MBAC 100th Anniversary Conference: Part 3

Still at the 100th Anniversary Technical Conference of the MBAC. With fermentation and history finished, it was time to move on to filtration.

Beer Haze & Colloidal Stability (Karl Sibert, Professor of Biochemistry, Cornell University)

If you’ve left beer in your fridge a long time, you know that eventually the beer will start to get hazy. First the haze only appears when the beer is cold but then disappears when the beer warms up — the classic “chill haze”. Leave that beer for a while and the haze becomes permanent, regardless of temperature. There is no way to prevent this increasing haziness other than by reducing the amount of haze-causing (or “haze-active”) particles in the beer before you bottle it.

As Professor Sibert explained — this was actually a reiteration of material we had covered in several classes of the Brewmaster program — hazes are caused by protein-polyphenol complexes that start as tiny particles but gradually clump together into larger and larger particles. Protein particles are hordein, which is found in barley (and for wheat beers, from a protein called gliadin.)

Dr. Siebert’s research shows that since haze-active proteins and haze-active polyphenols combine to create haze, it follows that reducing haze-active proteins by 50% should reduce haze by the same amount.

He also suggested that silica gel, a filtration aid now gaining favour with brewers, works by attaching itself to haze-active proteins, thus not allowing competing polyphenols to attach. If a significant number of the polyphenols are unable to bind with the haze-active proteins, beer haze will be reduced significantly.

Beer Filtration: The Current situation and Future Outlook (Ernst Meier, M & L Consulting)

We started with a look back at the past 70 years of beer filtration.

The 1940s saw the development of mass filtration or deep-bed filtration, where beer was passed through a very long box filled with cotton or sometimes even asbestos. In the 1960s, the excellent filtration properties of diatomaceous earth (the microscopic fossilized silica skeletons of a prehistoric hard-shelled algae, better known as kieselguhr in Germany) were discovered. The first DE filters were “plate and frame” style — cotton “plates” stretched on frames and covered with DE were clamped together and beer forced through the apparatus. In the 1980s and 1990s, DE filters using circular steel plates, either horizontal or vertical, were developed. These were soon followed by “candle” filters.

The interesting thing was not the development of this technology, but the relative cost of the filter: In the 1960s, 90% of your filtration cost was tied up in the filter itself. Today, the cost of the filter is only about 28% of your filtration cost — the other 72% is being spent on a complx web of tanks, pipes and peripherals, including in-line syrup dosing, flash pasteurization and in-line CIP (clean in place).

You would think it would be obvious, but many brewers run into problems by installing new filtration systems without regard to their existing systems. Apparently a recurring problem is installing new equipment in the old space, depsite the fact that it requires more space than the old system. What usually occurs is a lack of space for proper maintenance and access to the new systems.

As we heard earlier with regard to fermentation tank design, pre-planning a new filtration system is paramount.

Best line of the presentation: “Employees always make the same mistakes. Engineers always make new mistakes.”

Centrifuge Optimization and Maintenance (Marco Garcia, MillerCoors)

Large centrifuges are becoming popular with brewers as a means of quickly and efficiently removing yeast and other “large” particles from the beer before fine filtration. This reduces the load on the fine filters, and also speeds up filtration times. A modern centrifuge has a stack of metal cones inside it, with a clearance of a few microns between each cone. Yeasty beer fresh from the fermenter is forced in between the cones while they are being spun at 30,000 rpm. The yeast and other “heavy” particles are forced to the outside wall of the centrifuge and are drained away, while the now-clear beer is forced to the centre of the centrifuge, where it is drained to the next step of finer filtration or to a holding tank.

This can remove yeast from a very large volume of beer in a short time, but there some caveats. This is not a machine you want to run if you have the slightest doubt about maintenance issues. It is a big heavy machine with parts that are spinning incredibly fast — if anything were to happen, I would not want to be in the same building, let alone standing beside it.

At MillerCoors, they have discovered that measuring the discharge is essntial to optimizing performance. If the discharge starts to drop off, there could be a problem. They have also installed sensors that can detect if a shaft bearing is starting to fail. In addition, MillerCoors has instituted a schedule of cleaning and preventative maintenance that include semi-annual major overhauls, timed to avoid the busy summer brewing season. All of their American operations now use standardized maintenance practices, and maintenance personnel are trained to follow a Standard Operational Procedure (SOP).

Next up: Barrel Dwellers

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