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Does Vegetable Oil Go Bad? [Rancid, Expiry Tips]

Does Vegetable Oil Go Bad

Vegetable oil seems to keep for a very long time, and I often buy it in large amounts.

So, I was curious how long you can keep vegetable oil and whether it goes bad.

I did some research and here’s what I found.

Vegetable oil does go bad, according to the USDA.

Opened vegetable oil will last for 4 months, and unopened vegetable oil will last for 2 years if kept in a cool dark place.

Standard vegetable oils are highly processed and last longer than natural cold-pressed vegetable oils.

Today, I will explain whether it’s OK to use expired vegetable oil, if expired vegetable oil makes you sick, how to tell if vegetable oil is rancid, and what happens to your body if you eat rancid oil.

Is It Ok to Use Expired Vegetable Oil?

Is It Ok to Use Expired Vegetable Oil

Expired vegetable oil won’t necessarily be rancid.

And I’ve noticed that some foods that are expired are perfectly fine to consume after the use-by date.

But, is this also the case with expired vegetable oil?

Generally, it’s best not to use expired vegetable oil.

Although there is limited scientific evidence to draw a conclusion, vegetable oil is inexpensive.

Therefore, it’s best not to consume it, as there has been some concern about chemicals leaking into the plastic.

As a general rule, if you notice vegetable oil has gone past its expiration date it’s best to throw it out.

Vegetable oil CAN become rancid.

But, in other cases, it can have expired and exhibit no bad smell or taste.

The difference in shelf life: standard vegetable oil and cold-pressed oil

Standard vegetable oil such as the typical oil you find at the grocery store labeled as canola oil or sunflower oil is processed differently from cold-pressed oil.

Standard vegetable oil is first cold-pressed the same way that cold-pressed oils are.

But, then it goes through a range of other processes to further refine the oil, and remove any impurities.

This involves washing it in chemicals such as sodium hydroxide.

Because standard vegetable oil is much more refined it doesn’t contain various nutrients that are found in cold-pressed oil.

These extra ‘impurities’ cause cold-pressed oil to have a shorter expiry date.

Due to this cold-pressed oils can last 2 to 3 months once opened.

Whereas, if left unopened cold-pressed oils tend to last 9 to 12 months.

By comparison, standard vegetable oils go bad around 4 months after being opened.

And 2 years when kept unopened.

However, there is a lot of anecdotal evidence to suggest opened vegetable oil can last much longer than that.

There are three major factors that influence how quickly or slowly a vegetable oil expires.

These are:

  • Oxygen
  • Light
  • Temperature

These are all easy to limit. Simply keeping the oil in its plastic or glass container will stop any oxygen from getting in.

Light shining on the oil can speed up chemical processes and cause the oil to go bad sooner.

So, it’s best to keep it in a dark place.

Many people will keep cooking oil on the kitchen counter where it is easy to access.

However, this can mean it gets natural light and sometimes direct sunlight.

So, it’s best to keep it in the pantry or the fridge.

Temperature also affects the shelf life of vegetable oil.

If kept in the kitchen it can often be next to the stovetop.

When the stovetop is used it will heat the oil if it’s close by.

Overall, it’s best to keep it in the pantry or fridge.

And keep it in its original bottle or an airtight container to make it last the longest.

Interestingly, many vegetable oils will become slightly solid in the fridge.

Especially olive oil. Although olives are technically a fruit.

You may wonder whether cooling oil can also make it go bad faster.

And if cooling it and bringing it back to room temperature again is bad for it.

I explained the answers to these questions in this article about the differences between vegetable oil and olive oil.

What Does Rancid Cooking Oil Taste Like?

What Does Rancid Cooking Oil Taste Like

When vegetable oil goes bad it can develop a bad taste and odor.

If you’re concerned your cooking oil might be rancid, you can tell by the way it tastes.

Here’s what rancid oil tastes like.

