Posted tagged ‘centrifuges’

MBAC 100th Anniversary Conference: Part 3

February 24, 2014

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

Advertisements

Day 435

November 13, 2012

We’re up to the early 1970s in History of Rock & Roll. Yep, bell bottom jeans, platform shoes, polyester leisure suits, big hair. How did the period 1970-75 produce so much good music (Led Zeppelin, David Bowie, Black Sabbath, Deep Purple, Steely Dan, Queen), so much bad clothing, and so much REALLY BAD music? (The Bay City Rollers, Tony Orlando & Dawn, and The Captain & Tennille, who some day will have to answer for inflicting “Muskrat Love” on the world.) But if the bad music was really so bad, how did it prosper?

Although I lived through this period, I didn’t think at the time about why the good music/bad music dichotomy had happened–it just happened. So it’s very interesting to sit in a class and hear the reasons about why. (However, there was no theory about what had caused the bad clothes. And I will  continue to deny that I ever wore them.)

My head filled with “Bohemian Rhapsody”, it was off to Business Ethics, where we argued the pros and cons of child labour. I was on the “Pro” side of the argument, and I am pleased to report that by the time our side was finished, child labour  not only seemed viable but indeed necessary for the economic vitality of our country.

All of this was to prime us for our next major in-class activity which starts next week: one-on-one debates. We have already been assigned a debate opponent, and our topic. In my case, I will be arguing that it is ethical for celebrities to endorse products that they don’t actually use or like.  Hrm, have to think about that one.

We had a couple of hours between classes, so I drank gin cocktails. Well, sort of. We have this project coming up in Sensory Evaluation where we have to present a beer cocktail to the class. My partner and I have an idea that mixing Belgian wit and gin will work, but the devil is in the details, so this afternoon we  tried mixing them together with varying amounts of other ingredients. Results were encouraging, but we still feel there’s room for improvement. More experimentation is obviously called for.

Following that, I had the strangest urge to have a nap in FCF. Huh. And it was such an interesting topic: centrifugation; that is, using a centrifuge to remove solids such as yeast or trub  from your wort or beer. These machines have many benefits compared to filters–high throughput, very efficient, little chance of clogging, no expensive or unhealthy filter media to buy and store, etc. However, because they are relatively expensive, they are largely unknown in the craft beer world. Large brewers who can afford them use them extensively for everything from recovering as much wort as possible from spent grains to removing all but the smallest particles from finished beer just before sterile filtering.

We also took a quick look at pasteurization systems. Again, these are usually not found in craft breweries, firstly because they are expensive, and also because many craft brewers believe that pasteurization alters the taste of the beer in unacceptable ways. Pasteurization isn’t meant to sterilize the beer–the temperatures involved would render the beer undrinkable–but only to kill most microorganisms and make any remaining almost unviable. Each minute the beer is raised to 60°C is rated as 1 Pasteur Unit (PU); brewers generally want to apply about 10-15 PUs to their beer, the exact amount depending on the brewer. How the heat is applied is also up to the brewer–a slow gentle rise in temperature and holding it just at 60°C for a longer period of time will affect the flavour one way, suddenly heating the beer to much higher than 60°C for a shorter period of time will affect the flavour very differently.

There are two main types of pasteurizers in breweries:

  • tunnel pasteurizers: the already bottled beer is sent into a rather large machine. As the bottles advance on a conveyor belt, they move under water nozzles that spray hot water until the beer’s temperature rises above 60°C; the bottles then pass under cooler sprays which quickly chill the bottles.
  • flash pasteurizers: the unbottled beer is sent through a steel tube. Heat, in the form of steam or hot water, is applied to the outside of the tube, instantly raising the beer’s temperature above 60°C as it passes by.

There are advantages and disadvantages to each system–the tunnel pasteurizer is the size of a room, the flash pasteurizer is the size of an office desk, etc.

Now, time to hunt up some more ingredients for our gin & wit cocktail.

 


My Post-Apocalyptic Life

The world has ended, but movies and games live on.

Married to Beer

Seeing the humour in a spouse who loves suds!

Ruminations of a Canadian Geek

The thoughts and ruminations of a university chemistry and roleplaying geek

Madly Off In All Directions

A blog about whatever strikes my fancy...

It's what's on tap...

Brewing, mostly.