Vegetable oils are undeniably useful in the kitchen, whether you’re a master chef or a novice. Cooking oil is a cornerstone of any well-stocked pantry. Since vegetable oil is something every kitchen tends to have at all times and lasts so long, it’s possible to overlook when it’s no longer fit for consumption.
It’s not uncommon to stumble across a partially used bottle of vegetable oil. Given that cooks are known to reuse cooking oil, even after frying with it, one might be tempted to reason that, since it’s relatively shelf-stable, it probably doesn’t go rancid. Think again.
Vegetable oil, like anything, eventually goes bad. Let’s determine how to tell when that mystery bottle has passed its prime and how to keep it going as long as possible.
If you’re curious about how long a bottle of vegetable oil can last, you’re in the right place. But before we answer the question “does vegetable oil go bad,” let’s clear up some common confusion with the widely used umbrella term itself.
What Is Vegetable Oil?
To understand the storage and expiration of vegetable oil, let’s first look at the term itself and what it encompasses. Vegetable oils make up a wide variety of oils, some of which are seed or fruit-derived.
The list of vegetable oils is long and includes a variety of popular cooking oils, like avocado or canola oil, plus some more novelty-type items, like poppy seed or mustard oil. So if you’re working with a specific type of oil that technically belongs to the “vegetable” family, each unique variety may have particular differences to be aware of regarding its own respective shelf life.
Most of the information and tips included here can be broadly applied to other cooking and vegetable oils for general guidance to inform good practice, but for some fancier cousins like unrefined avocado oils, consider looking up the specific oil’s storage information.
Simply Labeled: “Vegetable Oil”
As we answer the question “does vegetable oil go bad,” we’ll focus specifically on bottles that are actually marked “vegetable oil.” This refers to cheaper, versatile blends which can contain soybean, canola, palm, safflower, and sunflower oils.
Bottles labeled as such are almost always refined, which renders them fairly odorless and flavorless. Refining them also endows them with a high smoking point, so they’re great for frying and cooking at high temperatures.
Canola oil can sometimes be labeled as vegetable oil, which is fine because all the information discussed here can be applied to canola as well. Moreover, vegetable oil and cooking oil tend to be used interchangeably, so take that into consideration.
Now that we’ve separated the oils, so to speak, on to vegetable oil’s spoilage and shelf-life details.
So Does Vegetable Oil Go Bad?
In short, yes, vegetable oil goes bad. Nothing lasts forever. While it may be known for its extended usability, especially compared to some other pantry items, that doesn’t mean it’s impervious to spoilage. Vegetable oil does indeed turn in time.
There’s no secret among manufacturers that oil is not forever. Bottles are dated for best use and should be discarded if they show signs of having spoiled. The easiest way to tell if your oil has gone off is to do a quick smell check.
Check Vegetable Oil for Freshness
There’s an old saying, “The nose knows,” which is especially helpful here in gauging your bottle’s freshness. Another good rule of thumb: “When in doubt, throw it out.” These basic guiding principles are at the core of a well-kept pantry.
If it’s not clear by smell whether the oil is okay to use, give it a small taste. If it continues to lack odor and flavor, then it’s most likely fine to use. That said, if it’s well past the marked sell-by date, consider replacing it soon and check it before each use.
How can you tell if your vegetable oil failed the sniff test? When it starts to go sour, it can give off a smell like old paint or nail polish remover, sometimes described as putty-like. This is quite distinct, so don’t dismiss it if your nostrils pick up on anything chemically.
Vegetable oil that has gone entirely rancid will have a sharp, bitter taste. This will be easy to discern when it happens, and consuming a tiny amount in this way is highly unlikely to cause any negative consequences.
Because it takes time for anything to go completely rancid, the flavor will begin mild and gradually become more robust. Always err on the side of caution if you suspect the taste is off so you don’t inadvertently waste whatever meal you’d use it on.
As long as it smells and tastes fine, odds are it’s okay. Once it becomes bitter, it’s better not to risk it.
