Hop crop 2012

Fig 1: Cascade in Spring 2012

Eureka, this is my hop crop report for 2012. The report from last year can be found here. I currently have four hop varieties: Hallertauer Mittelfrüh (since 2011), Northern Brewer (since 2011), Cascade and East Kent Goldings (both since 2012). And one plant of each variety. As the Hallertauer and Northern Brewer plants were in their second year, I hoped to finally be able to harvest some hops. I missed the right time to harvest the hops last year and got only a few grams of each variety. I bought two additional hop varieties this 2012 Spring (Cascade and East Kent Goldings) to have some very fresh aromatic hops available in the future. However, I did not expect a huge amount of both varieties in their first year.

Fig 2: Northern Brewer in Fall before crop

Well, the two varieties from last year (Northern Brewer and Hallertauer) grew very well (Fig 2). The Cascade and East Kent Golding plants grew as well but nothing compared to the two older varieties. However, I could harvest some hops of each variety by the end of August 2012 and beginning of September.

Fig 3: Fresh Northern Brewer hops

Fig 4: Fresh East Kent Goldings hops

Fig 5: Fresh Cascade hops

My hop crop for 2012:
– Northern Brewer: 1044 g (wet hops)
– East Kent Goldings: 80 g (wet)
– Cascade: 188 g (wet)
– Hallertauer Mittelfrüh: roughly 1’500 g (wet)

After cropping the hops, I left them on some screens to let the cones dry. Unfortunately, I don’t know the exact weight of the dried hops after the drying process. I assume the weight of the dried cones is somewhat like 10% of the wet mass.

I already used 150 g of dried Hallertauer hops for a kind of harvest ale (#64 Belgian Vienna Brown Harvest Ale). The remaining Hallertauer hops are in a well ventilated place to oxidize them and use them for sour ales in the future. The Cascade, East Kent Goldings and Northern Brewer hops are in vacuum sealed bags in my refrigerator. For further use…

I am quite happy about the 2012 hop crop. I finally got some fresh hops and used them for a recipe already. By the way, the Belgian Vienna Brown Harvest Ale I was talking about previously was my first batch where I used hop leaves instead of hop pellets. However, I still prefer hop pellets because the hop leaves do not settle down to the bottom of the kettle during the whirlpool as easily as the hop pellets do.

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Yeast basics: Check yeast viability

Eureka, its time for another yeast basics post. This post is all about yeast viability. Viability describes how many living cells there are in a cell population. The higher the viability the more living cells you have. Lets apply this definition to homebrewing. A high viability is very important in brewing since only living yeast cells can ferment wort. Pitching the right amount of yeast cells is important. However, viability is important to consider in the pitching rate calculations as well. Pitching a yeast with a low viability is basically the same as underpitching. Not only is it important to pitch the right amount of yeast but having viable yeast cells as well. Let me walk you through some of the most important facts concerning yeast viability and homebrewing.

How do you determine the yeast viability?

I would like to show you one example how you can determine the yeast viability by use of a microscope. If you do not have a microscope or are not interested in how it is done, please skip this chapter.

The easiest way to determine the viability is to stain yeast cells with methylene blue and count the yeast cells as described in a previous post about yeast counting. Methylene blue stains the dead yeast cells which then appear as dark blue cells. This could look like shown in Fig 1. The dark blue cells are dead, the other ones still alive.

Fig 1: Methylene blue stain of yeast sample

To perform a viability count, mix equal parts of your yeast solution with a 0.1% (w/v) methylene blue solution. Mix well and let it react for one minute then count the cells by use of a counting chamber. Concerning the methylene blue solution. Mix 0.1 g of methylene blue and dissolve it in 100 mL of distilled water.

First, the cell counting is done the same way as you would do it without the methylene blue staining. The only difference, you count the dead cells in parallel in the different squares of the counting chamber. If you like further information about yeast counting, please have a look at a previous post of mine concerning yeast counting. Now, count all the yeast cells including the dead (dark blue) ones. Lets say you counted 105 cells in total. Second, you count all the dead ones. Lets assume you counted 15. Next, you calculate the viability:

Viability [%] = (Total counted cells – total counted dead cells) / total counted cells x 100

In our example, you get a viability of 86%. Meaning that 86% of the yeast cells are still alive. 14% are dead. For further information about the methylene blue staining please consult Hemocytometer.org and the book called Yeast: The Practical Guide to Beer Fermentation” written by C. White and J. Zainasheff.

Include viability in the pitching rate

Assume you want to ferment a 20 L (5.3 gal) ale batch with a gravity of 12°P (OG 1.048). In this case you need to pitch: 20000 mL x 12°P x 0.75E6 cells mL-1 °P-1 = 180E9 yeast cells. You can calculate the pitching rate with a calculator as well if you want. Lets assume you made a 1 L starter, diluted the sample by 1:100 and counted a total cell concentration of 1.3E9 cells per mL (including the dead yeast cells). To get the appropriate amount of yeast for pitching you need 138 mL of the starter (180E9 cells divided by 1.3E9 cells mL-1 = 138 mL). We also determined the viability in parallel to be 86%. In this case you would need around 160 mL of the yeast starter to have the right amount of yeasts (138 mL divided by 0.86 = 160 mL). You can easily see, the lower the viability is the more volume of the yeast starter is necessary.

