Cooking oils and their diverse uses
Ever stand in front of the cooking oil selection at a market, trying to parse which out of the many oils available you should buy? Or, do you give up from the start, just grabbing whatever is on sale, whatever brand you know, whatever you vaguely remember someone telling you is a “healthy oil”? Well, this post is for you. But mostly it’s for my mom, who never understands why I always insist on using “expensive oil” for stir-frying.
Why shouldn’t we default to using a “healthy” oil, like olive oil/EVOO, for everything? The short answer has to do with its smoke point, which at only 375’F (according to this semi-official Serious Eats page) is relatively low compared to other oils. When an oil’s smoke point is crossed, chemical reactions turn this originally healthy oil into a carcinogen-laden oil. For many “low and slow” cooking techniques this doesn’t matter so much, but for stir-frying (typically 350-400′ F) and roasting (375-425’F) knowing the smoke point of your oil can create the difference between a perfectly browned (Maillard reaction-ed) meal, and burnt anti-vitamin veg.
Now, for use cold – say, in a salad dressing – because we’re not working with heat, any old oil should be fine, right? Theoretically, yes. But, technically, if you’re interested in a long answer, heck no. Not all oils are created equal because of two factors: types of oils, and qualities of oils within these types.
Let’s talk about types of oils first. Most people can smell, let alone taste, the difference between olive oil and sesame oil right away. Good olive oil is essential for creating a classic Mediterranean flavor profile, while sesame oil is a staple flavor in most Asian recipes. But beyond their regionally specific flavors, these oils also have different properties – those of the plants they’re squeezed out of. This means that olive oil is more cooling, and like the olives it derives from, slightly benefits the (Chinese physiological notion of the) liver and the eyes. Sesame oil is in contrast slightly warming, and like black sesame seeds, both somewhat lubricating (good for constipation) and known for “keeping the hair black,” meaning minimizing signs of aging.
The properties plant oils are as diverse as the plants themselves. Sunflowers are quite tall, soaking in the sun’s warmth in the height of summer. Thus sunflower seeds are thought to have a very yang (warm/active/sunny) nature, making them good to take in winter, to balance the cold/dark/stillness of the season. Soybeans are bland and good for digestion, making this theoretically a good general use oil. But, here we must detour out of the delightful land of Chinese dietetic theory, and into the thornier terrain of modern agricultural realities.
Soybeans are cheap and easy to grow, and because of their high protein content they are a very popular crop worldwide: not just for oils, soymilk, tofu, and edamame, but dominantly as an animal feed. This popularity of the crop goes hand in hand with mono-cropping (because who doesn’t want to maximize profit by planting of much as one thing as you can sell? this is basic capitalism). But mono-cropping often leaves plants very vulnerable to disease: fungus, invasive insects, weeds, whatever. To protect the investment of their cash crop against these dangers, then, farmers do what any rational capitalist would do, and seek out protection against them, mostly in the form of chemical pesticides such as glyphosate (Roundup), and atrazine. This is honestly a super complicated topic that has been made more complicated by a deeply entrenched “organic vs conventional,” “GMO vs non-GMO” binary that, like so many binaries, are ultimately misleading. But, this is a post about oils, not modern agriculture and labeling, so rather than run-off on a long “pesticides, GMO, and organic tangent” here, I’m going to save that for another more detailed post (don’t assume it’s as simple as “organic = good” please). Suffice it to say, people with food intolerances, irritable bowel, chemical sensitivities, etc, should probably consider the possibility of some of their reactions being triggered by the type of oil their food is cooked in – as much as they consider the foods themselves.
Once you’ve determined what type(s) of oils you need for your preferred methods of cooking, the last thing to consider is quality within that type. More refined oils often offer an increased smoke point, making them more versatile and less gritty. Blended oils are substantially cheaper than “pure” oils, but buyer beware, there is a lucrative market for “faked” fancy oils, so it’s important to do some sleuthing (i.e. carefully read the label) before you buy.
The location something is produced is often a good indicator of its quality. For instance, Spain and California are both known for producing olives; in contrast Italy is a net importer, and thus a lot of cheap/blended olive oils will be distributed by (not grown by) Italian companies. According to the Epicurious article above, Australia and Chile both have stringent testing standards; likewise, years of purchasing sesame oil has taught me that certain Japanese brands seem “fresher” (better flavor, no off-taste) than cheaper brands produced elsewhere.
And unfortunately my general awareness of problems with counterfeit food items (entire brands of spices, sauces, melamine in milk) means that as passionate as I am about Chinese medicine and food culture, I’m really, incredibly cautious about the consumables I buy that are produced in China: historical achievements don’t override the present realities of market-capitalism with Chinese characteristics. That said (and to pre-emptively stop anyone who somehow thinks the above statement makes me racist), for similar reasons I’m also hella skeptical about certain types of food produced in the U.S. (especially meat and dairy, omg), but, that’s a topic for another post.