So, Wheebz was giving me a hard time in my Bock thread: http://thehotpepper.com/topic/57204-gms-bock-die-sechste-welle/?p=1221241
There's always something to learn when that happens, so I've been digging around in white papers for days ...
Here's some bulletpoints and info I've gained since:
Lagering
- SO2 in solution keeps beer from staling during lagering.
- SO2 content correlated strongly with the ability of the beer to remain unoxidized.
- Sulfur odors will be mostly dissipated by itself, once the keg is vented.
- Overcarbing to 20-30 psi & venting a few times can scrub a lot of sulfur, quickly.
- Ensure yeast nutrient is rich in zinc, specifically. Servomyces is a good add for all beers.
- Aeration is increasingly important for lagers, and a feelgood in terms of hurdle theory.
- Brett, Lacto, and Pedio are microaerophilic, hence growing well in barrels.
- Post-ferment sulfur is likely mercaptan removable by contact with copper (penny in a glass test).
- Yeast selection, lower temperature, and yeast nutrients help lower H2S in the first place.
- There's an old rule of thumb to double all yeast counts for a lager - it's probably a poor model, though.
- Wort chilling is key for lagers, below 60F, and better yet at 55F or below.
- Diacetyl rest in primary recommended to give the yeast a chance to warm up and scrub.
- Most old texts recommend not moving the temp more than 5F/day, but this is iffy now.
- Lagering should always be below 40F, but most are going down to 32-34F commercially.
- Lagering length can be ballparked by 7-12 days per 2 degrees Plato OG. 1 Plato equals roughly 4 points of SG. 3-7 days for lighter beers.
- Lagers are increasingly flavor-stable and hold up well to being kept cool, but not necessary cold when done. It's more important to limit the fluctuation.
- Reducing the trub and dissolved oxygen in wort reduces hydrogen sulfide.
- Top-fermenting yeasts produce less than bottom-fermenting yeasts all other factors being the same.
- Autolysis caused by high osmotic pressure, extremely high temp, long-term storage, and sudden environmental changes. The normally encapsulated digestive enzymes are released and destroy the cell from the inside.
- Most of these come from the barley, and Canadian barley is known to produce a lot of DMS. Continental 2-row barley has been found to give a more refined sulfury flavor than midwestern six-row. Levels of SMM increase with protein content, thus British malts contribute negligible amounts of SMM compared to the others.
- 8% evaporative loss is the minimum amount needed to remove DMS, which has a boiling point of 100F.
- Cooling should proceed quickly through the ~140F point, where SMM converts to DMS.
- Don't mistake a lack of air-lock activity for a problem as cooler wort stores much more CO2 before it would appear in the airlock. Checking for a decrease in pH can be satisfying for knowing fermentation is taking place.
- You DO want to remove trub and cold break before lagering. They use sedimentation tanks, centrifuges, and bubbling it out.
- Expect a long lag time for lagers, 16-36 hrs is common.
- Lagers are a good candidate for a thermowell so you are controlling the temp of the beer during the part where fermentation slows, as opposed to probing the environment.
- Lots of yeast scientists for products recommend pitching close to 75F, even for lagers, but most homebrewers have found it's better to pitch cold, closer to fermentation temp, to avoid the shock as a priority. Kai says to keep it below 54F, and that 48F is better.
- Controlled use of pressure following the budding allows for control of ester and higher alcohol production at higher temperatures.
Here's a f**king beautiful chart from Kai:
And one w/ the verbal conclusions:
Also worth a read was George Fix's "Lagering - Is It Worth The Effort?" makes some interesting points:
Chill Proofing - ice brewing procedure where beer is reduced to a couple of degrees BELOW the beer's freezing point (gravity-dependent) and tiny ice crystals form and scrub the beer of haze etc. In his words, extensive research proves the resultant beer to be entirely chill proofed. The temp is around 27.9F for normal strength beers, and contact time as little as an hour.
Select yeast which have very low bacterial and mutant levels, and kraeusening the beer with fresh wort and yeast is more reliable than increased lagering time.