How to determine the viability without counting yeast cells?

I assume most of the readers here do not have a microscope, therefore have no counting chamber and no methylene blue. How could you determine the viability without a microscope? As far as I know, there is no other way to do it. Well there are ways but these methods are even more expensive than a simple microscope, a counting chamber and methylene blue. The easiest way to do it is using assumptions. A few things to get good assumptions:

1. Using commercial liquid yeasts: As far as I know there is a production date on every liquid yeast package you buy from the main two yeast suppliers (Wyeast, White Labs). It is therefore possible to estimate the yeast viability based on the manufacturing date if the yeast is stored in a refrigerator:

Fig 1: Viability as a function of storage time for yeast stored in a refrigerator

Every day, you lose viability (Fig 1). Storing the yeast for a month, you already lost about 20% of the living yeast cells! Another month and you already lost nearly half of the living yeast cells! You can calculate the viability with J. Zainasheff’s (aka mrmalty) yeast calculator and the date printed on the yeast package. This works if you pitch the yeast from the package/vial directly. But please avoid pitching any yeast with a viability less than 90-80%. I recommend to make a yeast starter if the yeast sample has a low viability.

Please keep in mind, we are speaking about assumptions here. I am sure the viability decrease is dependent on the yeast strain, storage conditions, storage temperature, pH, oxygen level etc. etc. etc. However, this does not change the fact that yeast viability only decreases over time and therefore not recommendable to store yeast for longer than a couple of months.

2. Using yeast from a starter: If you do a yeast starter, only the viable cells will divide. The dead ones remain and decrease the viability as they are still present in the starter. If you do a starter from a Wyeast Activator package being 40 days old, the viability of the yeast is around 70% (Fig 1). Meaning, only 70% of the yeast cells are still alive. If you now do a 1 L starter with this yeast, the 30% dead cells will remain. The maximal viability you can obtain with this 1 L starter-step will be around 80% (Fig 2).

Fig 2: Maximal yeast viability obtained by a 1 L starter

However, after the 1 L starter, you have approximately 125E9 viable yeast cells in the starter (Fig 3). A Wyeast package originally contains about 100E9 cells. Meaning, if you store your Wyeast package for 40 days, the viability is at 70% (Fig 1). From the original 100E9 cells, only 70E9 will be still viable. Then do a 1L yeast starter and your viability afterwards will be around 80% (Fig 2) and you have 125E9 viable yeast cells in total (Fig 3). Let me explain how the chart in Fig 3 must be read to get to the 125E9 cells. As mentioned a Wyeast Activator package has roughly 100E9 viable yeast cells at the beginning. Then store it for 40 days and do a 1 L yeast starter. Use Fig 3 to get from the 40 days to the 125% (or the equation). For the equation, use 40 days as x to get the 125% (as y). This means, from the original 100E9 viable cells you now have an increase of 125%, which is equal to 125E9 viable yeast cells in total.

Please notice, Fig 3 only works for Wyeast Activator packages and White Labs vial with an original yeast amount of 100E9 cells and a 1 L starter size. However, the equation from Fig 3 does not work for other yeast samples and other starter sizes. For these cases, use the calculator mentioned below.

Fig 3: Increase of (viable) yeast cells from Wyeast Activator package/ White Labs vial after a 1 L starter step vs. yeast age

Things to remember: The viability of yeast decreases over time (Fig 1). On the other hand, you cannot reach a 100% viability of an old yeast sample since the dead cells remain (Fig 2). The older a yeast sample is, the harder it is to increase the viability. And to estimate the viable yeast cells of a yeast sample after a 1 L yeast starter, use Fig 3.

Lets make a final example to show you how to use the charts:
Assume you want to ferment a 20 L (5.3 gal) ale batch with a gravity of 8.8°P (1.035). For this batch you need to pitch 132E9 cells. Assume you have a Wyeast package or White Labs vial being 30 days old. Now, use Fig 1 to determine the viability which is 76%. The Wyeast Activator/White Labs vial therefore only has 76E9 viable cells left. So not enough for a direct pitch. You therefore need to do a 1 L yeast starter and you will have 132E9 yeast cells at the end (Fig 3). That is just enough yeast to pitch. You therefore can pitch the yeast from the whole 1 L starter and have the right amount of yeast.

Because these charts only work for 1 L starters, use the yeast calculator from J. Zainasheff (mrmalty.com) for any other batch sizes, starter sizes etc. In this particular calculator all the assumptions and such are already implemented. I really like programs where you can fill in numbers and you get a result (such as the yeast calculator). However, now you know some of the equations behind the yeast calculator and how it maybe work. I am not related to J. Zainasheff or have any financial benefits from referring to his site. I do so because I use his calculator for some time now. I wrote my own calculator based on my own assumptions a few years back and luckily for me, the results from my calculator are very close to the one from J. Zainasheff. So no need for me to improve my calculator any further.

