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Critical Control Points in Brewing – Sourness in Beer

By Anonymous
By: Casey Staple
First-Year Brewmaster Student

I find that a constant topic and debate in the craft brewing industry is, when is it ethical to sell a soured contaminated beer? It has been known that some small local breweries try to bluff it through the markets to make a dollar and salvage what may have been lost in production. It is very understandable as to why an operations manager, or even an owner, would do this. Who wants loss? No one new to the industry can afford to dump beer because of a little tartness in the batch. There are bills to pay, and in a situation of being in a current state of catch up because of sold out product, how can a manager justify empty shelf space in the busy, booming, cutthroat industry we are in today.
As professionals in the Alberta brewing world, this is a legitimate problem we may face at some point. How we deal with this crossroad is up to us as brewers and managers. I believe that the first step towards releasing a consistent quality product is simply this: knowing what your beer’s parameters are, and what you determine as “true-to-brand.” You don't need a big sensory panel to do this; you need the 10,000 taste buds on your tongue, your olfactory system, some formal training, and a cerebral cortex to process it all.
I want to set some critical control points on the sourness of beer when sourness does not belong. This should never be a grey area; a light, crisp, easy drinking beer should not be jeopardized with a pejorative sour that does not belong. The specific area of sour sensitivity on our tongue is along the sides, and it’s the hydrogenous ions that we detect. As professionals, we have learned that sourness is one of the more simple flavours we can decipher because our cellular mechanisms have a lightning-quick reaction to acidity. 
So allow me to set the numerical parameters on the topic. Beer is usually a moderate acidic beverage having a pH of 4.5 to 4.0. Let’s call this the normal range, whereas sensitivity to acid in beer is at 3.8 pH. If we have proper data collection on our beer fermentation logs, we can always refer back to batch history and determine where the particular pH of the beer will finish. Consider this a reference point when beginning your process of elimination. If, statistically, the said beer finishes with a pH of 4.2, but a new batch is found to be at 3.6, well, Houston we have a problem! Call this your first hint, or a red flag if you will.
Not convinced? I’m not talking about making a kettle sour here. I’m explaining a situation in which your quality control failed because of quality assurance flaws within a brewery. Now is when the brewer, the manager, and the owner all sit down to do a sensory panel. I suggest that the best method to do this is a known true-to-brand sample versus a questionable batch sample. Of course, check things like clarity, even head retention; but more significant than that, taste the beer. Relate and compare the basis sample to the questionable samples.

The biggest challenge at this point is the panellist's psychological state and bias opinions; not the opinion of perceived tartness, but the rapid and rash decision to save the batch to cover costs and replenish bank accounts. Let's look at a decision tree, but please keep in mind, the subject is an established, true-to-brand beverage with an abnormal acidic flavour to it.

The acidity or sourness is typically based on the brewer's perception. Not only is it undesirable in most beer styles, but acidic flavours usually clash with hop bitterness. When the acidity in beer is abnormally high, it is indicative of contamination in the wort and/or the beer caused by bacteria. At which point, the decision to dump is the least of the problems. My advice is this: as professionals, we cannot standby, observe the problem and simply try to mask it. All this does is cause the issue to persist. I say if you remove the cause, the problem will expire and go away at which point preventative measures are in place to avoid reoccurrence. 

Casey Staple is a first-year brewmaster student in the 6th cohort. He is currently the head brewer at Siding 14 in Ponoka, AB. 

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