Can essential oils go rancid?

In this brief text we will provide the answer to the question: “Can essential oils go rancid?”. In addition, we will explain the differences between vegetable oils and essential oils.

Can essential oils go rancid?

Essentials don’t go rancid like cooking oils. In fact, after expiration, essential oils lose their sensory characteristics, becoming weak and lacking in power. They do not go rancid like fixed oils, but when exposed to light and air they oxidize and acquire resinous characteristics. 

They have characteristic odors and are immiscible with water, but soluble in ether, alcohol and most organic solvents.

What are the differences between vegetable oils and essential oils?

The main difference between the two types of oils has to do with their compositions, which directly affect physical properties (appearance, smell and viscosity) and their uses.

The main difference between the two types of oils has to do with their compositions, which directly affect physical properties (appearance, smell and viscosity) and their uses.

Vegetable oils are usually more viscous and do not have a strong aroma, this is due to their composition. Vegetable oils are composed of very long and “heavy” molecules (fats), thanks to this, these molecules are more “united” to each other, causing the liquid to become “thicker”, viscous. 

The vast majority of compounds that make up vegetable oils are formed by fatty acids. Many can be ingested and are used in cooking – some are very important for daily food, as they are sources of vitamins and omega-3.

Essential oils are very famous for their pleasant aroma. The fact that we can smell an essential oil is because the molecules present there are leaving the oil and spreading through the air to reach our noses. 

The molecules that make up essential oils are smaller and “lighter”, thanks to this they are less viscous and more volatile, evaporating more easily. Essential oils should not be ingested – if ingested, they can cause stomach upset and even nausea.

According to Botanical Online there are several differences between volatile oils and fixed vegetable oils (oils obtained from plants, consisting of a mixture of glycerols, fatty acids and other components, such as olive and peanut oil).

Volatile oils can be extracted from natural sources by distillation and do not consist of glycerol esters of fatty acids. Therefore, they do not leave a permanent greasy stain on the paper and cannot be saponified with alkali.

Depending on the botanical family, essential oils may be present in some structures, or specific parts of plants. For example: in cinnamon, these oils are present only in the bark and leaves; in the rose they are in great quantity in the petals; on mints, on the glandular hairs of the stem and on the leaves; in orange, one type of oil occurs only in the flower petals and another in the fruit peel.

Essential oils are the odoriferous principles found in various parts of plants. Because they evaporate when exposed to air at ordinary temperatures, they are called volatile, ethereal, or essential oils. This last term is used because volatile oils represent the core, the fullness, the “essence” of plants.

Volatile oils are made up of very complex chemical mixtures, which can be divided into two major classes: terpenoid and phenylpropanoid derivatives. Its chemical composition varies greatly. In them can be found almost all types of organic compounds (hydrocarbons, alcohols, ketones, aldehydes, esters and others). 

There are few that have a single component in a high percentage (for example, clove oil contains around 85% of phenolic substances, especially eugenol), and it is not uncommon for a volatile oil to contain more than 200 components and many Sometimes the trace components are essential to the aroma, which can be changed by the absence of one of them.

Another point to consider is the fact that plants of the same species, born in different regions of the world, generally have the same components, but the percentages in which they are present may differ, due to the climate, or because they were cultivated differently.

This difference in the chemical composition of essential oils can be easily understood and accepted when we realize that they are part of the plant’s metabolism, therefore they are in constant fluctuation as long as there is life. 

Thus, the modifications will occur, transforming some compounds into others, according to the part of the plant, the moment of its development or growth and the time of day of its harvest. 

And even after their extraction, due to the complexity of their composition, they can undergo physicochemical changes through chemical reactions between their constituents, the environment itself, such as sunlight and the container in which the essential oil is packaged.

Finally, it is important to mention that all plants produce essential oils, not just aromatic and medicinal ones, as they are fundamental for their survival and maintenance of the species.

But these oils cannot always be extracted, either because they are produced in very small quantities, or because there is some difficulty in cultivation and when we talk about products coming from nature, we must always think that extractivism should be avoided.


In this brief text we provided the answer to the question: “Can essential oils go rancid?”. In addition, we explained the differences between vegetable oils and essential oils.


Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.