Generally, rancid cooking oil has an unpleasant taste.

It doesn’t taste like anything in particular.

It also develops an unpleasant smell.

Non-expired cooking oil has a pleasant taste and scent.

Rancid cooking oil smells bad and can smell a bit like varnish.

Cooking oils that have a strong scent such as sesame seed oil, fish oil, and peanut oil tend to go off faster than oils that have only a mild scent.

Because cooking oil is a liquid, it goes through a whole dish.

For example, if you use it as a salad dressing, or in baking the entire salad or baked food will have an unpleasant taste.

It can be the case that you’ll use rancid cooking oil without realizing it, only to notice that the dish you prepared has a funny taste to it.

But, can’t quite put your finger on why.

This leads to the next question which is whether rancid or expired cooking oil can make you sick.

Can Expired Vegetable Oil Make You Sick?

Can Expired Vegetable Oil Make You Sick

Expired vegetable oils don’t generally look bad.

And it’s hard to tell whether an expired vegetable oil is bad just by looking at it.

So, you may be wondering if it’s OK to eat expired vegetable oil, here’s what I found.

Overall, expired vegetable oil will make you sick.

It can cause diarrhea, vomiting, and nausea.

These are the body’s natural reactions to get rid of toxins in the body.

Expired vegetable oil should be discarded immediately or within a few days after they expire.

Open vegetable oil tends to go bad much sooner than unopened vegetable oil.

Therefore, it can be a good idea to buy vegetable oil in small containers.

Depending on how much you use.

If you use vegetable oil for deep frying it’s easy to use a large amount.

But, if you don’t typically deep fry food and otherwise don’t use much vegetable oil, it’s best to buy in small amounts.

That way it won’t go bad before you use it all.

There is also what is called vegetable suet.

This is similar to lard, or shortening but is made from vegetable oil.

I explained what it is and why it’s used instead of vegetable oil in this article about what vegetable suet is .

What Happens if You Eat Rancid Oil?

What Happens if You Eat Rancid Oil

Expired vegetable oil that has gone rancid can spell OK still.

So, you may be tempted to consume it or use it to stop food from sticking when frying food.

But, is it bad, and what happens if you eat rancid oil?

Consuming rancid oil can lead to an upset stomach, diarrhea, vomiting, nausea, and headaches.

Rancid vegetable oil also has a bad taste to it.

Food prepared using rancid oil will taste bad, and it will have an unusual and unpleasant taste to it.

Certain oils such as olive oil that have gone a little bit off, can be a bit of an acquired taste.

And there is anecdotal evidence that suggests that as olive oil goes a bit off, it develops a slightly sour taste that some people enjoy.

Does Vegetable Oil Need To Be Refrigerated?

Does Vegetable Oil Need To Be Refrigerated

I’ve noticed vegetable oil labels don’t generally state how to store them.

So, I looked into whether vegetable oils need to be refrigerated and thought I’d share what I found.

As a general rule, you do not need to refrigerate vegetable oil.

When refrigerated it turns slightly hard.

Therefore, it is a minor inconvenience to warm it back up to use it.

However, keeping vegetable oil as cool as possible without turning hard will stop vegetable oil from going bad as quickly.

This is generally best achieved by keeping it in the pantry.

According to NowFoods, a food distributor it’s best to strike a balance between keeping it as cool as possible without keeping it so cool that it will go solid.

In the fridge, it will go slightly solid, and only a small amount if any will come out of the bottle when you use it straight from the fridge.

So, generally, a cool place such as at the bottom of your pantry is best.

Sunlight also causes vegetable oil to go bad faster.

So, you should keep it where it won’t get direct sunlight.

Depending on the layout of your kitchen, keeping it on the counter may not expose it to direct sunlight.

But, light can reflect off of the surface and it can be exposed to diffuse sunlight.

So, keeping it in the pantry with the doors closed will keep it in a dark environment which will make it last the longest.