1 Pack of US-05 split for 2 5.5 gal batches

[rmb]

So, I wanted to brew my remaining ingredients so I could go buy some more.

Problem was, I have enough LME and hops for two 5 gallon batches but only 1 pack of US-05 yeast.

So.... as you can tell, I split the yeast, started them in warm water with corn sugar, separated... while I was brewing my batches.

I put 1/2 a pack in each.

I was worried... but I am still seeing activity 6 days later and both buckets have krausen bubbling through the air locks ever so slightly.



Any known problems with doing this?

 

[libeerty]

Depends on the OGs of each. Sometimes one dry pack is over pitching, so it's not automatically bad.

 

[Cbaddad]

You probably underpitched, but you will have beer. Did you rehydrate?

 

[rmb]

You probably underpitched, but you will have beer. Did you rehydrate?

What are the effects of under pitching?

Both buckets were full go with activity.

I started at 68 for 5 days then upped it to 72 this week.

But my thought is... if people grow yeast from beers to get the exact strain, then why would this be much different? It will just take longer thats all... right?

 

[libeerty]

What are the effects of under pitching?

Both buckets were full go with activity.

I started at 68 for 5 days then upped it to 72 this week.

But my thought is... if people grow yeast from beers to get the exact strain, then why would this be much different? It will just take longer thats all... right?

No. Underpitching causes off flavors and the fermentation can stall. It is not so simple as taking the dregs from a bottle and pitching it (except in rare cases with sours, but totally different concept.) You have to carefully "step up" from the small amount of yeast cells in the bottle to a proportional size of low gravity wort, which then multiplies the cells, and then "step up" again, etc., etc.

Again, like I said in the first reply, if you give the OGs, you can know the answer to your question. I disagree with the person above that you probably underpitched. 5 gallon recipes sometimes require a 1/2 of a dry yeast packet. Do you know your OG? Or at least the recipe?

 

[rmb]

It is a simple recipe...
1) 6 lb of pilsen LME,
2) 1.5 lb cane sugar,
3) 0.5 lb carmel 120,
4) 2 oz kent goldings and
5) 1/2 a pack of US-05 that was started in warm water with corn sugar
and let sit for about an hour.

The other batch used 5.75 lb lme, 1 lb of chocolate, 0.5 Caramel 120, 1.5 lbs sugar, 2 oz kent goldings and 1/2 a pack of US-05.

Again, the yeast was tearing up the wort with krausen getting into my airlocks. My fermentation volume was closer to 5.75 gallons vs 5.00 gals.

 

[libeerty]

You pitched very close to the optimal amount for each if my math is right. Both are very low OG beers. No need to worry.

 

[tooldudetool]

You may want to reconsider your method for rehydrating your dry yeast though. Here are the rehydration instructions from Fermentis for S-05:

"Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 27°
c± 3°C (80°F ± 6°F). Leave to rest 15 to 30 minutes. Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel."

The whole spec sheet is available here: http://www.fermentis.com/wp-content/uploads/2012/02/SFA_US05.pdf

As you can see, you do not need to add any sugars to the rehydration water. Todays dry brewing yeasts have a nutrient supply included, which is released when the packet is rehydrated. What you did was proof the yeast, which is something common with bread yeast rehydration, but not modern brewing yeast. It is also recommended when making starters for liquid yeast to use DME, maltose, rather than sugars such as dextrose or sucrose for the best yeast health and growth. Despite all that, I'm sure your beer will turn out just fine!

 

[rmb]

Thanks... for the yeast starter... I did use dextrose and the temp was actually 80.

Although... I used tap water... so the chlorine probably was not the best idea for the small starter.

Thanks for the tips. This hobby is great... there is always something new to learn.

 

[rmb]

Well 2 weeks and 3 days later the beers were sitting at FG of 1.015... just as I was expecting.

We shalk see if everything is okay... but so far 2 5 gallon brews on 1 pack of US05 worked just fine fermenting wise.

 

[EarlyAmateurZymurgist]

Although... I used tap water... so the chlorine probably was not the best idea for the small starter.

The amount of chlorine that is added to drinking water does not kill all bacteria. It is just high enough to keep pathogens at bay; therefore, water that touches one's yeast culture should be boiled for at least 15 minutes and allowed to cool to room temperature in a covered sanitized container.

Ninety-nine percent of all beer infections are the result of poor yeast handling. Fermentation is little more than controlled spoilage. Bacteria cells divide every thirty minutes. Yeast cells divide every ninety minutes; therefore, one needs to pitch enough clean yeast to out compete any other microflora that may be introduced to one's wort. Cell division follows an exponential growth pattern; therefore, the increase in cell count for yeast can be calculated as:

initial_cell_count * 2^(elapsed_time_in_minutes_since_the_start_of_the_growth_phase / 90), where the symbol ""^" denotes raised to the power of.