If you’re worried you may have consumed rancid oil, fear not. Short-term one-offs are no cause for concern. Over time and in larger quantities, however, it can become problematic.
Factors to Consider
Now that we’ve answered “does vegetable oil go bad,” here are a few other things to consider when evaluating the state of your cupboard’s vegetable oil.
First, if there is any doubt about the quality, it’s best not to use it. Contamination is always a possibility, so be on the lookout for tell-tale signs.
Oil doesn’t grow mold, so if you spot any, throw it out immediately. If it has discoloration or debris, use is not recommended. Check bottles regularly at the neck, bottom, and top for unwanted residue that may indicate it’s no longer usable.
If it smokes too soon, it’s better to skip it. Last but not least, if food prepared with it comes out greasy rather than crispy, with foamy fat, it’s a goner.
If reused oil gives off the aroma of whatever it was last cooked with, you may be wondering if it’s okay to use it again. It’s probably nothing to worry about health-wise, but it’s worth considering how the smell may affect whatever you’d be using it to prepare next.
More than anything, trust your gut and follow your instincts. It’s always safer to replace it with a fresh bottle than to try getting by with an older one. There’s no need to take risks when it comes to your food and your health.
How Long Does Vegetable Oil Last Before Going Bad?
Vegetable oil can retain its quality for about six months after opening. Unopened, it can last up to two years with proper storage. Labeled dates will reflect this and are actually “best by” indications, intended as rough estimations.
When stored correctly, it can easily extend the labeled expectations by months with no signs of spoilage or negative outcomes. Expiration labels are known to be conservative, especially in the case of long-lasting refined oils.
Bottom line: if vegetable oil looks, smells, and tastes okay, then there’s no reason to toss it. If sellers advise otherwise, perhaps the motive is in the title.
For optimal quality preservation, it’s recommended to store vegetable oil in a cool place away from sources of light and heat. Pantries and cabinets work well if they don’t get too warm or bright.
While it may be tempting to stash the bottle beside the stove for convenience, heat and light sources are the enemy. Store the bottle well between each use, close it tightly, and inspect it regularly. This will pay off in the long run for preserving the quality of your oil.
Even with proper storage, the spoiling process speeds up once a bottle is opened and its contents are exposed to air. This is true for most oils. You might think of it like driving a new car off the lot.
Vegetable oil can be stored in the fridge for an extended shelf life. Don’t be surprised, though, if it appears a little cloudy when it’s cold. Cloudiness isn’t a sign of going off; it will quickly dissipate at room temperature. Refrigeration is fine but isn’t necessary since refined oils are renowned for their long shelf life.
If you must keep vegetable oil close by and out of the cupboard, it would benefit from being re-poured into a darker bottle. A darker container can provide added light protection to help retain quality outside the pantry.
Summary: Does Vegetable Oil Go Bad?
Keeping a bottle of vegetable oil for too long or in poor conditions will ultimately result in spoilage.
It’s wise to be conscious of expiration dates, but take them with a grain of salt and use your best judgment. Storing oils correctly will extend the time of their quality retention, as can refrigeration.
It’s essential to check the oil frequently, especially when it’s past the sell-by date. Inspect it visually, smell it, and if need be, taste it to ensure freshness before use. Anything off-putting is a message that it has gone wrong.
Refined oils are known to last a long time, but everything has its limit. Storing vegetable oil in a cool, dark place away from heat and light can help to extend its shelf life, but remember, once it’s opened, it will start to degrade faster than an unopened bottle would.
It’s fine to keep using oil as long as there are no signs of spoiling, “expired” or not, but that doesn’t mean it won’t eventually turn, so be wise and don’t push it!
Vegetable oil lasts quite a while, especially when stored correctly. Still, pushing the limit with an overextended bottle is ill-advised.
Thankfully, vegetable oil tends to be among the more affordable cooking oils, and a new bottle likely costs less than whatever food would be ruined in trying to use it once it has spoiled.