New approaches to testing natural fragrances & flavors: Aveda researchers outline a novel technique to determine subtle differences in the physical, chemical and energetic properties of natural materials.
Advanced instrumentation and specialized techniques have been developed to accurately distinguish minor differences in similar samples, but these have a number of disadvantages. (1,2) High-resolution capillary gas chromatography (GC) cannot distinguish between optically identical pairs of aroma ingredients unless coupled with other specialized techniques, such as the use of chiral columns (3) or the use of nuclear magnetic resonance shift reagents. (4) Single instrumental techniques generally provide unreliable and incomplete results, yet using multiple techniques can be expensive and time-consuming.
Coupling GC with mass spectrometry has significantly enhanced the accuracy and reliability of measurements, but is still incapable of reliably distinguishing natural from synthetic ingredients, or molecules that are structural mirror images (optical isomers). High-resolution mass spectrometry, a highly specialized technique that is both costly and time-consuming, has been used successfully to confirm the authenticity of the essential oils and natural aroma ingredients. (5) This is accomplished by measuring accurately the isotopic ratio of 12C/13C, and when coupled with natural 14C isotopic abundance, this technique may be a powerful indicator of authenticity.
Unfortunately, unscrupulous traders of essential oils or aroma ingredients may decide to adulterate these ingredients with materials that obfuscate the natural 12C/13C isotopic abundance. This has been seen in the adulteration of natural vanilla supplied to the flavor and fragrance industry. (6) While advanced techniques, such as SNIF-NMR, are capable of verifying the authenticity of aroma materials which have been altered in this fashion, (7) such techniques can be expensive, time consuming and not practical in a production environment governed by tight launch schedules.
Thus, it is evident from the brief review outlined above that no single, simple inexpensive instrumental technique exists that can consistently and rapidly distinguish between ingredient samples of synthetic and natural origin. Additionally, pairs of essential oils that are grown in different locations or that are extracted or distilled differently are difficult to distinguish.
Oils and other botanical materials arising from different growing and cultivating conditions can be assumed to have proceeded through different biological, physical and chemical pathways. Therefore, subtle differences in their intrinsic properties--physical, chemical and energy--may be observed. A technique called Dynamic Gas Discharge Visualization (GDV) has shown the ability to measure and analyze subtle energetic changes of different samples of the studied essential oils. This simple, rapid and relatively inexpensive technique has been utilized to supplement the traditional olfactory and advanced analytical techniques used to register the differences of a given natural plant ingredient due to its source (botanic or petrochemical) and differing geographical origins.
Significant progress has been made in utilizing the technology of GDV to compare similar samples which are chemically identical under GC analysis. GDV is a technique based on corona discharge, a physical phenomenon observed as a glow during the interaction of a subject with a strong electromagnetic field (EMF). (8,9) In GDV, the corona discharge effect is recorded using digital imaging and processed with software to quantify visual parameters. The technique of Dynamic GDV conducts multiparametric analysis on variations of GDV parameters in real-time through the use of frame-by-frame analysis of video footage. (10)
Measuring Potency and Purity
Using this technique, one seeks to indicate the differences that materials may possess that can affect their potency and purity. Such differences, though not detectable with chemical analysis, may be related to intrinsic energy. Such differences can be important signs of authenticity. GDV couples the analysis of physical phenomena with digital imaging and quantification to assist in identifying these subtle differences. This represents an important tool in the effort to maximize investments in essential oil ingredients.
The purpose of this work was to elucidate the application of Dynamic GDV in differentiating identical odorant chemicals that are made synthetically, versus samples made by extraction from natural essential oils. To further explore GDV's application in sourcing issues, testing was also performed on chemically identical odorant chemicals which differed only in geographical origin.
In the case of odorants representing optical isomer pairs, many can be easily distinguished using the nose. However, it is also of value to demonstrate the ability of GDV to distinguish differences where basic chemical analysis cannot. In all cases, the pairs were identified through GC analysis as being identical high-purity chemical samples. Thirty-five different odorants were tested.
