Cooking

I can't taste the rancidity either. They say if olive oil smells like crayons, it's rancid; if it tastes peppery, it's good. I bought a bottle of the California Ranch brand everyone says is reliable. It smells like crayons and tastes peppery just like every cheap bottle I've tried

I read an article once that suggested that rancidity is something you learn to pick up on and that the inclusion of certain preservatives such as hydrogenated oils in US foods means a lot of us have lost the ability to detect rancidity vs people in other countries that don't use these preservatives and food has a shorter shelf life. It took me a very long time to recognize what rancidity smells like, but now that I do, I can smell it in a large variety of items. I've smelled it in dry cereal, corn chips, nuts, oils, etc. sometimes it's stronger and more obvious and other times it's faint. It can have a slightly different smell depending on what's rancid, but that base smell always seems to be the same. Here's my suggestion, and it may sound weird... Go to a Mexican grocer or local Mexican restaurant and get some tortilla chips that they fry in house. Put them in a paper bag and leave them somewhere and forget about them for a few months. When you open the bag again, you will get the strongest whiff of rancidity you've ever experienced. Hopefully you'll know after that, what to lookout for. I don't know what it is about fresh tortilla chips, but damn they get rancid in the worst way 🤮

I think it depends on the oil/fat. I think the word "rancid" conjures up the idea that it would taste like pure garbage, but that isn't really the case. What you are tasting is oxidation (and technically some other reactions, too), and not all flavors of oxidation are "bad" flavors. Sherry, for example, is partly defined by the oxidation.

Most "refined" oils (e.g., soybean, peanut, canola) are going to be fairly resistant to oxidation because they don't have many compounds that oxidize easily. Something like extra virgin olive oil or flaxseed oil, though, has a lot of compounds that can oxidize. That's why some oils come in opaque containers, and warn you to keep them away from heat. Some, you even need to refrigerate. If you did side by side testing, you'd probably pick it up. Oxidation is one of the reasons you get rid of old fry oil; the heat speeds up the reactions.

Whole wheat, I can definitely detect the difference, and I've definitely had rancid avocado oil before. Nuts, I'm not sure about, but I think the flavor of an oxidized nut wouldn't really be bad, just not as good.

The taste of oxidation is often described as "wet cardboard", which I agree with for a lot of things. "Fishy" is another word I've seen for oil that's gone rancid

You know, when I used to go to stores that sell various fancy imported olive oils-- in bottles, I haven't tried the bulk bring-your-own-container ones-- I so often found the oil already rancid that I've just stopped going and wondered how they do business. But, now I wonder if it's like so many things where some people are just less sensitive to the flavor. I have to say, in oils it it's never so bad to me that I refuse to cook with it, but to drizzle it on salad or bread 'raw' would be gross. In nuts, it can really put me off, though, especially if the nuts seem stale in other ways. I'm also not a big fan of nuts generally, though. Rancid butter is another thing and I'll just throw it away. Happens at my parents' all the time because they don't refrigerate it and they live in a warm climate. My mom doesn't care about rancid butter but will complain all night about rancid olive oil if you put it on her salad. So I guess it's complicated. Or just kind of on the edge of being yucky, so other factors can take precedence.

Butter too. Supposedly when it changes color it’s going rancid but it just tastes like butter

I understand what you are saying, I don't know that I taste it, even in the same batch that others do. My thoughts are it comes to experience. I don't use olive oil, or butter, alone, just in cooking, but if I sample it, it always tastes fine. But with tea, then ya, it was too hot water, or over steeped. But I do drink a lot of tea. Maybe we both could benefit by going to some tastings. And bring some rancid oil with us to compare? Not sure how popular we would be ☠️