem is that light can also break it down. So as olive oil sits in a clear bottle, it's slowly breaking going bad. Depending on how long it's been sitting under the lights of the store, it could be bad before you buy it. And even if it's just a little rancid, once you open it and let oxygen into the bottle, the process of decomposition speeds up.
So, even though olive oil looks really nice, you should only buy it in a tin container so light has not broken it down, and unless you use an insane amount of olive oil every day and can go through a large tin quickly, you should buy small tins to lessen the amount of time the oil would have to break down in the presence of oxygen.
This article appears in Nov 17-23, 2011.