Testing Aromas: A Beginner's Guide To Evaluating Scents

Testing aroma is a complex process that involves various methods and tools. One common approach is to use fragrance testing strips, which are made of thick, odourless paper, to evaluate the aroma of essential oils and other aromatics. This method allows for the assessment of the aroma's complexity and its full palette of aromatic notes. Another technique is the Affordable Rapid Olfaction Measurement Array (AROMA), which is an essential oil-based smell test that has been validated for point-of-care olfactory testing. Additionally, aroma profile analysis, performed according to DIN EN ISO 13299:2016, provides insights into the overall aroma of food products and helps identify dominant odour notes and off-flavours. The Adaptive Olfactory Measure of Threshold (ArOMa-T) is a novel, rapid test of olfactory function that employs an adaptive Bayesian algorithm. These methods contribute to our understanding and evaluation of different aromas.

Using fragrance testing strips

Choosing the Right Strips

Fragrance testing strips are typically made of thick, odourless paper that can absorb fragrances. Look for strips designed specifically for this purpose, such as those made from 230 GSM paper. The strips should be wide enough to dip into the oil or have a small end for easy dipping. You can find these strips online or at specialty stores.

Preparing the Strips

If you're testing multiple aromatics, label each strip with the name of the aromatic. This will help you identify them later. You can also use different strips for each oil if you want to compare them over time.

Applying the Aroma

There are two ways to apply the aromatic to the strip. You can either apply 1-2 drops of the aromatic directly onto the strip using a dropper, or you can dip the thin end of the strip into the bottle if it doesn't have a dropper. Be careful not to let the strip come into contact with your skin if the aromatic is undiluted, as some essential oils can cause skin irritation.

Evaluating the Aroma

After applying the aromatic, sniff the strip to evaluate the fragrance. You can do this immediately after application and then at set intervals (such as 5 minutes, 15 minutes, 30 minutes, and even after several hours or a day) to observe how the aroma changes over time. As the aromatic dries, the top notes will fade first, followed by the middle notes, and then the base notes.

Storing the Strips

Fragrance testing strips are made of absorbent paper, so store them in the bag they came in, away from anything fragrant that could impart its scent to the strips.

By using fragrance testing strips, you can more accurately assess the aroma of essential oils and other aromatics, and also evaluate how the fragrance changes over time.

Comparing samples

A recommended method for comparing samples is to use fragrance testing strips, also known as scent strips or fragrance blotters. These strips are made of thick, odourless paper and are ideal for evaluating essential oils and other liquid aromatics. To use these strips, apply one or two drops of the aromatic liquid to the strip and then sniff. Alternatively, the thin end of the strip can be dipped directly into the bottle if it does not have a dropper. It is important to avoid direct skin contact with the portion of the strip containing the aromatic liquid, especially if it is undiluted essential oil, as this may cause skin irritation.

When comparing samples, it is best to assess one or two essential oils at a time to minimise the risk of olfactory fatigue, which can occur when smelling numerous aromatics in a short period. It is also helpful to evaluate the aroma at set intervals, such as immediately after application, and then again after a minute, five minutes, 10 minutes, 30 minutes, one hour, six hours, 12 hours, and one day. This allows for a more thorough assessment of the oil as its aroma changes over time due to the evaporation of different constituents. Keeping a notebook to record aromatic evaluations can be beneficial.

By following these methods, you can effectively compare samples of essential oils or other liquid aromatics, gaining a deeper understanding of their complex aromas and making more informed assessments.

Assessing olfactory performance

Imaging Techniques:

• Optical brain imaging methods such as functional near-infrared spectroscopy (fNIRS) and functional magnetic resonance imaging (fMRI) can be used to evaluate olfactory performance by measuring hemodynamic changes in the prefrontal cortex. These techniques are non-invasive and can provide valuable insights into brain activity associated with olfaction.
• A review of seven studies using fNIRS/NIRS to assess olfactory performance concluded that these techniques can effectively measure hemodynamic changes in response to olfactory inputs and are particularly useful for evaluating healthy individuals without neurodegenerative disorders.

Olfactory Tests:

• The University of Pennsylvania Smell Identification Test (UPSIT) and the Sniffin' Sticks Test (SST) are commonly used olfactory tests in research. UPSIT involves scratch-and-sniff identification, while SST includes smell threshold, discrimination, and identification testing. However, these tests may be time-consuming and expensive for routine clinical use.
• An alternative test called the Affordable Rapid Olfactory Measurement Array (AROMA) has been developed, which uses multiple concentrations of odorants and tests both scent detection and identification. AROMA has shown a moderate correlation with SST and may be more reflective of subjective smell loss, making it a useful tool for clinical evaluation.
• When assessing the aroma of essential oils or other aromatics, it is recommended to use fragrance testing strips instead of sniffing directly from the bottle. This allows for a more comprehensive evaluation of the aroma by capturing its complexity and different aromatic notes.

Testing for olfactory dysfunction

Olfactory testing primarily provides information about quantitative impairment, while the history gives crucial information on qualitative impairment. The general concept involves presenting an olfactory probe at the patient's nostrils and documenting their response. This is also referred to as psychophysical testing.

Olfactory tests are generally subdivided into odor threshold tests and suprathreshold tests of olfaction, such as for odor identification and discrimination. Odor threshold tests present probes with either phenyl ethyl alcohol or n-butanol in increasing concentration, and patients are asked to answer, even if uncertain. Suprathreshold tests, on the other hand, use odor concentrations that are detectable by the patient. The most common suprathreshold tests are odor identification tests.

Olfactory dysfunction can be secondary to sinonasal disease, post-infectious, post-traumatic, associated with neurological disease, associated with aging, associated with exposure to drugs and toxins, congenital, or idiopathic.

Evaluating aromatics from a bottle

When it comes to aromatics, it's only natural to want to sniff straight from the bottle. However, this isn't the best way to truly appreciate the complex aroma of essential oils or liquid aromatics. The narrow neck of the bottle can limit the release of the full range of aromatic notes. The oil near the opening of the bottle may also have a different scent due to oxidation. Additionally, any residue on the bottle or label from other aromatics can interfere with your assessment.

A better way to evaluate aromatics is to use Fragrance Testing Strips, also known as Scent Strips or Fragrance Blotters. These strips are made of thick, odourless paper and are ideal for assessing essential oils, CO2 extracts, absolutes, fragrance oils, and other liquid aromatics. They are also useful for evaluating blends and fragrances for personal care or aromatherapy purposes.

To use a Fragrance Testing Strip, simply apply one or two drops of your aromatic to the strip using a dropper and then sniff. Alternatively, you can dip the thin end of the strip directly into the bottle if it does not have a dropper insert. Ensure that the portion of the strip with the aromatic does not touch your skin unless the aromatic is sufficiently diluted, as some undiluted essential oils can cause skin irritation.

Fragrance Testing Strips allow you to assess the aroma of the aromatic immediately after application and also as it changes over time. The aroma of an aromatic can evolve as it dries out, with the top notes fading first, followed by the middle notes, and finally, the base notes. By using these strips, you can evaluate the aroma at different intervals, such as 5 minutes, 15 minutes, 30 minutes, and even several hours or a day later.

When storing your Fragrance Testing Strips, keep them in their original bag and away from anything fragrant that could impart its scent to the strips.

Frequently asked questions