What is "Limonene" and what is its utility?

Represented by the chemical formula C10H16, Limonene, also known as 1-methyl-4-prop-1-en-2-yl-cyclohexene, is a terpenic hydrocarbon. Obtained after distillation, it is present in numerous essential oils. Belonging to the group of terpenes, mainly limonoids, it is an aromatic ingredient found in various plant species and in certain foods. Limonene can also have a synthetic origin. Its name derives from the lemon in which it is found in high quantities. It consists of two isomeric forms, namely:

• D-limonene: This form is among the most common terpenes found in nature. It naturally occurs in many fruits, vegetables, and plants. D-limonene is particularly found in citrus fruits (lemon, mandarin, orange, grapefruit, etc.).

• The l-limonene: this isomeric form is predominantly found in the oils of mint, pine, and turpentine.

At room temperature, Limonene appears as a colourless liquid. The scent varies depending on the isomeric form. D-limonene gives off a strong orange aroma, while l-limonene is characterised by a pine and turpentine smell.

Limonene is utilised across various sectors: food, pharmaceutical, cleaning industry, and more. This ingredient is also employed in the field of cosmetology. Limonene is particularly favoured for its deodorising functions, providing it with the ability to reduce or mask body odours. This ingredient is also used as a masking agent, allowing the reduction or masking of the base taste or smell of a skincare product. Furthermore, Limonene is capable of dissolving other substances due to its solvent properties. It also serves as a fragrance agent used in the aromatic raw materials of a skincare product. Limonene contributes a scent to a skincare product.

Limonene is classified among the 26 regulated allergens in Europe. Its presence in the formulation of a skincare product sometimes needs to be mentioned in the list of ingredients referred to in Article 19, paragraph 1, point g. This is the case when Limonene is present at 0.0001% in leave-on products such as creams and serums, and at 0.01% in rinse-off products like hair masks, it must be included. Furthermore, the peroxide value of this ingredient should not exceed 20 mmol/L.

Thanks to its refreshing scent, Limonene is used in the formulation of perfumes and deodorants. Its various properties also allow it to be incorporated into the composition of face creams, body care products, solid soaps, and hair care treatments, including hair masks.