During my 30-year career in the sensory and consumer research industry, I’ve found that some of the most misused and misunderstood tests by food manufacturers are difference tests, which determine if the attributes of two food products are different. One common difference test is a triangle test, which presents panelists in a study with three different samples to taste. Two of the samples are from the same product and one is from a different product. The test determines if the panelists are able to pick out the sample of the different product from the three presented.

Another common difference test is called a duo-trio test, in which a participant is presented with one sample from the manufacturer’s reference product. Then, the panelist is presented with two additional samples, one from the reference product and one from a different product. The panelist must then identify which from the second set of samples matches the reference sample.

A third type of difference testing is paired comparison, which gives panelists the opportunity to taste two samples and then answer specific questions to differentiate between the two. Questions may include which sample is sweeter or which sample the panelist prefers.

Between requests for triangle, duo-trio, paired comparison and similar tests, I often get clients who say they’d like to “run a quick difference test.” In these cases, food manufacturers will often ask for a triangle test or a similar test that can be completed quickly but not break the bank. Does this sound familiar? These types of requests often raise red flags because they are connected to an expectation that the test will be very quick and inexpensive, but more often than not they fail to meet the client’s true needs.

Don’t get me wrong, I believe wholeheartedly in difference testing when you only want to determine if there is a difference between two products. However, in my experience, simply determining that a product is “different” is almost never enough information to satisfy a client’s needs. It seems to suffice if the result is what the client is expecting. However, if the result is contrary to an intended outcome, you will always need more information to proceed with product development or reformulation.

While difference testing does meet a very specific need, it also has a limited scope and delivers no indication of direction, intensity or which attributes of a product cause it to be different. Direction in sensory testing can indicate if a manufacturer’s product is more or less salty, sweet, crunchy, etc. than the other sample. “Creative” methodologies might ask the respondents to complete a difference test and then follow up by asking them to identify what they thought was different. This is an attempt to stretch the scope of a difference test and glean more information for their testing dollars, but that too is limited in power. In this case, only comments from respondents who correctly completed the test should be considered useful or reliable.  

Difference testing is also often limited to products that are visually homogeneous or for which you can effectively mask any visual differences. Because camouflaging can be challenging and manufacturers may require additional information to guide reformulation, you may want to consider using other methods of testing. While there seems to be a misconception that difference testing is cheaper than other sensory tests, it can actually cost more for sample preparation and logistical coordination than other options. This means it can be just as expensive or even more costly than other sensory testing methods, such as descriptive analysis.

Further, the results from a descriptive analysis are much more robust and actionable than simply finding out if two products are perceived as “different.” A descriptive analysis test will specifically identify the similarities and differences between two samples. The next time you are trying to choose between difference, triangle, duo-trio or paired comparison testing, consider using descriptive analysis testing instead.

A descriptive analysis profile will identify exactly which attributes are different, the direction to take each attribute and the magnitude of the difference in each attribute. If the outcome is not as expected or intended, this profile will diagnose the attributes that are different and give you insight as to the direction you need to move each attribute to bring the profiles together. For example, based on the data, you may find that your cookie product needs to be less sweet to match the other product’s sample. Depending on the complexity of the sample being profiled, the cost is equal to or sometimes less than the cost of a “quick difference test,” but when it’s over, you will have significantly more information and directional guidance.  

Choosing between difference testing and descriptive analysis can be compared to an unexpected upgrade of a rental car. Say you reserve a budget-friendly car instead of a top-of-the-line luxury vehicle, but when you pick it up, they offer you the luxury car at no additional cost. While both cars will get you to your destination, the value for your dollar is enhanced with the luxury car because it offers additional features. Think of the extra information provided by a descriptive analysis test of your upgraded car. So often, additional features, or testing insights, must take a backseat to budget. However, in this case, you can opt for the stylish ride, or the more in-depth offering, that will support your decision-making with confidence for the same price as the lesser option.

Before ordering your next difference test, consider elevating your “ride” to save time and money. It’s time to experience the luxury of descriptive analysis. Are you ready to get started with your descriptive analysis or other sensory testing today? As a leading global provider of sensory and consumer services, Mérieux NutriSciences‘ experts can help you quantify and predict the performance of your products in the marketplace. We utilize an innovative toolbox to provide you with the professional services you need from a highly qualified sensory partner. Download our sensory evaluation services materials today to learn more!


Meet the Author

Jean Ann Hankins, Business Development Manager, Sensory & Consumer Science
Jean Ann has over 30 years of experience in the Sensory and Consumer Science Industry. She has worked at Mérieux NutriSciences for nine years now. Prior to that, she worked for Campbell Soup Company, University of Arkansas and Sensory Spectrum, to name a few.

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