Sensory Beyond Quality Control

quality control

Almost all breweries run a final quality check on their beer before shipping it out, but in each part of the brewing process lies the possibility of the unexpected. Setbacks such as diacetyl and acetaldehyde contaminants are going to appear in various parts of the brewing process. Assessing the final product’s quality is always going to be critical, but is there anything that can be gained from sensory analysis during production?

Imagine QC checking a post-production batch both in the lab and with sensory only to find out that that the flaw detected could have been remedied or prevented earlier during production. Imagine that same batch was bound to be flawed from an issue that occurred prior to wort preparation and could not be remedied.  At what critical control points during the brewing process do you decide to either cut your losses and dump the batch or move forward with a flaw mitigation technique? Why take a chance on the time, energy, and resources of fermenting that batch if early detection is at your disposal?

Right now it’s common practice to take evaluative measures during production, but why wait to bring sensory into the picture only after the beer is finished? Sensory can be used to detect and flag flaws and alert you to off-flavors perceptible to the consumer. It’s highly impractical to go through and flag every detectable flaw at every critical control point during production from an analytical chemistry perspective. However, sensory can catch anything perceivable to the consumer at any stage. Of course, sensory doesn’t detect all precursors, but that’s not where sensory shines. It serves as a simple, efficient, cost-effective, and unfortunately underutilized methodology that empowers you to save time and money.

By using sensory at each critical control point you can detect flaws in real-time. This data can be leveraged to make an informed choice to either dump the batch or find a solution to remedy the deviation. The key component is determining not only which flaws are there but also whether they can be easily mitigated or are permanently problematic.

We have identified seven critical control points in which flaws can be identified and potentially mitigated via sensory evaluation. These key critical control points are:

  1. Wort chilling
  2. End of fermentation
  3. Cold filter
  4. Pre-blending/Brite tank
  5. Pre-packaging
  6. Post-packaging
  7. Degradation testing



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Let’s take a look at two compounds that can be identified as flaws during wort chilling.

    • Cis-3-hexenol (hops-derived flaw that smells leafy) cannot be removed or mitigated after the wort is chilled. At concentrations that are highly perceivable, the batch should be dumped.
    • Ferrous sulfate (often an equipment-derived flaw that tastes metallic), if detected, can be removed through a chelating agent such as EDTA to remove metal ions from solution.

Depending on which flaws are present, you may have to simply dump the batch immediately or use flaw mitigation techniques for flaws that can be remedied. In practice, this is done case-by-case and, as a brewer, the reward of successfully recovering a batch versus the risk of unsuccessfully recovering the batch is a balancing act. Either way, catching a problem earlier rather than later and being able to make a decision when a flaw comes up is indefinitely empowering and saves you a lot of trouble in the long run. Implementing critical control points for sensory evaluation into your standard operating procedures takes sensory from a mere quality control measure to a quality assurance (QA) tool.

There are many different conventions to individual flaw recognition via sensory evaluation in complex beverages. A common method is to train panelists on what individual flaw compounds taste like by using flavor standards. However, these techniques heavily depend on a panelist’s skill and experience and are highly subject to human error. It is very difficult to accurately and consistently record, track, and analyze human sensory data on most platforms, especially when tracking and paneling the over 60 common flaws found in beer. There has been substantial research in recent years to solve this problem utilizing machine learning and artificial intelligence techniques very similar to methods used by “big data.” This research is aimed at making flavor objective and striping user/panelist bias to leverage sensory data to its full potential in detecting batch-to-batch variations, flavor profiling, flagging individual flaws, cognitive marketing, and demographic targeting.

Through better sensory evaluation platforms and data science techniques, models and algorithms can be trained for individual flaw recognition. But what good does detecting a flaw at a critical control point really do in the long run? It can potentially save the batch or prevent you from wasting time and resources in finishing that batch if it has a permanent flaw not acceptable to consumers in the short run, but determining what caused the flaw(s) is critical to preventing that flaw from reoccurring. By graphically mapping all the production processes in beer with issues and flaws that can occur at each step, probabilistic clustering models can be made to “back-trace” one or multiple flaws to their issue(s) of origin. This knowledge will help prevent the brewer from making the same mistake twice. Sensory data cannot only be leveraged for quality assurance (QA) by catching a bad batch early. Through further analysis at each critical control point by utilizing back-tracing techniques in graphical databases, sensory can be leveraged for quality improvement (QI).

By utilizing critical control points in your sensory program, you will be able to properly deal with or dump bad batches during production instead of after. Performing sensory analysis at every critical control point during production can further utilize the same tasting data for quality assurance (QA) by identifying a bad batch early and for quality improvement (QI), to improve the standard operating procedures throughout the brewing process. Analytical Flavor Systems offers the analyses mentioned above and builds tools to fully utilize the power of sensory by using it as a platform for quality control, quality assurance, and quality improvement at critical control points in the brewing process.

If you are interested in more resources and in-depth explanations of the technology discussed above, please visit the following:


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