November 23, 2012

Yeast Project Post #2

I decided to start the project by testing three strains: RAM-1 (WLP 300); RAM-2 (Stroh); and RAM-10 (Blatz). I figured the two probable lager strains would be good to test side-by-side and the WLP300 sample would be a good benchmark for my process, since I know what that strain should produce.

Overall Process

I first needed to grow the cultures in a small volume of wort, so each received 10ml of 1.040 wort with manual aeration (shaking). Part of the culture will then be moved to a 90ml solution of 1.030 to grow for a fermentation test. Once the 90ml starter is fermented, the liquid will be decanted and 13oz of 1.040 wort will be added. The fermentation will occur at 61F for five days, followed by one week at room temperature. The beer will be siphoned off, gravity-tested and bottled. It will be conditioned for three weeks as usual. The remaining cake will be rinsed and then stored for either further tests or addition to my frozen yeast bank. The beer will be tasted for flavor profile (the worst part of the project!).

Depending on the strain and results, additional small fermentations may be done to test the strains productivity at higher or lower temperatures. Lager strains may get a test at a higher temperature to test upper limits of usefulness but probably not lower. I hope to be able to identify the lager strains by esters produced in the low 60s due to their usual clean performance in the 50s.The ale strains will probably undergo testing at 61F, 68F and some in the mid-70s, depending on the strain and how it performs at lower temperatures. If it produces undesired esters at 68F, no reason to test it at 75F.

Notes for RAM-1, RAM-2 and RAM-10 -- 11/1/12

Since I just brewed the mesquite porter I was able to coax out some additional runnings from the grains and boil it down to a useful gravity. I went ahead and hopped the wort for convenience and minor bacterial defense. This same wort will be used in the final fermentation tests, too. It's not an ideal environment for any of these three yeasts but it's mild enough to allow yeast flavor to come through.

10ml cultures
Each culture received 10ml of wort at 1.040 with shaking for aeration. RAM-10 (Blatz) showed the quickest sign of reproduction with a small dusting of yeast on the bottom of the vessel and obvious CO2 production, roughly 24 hours after pitching. Both RAM-1 and 2 are lagging roughly 42 hours later but showing some signs of CO2 production (or just air venting back out of the liquid when I shake it). The worts in 1 and 2 are more clear, suggesting less yeast activity. My source says it may take as much as five days for solid growth to occur.

RAM-10 already smells like a drier beer with some light-struck character, like corona. Since it was showing positive signs of significant growth I removed roughly 4ml and added to a 90ml 1.030 starter, receiving shaking (I'm feeling like I have a lot of plates spinning now).

Notes for RAM-1, 2 and 10 -- 11/2/12

I woke up this morning to some happy looking yeast. Each vial, when shook for aeration, produced positive pressure in the vial, which suggests significant fermentation has occurred/is occurring. The RAM-1 smells like hefe yeast, as it should. RAM-10 continues to smell Corona-like. RAM-2 smells more clean with a slight fruity character.

The starter of RAM-10 is also showing signs of bubbling. There's a thin layer of bubbles growing on the top but it doesn't look like krausen, yet. I'm keeping an eye on krausen growth to try to determine if this is a lager or ale strain.

Notes for RAM-1, 2 and 10 -- 11/3/12

RAM-10 has developed a nice, thick layer of yeast at the bottom of the starter. At the end of the day both RAM-1 and 2 were showing good signs of fermentation so I added them to their own respective 90ml starter. The RAM-10 starter lost the skunky smell and is starting to exhibit a slight fruity-ester character and some of the smell of well, a lager.

Notes for RAM-1, 2 and 10 -- 11/4/12

RAM-10 has a very thick layer of creamy white yeast. It appears to be ready to be stepped up. RAM-2 is showing some signs of fermentation in the starter. RAM-1 is showing some, but slightly less than RAM-2. I will probably hold off on stepping up RAM-10 so I can do all three at once and put them in the fermentation chamber as the mesquite porter is coming out.  

By the end of the evening the starters looked inactive so I put them in the fridge to cold crash and expect to get fresh wort in there for a fermentation test tomorrow. 

Notes for RAM-1, 2 and 10 -- 11/5/12

Poured out the starter liquid today and added fresh wort of 13oz to each starter. Will ferment at 65F for three days, then let rest at room temperature for a week. Added 13oz of 1.040 wort with aeration and yeast energizer at 1pm.

Tasting notes on starters: RAM-1 tasted like light struck porter with hints of banana and clove, just as should be expected from a hefe strain. RAM-2 had strong caramel and apricot flavor, slightly reminiscent of steam beer. RAM-10 was similar to RAM-2 but with less caramel, more apricot and a slight skunky character like the initial starter.  

Roughly six hours after adding fresh wort there is a thick layer of foam in each vessel. Perhaps each yeast actually is an ale strain and it is krausen on each. Could still just be escaping CO2 crowding into a foam.

Notes -- 11/8/12

After three days at 65F I let the temperature rise to 69F with the intent of letting it rise to 75F (or as warm as it will get at room temperature). I will let it stay at these temperatures for seven days and then test the FG and bottle. RAM-1 looks fairly clear with a good compact cake of trub with lots of yeast. RAM-2 also looks clear but with a little less yeast. RAM-10 has very little yeast in the cake but the walls of the jar are lined with yeast. I wish I could get them to fall off into the cake to try to keep a larger volume from the batch.

Notes -- 11/15/12

Today I bottled each beer as a sample. I ended up with around 8-10oz in each bottle because I was trying to leave as much yeast behind as possible. I haven't quite decided how I am going to try to wash the yeast down to an amount I can put in my frozen yeast bank but I have plenty of time to figure it out and for now the cakes are sitting in mason jars under sterilized water in my fridge. The leftover runnings I used from the porter didn't make a great test wort because there's a lot of unfermentables in it and I added way too many hops so it's pretty bitter. I'll just buy some DME at the homebrew shop next week and make my life a whole lot easier.

I tested the beers for gravity and sensory perception. Results were not too surprising:

  • RAM-1 (WLP300): pretty much what was expected, some clove and banana underneath the porter and hops. Hefe yeast does not belong in a porter. FG was 1.012.
  • RAM-2 (Stroh's): strong caramel aroma, some yeast esters, slight diacetyl. Tasted same as it smelled. FG was 1.011.
  • RAM-10 (Blatz): intense aroma apricot and caramel, sort of an apricot cobbler aroma. Taste was less apricot-y with slight skunky character. FG was 1.012.


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