Geranyl acetate: properties, uses, pros, cons, safety

Geranyl Acetate is a monoterpene ester of geraniol and acetic acid, used mainly as a fragrance ingredient in cosmetics, perfumery, detergency, and flavourings. It has a typically floral, rosy, fruity, green, lavender-like, and slightly waxy olfactory profile. In cosmetics, the functions reported by CosIng are tonic and perfuming, while the main regulatory point is its inclusion in Annex III, entry 369, with mandatory label declaration above threshold.

Description

Geranyl Acetate is an odorant substance naturally present in several essential oils and also used as a synthetic or semi-synthetic raw material. It is closely related to Geraniol, from which it derives by acetylation, and should be distinguished from Neryl Acetate, the cis/Z geometric isomer related to nerol. This distinction is important because isomers and esterified derivatives may have different olfactory and regulatory profiles.

From a cosmetic standpoint, it is used almost exclusively to improve the olfactory pleasantness of the product or to contribute to a “tonic” and fresh cosmetic sensation. It should not be interpreted as a curative dermatological active: its main function is sensory.

Regulation (EU) 2023/1545 included it among fragrance allergens to be indicated individually in the ingredient list when it exceeds 0.001% in leave-on products and 0.01% in rinse-off products. This does not mean that it is prohibited, but that it must be declared to protect sensitized consumers.

Production process

Geranyl Acetate can be obtained by isolation from essential oils or by synthesis. The natural route involves fractional distillation or separation from essential oils that contain it. The most common synthetic route consists of the acetylation of geraniol with acetic acid, acetic anhydride, or other acetylating systems, followed by purification and control of olfactory quality.

After synthesis or isolation, the usual controls include assay, odor, color, acid value, isomers, process residues, solvents, peroxides, and stability. In perfumery and cosmetics, quality does not depend only on chemical purity, but also on odor refinement, oxidative stability, and the supplier’s regulatory documentation.

Main compounds present

In the pure grade, the main compound is Geranyl Acetate. In natural grades or materials isolated from essential oils, small amounts may be present, including:

• Geraniol;

• Nerol;

• Neryl Acetate;

• Citronellol;

• Linalool;

• Linalyl Acetate;

• minor terpenes and other odorant esters.

From an allergological standpoint, it is important to remember that Geranyl Acetate is an ester of Geraniol, a substance known for its relevance among fragrance allergens. SCCS documentation on fragrance allergens also considers the issue of odorant esters that may be hydrolyzed or related to their parent alcohols.

Identification data and specifications

Indicative physicochemical properties

JECFA specifications describe it as a colorless liquid with a floral odor, soluble in alcohol and fixed oils, insoluble in water and glycerin, with a boiling point around 240-245 °C and minimum purity of 90% by ester determination.

Food

In the food sector, Geranyl Acetate is used as a flavouring, not as a nutrient. FEMA reports it with FEMA No. 2509, JECFA No. 58, reference 21 CFR 182.60, and a lavender/rose aromatic profile.

JECFA classifies it as a flavouring agent and indicates no safety concern at current levels of intake when used as a flavouring; a group ADI expressed as citral is maintained for citral, geranyl acetate, citronellol, linalool, and linalyl acetate.

From a nutritional standpoint, it does not provide direct benefits. Its value is sensory, linked to floral, fruity, rosy, and aromatic notes.

Cosmetics

In cosmetics, Geranyl Acetate is used mainly as a perfuming ingredient. It may appear in perfumes, creams, lotions, soaps, cleansers, shampoos, conditioners, deodorants, body products, hair products, and formulas where a rosy, floral, fruity, or lavender-like note is desired.

The perfuming function is the most relevant. The tonic function reported by CosIng should be understood as a cosmetic sensory/toning function, not as a therapeutic or curative effect.

The central regulatory point is Annex III, entry 369. If the concentration in the finished product exceeds:

• 0.001% in leave-on products;

• 0.01% in rinse-off products;

the presence of the substance must be indicated in the ingredient list. The restriction entry concerns the substance 2,6-Octadien-1-ol, 3,7-dimethyl-, 1-acetate, (2E), linked to the common name Geranyl Acetate.