1. Oil derivatives of differing nature:
* Bitter almond versus synthetic benzaldehyde.
* Linalool synthetic versus linalool extracted from bergamot.
* Linalool synthetic versus linalool extracted from bois de rose.
* Linalool synthetic versus linalool extracted from pinene.
* Linalool synthetic versus linalool extracted from shiu oil.
Oils of differing nature:
* Peppermint organic versus peppermint conventional.
* Lavender organic versus lavender conventional.
* Cloveland organic versus cloveland conventional.
2. Oils received in different climatic conditions and extracted by different ways (oils from different sources):
* Jasmine oils: Algerian, Indian and Moroccan.
* Orange oils: cold-pressed Valencia FCC+, midseason FCC+ and Brazil cold-pressed high aldehyde content.
* Rose oils: Bulgarian, Bulgarian (Otto), Bulgarian alba organic, Moroccan (Otto), Russian and Turkish Bulgarian type.
3. Oils of various optical activity:
* Dextro carvone versus laevo carvone.
* Dextro limonene versus laevo limonene.
* Dextro linalool versus laevo linalool.
Synthetic vs. Natural
Benzaldehyde is the main component of oil of bitter almond. (11) Benzaldehyde can also be manufactured synthetically from a petrochemical source at an equivalent purity. Because the availability of the natural oil of bitter almond is limited, its price is high. With the demand for a cherry note in flavors and fragrances at an extremely high level, suppliers have met the demand with relatively unlimited quantities of synthetic benzaldehyde at a fraction of the cost.
Typically, oil of bitter almond contains at least 95% pure natural benzaldehyde, while synthetic benzaldehyde is 99.00% to 99.5+% pure. Analysis by GC and GC/MS of the tested samples reveals identical profiles, each with purity over 99% (Figs. 1 and 2). However, GC analysis by itself has its limitations. That is, it cannot reveal the subtle differences between the two materials (however, once again, except under unique advanced techniques that are expensive, time consuming and not readily available). This is why analysis by Dynamic GDV has been applied to this situation.
[FIGURES 1-2 OMITTED]
It is true that traces of benzyl chloride, its isomers and possibly toluene may be present in amounts of parts per million as a remnant of the synthetic origin of benzaldehyde; however, this may be overcome by reliable purification techniques. High-resolution mass spectrometry coupled with high-resolution NMR may also produce reliable information on authenticity. (12) However, the GDV method would provide a relatively inexpensive and quick way to differentiate between the synthetic and natural forms.
In our Dynamic GDV study, the average realizations for both natural oil of bitter almond and synthetic benzaldehyde were measured in terms of the Average Intensity parameter (Fig. 3). Using Fisher's Test at 95 percent confidence intervals, the measurements show a statistically significant difference between synthetic benzaldehyde and natural Oil of Bitter Almond that appears after about three seconds from the initial moment of registration of the Dynamic GDV process. This indicates significant differences in available energy, rather than in composition, between the samples, as they are chemically identical.
[FIGURE 3 OMITTED]
Origins of Essential Oils
While it is true that an experienced perfumer or flavorist can differentiate between pairs of essential oils, either through smell, taste or the use of capillary GC (exhibiting slightly differing profiles in the chromatogram), it is nevertheless reserved to the specially trained individual to utilize advanced analytical techniques. Occasionally, it is difficult to distinguish misbranded essential oils from different geographical areas due to combinations of materials of different origins. Oils from different geographical regions may differ due to many different parameters of cultivation and harvesting, including environmental factors such as the amount of sun, water and pattern of lunar cycles. These differences, though subtle, can be theorized to leave energetical traces on their derived products that are measurable using GDV.
