Dry yeast 1pkg, or 2?

It has been a while since I have used dry yeast, and when I did I always used 1 satchel rehydrated. Now I see that some of the manufacturers are recommending two satchels. Also I see that a lot of them are saying to simply sprinkle the yeast in the wort. Are they just accounting for half the cells to die off and doubling the amount, at the same time selling you more yeast?

For some reason, the manufacturers still recommend just sprinkling. However, most everyone else says to rehydrate. I would absolutely rehydrate. No questions.

As for the 2 packets (I assume your talking about 11.5 g packets for a 1.050 5 gal beer), do some research on the actual amount of yeast in the packet. If you use Mr Maltys calculator, he will tell you to use 1 packet. However, others have questioned that research (brew kaiser). Check the lit review that brewersfriend.com covers in their calculator.

After reading a little bit about myself, I would say consider doing two packs. But doing own research is much more fulfilling.

What is your OG? You can't or shouldn't just arbitrarily pitch two packets of yeast for kicks. Use Mr. Malty or my favorite which is Yeast Calc.

MKBoitnott said:

For some reason, the manufacturers still recommend just sprinkling. However, most everyone else says to rehydrate. I would absolutely rehydrate. No questions.

As for the 2 packets (I assume your talking about 11.5 g packets for a 1.050 5 gal beer), do some research on the actual amount of yeast in the packet. If you use Mr Maltys calculator, he will tell you to use 1 packet. However, others have questioned that research (brew kaiser). Check the lit review that brewersfriend.com covers in their calculator.

After reading a little bit about myself, I would say consider doing two packs. But doing own research is much more fulfilling.

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Should have said I was talking in general about an average gravity beer, so yes 1050. Thank you for directing me to that website, I hadnt been there before and that was an interesting read. Seems that noone agrees on the cells/g. Seems odd to me that jamil would be almost double what others are saying.

Many people have done cell counts and found the cell density of dry yeast to be very close to 20 billion cells per gram - Clayton Cone, Sean Terrill, JZ, even Braukaiser has said his results were in agreement on his website (July 2013 yeast starter experiment). How many cells survive rehydration is going to depend on how the rehydration is done. If you are rehydrating in 95-100° water that is slightly hard like most tap water, you will have more viable cells than if you used 70° water or worse, wort. Fermentis says each 11.5g packet has an average of 150 billion viable cells at the time of packaging.

I haven't read the study referenced on the Brewer's Friend calc, but I would be interested to learn how it was conducted.

MKBoitnott said:

For some reason, the manufacturers still recommend just sprinkling. However, most everyone else says to rehydrate. I would absolutely rehydrate. No questions.

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They recommend that on their packets, but if you get the datasheets, many encourage rehydration.

Danstar Nottingham has a pitch rate formula that recommends 2 packets for a typical 5gal batch. I think US-05 recs just one. Clearly many people do not follow the mftrs recommendations and do fine, though...

Interesting, I emailed fermentis about this exact topic. They actually told me not focus on cell counts (due to variations in cell density). The contact told me to reference the weight, and told me that 11.5 g would be good for a standard batch.

MKBoitnott said:

Interesting, I emailed fermentis about this exact topic. They actually told me not focus on cell counts (due to variations in cell density). The contact told me to reference the weight, and told me that 11.5 g would be good for a standard batch.

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I believe what you are saying, but since we had a thread a while ago where someone was able to get a rep from Fermentis to tell them the average number of cells per packet, I wanted to share that discussion:

https://www.homebrewtalk.com/f39/fermentis-dry-yeast-users-433698/index5.html#post5550546

Fermentis has a faq: https://www.homebrewtalk.com/f163/dry-yeast-1pkg-2-a-454055/#post5829575

It says an 11.5g sachet is good for 4-6 gallons. The US-05 datasheet says 50-80 g/hL (1 hL=100 L), which is 2-3 g/gal, or 10-15 g for a 5 gallon batch. That works out.

Their rehydration instructions read:

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.
Alternatively, pitch the yeast directly in the fermentation vessel providing the temperature of the wort is above 20°C (68°F). Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes, then mix the wort using aeration or by wort addition.

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The Lallemand/Danstar Nottingham data sheet doesn't specifically recommend a pitch rate, but they give an example of 100g/hL, which is 3.8 g/gal, or 19 g for a 5 gallon batch. Their usage instructions only describe rehydrating with water and explicitly discourage using wort for that purpose.