Examples

Cell count after 90 minutes of growth

initial_cell_count * 2^(90 / 90) = 2 x initial_cell_count


Cell count after 6 hours of growth

initial_cell_count * 2^(360 / 90) = 16 x initial_cell_count


There is a period between pitching and the growth phase (a.k.a. exponential or log phase) known as the lag phase. The lag phase is where the yeast cells that were pitched prepare themselves for growth.

 

[rmb]

The amount of chlorine that is added to drinking water does not kill all bacteria. It is just high enough to keep pathogens at bay; therefore, water that touches one's yeast culture should be boiled for at least 15 minutes and allowed to cool to room temperature in a covered sanitized container.

Ninety-nine percent of all beer infections are the result of poor yeast handling. Fermentation is little more than controlled spoilage. Bacteria cells divide every thirty minutes. Yeast cells divide every nineties minutes; therefore, one needs to pitch enough clean yeast to out compete any other microflora that may be introduced to one's wort. Cell division follows an exponential growth pattern; therefore, the increase in cell count for yeast can be calculated as:

initial_cell_count * 2^(elapsed_time_in_minutes_since_the_start_of_the_growth_phase / 90), where the symbol ""^" denotes raised to the power of.

Examples

Cell count after 90 minutes of growth

initial_cell_count * 2^(90 / 90) = 2 x initial_cell_count


Cell count after 6 hours of growth

initial_cell_count * 2^(360 / 90) = 16 x initial_cell_count


There is a period between pitching and the growth phase (a.k.a. exponential or log phase) known as the lag phase. The lag phase is where the yeast cells that were pitched prepare themselves for growth.

Holy crap I did not know that. Now it makes a lot more sense.

Thank you! I learned sonething today.

 

[EarlyAmateurZymurgist]

Holy crap I did not know that. Now it makes a lot more sense.

Thank you! I learned sonething today.

This situation gets ugly really quickly when one tracks yeast versus bacteria growth.


Yeast Cell count after 90 minutes of growth

initial_yeast_cell_count * 2^(90 / 90) = 2 x initial_yeast_cell_count

Bacteria Cell count after 90 minutes of growth

initial_bacteria_cell_count * 2^(90 / 30) = 8 x initial_bacteria_cell_count


Yeast Cell count after 6 hours of growth

initial_yeast_cell_count * 2^(360 / 90) = 16 x initial_yeast_cell_count

Bacteria Cell count after 6 hours of growth

initial_bacteria_cell_count * 2^(360 / 30) = 4,906 x initial_bacteria_cell_count


Yeast Cell count after 12 hours of growth

initial_yeast_cell_count * 2^(720 / 90) = 256 x initial_yeast_cell_count

Bacteria Cell count after 12 hours of growth

initial_bacteria_cell_count * 2^(720 / 30) = 16,777,216 x initial_bacteria_cell_count


Yeast Cell count after 24 hours of growth

initial_yeast_cell_count * 2^(1440 / 90) = 65,536 x initial_yeast_cell_count

Bacteria Cell count after 24 hours of growth

initial_bacteria_cell_count * 2^(1440 / 30) = 281,474,976,710,656 x initial_bacteria_cell_count


The single biggest improvement that an amateur brewer can make is to learn how to properly handle and propagate yeast. Yeast is the most important ingredient in beer. The off-flavors produced when one pitches too little yeast are more often than not caused by house microflora that established a foothold at the beginning of fermentation.

 

[rmb]

You made a skeptic into a believer. Good job man!

 

[DrPiglet]

Wow. As if I didn't have enough research on my plate. But it sounds like this is far more important than types and variances of honey.

What about over pitching? I've been told it is fine to use a full packet (11.5 grams) of yeast for a 1 gallon batch. I have experimented with using less, but it seems as though I get pretty similar results. Thoughts on this?

 

[stz]

Brewing commercially we pitch absolutely loads of yeast in comparison to home brewing. Like 3.5G/L for ale at SG45 and twice that for lager. We want the primary fermentation done inside of three days because we need the fermentation space again and for the reasons mentioned already such as out competing any other microorganisms which are ALWAYS present in the house strain before they contribute to significant off flavours and degrade the shelf life. A long lag phase is pretty unacceptable because it gives unwelcome visitors time to get established in the wort and these will be harvested and scaled up through the generations with our yeast handling. Because we harvest and repitch constantly we eventually reach a point where there is too much bacteria in the yeast and we must renew the yeast. This is about every 6 months or 50 brews. Surprisingly genetic drift is not the massive problem it is made out to be compared to eventual contamination (I started out terrified past 8 brews). We perform cell counts and viability with a haemocytometer and while I don't have the exact dilution we use to hand, we tend to aim for a count >100 and consider yeast with >10 rods very dirty/heavily compromised. You would be surprised how many commercial beers have bacterial counts over 10. You'd be surprised how it makes very little difference in beers drunk within 6 months of packaging.