Yeast Series: Temperature Affects on Yeast Fermentation

I was asked by my father if I could brew a beer for my cousin’s post wedding party. His request was for BBQ and German beer. Well unfortunately I assumed that he was thinking German lager, which only a month out I could not produce. Since most German beers are lagers, I didn’t have many options. Kölsch, Alt, and Hefeweizen are pretty much my only options for a quick turnaround beer. We decided to brew 10 gallons of Hefeweizen and keg it. 

I wanted to attempt to do a multistep mash and try to produce more clove aroma then banana compared to my last attempt at brewing a hefeweizen. Granted the last time I brewed a hefeweizen I believe it was over a year ago and I dry hopped it. Before that I think the last time I brewed one was the first beer I brewed. Since that time my brewing has drastically improved so I was intrigued to see how the beer would turn out compared to the first time I brewed. In attempting to add more clove aroma and flavor I knew that fermenting at a lower temperature causes the yeast to produce more 4-vinylguaiacol, which is the ester that produces clove. On top of that I’ve read that mashing at 113^oF will provide the precursor for that aroma. However, after more research and seeing an experiment conducted by Braukaiser, I decided it was not worth the extra effort. Kai’s experiment consisted of brewing two different hefeweizens using the same yeast and same ingredients. The only difference is that one beer he performed a ferulic mash rest and the other he did not. The outcomes essentially produced the same beer, thus in my opinion it wasn’t worth it.  

I used what most people would call an excessively complex grain bill for this beer since traditionally, and in fact by law in think in Germany, hefeweizens are 50% Pilsner malt and 50% wheat malt. I didn’t feel like doing an extended 90 minute boil for the Pilsner malt since we had people coming over that night for a bottle share, however I did want some of the crispness that Pilsner malt contributes. I also decided to add a little melanoidin malt for a touch of bready complexity. Of course the acid malt is for lowering my mash pH into the right range. I was also this time able to correctly use my pH meter to confirm my mash pH.  Since I didn’t have room to ferment both beers in my chest freezer I decided to ferment one in the chest freezer at a low temperature to attempt to keep the banana under control and increase the clove aroma. The other will be fermented at ambient temperature so we should end up with two pretty different beers and it should highlight the affect yeast has on a beer. 

Beer Stats

Grain Bill: 17.5lbs

Boil time: 75 minutes

Batch size: 10.5 Gallons

Estimated OG: 1.043

Measured OG: 1.042

Measured OG:

ABV:

SRM: 6.4^o

IBU: 20

Grain Bill

8lbs – White Wheat

5.5lbs – Pale Malt

2.5lbs – Pilsner Malt

1lb – Acid Malt

0.5lbs – Melanoidin Malt

Hop Schedule

60min - Hallertauer (Ger.) – 2.5oz

0min – Hallertauer (Ger.) – 1.5oz

Mash Schedule

Double infusion saccrification rest 45min 144^oF Beta Amylase rest followed by 30min 155^oF Alpha Amylase rest infused with boiling water

Yeast

1.5L Starter – WPL300 Weihenstaphen 

Notes:

5/10/14 – Brewed with my Dad. Only 0.001 off of target pre-boil gravity so no adjustments made. Mash pH was 5.55 and final boil pH was 5.37. I would have preferred for the mash pH to be a little lower, but still acceptable. Chilled to 80^oF, half of the batch was placed in my chest freezer with the temperature set to 39^oF, the other half was placed in my beer room to ferment at ambient temperatures. Three hours later the chest freezer temperature was increased to 65^oF and the yeast starter was split between each carboy. The plan is to have a comparison between fermentation temperatures. 

5/11/14 – Fermentation has started on the upstairs beer.

5/12/14 – Signs of fermentation in the chest freezer beer.

7/31/14 - Long over due update. Life got in the way and I ended up only having one glass of the temperature controlled version. It was not finished carbonating yet but it needed to be served so it was as ready as it's going to be. It looked great, it smelled great, much less banana then normal and more clove and spicy esters. The only down side was low carbonation and no head. That's the good news. The bad news is that the other half of the experiment sits in my beer room because it's infected. I don't know how it's infected because I've been afraid to try it knowing that it was probably infected by the flies that got into the house. Maybe I'll be brave enough to try it soon. If it's bad I'll dump it so I can have the carboy back. 