Fermentations conducted at ambient temperatures (65-68F) should end with all relevant sulfur compounds well below their threshold. An exception usually indicates infection by gram-megative microbes.
Widespread agreement that too much control of sulfur leads to an insipid beer, and some sulfur is important as an oxygen scavanger and is key to the excellent flavor stability of the style. Fix finds that most sulfurs can be reduced by 1 week at 32-36F.
Fix says pitching rate is more critical to sulfur production than strain. Rate should be 1-2 million cells per ml for each degree Plato. Using very large starters can lead to excess sulfur, and create an variety of off-flavors due to yeast autolysis - and is why the double-everything from day's old isn't a good model.
Lagering depends on having living yeast to esterify fusel alcohols, and thusly must proceed the ice brewing stage.
Dry hopping during lagering is a good technique, and you get approx 1 month of resultant flavor from 1 month of contact time. Lagers are traditionally naturally carbonated during the lagering.
People sensitive to carbonic acid, who dislike gassy beers, tend to prefer by a wide-margin the flavor of beers made with natural carbonation when CO2 levels are in excess of 2.4 vols. CO2 might be more tightly bound up with other constituents.
Some new terms:
Jungbuket - the smell of fresh beer
Spundungsapparat - system w/ Spunding valve to naturally carbonate in accord with German Beer Purity laws.
A strain rec from ProBrewer from my day spent researching:
Augustiner lager strain - reportedly low in production of sulfur esters, pitched into 50F, fermented at 54F, spunding places 1 Plato above target gravity. 4 days of diacetyle rest at ferm temp, chilled to 38F for 10d, and finally down to 30F for 2 days.
The best few of the many things I read:
Kai: http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers
Finally, a shortened method worth trying: http://brulosophy.com/methods/lager-method/
And some more Brulosophy on fermenting under pressure:
- http://brulosophy.com/2015/04/27/under-pressure-the-impact-of-higher-psi-fermentations-exbeeriment-results-2/
- http://brulosophy.com/2015/09/07/under-pressure-pt-2-the-impact-of-pressurized-fermentation-on-saison-xbmt-results/
There's always something to learn when that happens, so I've been digging around in white papers for days ...
Here's some bulletpoints and info I've gained since:
Lagering
- SO2 in solution keeps beer from staling during lagering.
- SO2 content correlated strongly with the ability of the beer to remain unoxidized.
- Sulfur odors will be mostly dissipated by itself, once the keg is vented.
- Overcarbing to 20-30 psi & venting a few times can scrub a lot of sulfur, quickly.
- Ensure yeast nutrient is rich in zinc, specifically. Servomyces is a good add for all beers.
- Aeration is increasingly important for lagers, and a feelgood in terms of hurdle theory.
- Brett, Lacto, and Pedio are microaerophilic, hence growing well in barrels.
- Post-ferment sulfur is likely mercaptan removable by contact with copper (penny in a glass test).
- Yeast selection, lower temperature, and yeast nutrients help lower H2S in the first place.
- There's an old rule of thumb to double all yeast counts for a lager - it's probably a poor model, though.
- Wort chilling is key for lagers, below 60F, and better yet at 55F or below.
- Diacetyl rest in primary recommended to give the yeast a chance to warm up and scrub.
- Most old texts recommend not moving the temp more than 5F/day, but this is iffy now.
- Lagering should always be below 40F, but most are going down to 32-34F commercially.
- Lagering length can be ballparked by 7-12 days per 2 degrees Plato OG. 1 Plato equals roughly 4 points of SG. 3-7 days for lighter beers.
- Lagers are increasingly flavor-stable and hold up well to being kept cool, but not necessary cold when done. It's more important to limit the fluctuation.
- Reducing the trub and dissolved oxygen in wort reduces hydrogen sulfide.
- Top-fermenting yeasts produce less than bottom-fermenting yeasts all other factors being the same.
- Autolysis caused by high osmotic pressure, extremely high temp, long-term storage, and sudden environmental changes. The normally encapsulated digestive enzymes are released and destroy the cell from the inside.
