How do you know if avocado oil went rancid?

[HowardLi]

I have a bottle I just bought, not yet past "best by" date, but it doesn't taste good. Should I return it or live with it?

[Chris Hennes]

Rancidity is typically a pretty easy smell to recognize, but it's hard to describe if you've never experienced it. Have you used this avocado oil before? Do you know what it's supposed to smell like? If it was exposed to high temperatures during shipping or storage, or was just mishandled, etc. it's certainly possible for it to develop some rancidity before its (somewhat arbitrary) "best by" date has passed.

[Lisa Shock]

Actually, oils can go rancid before humans can taste or smell it. (I add a little BHT to oil as soon as I bring it home and store it in the fridge. And, I buy small quantitites.) If it smells/tastes bad, then it probably is bad, whether rancid or contaminated. There have been some recent scandals involving oils being sold as one type, but actually being another type, some with chemical additives. I'd return it. If you buy more, avoid that lot number.

[Chris Hennes]

You might also want to read through this topic on rancidity: it's a specific type of spoilage that takes place over time. Oxidation begins the moment the oil is produced: at some point it crosses a threshold at which it can be tasted, and we call that "rancidity." We've also got this topic on Detecting Rancidity in Oil.

[weinoo]

I think if you're wondering whether it's rancid, it's rancid.

[Chris Hennes]

Well, it might just be nasty. I've had some olive oils that weren't rancid: they were just gross.

[dcarch]

It tastes like WD-40.

dcarch

[GlorifiedRice]

Consumption of rancid oils can prevent the absorbtion of or leaching out of Vitamin K from the body, Vitamin K is vital to blood clotting.

Just like rancid grains smell of crayons, rancid oils can also have a crayony odor.