Sunflower Oil – The Quick Spoiler That Deceives Many
Sunflower oil might seem harmless sitting in your pantry, but this popular cooking oil has a sneaky habit of turning rancid faster than you’d expect. Exposure to air leads to oxidation, which can make the oil go rancid. Keeping sunflower oil at a consistent, cool temperature can extend its lifespan. Fluctuations in temperature can accelerate spoilage. Sunflower oil is rich in polyunsaturated fats, which break down more quickly over time when exposed to elements like light, oxygen, and heat. Sunflower oil should last up to two years when sealed, or one year after opening when stored in the pantry (or 1-2 years opened in the fridge). Opened sunflower oil should last up to a year at room temperature and 1-2 years when stored in the fridge or freezer. Once you notice that telltale bitter taste or that funky smell reminiscent of old paint, it’s time to say goodbye to your bottle.
Canola Oil – The Rancid-Prone Darling Of Modern Kitchens
Canola oil is also prone to rancidity from the refining process and is often rancid before it even reaches store shelves. Canola oil is largely used in cooking, frying, and in process foods, but since it contains a considerable amount of PUFAs in addition to often being rancid, this only heightens its inflammatory effects. What makes this even more frustrating is that canola oil’s heavy processing creates a product that’s already compromised before you even buy it. Once opened, vegetable oil typically stays fresh for about 12 to 18 months, although it can vary depending on the type of oil and storage conditions. For instance, canola oil may last about 6 to 8 months, while corn oil can last up to 1 year. The oil’s high polyunsaturated fat content makes it particularly vulnerable to oxidation when exposed to heat, light, or air. Think of it like leaving a peeled apple on the counter – the breakdown happens whether you can see it or not.
Corn Oil – The Oxidation Champion That Spoils Surprisingly Fast
Some oils have more carbon-carbon double bonds than others, meaning they will probably spoil more readily. So, in a three-way contest among three oils she randomly picked, corn oil will likely spoil fastest, canola oil next and olive oil last. Corn oil’s molecular structure makes it a prime candidate for rapid deterioration, especially when stored improperly. These bonds can be broken by oxygen in the air. This carbon-oxygen bond can lead to a number of products, including an aldehyde, ketone or carboxylic acid. Some of these products have rancid odors and tastes. Corn oil can last up to 1 year. But here’s the kicker – that timeline assumes perfect storage conditions, which most of us don’t have in our kitchens. The moment you notice your corn oil developing a sharp, metallic taste, it’s already game over.
Walnut Oil – The Delicate Beauty That Can’t Handle Heat
Unsaturated fats like olive, avocado, palm, macadamia, walnut, fish and flax oil should be kept in a cool, dry, dark place as they are oxidized by light and heat. For example, don’t keep them near your stove/oven but rather in a place with a more consistent temperature. Also keep the lids on them tightly whenever they are not in use. Walnut oil is particularly finicky because its high concentration of omega-3 fatty acids makes it extremely sensitive to environmental factors. Think of walnut oil as the vampire of cooking oils – it absolutely cannot tolerate light or heat without breaking down rapidly. The more saturated a fat is the less prone it is to becoming oxidized from light and heat exposure, the less likely it is to go rancid. The less saturated they are the more prone they are to breakdown with light and heat. Unlike more stable oils, walnut oil can develop an unpleasant bitter taste within weeks of opening if not stored properly in the refrigerator.
Flaxseed Oil – The Health Superstar With A Ticking Clock
The body cannot efficiently convert the ALA in flax oil to the active, highly beneficial EPA and DHA fatty acids found in fish oil. That said there no reason to avoid flax oil as it is part of a healthy diet. I do recommend only using it as freshly ground flax seeds because bottled flax oil and the oil in pre-ground flax tends to go rancid quickly. Flaxseed oil is essentially the speed demon of oil spoilage – it can turn rancid in as little as six weeks after opening, even when refrigerated. The high levels of alpha-linolenic acid that make this oil so nutritionally valuable also make it incredibly unstable. You’ll know your flaxseed oil has gone bad when it develops a fishy smell that’s impossible to ignore. I’ve read all the stuff about flaxseed oil, but couldn’t get around the smell. For vegetarian oils, flax, safflower and sunflower seemed to have worked well for us in the past. She recommends flaxseed oil. Many nutrition experts recommend buying flaxseed oil in small quantities and keeping it in the freezer to slow down the oxidation process.
Safflower Oil – The Misleading “Stable” Option
Safflower oil gets a lot of praise for being a “healthy” cooking oil, but it’s actually quite vulnerable to spoilage due to its high polyunsaturated fat content. My personal, unsubstantiated experience, picked up from a similar question, is that safflower oil is the best thing in the world so far to season any kind of cast iron. I won’t use anything else now. The difference between what safflower oil will do to for your Dutch Oven and what other oils will do is remarkable. While some people swear by safflower oil for certain applications, its shelf life tells a different story. Monounsaturated fatty acids are found in olive, canola, and sunflower oils. Polyunsaturated fatty acids are found in sunflower, soybean, and cottonseed oils. The oil’s light color and mild flavor might mask early signs of rancidity, making it easy to use spoiled oil without realizing it. Once opened, safflower oil typically lasts about 6 to 12 months under ideal conditions, but heat and light exposure can cut that time significantly.
Avocado Oil – The Expensive Disappointment That’s Often Pre-Rancid
Here’s a shocker that might make you reconsider that premium bottle of avocado oil: They discovered that 82 percent had gone rancid before their expiration date, or had other, cheaper oils mixed into the bottle. They discovered that 82 percent had gone rancid before their expiration date, or had other, cheaper oils mixed into the bottle. Researchers found that nearly 70% of private label avocado oil is rancid or adulterated. Cheaper avocado oil was more likely to be tainted with other oils. Even when you buy authentic avocado oil, Even pure avocado oil will go bad around six months after opening, especially if it isn’t stored correctly. Store it in a cool, dark place, such as a cabinet away from the stove. It starts to smell stale, sort of like play dough. The oil’s popularity has outpaced quality control measures, meaning many bottles on store shelves are already compromised before you even get them home. What makes this particularly maddening is that you’re paying premium prices for what might essentially be expensive rancid oil.
