For a brand to succeed, transparency, authenticity, and accountability cannot be compromised. Essential oil is a highly volatile material that is extracted from a single botanical species, fragrant plant. The oil derives its name from the plant.1 The cost of a kilogram of essential oil can range from dollars to thousands of dollars due to the high cost and restricted availability of natural oils, experts in the field and researchers are looking into and developing alternatives to satisfy consumer demand. While nature offers varying qualities depending on the source, growing season, harvest time, and origin, the industry seeks uniform qualities, standardization of the oil. In order to target the quality of the authentic essential oil and reduce the cost to a more affordable price, the authentic oil is blended with other natural oils, isolates, and/or synthetic compounds. While the industry allows standardization through blending, any product labeled as FTNF (from the named fruit) must be source species specific.
The flavor and fragrance of citrus oils come from a wide range of volatile and non-volatile constituents, making them incredibly complex. When there is a lack of transparency and "alternative" materials are marketed as authentic essential oils, problems can arise. If the essential oils are not marketed as authentic, using non-FTNF essential oils is not problematic. By providing substitute oils for applications that do not require authentic essential oils, alternative non-FTNF blends contribute to increased sustainability and lower cost.
Challenges in Citrus Oil Segment
Citrus essential oils, which are vital to natural flavors and fragrances, face a number of issues that can alter their composition or quality from season to season and even within a given season. These issues may cause low aldehydes or increase in other undesirable components. Fruit processing results in the production of citrus essential oils. Citrus cold-pressed oil is extracted mechanically from the peel, and essence oil is extracted during evaporation from the juice. Among other things, disease, natural disasters, and changes in the weather during the growing season are the causes of the issues. Not only is the availability in jeopardy, but also the quality. There is less citrus fruit being processed, which drives up prices and reduces the amount of oil available.
Adulteration
Essential oil adulteration might include diluting essential oils with other oils, adding cheaper synthetic ingredients, introducing more natural isolates, or misrepresenting the oil's provenance and other volatile components. Adulteration may be detected using a variety of scientific techniques, as well as by comparing the cost to the authentic essential oil. It should be mentioned that during the extraction of genuine oils, there is a chance of involuntary mixing of the specific citrus fruit oil with other citrus fruit oils as the product line changes. This event is not adulteration. This kind of contamination, which usually causes minor alterations in the oil, is not motivated by economic factors yet rather arises from the processing of fruits and product crossover. When materials are purposefully added to the genuine product to mimic the genuine oil and make it seem better or more valuable, this is known as economic adulteration. Cold-pressed bergamot oil is an example. Bergamot oil is more expensive and less readily available than substitute or reconstituted oil, costing three to four times as much.
Citrus oils include both volatile and nonvolatile components as well as enantiomeric compounds, providing various properties for detecting adulteration. Unique chemicals in citrus tonalities, such δ-3-carene in sweet orange, can be used to detect adulteration. Citrus sinensis, or sweet orange, contains δ-3-carene, a monoterpene. This compound is present in trace amounts and/or undetectable in chemical analysis in other citrus oils such as lemon, lime, grapefruit, and mandarin. The presence of δ-3-carene in the other tonalities shows probable adulteration. Orange terpenes are a very affordable oil, making them an economical choice for use as an adulterant in other citrus oils.
Chiral Analysis
Citrus fruits are known to have characteristic enantiomeric key compounds. Chiral analysis can be used to discriminate authentic essential oils and oils mixed with synthetic compounds. Citrus oils also have numerous chiral compounds, such as a-pinene, d-limonene, a-camphene, a-phellandrene α-thujene, α-pinene, camphene, β-pinene, sabinene, α-phellandrene, β-phellandrene, limonene, linalool, camphor, citronellal, linalyl acetate, terpinen-4-ol, and α-terpineol.
To produce premium citrus qualities, it is paramount to control the fruit origin ensuring traceability to the species and growing region, in addition to analytical testing. As part of the authenticity focus, external samples are typically presented as natural bergamot oil, obtained from various sources, and analyzed by gas chromatography. Adulteration in bergamot is caused by the scarcity and high cost of real oil. After Semmler and Tiemann discovered in 1892 that linalyl acetate is a major part of bergamot oil, it became frequent practice to adulterate bergamot oil with esters derived from various non-bergamot and/or synthetic sources, which have a lower economic value.2 This practice can be seen today.
Based on chiral analysis, some of the external samples obtained were authentic bergamot cold pressed oil and others adulterated with synthetic linalyl acetate recognizable by the substantial change in the enantiomeric ratios of linalool and linalyl acetate. In nature, enantiomeric key compounds are biosynthesized by highly stereoselective enzymatic mechanisms in plants and in most cases one enantiomer is dominant. Ratios of enantiomeric compounds from authentic oil for various plant species are published by ISO (the International Organization for Standardization). In addition, peer-reviewed journal articles provide information on ratios of enantiomeric compounds for authentic oils.3,4,5,6 In addition, adulteration using synthetic linalyl acetate is detected by the identification of the compounds dihydrolinalyl acetate and plinyl acetate. Dihydrolinalyl acetate and plinyl acetate are trace compound markers generated during the synthesis of linalyl acetate.
Overview
Using citrus oils presents a challenge because of the possibility of adulteration, which is mainly caused by the expensive and limited availability of authentic oil. Deceptive practices may also become more subtle as analytical methodologies to detect adulteration become more sophisticated. With a dedication to quality, transparency, sustainability, and cooperation, the industry can preserve the authenticity of citrus oils.
References
1. Britannica, The Editors of Encyclopaedia, Essential oil, Encyclopedia Britannica (June 14 2024)
2. F Tiemann & FW Semmler, Ueber sauerstoffhaltige bestandtheile einiger aetherischer oele [On oxygenated constituents of some essential oils], Ber 25 1180–1188 (1892)
3. G Dugo and I Bonaccorsi (Eds) Citrus bergamia: Bergamot and its derivatives (1st ed), CRC Press (2013)
4. F Capetti, A Marengo, C Cagliero, E Liberto, C Bicchi, P Rubiolo and B Sgorbini, Adulteration of essential oils. A multitask issue for quality control. Three case studies. Citrus limon (L.) Osbeck. Molecules 26 5610 (2021)
5. I. Bonaccordi, D Sciarrone, A Cotroneo, L Mondello, P Dugo and G Dugo, Bonaccorsi, Enantiomeric distribution of key volatile components in Citrus essential oils, Brazilian Journal of Pharmacognosy 21(5) 841-849 (2011)
6. JH Hong, N Khan, N Jamila, YS Hong, EY Nho, JY Choi, CM Lee and KS Kim, Determination of volatile flavour profiles of Citrus spp. Fruits by SDE-GC–MS and enantiomeric composition of chiral Compounds by MDGC–MS, Phytochemical Analysis 28 392-403 (2016)