- Most of these come from the barley, and Canadian barley is known to produce a lot of DMS. Continental 2-row barley has been found to give a more refined sulfury flavor than midwestern six-row. Levels of SMM increase with protein content, thus British malts contribute negligible amounts of SMM compared to the others.
- 8% evaporative loss is the minimum amount needed to remove DMS, which has a boiling point of 100F.
- Cooling should proceed quickly through the ~140F point, where SMM converts to DMS.
- Don't mistake a lack of air-lock activity for a problem as cooler wort stores much more CO2 before it would appear in the airlock. Checking for a decrease in pH can be satisfying for knowing fermentation is taking place.
- You DO want to remove trub and cold break before lagering. They use sedimentation tanks, centrifuges, and bubbling it out.
- Expect a long lag time for lagers, 16-36 hrs is common.
- Lagers are a good candidate for a thermowell so you are controlling the temp of the beer during the part where fermentation slows, as opposed to probing the environment.
- Lots of yeast scientists for products recommend pitching close to 75F, even for lagers, but most homebrewers have found it's better to pitch cold, closer to fermentation temp, to avoid the shock as a priority. Kai says to keep it below 54F, and that 48F is better.
- Controlled use of pressure following the budding allows for control of ester and higher alcohol production at higher temperatures.
Here's a f**king beautiful chart from Kai:
And one w/ the verbal conclusions:
Also worth a read was George Fix's "Lagering - Is It Worth The Effort?" makes some interesting points:
Chill Proofing - ice brewing procedure where beer is reduced to a couple of degrees BELOW the beer's freezing point (gravity-dependent) and tiny ice crystals form and scrub the beer of haze etc. In his words, extensive research proves the resultant beer to be entirely chill proofed. The temp is around 27.9F for normal strength beers, and contact time as little as an hour.
Select yeast which have very low bacterial and mutant levels, and kraeusening the beer with fresh wort and yeast is more reliable than increased lagering time.
Fermentations conducted at ambient temperatures (65-68F) should end with all relevant sulfur compounds well below their threshold. An exception usually indicates infection by gram-megative microbes.
Widespread agreement that too much control of sulfur leads to an insipid beer, and some sulfur is important as an oxygen scavanger and is key to the excellent flavor stability of the style. Fix finds that most sulfurs can be reduced by 1 week at 32-36F.
Fix says pitching rate is more critical to sulfur production than strain. Rate should be 1-2 million cells per ml for each degree Plato. Using very large starters can lead to excess sulfur, and create an variety of off-flavors due to yeast autolysis - and is why the double-everything from day's old isn't a good model.
Lagering depends on having living yeast to esterify fusel alcohols, and thusly must proceed the ice brewing stage.
Dry hopping during lagering is a good technique, and you get approx 1 month of resultant flavor from 1 month of contact time. Lagers are traditionally naturally carbonated during the lagering.
People sensitive to carbonic acid, who dislike gassy beers, tend to prefer by a wide-margin the flavor of beers made with natural carbonation when CO2 levels are in excess of 2.4 vols. CO2 might be more tightly bound up with other constituents.
Some new terms:
Jungbuket - the smell of fresh beer
Spundungsapparat - system w/ Spunding valve to naturally carbonate in accord with German Beer Purity laws.
A strain rec from ProBrewer from my day spent researching:
Augustiner lager strain - reportedly low in production of sulfur esters, pitched into 50F, fermented at 54F, spunding places 1 Plato above target gravity. 4 days of diacetyle rest at ferm temp, chilled to 38F for 10d, and finally down to 30F for 2 days.
The best few of the many things I read:
Kai: http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers
Finally, a shortened method worth trying: http://brulosophy.com/methods/lager-method/
And some more Brulosophy on fermenting under pressure:
- http://brulosophy.com/2015/04/27/under-pressure-the-impact-of-higher-psi-fermentations-exbeeriment-results-2/
- http://brulosophy.com/2015/09/07/under-pressure-pt-2-the-impact-of-pressurized-fermentation-on-saison-xbmt-results/
