The use of Human Panels for Odor Analysis

By Fanny Turlure

Odors are complicated and deciding what is “OK” or “Not OK” and what “ideal” is differs across regions and cultures. Although it’s often easy to standardize the evaluation of tactile and visual attributes of a product, odor evaluation remains difficult to standardize.

Analytical techniques are often less sensitive or unable to account for the combined interactions that create odor—so humans panels remain the best known method for perceived olfactive quality for a range of industries—from flavor and fragrance to automotive. For decades, manufacturers have relied on these panels—both trained and untrained—which are often expensive to take on, involve significant coordination and are often regarded as fairly subjective.

In addition, human panels have shown a lack of repeatability, reproducibility, and discrimination ability. The variability between panelists, in particular with malodor/unpleasant odors which can illicit strong emotional reactions, can mitigate the results of the test. It is not the odor itself that is rated but the odor associated to the emotional reaction. In addition, the continued use of human panels for some products—like hot plastics—can represent the evaluation of potentially toxic VOCs which bring forward a whole host of health and safety concerns.

In flavor and fragrances, panelists are used to create a 4D view of the product which takes into account the emotional response of the consumer. For any given product, formulations may go through multiple rounds of internal and external human panels. Internal panels are often used for early stage product development to select candidates that are most in line with the end goal. While external panels, which have a major cost, are often only used for final analysis and are often a requirement for any final product. Implementing a digital olfaction solution could reduce the need for internal panels, allow for additional rapid development rounds for final product candidates, and increase the confidence in the outcomes of final external panels.

In automotive, a number of industry standards like the VDA 270, specify trained panels for odor characterization. These tests are well-known for their inconsistency—not only because of the ambiguous rating scale, but the nature of the panel training. Panelist training, which is typically done on an annual basis, consists of smelling prepared samples with reference ratings certified by a third party. The definition of “acceptable” versus “unacceptable” is not well defined and the subjective nature of olfaction lead to inconsistency in test results.

Finally, some industries—such as home care products—are most interested in the evolution of an odor over time. Some products are expected to provide a long lasting odor and are not meant to evolve very fast, meaning that human panelists must assess odors over a long period of time. For example, a floor cleaner may be assessed when it is applied, and then a few times over an eight hour period. Gathering this type of data with a human panel means that not only is the panel required for a long time but it also depends on the panelist’s ability to compare a smell to another one experienced as long as eight hours ago.

Digital olfaction is an instrumentation approach that delivers more transparent and traceable results as it classifies odor data in a way that is objective and repeatable. Bio-based technologies mimic the human sense of smell to provide results the align with the human perception. By adapting training protocols for human panels to experiments with our NeOse Pro, Aryballe has been able to study our sensor performance in the context of these human panel ratings.

As digital olfaction solutions become more widespread, incorporating these technology solutions can complement human panel results to provide a more complete picture of panel scoring. Through this intermediate step, industries can begin to move away from human panels as the sole measure of olfactive quality for products.