Rustic Saison

With the impending ending to my Conan Black IPA and the subsequent loss of my Brett Black IPA I was getting dangerously close to not having a keg of beer. The horror. Since I had Good Friday off I decided it would be a good time to brew a beer for the summer. Currently my chest freezer is occupied with lagering my Helles I needed to brew something that doesn’t need temperature control or low temperatures in general, which basically leaves me with Saisons and Belgian style ales. I decided to brew a “rustic” Saison and in traditional fashion, try a new technique that I’ve never tried before. I decided to use honey for the first time instead of candi sugar. I’ve always felt that using honey in beer is mostly a waste. It’s an expensive source of sugar that is normally over powered by the beer. If I’m going to spend the money to use honey I want to make sure that you can tell honey was used. I read up on making mead since honey is the only source of sugar for mead and thus the honey is perceivable. When making mead the prevailing process was either add the honey to water at 170F to sterilize or add it to warm water since honey has natural preservatives or has been processed. I decided since honey is delicate and the flavors can easily be driven off through heat I would take the risk and add it straight to the fermenter.  It’s supposed to be a rustic Saison so if there is any Brett in there I’m fine with it or if it ends up slightly tart I’m also fine with that. The plan is to hopefully preserve some of the honey flavor and aroma by adding it after the beer has been cooled. 

This was also my first time using the pH meter that my wife got me for Christmas. I’ve wanted to use it but I wanted to make sure I had enough storage solution for the electrode. I’m not sure when to measure the mash pH. When I first took the reading it registered at 6.3 so I figured I should wait for conversion to begin. I added a half pound of acid malt, waited and took a reading. It was only down to 6.1 so I added the rest of the acid malt but also started to panic because I knew I wouldn’t have enough acid malt to lower it to 5.3, which was my goal. I calculated the lactic acid addition needed to lower it, which was 3.1mL. I don’t think my readings were off because of temperature since I cooled my samples and my meter has temperature adjustment. After mash and sparge I took a reading when the beer was heating for the boil, it read 4.93. I’m assuming the lactic acid addition took it all the way down, whereas my acid malt would have probably hit my target. Although I’m not too worried about the pH, aside from yeast fermentation, but it is Saison yeast. Saisons and particularly rustic style Saisons generally have a slight tartness from lactobacillus. 

I attempted to aerate as best I could since I still don’t have an O2 tank (hopefully that will change soon). I think I either did a pretty good job of aerating or my yeast pitch was very healthy since this is the first time I’ve had fermentation take off the same day I brewed. 

Recipe

Batch Size: 6 Gallons

Boil Time: 110 minutes

Target OG: 1.062
Measured: 1.058
Measured FG: 1.011
ABV: 6.2%

SRM: 7^o

IBU: 30

Grain Bill

7lbs- Belgian Pilsner malt

2lbs – Rye malt

1.5 lbs – White Weat

1.5lbs –Pale malt

1.5lbs – Wildflower honey

0.75lbs – Acid Malt

Hop Schedule

90 minutes – Saaz – 2.5oz

0 minutes – Saaz – 1.5oz

Mash Schedule

148F - Single infusion

Yeast

Wyeast 3711 – French Saison

Notes:

4/18/14 – Brewed by myself. Easy brewday, not sure when I need to measure my mash pH so I added too much acid. I also accidently added my hops at 90 minutes instead of at 60, but it will only add 4 more IBUs. Ended with 8.75 gallons of 1.034 wort so I extended the boil to increase the gravity. Finished with 5.5 gallons of 1.052 wort prior to adding the honey. Pitched a 1.8L starter that I made the day before. Fermentation started a few hours later.

5/4/14 - Gravity down to 1.011. Placed in chest freezer at 37F to cold crash.

5/6/14 - Gravity down to 1.011 racked into keg. I found out only after I started racking into my keg that I was out of CO2. Luckily I still had two empty kegs that I haven't cleaned and were still pressurized. I used the empty keg to flush the saison keg and pressurize it to seal it. I'll pick up CO2 tomorrow to carbonate it.

5/7/14 - Got a full CO2 tank and now the the Keg is hooked up to 16psi at 38F.