Pros

• It has a floral, rosy, fruity, and pleasant olfactory profile.

• It is very useful as a perfuming ingredient in cosmetics, detergents, and hair products.

• It can contribute to rose, lavender, geranium, citrus, and green notes.

• It is naturally present in several essential oils, but can also be obtained synthetically.

• It is also recognized as a flavouring agent in the food sector.

• EU regulation is clear: above threshold, it must be declared on the label.

• At low concentrations and in well-designed formulas, it can provide a good sensory contribution.

Cons

• It is not a nutritional food ingredient: in food it has only an aromatic function.

• In cosmetics it is a fragrance allergen to be declared above threshold.

• It may be problematic for individuals sensitized to fragrances or to geraniol-related compounds.

• As an odorant ester, stability and possible degradation/hydrolysis must be controlled.

• It is poorly soluble in water and requires correct solubilization.

• Quality varies according to purity, natural/synthetic origin, isomeric profile, and storage.

• In complex essential oils it must be assessed together with other fragrance allergens present in the mixture.

Safety, regulatory aspects, and environment

From a cosmetic standpoint, Geranyl Acetate is not prohibited, but it is subject to mandatory label declaration above the Annex III thresholds. The purpose is to inform sensitized consumers and reduce the risk of unrecognized exposure to fragrance allergens.

The main risk concerns skin sensitization and possible reactions in subjects who are already allergic or predisposed. SCCS documentation on fragrance allergens highlights that, for some odorant substances and their esters, hydrolysis, relationship with the parent compound, and cross-reactions should also be considered.

As a concentrated raw material, Geranyl Acetate may require caution for skin, eyes, and the aquatic environment, according to the supplier’s specific SDS. This does not automatically imply the same level of risk in the finished cosmetic product, but it makes assessment of the actual concentration and complete formula necessary.

For correct cosmetic use, it is advisable to request from the supplier:

• updated SDS;

• certificate of analysis;

• allergen declaration;

• IFRA certificate;

• data on purity and isomers;

• data on acid value, peroxides, and stability;

• actual concentration in the fragrance;

• declaration of compliance with the EU Cosmetics Regulation;

• verification of the concentration in the finished product against Annex III thresholds.

From an environmental standpoint, Geranyl Acetate is a volatile and lipophilic molecule. Its real profile depends on raw material origin, production process, biodegradability, amount used, product category, and environmental fate. In rinse-off products, release into wastewater must be considered; in leave-on products, the main issue remains skin exposure and allergen labeling.

Conclusion

Geranyl Acetate is an ingredient of strong olfactory interest, used mainly as a perfuming ingredient and aromatic component. Its main value is its floral-rosy, fruity, and green note, useful in perfumes, cosmetics, detergents, body products, and hair care.

Professional assessment must consider the updated cosmetic regulation. Geranyl Acetate is included in Annex III, entry 369, with mandatory label indication above 0.001% in leave-on products and 0.01% in rinse-off products. It is therefore not an ingredient to be automatically avoided, but a fragrance allergen to be managed with precise documentation.

In a well-designed formula and with complete supplier documentation, it can be a useful and favorable ingredient. The points to control are purity, origin, stability, solubilization, concentration in the finished product, allergen declaration, IFRA certificate, SDS, COA, and compliance with Annex III of the European Cosmetics Regulation.

References____________________________________________________________________________

Wu T, Li S, Zhang B, Bi C, Zhang X. Engineering Saccharomyces cerevisiae for the production of the valuable monoterpene ester geranyl acetate. Microb Cell Fact. 2018 Jun 5;17(1):85. doi: 10.1186/s12934-018-0930-y. 

