Citronellol is a naturally occurring organic compound with a distinctive fresh, floral, rose-like aroma and sweet, citrusy undertones. This colorless to pale yellow liquid is a common component found in the essential oils of various plants. Its pleasant scent makes it a widely used ingredient in many consumer products.
Chemical Makeup and Natural Sources
Citronellol is classified as a monoterpenoid alcohol, an organic compound found naturally in various plants. Its molecular structure features a branched carbon chain with a hydroxyl group. This compound exists in two primary forms, or enantiomers: (+)-citronellol and (-)-citronellol, which can influence its specific aroma and properties.
The distribution of these forms varies across plant sources. For instance, (+)-citronellol is predominantly found in citronella oils, particularly from Cymbopogon nardus, where it can comprise around 50% of the oil’s composition. Conversely, (-)-citronellol is more abundant in rose oils, often making up 18-55% of the oil from Rosa damascena, and in Pelargonium geraniums.
Geranium oil, from Pelargonium graveolens, can contain citronellol ranging from approximately 24% to over 40%. Lemongrass oil, derived from species like Cymbopogon citratus, also contains citronellol, typically around 11-14%, contributing to its overall fragrance profile.
Everyday Applications
Citronellol finds widespread application across various industries. In the fragrance industry, it is a common ingredient in perfumes, colognes, cosmetics, soaps, and detergents, imparting a clean, fresh, and rosy aroma. It is a building block for creating rose accords and muguet (lily of the valley) type scents. Its stability makes it suitable for use in household cleaners and fabric softeners, where it also helps mask unpleasant odors.
Beyond its pleasant scent, citronellol is well-known for its role as a natural insect repellent. It is a key component in citronella oil, used in products such as candles, sprays, and lotions designed to deter mosquitoes and other insects. The repellent mechanism involves masking scents that attract insects, making it difficult for them to locate their targets. Formulations often complex citronellol to improve its stability and prolong its repellent effect.
Citronellol also serves as a flavoring agent. It is added in small quantities to products like candies, beverages, and desserts, where it contributes mild citrus or floral notes. It can be found in hard and soft candies, chewing gum, ice creams, and baked goods, typically in concentrations ranging from 1 to 40 parts per million.
In aromatherapy, citronellol is valued for its calming and soothing properties. Its floral aroma is utilized in massage oils and diffusers to promote relaxation, reduce stress, and enhance mood. Research suggests that when inhaled, citronellol interacts with the olfactory system to stimulate the brain’s limbic system, which is involved in emotions and relaxation.
Safety Profile and Regulation
Citronellol finds widespread application across various industries, primarily due to its appealing scent. In the fragrance industry, it is a common ingredient in perfumes, colognes, cosmetics, soaps, and detergents, imparting a clean, fresh, and rosy aroma. It is a building block for creating rose accords and muguet (lily of the valley) type scents, and its stability makes it suitable for use in household cleaners and fabric softeners. This compound helps to provide volume, freshness, and longevity to fragrance compositions, also helping to mask unpleasant odors in various formulations.
Beyond its pleasant scent, citronellol is well-known for its role as a natural insect repellent. It is a key component in citronella oil, which is used in products such as candles, sprays, and lotions designed to deter mosquitoes and other insects. The repellent mechanism involves masking scents that attract insects, making it difficult for them to locate their targets. Formulations often complex citronellol to improve its stability and prolong its repellent effect against insects like mosquitoes.
Citronellol also serves as a flavoring agent, particularly in the food and beverage industry. It is added in small quantities to products like candies, beverages, and desserts, where it contributes mild citrus or floral notes. It can be found in hard and soft candies, chewing gum, ice creams, and baked goods, typically in concentrations ranging from 1 to 40 parts per million. The United States FDA considers citronellol as “Generally Recognized As Safe” (GRAS) for food use.
In aromatherapy, citronellol is valued for its calming and soothing properties. Its floral aroma is utilized in massage oils and diffusers to promote relaxation, reduce stress, and enhance mood. Research suggests that when inhaled, citronellol interacts with the olfactory system to stimulate the brain’s limbic system, which is involved in emotions and relaxation. It is also believed to possess antioxidant and anti-inflammatory effects that contribute to overall well-being.
Safety Profile and Regulation
While generally considered safe for use as intended in consumer products, citronellol can cause skin irritation or allergic reactions in some sensitive individuals. This sensitivity can manifest as contact dermatitis, with redness, itching, or swelling. Notably, oxidized citronellol, formed when the compound is exposed to air, has been identified as a stronger sensitizer than its pure form. For those with known sensitivities, or when trying new products, conducting a patch test on a small skin area is advisable.
Regulatory bodies oversee the use of citronellol to ensure consumer safety. The International Fragrance Association (IFRA) sets standards that restrict its concentration in various fragrance products due to its potential to cause sensitization. In the European Union, citronellol is among the fragrance allergens that must be explicitly declared on cosmetic product labels if present above specific thresholds (0.001% for leave-on products and 0.01% for rinse-off products). The United States Food and Drug Administration (FDA) recognizes citronellol as “Generally Recognized As Safe” (GRAS) for its use as a flavoring agent in food.
The Environmental Protection Agency (EPA) has registered citronellol as a biopesticide, noting its low mammalian toxicity and non-toxic mode of action as an insect repellent. When used in accordance with label instructions, it is expected to pose minimal risk to humans and the environment. Citronellol is biodegradable and readily metabolized, and generally considered to have a low environmental impact. However, some studies at higher concentrations have indicated potential acute toxicity to certain non-target aquatic invertebrates and soil organisms.