Barrel Fermented Wild Ale

I’m way behind on doing the write up for this beer. Mostly because it’s the same recipe that I always use for my wild ales and the only variation is that I’m trying to do a 100% barrel fermentation this time. I bottled the previous beer the night before and added boiling water to it to clean the inside of the barrel. At this point there are so many critters in the barrel I can only use it for wild ales. I’m hoping that there is no acetobacter in the barrel, but there probably is at this point. The whole point of adding the boiling water was to attempt to clean out all of the yeast that have fallen to the bottom over time. After I drained the water I closed it up and left it in my beer room over night until I brewed the next day. 

A few days before brewing I made a small starter using the dregs from a Crooked Stave Vielle Saison, just in case I need something extra to start fermentation. I had no idea if there was anything alive in the bottle or what is used for brewing the beer but I figured it couldn’t hurt. At the end of racking the cooled beer into the barrel I used what was left to top up my starter to 2L, which had showed some signs of fermentation. Well the fresh wort definitely caused the starter to take off and was bubbling over the side by the next day. 

The barrel never really showed signs of fermentation like I had hoped, even after adding some of the starter. I do know that something in there is fermenting because there is a pellicle over the top of the beer, but the activity was never very strong. Eventually I’ll take a gravity reading to see where it’s at. 

Stats

Batch size: 6 gallons

Boil time: 90 min

OG Est: 1.048

OG measured: 1.048

FG Est: 1.006

SRM: 3^o

IBU: 6

Grain Bill

Pilsner Malt – 7lbs

Belgian Wheat – 3.5lbs

Acid Malt – 0.5lbs

Hop Schedule

90min – Willamette – 3.5 oz (aged 3 years)

Yeast

Barrel bugs and Crooked Stave Vielle Sasion dregs

Mash Schedule:

Single infusion – 158F – 45minutes

Notes:

3/29/14 – Brewed by myself. No issues brewing. Acid malt added to lower my pH into a more optimal range. Should be at 5.5pH.  Added 4 grams of gypsum and CaCl to the mash to up my calcium levels. Chilled and racked directly into the barrel.

4/01/14 – Signs of strong fermentation in the starter, no signs in the barrel. Barrel topped up to reduce head space and add fresh bugs.

4/05/14 – Still no signs of fermentation but there is a pellicle. 

11/28/14 - Bottled with 98 grams of table sugar. Gravity was down to 1.014, which in retrospect might have been too high to bottle. Good thing I used thick bottles. 

Hell Camino: Municher Helles

Since I have a stir plate and a temperature controlled chest freezer I finally decide I should brew a lager. I thought a Municher Helles would be a good start. I’ve wanted to brew a lager for a while but have honestly always been a little intimidated by the process. This might sound strange since I have no problem diving right into barrel aging and using bugs, but for those beers I can get away with being lazy and they are my favorite styles. Like most people lagers were the first style of beer I tried and like most people I didn’t really like them. Eventually I moved on to other stuff and had essentially sworn off of lagers, but I think there is a point in every beer nerd’s journey where you go back to where you started. I’ve been gaining a new found appreciation for lagers, which is in part because I can find good, fresh, domestic sources (not BMC, but domestic craft). I have started to revert back to enjoying beers at 5% ABV or below that are easy to drink and complex enough to hold my attention. Lagers fit the bill along with pale ales and session ales. 

In order to brew a good lager you need to have more equipment then the average home brewer (especially if you live in a warm climate). Lager yeast if fermented too warm will start to produce a lot of off flavors, generally DMS, and by warm I mean over 55^oF. However, if not fermented correctly they can also produce a lot of diacetyl, which smells like butter popcorn. To prevent this you must perform a diacetyl rest. This involves slowly raising the temperature so is not to cause off flavor and yet keeping the yeast active so that they will clean up any diacetyl. Then they must then be “lagered” or stored at close to freezing temperature for conditioning for extended periods of time, usually 6-8 weeks or more depending on the starting gravity. On top of that if you read anything about brewing a German style lager or a Pilsner you will notice the complex mash schedules that are used. Most people will tell you that you don’t need to conduct a decoction mash for a lager since most malt available to homebrewers is highly modified, but I like a challenge. I decided that if I was going to brew a German style lager then I might as well use a decoction. I did,  however, modify the schedule a little to fit my needs. 

