Debunking 5 Myths About Dissolved Oxygen

Myth 1: Dissolved Oxygen (DO) is the same thing as Total Packed Oxygen (TPO).

Not true! A DO measurement only reveals what is in the liquid and paints a partial picture. A TPO measurement tells you how much oxygen is in the liquid and the headspace, and can be determined through a shaken sample that blends dissolved oxygen and headspace O2. Shaken samples provide an accurate picture of TPO and are a better tool for gauging a beer’s oxygen-related shelf life.

Unfortunately, most quoted DO measurements in the field are DO, not TPO measurements. However, getting an accurate TPO measurement requires costly equipment out of range for many small brewers, so relying on the quality of your filling technology is even more important. Learn more about TPO measurements on
the Master Brewers Podcast.

Myth 2: Measuring DO is the best gauge of oxygen pickup in the can.

Most oxygen pickup from packaging will live in the headspace. So a shaken TPO measurement benchmarked against measured DO in the brite tank just before canning is the best way to determine total O2 pickup. If the target TPO values go up during canning, this is a strong indicator that you’re not properly capping on foam and have oxygen pickup issues. By knowing the shaken TPO measurement, you can more effectively determine when and where DO pickup is taking place and how to then troubleshoot the problem. Again, the trusted quality at the filler for addressing headspace O2 is key.

Myth 3: Bubble breakers and foam control solutions are required to keep DO low.

Bubble breakers and foam control solutions can be helpful for breaking headspace foam and curbing product loss from over foaming. But they are not required, and on most micro-canning systems they are in place only to correct for excessive post-fill foam generation. Cask’s proprietary fill technology is designed to create the perfect fill from the beginning to eliminate need for post-fill corrections.

How? We directly address foam factors from the start and throughout the fill. A slow laminar flow of pre-fill foam eliminates breakout and enables a controlled cap-on-foam process. Fill level sensors then react with the conductivity of the beer to stop flow and keep product loss below 1%.

Click the link below to watch how we fill at #caskfillpornfriday.

Myth 4: Atmospheric filling leaves beer at risk for higher DO pickup.

Another misconception, inspired in part because (prior to Cask inventing micro-canning in 2002) beer could only be canned by mass market brewers with large-scale rotary systems using counter pressure technology. (And done long before most craft brewers understood the freshness-crushing impact of DO in packaged beer.) Cask’s proprietary filling technology ensures the highest quality and the lowest oxygen-containing packaged product for craft producers.

What makes it work so well? Protective oxygen-reducing layers are built in the can beginning with the CO2 pre-purge, followed by a dense layer of micro-foam, and filling beer from the bottom up – underneath this double barrier of foam and CO2.

Individual fill heads that deliberately create and manipulate foam enable that foam to be used as a protective layer. The collective result is TPO equivalent to or even lower than counter pressure technologies.

Note: Counter pressure and atmospheric filling technologies both require downstream capping that exposes product to the atmosphere after the can leaves the filler. While counter pressure fillers will use a bubble breaker to attempt to generate foam post-fill and remove sitting oxygen, Cask uses under-lid CO2 gassing to remove any oxygen on top of the protective layer of foam and inside the lid cavity.

Myth 5: Overfilling is required for low TPO.

And the world is flat? If you’re not properly capping-on-foam, overfilling can help purge cans of oxygen and help to reach lower DO. But this overfilling is not required with properly engineered fill technology, and it’s also very costly. A 5-10% overfill of each can means losing 5-10 BBL down the drain on a 100 BBL per month production volume.

The best way to achieve proper fill levels and low DO? Tight controls on temperature, pressure, carbonation levels and tank-to-canning-system distance, coupled with a Cask system’s unmatched range of features for keeping foam, DO and product loss in-check. That combination provides extremely low DO-pickup levels (verified 15-20 PPB) combined with super-low product loss of less than 1%.


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