Perhaps now more than ever, you’re forced to do more with less at your brewery. With money likely tight and a staff that’s probably stretched thinner than usual, we’re all seeking to maximize efficiency, productivity, cost savings and time.
BrewMonitor is the industry’s first real-time, comprehensive fermentation monitoring and analysis solution, purpose-built to enable brewers to increase quality and profitability through greatly enhanced fermentation-process control. To show exactly how real-time fermentation monitoring helps make better beer, reduces workloads, and minimizes stress, we’re publishing a series of blog posts to walk you through what it can do for you at each step of fermentation.
We’ll post another installment within a few weeks. Keep monitoring this space!
DAY ZERO – BEFORE YOU PITCH YOUR YEAST
BrewMonitor gives you a number of valuable data points the minute you turn it on. While most brewers take a gravity reading, and maybe a pH reading before they pitch, BrewMonitor collects data on gravity, pH, dissolved oxygen and conductivity — giving you a much more robust baseline for your wort.
If you’re trying a recipe for the first time, do the numbers match your predicted values? For repeat batches, do the numbers fall within specifications? If not, what can you do about it — now — before you risk brewing an unusable batch?
Let’s look at the readings one by one.
The first question to ask at this point is the usual one: did I hit my target gravity? If not, how far over or under am I? How will that affect the outcome of the beer and its consistency with previous batches? Tracking these answers can help figure out solutions to any future irregularities.
Some breweries monitor pH but not all. If the pH level is too high, you can take a representative sample of the wort, adjust the pH to the desired point, then scale the volume of acid added to the whole batch – and then add that volume to the fermenter. After you’ve run a few batches, do you notice pH showing up as a recurring problem? This may indicate that you need to acidify your mash with some acidulated malt or phosphoric acid. Consider adjusting your brewing-salt additions to increase or decrease the pH in future batches. These techniques will prevent you from having to rely on adding acid after brewing.
Dissolved Oxygen (DO)
Most small brewers don’t measure DO at this stage, if ever, but it’s impossible to overstate the potential consequences of out-of-spec DO on yeast health and fermentation performance, i.e., stalled fermentations or fermentations running longer than planned.
Over-oxygenation can prove toxic to yeast. If more oxygen is present than needed for the production of fatty acids and sterols, which is the reason we add oxygen, it can lead to DNA damage, rapid aging of yeast, poor fermentation performance and a reduction to the number of possible re-pitches. In addition, excess O2 can cause the formation of pre-staling compounds which reduce the shelf life of finished beer.
With too little oxygen the yeast may not be able to produce enough fatty acids and sterols, reducing their growth as they run out of components for making extra cell membranes during cell division. Even if the total growth is sufficient, your yeast may lack the ability to remodel the cell membrane as acidity and ethanol levels increase, reducing overall viability and health for repitching. If yeast haven’t been pitched yet and the fermentation vessel has a carbonation stone in place, some O2 may be scrubbed off by bubbling CO2 through the wort.
Conductivity is a quantity most brewers don’t measure despite it being a critical indicator of wort quality, given that it measures the combination of the salts and other charged compounds — proteins, amino acids, organic acids — within. If conductivity is out of range, it may indicate issues with water chemistry and or/mash problems. (Have you changed grain suppliers? Is there harvest to harvest variation? Do the grain specs match?)
Conductivity also indirectly measures the buffering capacity of the wort, meaning how much it can resist pH change within a limited range. Out-of-spec conductivity can compromise fermentation as the growth environment for the yeast will change in ways you don’t want. For instance, decreased conductivity may indicate decreased Free Amino Nitrogen (FAN), which will have a negative effect on yeast growth and fermentation performance. When buffering capacity gets exhausted, conductivity will change as yeast acidify the wort, use up amino acids and fatty acids and start to produce organic acids.
Brewing Multiple Batches
If you’re fermenting multiple batches at once, each successive batch addition should change the sensor reading in a predictable way. So what are we looking to see here? We often see a fast rate of fermentation on the first knockout, which slows after the second. This is normal. Though we’re still working to pinpoint an explanation, we suspect this happens because the concentration of yeast is getting diluted to the expected level.
Do you oxygenate the next knockout? Yes but only if the wort DO has NOT dropped to zero. Before you perform the next knockout, don’t forget to do your due diligence by cell counting to ensure you have the cell density to support another round.
Getting Your Weekends Back
Once you’ve okayed your starting levels and pitched your yeast, you can practically set it and forget it. As Denver Smyth, head brewer and owner of Western Red Brewing in Poulsbo, Washington, has discovered, automatic digital readings mean he can track his fermentation from home instead of driving 30 miles to and from the brewery every Saturday and Sunday to take gravity readings, as was his custom: “My favorite thing is when I pitch a yeast on Friday night, I can leave and I don’t have to come in because I can see exactly what’s happening. Now it’s pretty rare that I run to the brewery on a Saturday or Sunday at all.”
Check back for the next installment, where we’ll discuss the first 24 hours after pitching your yeast.