It is traditionally used for sautéing and frying, though western kitchens have come to love it for the nut-like quality and sweetness for baking, pastries and popcorn. Coconut oil is especially popular among kitchens following a ketogenic or paleo diet.
Virgin coconut oil is fresh pressed from the meat of a coconut, and like any fresh food it will deteriorate with age. Yes, coconut oil can go bad.
Experts say that the incredible amount of saturated fat found in coconut oil gives it an exceptional shelf life when compared with other unrefined cooking oils. Even so, it will still become rancid with time.
Why Does Coconut Oil Go Bad?
Coconut oil is almost entirely made of fat, including more than 80% of saturated fats. Half of this saturated fat is in the form of a medium-chain fatty acid called lauric acid. Surprisingly there are only trace amounts of fiber, cholesterol, vitamins, minerals or plant sterols present.
Although the lion’s share of coconut oil is saturated fat, it’s actually unsaturated fats that will cause it to spoil.
All fats are organic compounds, meaning that they’re composed of chains of bonded carbon atoms. Unsaturated fatty acids, like those found in coconut oil, are distinct from saturated fats because they contain double bonds between some carbon atoms.
Double-bonded carbon in unsaturated fats is somewhat unstable, and likely to break down in the presence of oxygen through a process called “oxidation.” As these bonds break, the fat transforms into peroxides which give off characteristically unpleasant “rancid” smells and flavors.
Oxidative rancidity is a gradual degradation that begins when an oil is first pressed, and continues over time. Exposure to light, heat and oxygen accelerate this process.
The oxygen found in water molecules may also be damaging to coconut oil through a similar process. This is called hydrolytic rancidity. If your oil becomes contaminated by bacteria or mold, the enzymes they produce can similarly catalyze microbial rancidity.
Of these three common types of rancidity, oxidative is by far the most common cause. Practically speaking, you can’t stop it, but with proper care you can slow it down.