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Composition biochimique hydrolat de citron.

Everything you need to know about the biochemical composition of lemon water.

Lemon water is a natural ingredient found in various cosmetic treatments, containing several active compounds with intriguing properties. Discover here which active molecules are present in lemon water and what their benefits are.

Published February 14, 2024, by Pauline, Head of Scientific Communication — 6 min read

Lemon water or hydrolat: what is it?

Grown throughout the Mediterranean basin, the lemon tree is a shrubby plant from the Rutaceae family. Originating from the Middle East, its introduction to the West dates back to the 4th century BC, under the influence of Alexander the Great. During antiquity, the Greeks and Romans appreciated this fruit for its culinary properties and its anti-nausea action. Its use was then expanded and the lemon was quickly employed to alleviate minor wounds and pains.

Also known as lemon hydrosol, lemon water (INCI name: Citrus Limon (Lemon) Fruit Water) is obtained through steam distillation. It presents itself as a colourless liquid, sometimes slightly opalescent, and has a characteristic fresh and lemony scent. Although the lemon hydrosol is only weakly charged with essential oil, it remains a valuable commodity that can be incorporated into skincare products.

What is the composition of lemon hydrosol?

Unlike lemon juice, which is highly acidic, lemon hydrosol is not photosensitising and is a gentle treatment. It can be used by the whole family, including pregnant women and young children.

Lemon water is rich in limonene.

Limonene is an ingredient found in all lemon derivatives and is a component of lemon hydrosol. It is responsible for giving this citrus fruit its fresh and tangy scent. This is indeed why limonene is often used in perfumery and skincare products. Limonene is also utilised for its antibacterial properties. Studies have indeed shown that it prevents the proliferation of certain bacteria, known as Gram-positive, such as Escherichia coli. Limonene works by causing the rupture of the bacterial membrane, which compromises the cellular integrity of the bacteria. It can thus be used as an antiseptic in case of injury, to prevent bacterial contamination.

The lemon hydrosol contains pinenes.

Lemon hydrosol also contains pinenes. These compounds are both antibacterial. Studies have shown that alpha-pinene and beta-pinene have a bacteriostatic action, meaning they inhibit the multiplication of bacteria, without necessarily killing them. However, it should be noted that this property has only been demonstrated for Gram-positive bacteria.

Lemon water contains geranial.

Geranial is also a component of lemon hydrosol. It is one of the two stereoisomers of citral, a major constituent of the citrus fruit. It indeed has a strong lemony scent and is often used as a flavouring in food or cosmetics. Geranial is also attributed with anti-inflammatory properties. In fact, a study has shown that geranial inhibits the activity of NLRP3, an inflammasome complex that triggers an inflammatory signalling pathway and the synthesis of pro-inflammatory cytokines. It can thus be assumed that the application of lemon hydrosol may help to soothe pain and aid certain wounds in healing.

Lemon hydrosol is rich in linalool.

One of the other ingredients found in lemon hydrosol is linalool, which belongs to the family of monoterpenic alcohols. This compound notably promotes the synthesis of HSP70 proteins (Heat Shock Protein). These proteins ensure the correct conformation of proteins found in the body's cells and help them to protect themselves from external stresses (heat, heavy metals...), potentially causing inflammatory phenomena. By contributing to the inhibition of these reactions, linalool thus has a anti-inflammatory action. Furthermore, this active ingredient is capable of limiting the proliferation of parasites, such as Leishmania amazonensis, responsible for leishmaniasis, and bacteria, like Cutibacterium acnes, involved in the mechanism of acne. The antibacterial properties of lemon hydrosol thus help to prevent and soothe skin eruptions.

Lemon water contains traces of Vitamin C.

We also find a small amount of vitamin C in lemon water. This molecule is an antioxidant agent, capable of eliminating free radicals from the body. These are responsible for damage to DNA and certain cells. They also accelerate the skin ageing process, and the appearance of wrinkles and fine lines. However, it has been shown that vitamin C is only an effective reducing agent when it is present at more than 5% in a skincare product. The percentage of vitamin C found in lemon water is less than this figure. Therefore, we cannot consider that lemon hydrosol truly has an antioxidant effect. Moreover, several studies have shown that vitamin C has a depigmenting power. Its mechanism of action is based on the inhibition of tyrosinase, an enzyme responsible for the conversion of the amino acid tyrosine into melanin. This property of vitamin C is the origin of the lightening effect attributed to lemon hydrosol.

The lemon hydrosol contains traces of flavonoids.

Flavonoids are molecules from the polyphenol family, possessing, like vitamin C, antioxidant properties. They function by increasing the activity of superoxide dismutase (SOD), an enzyme produced by the cells of living organisms. Its role is to trap free radicals produced by metabolism. A study also showed that the daily application for four weeks of a cream enriched with 5% flavonoids on mice resulted in a decrease in the level of plasma malondialdehyde (MDA) in the body. This compound is one of the end products of the oxidation of polyunsaturated fatty acids. A low MDA level signifies low lipid oxidation, and therefore low oxidative stress.

However, it should be noted that the concentration of flavonoids in lemon hydrosol is less than 5%. Therefore, we cannot assert that this ingredient possesses antioxidant properties.


  • CHABUCK Z. & al. Antimicrobial activity of different aqueous lemon extracts. Journal of Applied Pharmaceutical Science (2013).

  • LI G. & al. Effect of lemon peel flavonoids on UVB-induced skin damage in mice. RSC Advances (2020).


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