Marin Society of Homebrewers
Quarterly Style Q1 2017
Lagers are differentiated from ales for a number of reasons but the most relevant is the yeast strain. There are 2 main yeast strains used in brewing, Saccharomyces Cerevisiae (ale) and Saccharomyces Uvarum (lager), fka Saccharomyces Carlsbergensis. This quarter the style that is brewed must use a Saccharomyces Uvarum strain or bottom fermenting yeast, see the lists below for options. Lagering is merely cold storing the beer and although it’s generally accepted that longer cold storage makes for a better a lager it isn’t necessarily required to be aged for long number of months.
Most lager yeasts perform well in the 45-60° F range for fermentation. There are some exceptions, like San Francisco lager yeast, which can work into the mid 60°’s. Many lager strains will produce sulfur and a little bit can be a big aroma, keep this in mind. In addition to the sulfur, acetaldehyde and other off-flavors will be produced. One that is potent and very common is diacetyl requiring a diacetyl rest as part of the fermentation. A diacetyl rest is merely warming the beer around the end of fermentation in order to make the yeast more active so that it will clean up the off-flavors. This is generally raising the beer to roughly 62° after 2 weeks of fermentation and keeping it there for a few days. The benefit of this is that in addition to cleaning up the diacetyl it will mop up other off-flavors as well. Usually only time will clear up sulfur.
Once this is complete on around days 17-20 you can move the brew to a secondary for lagering. This can be another carboy or a keg. The best option is too slowly lower the temp about 5 degrees per day until you’re at around 35°. Please keep in mind this is the ideal practice for lagers and it’s not required these steps be followed to a T. For example I generally just transfer my brew to a keg after 3 weeks and stick it in my keezer, essentially cold crashing it. I haven’t looked into what kind of impact this has on the brew.
It can be difficult for brewers, like myself, that don’t have an easily temperature controlled fermentation chamber to make a lager. Some of the practices used in the heat of summer can be applied here as well. If you happen to have a spare refrigerator they are excellent fermentation chambers but may require an external thermostat to be allowed to get as warm as many lager fermentations require.
Important Items to Note
Valid Yeast strains examples
Valid from White Labs - (please excuse any typos in transcription) http://www.whitelabs.com/yeast-bank?show=yeasts&type=lager&tid=220 (NOTE only those with lager in the name from this page, Irish and Scottish Ale yeasts are not lager yeasts)
WLP 800, 802, 810 (SF strain), 815, 820, 830, 833, 835, 838, 840, 850, 860, 862 (hybrid), 885, 920, 925, 940
Valid from Wyeast - (please excuse any typos in transcription) https://www.wyeastlab.com/beer-strains?field_style_category_target_id%5B%5D=14
2000, 2001, 2002-PC, 2005-PC, 2007, 2035, 2041, 2105-PC, 2112, 2124, 2206, 2247-PC, 2272-PC, 2278, 2308, 2352-PC, 2487-PC, 2575-PC, 2633, 2782-PC