What do we have here? Another Beer Sensory Science article? Yeah, maybe a few. I just recently gave a talk about something related to this, so I thought it might make a good subject for a blog article. It’s a lengthy topic, so I may be breaking it up into multiple entries. The trick will be posting them all within the same calendar year…
The road to descriptive profiling, part i: Intro
Descriptive profiling is probably the Holy Grail of testing methods in sensory science. Whenever a product has multiple flavor and texture characteristics that are anticipated by consumers to be at specific and consistent intensities, the most comprehensive way of ensuring that all of these meet their targets is to use a trained panel to conduct frequent descriptive profiling sessions. Results from descriptive profiling can illuminate issues in your production processes, can help design new products to fit certain flavor criteria, and can be used in powerful statistical analyses which can uncover interesting patterns in the data. In short, a properly-tuned descriptive profiling panel is a powerful force in sensory projects, and one that each taste panel should eventually try to aspire to be capable of performing.
But getting a properly-tuned descriptive profiling panel is no brief task. It requires several weeks or even months of repetitive work for both panelists and their panel leader. Multiple tiers of training must be mastered before useful profiling data can be collected, and each of those tiers is just as essential as the others as they all build on each other to create a complete and effective sensory utility. Not only does descriptive profiling training involve being thoroughly trained in multiple different types of sensory tests, but it also requires a specific environment in which to collect this data – an environment that allows sufficient focus on the tasks at hand by limiting the multitude of distractions that seek to derail the concentration of the taste panelist.
This article will outline the numerous steps that it takes to walk this road from the little shanty town of informal “go/nogo” tastings in your pub to the metro-utopia of Descriptive Profiling in a properly-structured sensory panel room. It’s a long road, but we’ll take it slow and easy and we’ll be there before you know it.
Part ii: Environment
In order to do this right, we need to start at the beginning. Where is your panel tasting their samples? Is it in a place where they can fully concentrate on the sample in front of them, or are there various things around that are vying for their attention? Biases and distractions are everywhere in the world around us and the taste panel room should be as effective as possible at cutting all that out. Even just focusing on the ‘distractions of the mind’ first, we can find many potential sources: buzzing cell phones, street noise, tourists walking by the taste panel room, noises from the production floor, refrigerator compressors turning on, an atmosphere that is too hot or cold, off-topic conversations, and the list can go on. The taste panel room should be isolated enough and engineered appropriately so that these types of distractions do not pose problems for the focus of the panelists. Air conditioning should be comfortable and consistent, ideally in the 72-75F range with 45-55% humidity. Lighting should be bright, even, and natural. Some facilities have an alternate light source in their panel rooms, usually red, to help mask color differences between samples (when those differences should not be part of the assessment). The paint colors in the taste panel room should be neutral and bright enough to allow for good visibility of the materials under scrutiny.
Depending on the nature of your sensory tests, you may want to separate the gaze of your panelists by using booths or dividers. I realize that panelists often use Taste Panel as a free time to discuss various things while they taste beer, but this is a counter-productive approach. In the early phases of basic taste training, open and on-topic discussions between panelists is fine, but once Taste Panel gets more routine and the panelists know what they’re doing, all discussions become distractions. Dividers, or a very high level of discipline, are needed. Later, as Descriptive Profiling training gets going, on-topic conversations between panelists must begin again as that is how consensus is built for this type of test (more on that later).
Other sources of distractions or bias from the environment have a more direct impact on the performance of the panelists, and these usually take the form of errant aromas. The taste panel room should ideally have some minor positive air pressure so that aromas from the rest of the building do not infiltrate this neutral space, and the materials in the room should be made of non-aromatic substances. Panelists should be instructed to not wear cologne or perfume and not to smoke or eat within 30 or more minutes of panel or bring coffee or other food into the panel room. The personal hygiene of your panelists is also of great importance, and in some ways can be the trickiest to control. One of the most difficult jobs a taste panel leader might have would be telling a talented panelist that they need to shower more. Hopefully your panelists do not present you with that problem, but one way to mitigate that issue would be to issue a blanket, non-targeted, statement to all your panelists espousing the importance of a neutral testing environment, and that the various distractions mentioned here have a deleterious effect on the value of the data collected by the panel. A truly committed panelist will take this information to heart and do what it takes to maintain “good member” status. It’s your responsibility as a trained panel leader to choose the panelists who will provide to you the best experience for your panel as a whole. If someone doesn’t fall into your line, it’s your right to remove them from your panel. You’re here for the data, not to make friends.