The oils of Moroccan rose, Bulgarian rose and Russian rose are chemically similar though sourced from different locations. During the initial moments of measurement (Fig. 4), the time series for area for each oil coincided with each other. However, in less than one second, each of the curves began to deviate and differ significantly from one another. The tests illustrated the sensitivity of this parameter to the physical and chemical properties of the liquids. In addition, no statistically significant difference between Moroccan rose and Bulgarian rose oils was found, but they both differed significantly from Russian rose oil.
[FIGURE 4 OMITTED]
Although jasmine is a different type of bloom than rose, we can see that it also shows differences between flowers sourced from differing geographical locations. In Fig. 5, the corresponding GDV graph demonstrates statistically significant differences between the Indian and Algerian Jasmine absolute oils with respect to the glow area.
[FIGURE 4 OMITTED]
Enantiomeric Aroma Ingredients
Many molecules can exist in multiple configurations called isomers. In certain cases, two isomers are "mirror images" of one another. In this situation, they are said to be enantiomers, and they present an interesting area of study for fragrance ingredients. Despite being identical in terms of their chemical structure and possessing physical properties that are indistinguishable from one another; such pairs sometimes elicit different reactions from the olfactory system. Despite their close similarity, they nonetheless interact with chemical receptors in different ways.
Certain pairs of these enantiomers have distinctly different odors. Others can only be differentiated by the nose of a trained perfumer. But chemically, to all but the most advanced instruments, they are identical. The high-resolution GC, GC/MS, NMR, IR and UV techniques are incapable of distinguishing oils and ingredients of differing optical activity. The expensive high-resolution GC/MS or HPLC techniques along with optical polarimetry methods and chiral techniques, on the other hand, can accomplish this task.
Dynamic GDV measures the photon emission representing the response of a substrate to electromagnetic excitation. The process of olfaction depends on the electromagnetic interactions of chemical odorants and olfactory receptors. These interactions may be different based on minor differences in the structural configuration of the enantiomer. The potential of GDV to distinguish between two identical compounds based on how they respond to an electromagnetic field environment suggests that the technique may have a broad application in the field of sensory evaluation.
The Dynamic GDV graphs for both dextro and laevo linalool ingredients reveal different values for the Average Intensity and Area parameters (see Figs. 6 and 7). From these tests, based on five trials, one can conclude that the average values of the oil realizations for both area and average intensity (taken at 95(12) confidence intervals) have statistically significant differences after about 2.5 seconds from the beginning of the observation. Focusing on the area trends of the compared oils only, notice that dextro linalool oil has a trend that practically exhibits a linearly increasing character. On the other hand, laevo linalool oil has a trend that is close to that of an increasing power function. Apparently, the ionization process for laevo linalool oil considerably exceeds the process of its evaporation. At the same time, the dextro linalool oil evaporation process sometimes competes with its ionization process; however, the latter dominates for the larger part of the time of the registration. The dextro linalool was isolated and purified from coriander seed oil, whereas the laevo linalool was isolated from ho oil. Normally, the human nose is the only instrument that can distinguish between certain pairs of optical isomers; GDV shows promise as a technique to rapidly differentiate such pairs.
In science, the interaction of molecules has a known effect on the energy state of the system in which the molecules exist. If the intrinsic energy of the natural material was known to be different than the synthetic, one could then use this information as a guideline for formulation work, claim substantiation or raw material procurement.
This proposed Dynamic GDV technique has shown promise in detecting those subtle energy differences in ingredients isolated from botanical sources as opposed to those isolated from petrochemical sources. These subtle differences result in differing corona discharge dynamics, allowing the researcher to distinguish between natural and synthetic counterparts.
We are encouraged by the preliminary results that this methodology can act as a valuable addition to the analytical techniques that are available to distinguish the subtle differences between synthetic and natural materials. This technique can be used as an indispensable tool in the field of aroInatherapy, where energy considerations for the given individual are paramount. Additional experiments are under development to solidify our initial findings using this Dynamic GDV technique.
The authors would like to thank the following for their assistance: Ko-ichi Shiozawa, Aveda Corporation; Nadim Shaath, Alpha Research and Development; Dr. Vinod Upadhyay.
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