I like to emphasize again, all the charts shown in this post are based on assumptions. I would not be surprised if someone comparing the calculated viability done with the graphs above and a real cell count encounters differences. In addition, I would not be surprised either if differences between yeast strains exist as well. Even a cell count done with a counting device is not 100% correct. Luckily for us, brewing beer is not like rocket science and does not have to be very precise. Cheers on that!

#22P Vienna SMaSH

Eureka, another small batch post. Today’s recipe is all about a simple recipe and two different yeast strains. The whole idea behind this recipe was to get some experience with two dried yeasts: Fermentis Safale S04 vs Fermentis Safale US05. To get the most out of the yeasts, I went with a SMaSH recipe. SMaSH stands for single malt and single hop. So basically a recipe with just one kind of malt and one type of hops. This kind of recipe is very common to either test new base malts or new hop varieties. Or in my case to get the flavor characteristics of two different yeast strains. That’s it already for the introduction.

Recipe: Vienna SMaSH
Numbers: Volume [L] 5 (1.3 gal)
Original gravity 11.9°P
Terminal gravity N/A
Color Around 8 EBC
IBU 23 IBU
ABV N/A
Grains: Vienna malt (8 EBC) 1 kg
Hops: Tettnanger (4.2% AA) 7 g and boil for 60 min
Tettnanger (4.2% AA) 5.5 g and boil for 30 min
Yeast: Fermentis S04 vs. US05
Water: Burgdorf Mash: 2.5 L (0.66 gal)
sparge: 4 L (1.06 gal) @78°C (172°F)
Rest: Mash in @66°C (151°F)
60 min @66°C (151°F)
10 min @ 78°C (172°F)
Boil: Total 60 min
Fermentation: Primary 6 days @20°C (68°F) in plastic fermenter
Secondary N/A
Maturation: Carbonation (CO2 vol) 2 vol with sugar
Maturation time 3 weeks

02/13/2011: Smooth small batch brew day. Iodine test was negative after resting for one hour. Then sparged and boiled the wort with the two Tettnanger hops additions for 60 min. Cooled the wort down to 22°C (72°F) and split the wort into two fermentation buckets. Then added the calculated amount of yeast to the fermenters. US05 to one bucket and S04 to the other one.

02/19/2011: Bottled the beer after six days already with an addition of sugars to get to a carbonation level of approximately 2 vol of carbon dioxide. Unfortunately, I did not measure the terminal gravities… Then left the bottles carbonate for another week and stored the bottles in my refrigerator for three weeks.

03/18/2011: Tasting:

US05

Aroma: Slight fruity character (apples) and hint of malty sweetness. No hop character.

Appearance: Yellow-gold colour, poor head retention. The two beers look quite similar.

Flavor: Could detect only some malty character (presumptive from the Vienna malt) and a slight bitterness. No typical yeast character detectable (fruit esters, phenolic etc.)

Mouthfeel: Light to medium body, lively carbonation, short lasting malty aftertaste.

Overall Impression: First, the recipe is exactly what I was looking for: Not a lot of character… In my opinion a very, very boring beer. However, I was not looking for a mind-boggling beer here. The recipe did a very good job. It gave the yeast the opportunity to shine through. Second, how would I describe the character of this yeast in one word? Clean. Clean is a very good descriptive word for this yeast. The yeast ferments very clean and leaves the show to the malts and hops. Sure there was a subtle apple character in the aroma. However, I could not detect any apple character in the flavor. I therefore leave the apple character aside.

S04

Aroma: Light hoppy character. No fruity character.

Appearance: Yellow-gold colour, poor head retention. The two beers look quite similar.

Flavor: Again some malty and bitter character. However, some hoppy character could be detected. And the intensity of the flavors was more pronounced in this beer relative to the one fermented with the US05 yeast.

Mouthfeel: Light to medium body, lively carbonation, medium lasting malty aftertaste. The aftertaste was more pronounced compared to the US05 one.

Overall Impression: Once again, the recipe was in the background. In this case, the malty character was more pronounced compared to the US05. There was even a hoppy character on the palate. I have to keep in mind the gravities here. It might be that the S04 beer finished at a higher terminal gravity than the US05 and therefore the higher terminal gravity might lead to a more pronounced malty character. However, if the S04 finished at a higher gravity than the US05 due to a lower attenuation, the strain still accentuates the malty character. Just by finishing at a higher gravity (less attenuative than the US05 strain). Fermentis describes both strains as medium attenuative.

The S04 yeast strain seems to accentuate the malty and hoppy character of a beer. And does not add any fruity character or any other like phenolic character. A rather clean yeast as well.

To summarize, the US05 seems to be a very clean fermenting yeast. On the other hand, the S04 strain seems to be less clean fermenting and accentuates the hop and malt character of a beer. I would choose the US05 strain for a typical US Pale Ale or an American IPA. The S04 strains seems to be appropriate for English Pale Ales, Mild, Bitter, ESB or English IPAs. If you are not sure what strain to choose, just split a batch and ferment the shares with different yeast strains to see the impact the yeast has on the beer. Cheers!