Abstract. Background: Geranyl acetate is widely used in the fragrance and cosmetic industries, and thus has great economic value. However, plants naturally produce a mixture of hundreds of esters, and geranyl acetate is usually only present in trace amounts, which makes its economical extraction from plant sources practically impossible. As an ideal host for heterologous production of fragrance compound, the Saccharomyces cerevisiae has never been engineered to produce the esters, such as geranyl acetate. Results: In this study, a heterologous geranyl acetate synthesis pathway was constructed in S. cerevisiae for the first time, and a titer of 0.63 mg/L geranyl acetate was achieved. By expressing an Erg20 mutant to divert carbon flux from FPP to GPP, the geranyl acetate production increased to 2.64 mg/L. However, the expression of heterologous GPP had limited effect. The highest production of 13.27 mg/L geranyl acetate was achieved by additional integration and expression of tHMG1, IDI1 and MAF1. Furthermore, through optimizing fermentation conditions, the geranyl acetate titer increased to 22.49 mg/L. Conclusions: We constructed a monoterpene ester producing cell factory in S. cerevisiae for the first time, and demonstrated the great potential of this system for the heterologous production of a large group of economically important fragrance compounds.

Patel V, Shah C, Deshpande M, Madamwar D. Zinc Oxide Nanoparticles Supported Lipase Immobilization for Biotransformation in Organic Solvents: A Facile Synthesis of Geranyl Acetate, Effect of Operative Variables and Kinetic Study. Appl Biochem Biotechnol. 2016 Apr;178(8):1630-51. doi: 10.1007/s12010-015-1972-9. 

Abstract. The present study describes grafting of zinc oxide (ZnO) nanoparticles with polyethyleneimine (PEI) followed by modification with glutraldehyde used as the bridge for binding the enzyme to support. The prepared nanocomposites were then characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy, utilized for synthesis of geranyl acetate in n-hexane. Among all the three prepared nanocomposites (ZnO + PEI, ZnO + PEI + SAA, ZnO + PEI + GLU), Candida rugosa lipase immobilized on ZnO-PEI-GLU was found to be best for higher ester synthesis. The operating conditions that maximized geranyl acetate resulted in the highest yield of 94 % in 6 h, molar ratio of 0.1:0.4 M (geraniol/vinyl acetate) in the presence of n-hexane as reaction medium. Various kinetic parameters such as V max, K i(G), K m(G), and K m(VA) were determined using nonlinear regression analysis for order bi-bi mechanism. The kinetic study showed that reaction followed order bi-bi mechanism with inhibition by geraniol. Activation energy (E a ) was found to be lower for immobilized lipase (12.31 kJ mol(-1)) than crude lipase (19.04 kJ mol(-1)) indicating better catalytic efficiency of immobilized lipase. Immobilized biocatalyst demonstrated 2.23-fold increased catalytic activity than crude lipase and recycled 20 times. The studies revealed in this work showed a promising perspective of using low-cost nanobiocatalysts to overcome the well-known drawbacks of the chemical-catalyzed route.

Terada Y, Yamashita R, Ihara N, Yamazaki-Ito T, Takahashi Y, Masuda H, Sakuragawa S, Ito S, Ito K, Watanabe T. Human TRPA1 activation by terpenes derived from the essential oil of daidai, Citrus aurantium L. var. daidai Makino. Biosci Biotechnol Biochem. 2019 Sep;83(9):1721-1728. doi: 10.1080/09168451.2019.1611405. 

Abstract. Daidai (bitter orange, Citrus aurantium) is characterized by its fresh citrus scent. In Japanese cuisine, its juice is an important ingredient. As tons of industrial waste is obtained while processing the daidai juice, additional utilization of this waste has great social value. In our study, we prepared the essential oil from the waste obtained during daidai juice processing and demonstrated that the oil activates human TRPA1 (hTRPA1). This oil contains 10 types of terpenes, all of which activated hTRPA1 with an EC50 value of 6-167 µM. To our knowledge, this study is the first to show a hTRPA1 activation by five terpenes: linalyl acetate, geranyl acetate, osthole, geranyl propionate, and neryl acetate. Because physiological benefits of TRPA1 agonists, such as enhancement of energy metabolism and promotion of skin barrier recovery, have been reported, the oil could be a promising ingredient for anti-obesity food products and cosmetics.