Part iii: Attributes
Now that you have your tasting environment tailored to provide maximum concentration potential for your panelists, it’s time to move on to teaching them to identify flavor attributes. Part of the groundwork for this is to gain familiarity with the types of flavors you want in your various products, as well as the types of flavors that could potentially spoil your product. Laying this groundwork requires frequent assessments of all your brands’ production runs by as many tasters as possible and a comprehensive understanding of where in the production process things can go wrong. Once you have an idea of all the positive and negative flavors that have an influence over your products, you need to begin presenting these to your panelists on an individual basis. In order to do this, you’ll need to acquire some substances that are good representations of these flavor attributes. In some cases, these can be purchased from vendors who specialize in these flavors [flavor standards] and in others cases you can make your own using chemical supply companies, or sometimes even with items obtained from the grocery store. In any case, you can find relevant information for how to create these flavor standards in the ASBC webinars and Methods of Analysis if you’re a member (and you should be!) [ASBC MoA/Webinars].
The main thrust of this effort is for your panelists to be able to identify and quantify these flavors in their samples, so presenting these flavors on a frequent and ongoing basis is necessary. At first, these flavors can be added to water (if the solubility of the compound allows) so that the only flavor in the sample is from the attribute in question. Before long you’ll want to be adding these to beer, and ideally you should be using one of your own products that is low in overall flavor intensity. If you have no products that will fit the bill, you can use something like Bud Light or something similar. Just make sure you have a “control” sample present so that your panelists can compare the “spiked” flavor standard against the same beer with no flavor added. Since you’ll be starting to train panelist who have little-to-no familiarity with many of these flavors, you’ll likely want to start at a higher intensity to make sure it is detectable and gradually move to lower intensities as your panelists’ acuity improves. As you work through this, take note of any panelists who have difficulty with specific flavors. In many cases, you’ll likely find that some panelists are completely blind to certain flavors (called an “anosmia”). As panel leader, you’ll need to know which panelists are sensitive to which flavors so that you can tailor the experience appropriately and interpret the panel’s results accordingly. About the same time that you begin to lower the intensities of your flavor standards, you can begin to present them to your panelists blind and ask them to identify them from a list of potential choices. This is where you truly get to understand the detection abilities of your panelists, and collecting this data for future analysis is helpful.
One very important thing that the panel leader should keep in mind is that the panel should be merging together in the way they describe these flavors. This is done by standardizing the vocabulary used by the panel. Instead of calling a flavor “banana” or “buttery”, they should use the compound’s name if possible: “isoamyl acetate” or “diacetyl”. Instead of using broad terms like “floral” or “fruity”, find more specific flavor standards to train with that will allow you drill down into those terms and further differentiate them. Similar with “phenolic”, “oxidized”, and “sulfury”; all these terms are too broad to be useful in sensory science, and each of these terms can be applied to various flavors that are actually quite distinct from each other in character and source. If we are trying to achieve consensus then all efforts must be made to make sure the consensus is real. Many discussions with the panel will be needed to clarify what everyone means when they use their terms, and the sooner everyone is speaking the same language the better.
After several weeks of intensive flavor attribute training, your panelists should be feeling one or both of two things: they’re probably feeling fairly powerful in their new-found abilities to dissect beer flavor, and they could be feeling a bit overwhelmed by all the chemistry vocabulary. At some point, they may even start to become jaded beer drinkers who have a tendency to find problems in each beer they taste. Sensory training is a double-edged sword – I’ve had potential panelists repeatedly decline to become involved in taste panel because they don’t want to “ruin” their beer drinking experience. It’s hard for me to fault them for such views, but usually a truly devoted panelist can see past this drawback and persevere for the sake of science and brewing progress. And if they’re not truly devoted, do we want them on our taste panel?
The next article will be about intensity training and building profiling ballots. The final article will cover the profiling itself, reporting of the data, and some insight into managing profiling data. No, you won’t have to wait a year for them to be posted.