Decoction mashes were created prior to proper temperature control for mashing. So the only way to estimate your temperature increases was to add boiling mash or water, since you knew the temperature of the boiling mash. Another reason was due to the Reinheitsgebot, which prevented you from using acid in the mash, so Germans utilized an acid rest for lowering their mash pH. For my mash I utilized a Hochkurz decoction mash, which I found information from courtesy of Braukaiser, since it gave me what I needed for my beer, without having to go through three decoctions. A Hochkurz mash uses two infusions, one for a protein rest and the other to raise the mash to a maltose rest for beta-amylase conversion. I missed both additions since I was winging two equations to calculate the amount of water I needed so I had to add ice cubes to chill the first addition and then add more boiling water to raise the second addition. For the first decoction you scoop out part of the mash (wort and grain) and slowly bring it to a boil while stirring to prevent scorching. When you add this back into the mash it raises it to your next target, in my case a dextrinization rest, alpha-amylase. The second decoction raises the temperature to your mash temperature and stops any conversion. 

This is a copy of the chart that I used from Braukaiser. Again I over shot my decoction temperatures because I took too much of a decoction from the mash tun since I didn’t have an equation nailed down at the start of my brew day. I thought what I had was good enough, it may have been just been my own calculations. 

The decoctions did certainly add more time to my brew day and I have no idea if it will make any kind of a difference. But what I do know is that I have never had wort that clear during lautering and after flame out then I had with this wort. There was a lot of protein material left in the mash tun and the hot break was quick and easy. We shall see how the finished beer is in a few weeks. 

Batch size

Boil Time: 90 min

Batch Size: 5.25 gallons

Boil Size: 7.5 gallons

Boil Gravity: 1.035

Efficiency: 70% (brew house)

Stats

Original Gravity: 1.050

Measured: 1.050

Final Gravity: 1.012
Measured: 1.014

ABV (standard): 4.7%

IBU: 15

SRM: 5

Grain Bill

8.5 lb - German - Bohemian Pilsner (85%)

0.75 lb - German - Munich Light (7.5%)

0.5 lb - German - Acidulated Malt (5%)

0.25 lb - German - Melanoidin (2.5%)

Hops

1 oz - Hallertau Mittelfruh, Type: Pellet, AA: 3.75, Use: Boil for 60 min, IBU: 15.55

MASH GUIDELINES:

1) Infusion, Temp: 131 F, Time: 25 min, Protein Rest (actual 129F)

2) Infusion, Temp: 144 F, Time: 60 min, Maltose Rest (actual 141F)

3) Decoction, Temp: 158 F, Time: 60 min, Dextrinization Rest (actual 155F)

4) Decoction, Temp: 167 F, Time: 20 min, Mash out (actual 169F)

YEAST:

White Labs - German Lager Yeast WLP830

Pitch Rate: 1.5 (M cells / ml / deg P)

Notes:

3/14/14 – 3.5L starter at 1.040, 2L on the stir plate and 1.5L in a growler that I shook. 

3/16/14 – Brewed by myself with help from John to watch my mash out while I was gone. Added 4 grams of CaCl to up my Calcium levels. Other than mash temperature difficulties a decoction mash was not that hard. I’m actually thinking about starting to perform a protein rest on some of my future mashes if it helps with clarity. I ended with too much wort, probably due to extra added during the decocotion and not adjusting my sparge. I extended the boil by an extra 45 minutes to compensate. Started my 90 minute time at the point my gravity hit 1.035. 

Chilled to 75F and placed carboy in the freezer at 38F to chill overnight and cold crash. Shook to aerate (I really need an O2 system).

3/17/14 – Racked to another carboy and added the yeast. Put back into the chest freezer and set temperature to 48F. 

3/18/14 – Signs of fermentation have started

3/20/14 – Gravity down to 1.031, raised the temperature to 52F

3/22/14 – Gravity down to 1.019, raised the temperature to 56F

3/27/14 - Gravity down to 1.014, raised the temperature 61F

3/30/14 - Cold crash starting at 61F, lowering the temperature 3F every day to avoid shocking the yeast

4/8/14 - Temperature down to 37F for lagering stage

5/7/14 - Keg pressurized to16psi at 38F