Dry Yeast - Why Rehydrate??

[brew captain]

What is the point of rehydrating dry yeasts before deploying them? Would they not rehydrate in the wort just fine?

What do you guys do? If you just pour it dry into the carboy, what are your lag times?

Cheers!

[spkrtoy]

Robert,

Did you just digress to a newbie?

Dry yeast will take up to 48 hours till they'll wake up and start fermenting. Start it like you would any liquid yeast to get them hungry for that swill you call beer.

[Rezzin]

Taken from the Fermentis website:

An alternative method is to sprinkle dry yeast direct into the wort and allow to stand for 30 minutes before mixing to distribute and aerate the wort.

I've never heard of anyone actually doing this (30 min wait) but I guess this would be the correct way to add the dry yeast to the wort. I haven't used dried yeast in years but everyone who has used it seems to like it. I guess it all depends on the beer you are brewing. I plan on using it with the Blond I'm brewing next.

[brew captain]

Mike - American or Belgian Blonde? I got some T-56 that I am going to try out on a Tripel this Tuesday...

Lyn - I have never heard of anyone making a starter with dry yeast and that comes from standing around talking with fellow homebrewers for the last seven years. I would be interested in hearing how you have practiced this in the past.

The cell count is suggested as sufficient for a five gallon batch per 11g sachet. I am sure I could pull off the rehydration step without contaminating or killing the yeast, but is it really necessary?

I think I am going to go back and start a poll on this...


Cheers!

[spkrtoy]

Here's a little info on yeasties from our BJCP class:

Yeast are single-cell fungi that literally make the beer. Brewers merely make wort. Yeast primarily reproduce asexually by budding, thus each cell from a given clonal strain is identical and has identical fermentation characteristics. Yeast do not exist to make beer. They exist to make more yeast. Beer, which is a collection of metabolic byproducts of yeast metabolism, is only a sideline for yeast. Everything needed by yeast to make more yeast is present in unfermented wort.
Beer yeast are of the genus saccharomyces. Although there are only three species of yeast in general use in brewing (s.uvarum, s.cerevisiae, and s.delbruckii) there are many different varieties (strains). Technically, the only real difference in lager yeast and ale yeast is that lager yeast fully ferments the trisaccaride raffinose. (Ale yeast partially ferments it.) Also, recent opinion places s.uvarum (lager yeast) in the species of s.cerevisiae. The terms “top fermenting” and “bottom fermenting” are a bit misleading as yeast ferment all around the fermenter and throughout the wort.
Carbon dioxide (CO2) and ethanol (CH3CH2OH, grain alcohol) are the two main products of fermentation. The many byproducts of fermentation include: phenols, fusels, esters (especially at temperatures in the 60sF or higher), aldehydes (especially acetaldehyde), diacetyl, and sulfur (greater presence in lager strains). The yeast absorb some of these byproducts at the end of fermentation (especially diacetyl, acetaldehyde, and sulfur―sulfur primarily during the lagering process). It’s important to keep the beer in contact with the yeast for some time; avoid these byproducts in your final beer by not racking from primary or dropping the temperature too soon.
Influences on yeast behavior include:
1) Yeast strain
2) Physical environment (temperature, pH, specific gravity, head pressure)
3) Nutrients
4) Oxygen levels
5) Good initial health
6) Amount
Five considerations for choosing a yeast strain:
1) Attenuation
2) Flocculation
3) Alcohol tolerance
4) Temperature range
5) Diacetyl and other byproduct formation
Oxygen
The role of oxygen has been misleading to the point of making it seem that oxygen is needed for saccharomyces to grow. It is the only genus of yeast to not require it. In the presence of sufficient nutrient, beer yeast do not require oxygen. But beer yeast will use what is present and respire in wort even though brewers yeast do not need oxygen to respire. To most people, respiration means simply the consumption of oxygen (breathing). To a biochemist, respiration is the production of biochemical energy. This process is absolutely dependant on oxygen. Oxygen enables the cell walls of yeast to grow much faster and reach a higher cell density. The real requirement of oxygen is to help produce fatty acids and sterols―essential components of cell membranes. The membrane structure controls what flows into and out of the cell. Weakened cells can be intolerant of alcohol and not survive. Dissolved oxygen leads to respiration and a shorter lag time. This helps ensure a quicker fermentation.
Oxygen is detrimental if introduced during fermentation (such as splashing during racking). This can lead not only to oxidation (staling effect), but also diacetyl production.
Common Yeast Strains
• American Ale (WY1056) (aka Chico ale)―A common American brewpub ale strain. Very clean. Attenuative and med-low flocculating. Can ferment as low as 55˚F
• Bavarian Hefeweizen (WY3068)(Weihenstephan―Essential for Bavarian Wheat styles, even Roggenbier). This is technically a mixture of s.uvarum and s.delbruckii. Low flocculating for an appropriately cloudy appearance
• Bavarian Lager (WY2206)―The most common lager strain. Typical of brewpubs making lagers. Medium flocculating and medium attenuation.
• London ESB (WY1968)―A very flocculent English ale strain. Low attenuation is common. Prone to diacetyl if not resting long enough at fermentation temperature once fermentation has ended.
• California Lager (WY2112)―A lager strain for steam beers. Low ester production at ale temperatures. Usually ferments wort between 60˚-68˚F
Yeast Practice
The optimal pitching rate is one-million yeast cells/milliliter/degree Plato of wort. Actually slightly higher for lagers and slightly lower for ales.
Lagering depends on contact with yeast. One does not filter, then lager. Once a beer is filtered, it is at it’s peak and diminishes. Lagering helps to absorb byproducts and smoothes out the beer (absorb harsh hop compounds and sulfur). Filtering replaces lagering only in respect to clarification. It leaves the beer more stable (it strips out bacteria depending on the degree of filtration) but at a price. It can strip out body, hop character (even IBUs) and color.
Wild yeast include Brett (brettanomyces), which can cause barnyard, horse blanket, and leather character.
Bacteria include Lacto-b (lactobacillus―responsible for sourness) and Pedio (pedioccocus―responsible for diacetyl, physical stringiness and sauerkraut character). These abbreviations are good and will be understood on the exam and in conversation.
Bacteria are smaller than yeast and many bacteria are part of Lambic and other sour beers
Wild yeast and wild bacteria are any strains not intentionally added by the brewer.>
History
A discussion on history can mention the following:
• Pilsner Urquell
• Louis Pasteur
• Emil Hanssen
• Godisgood was an early name for yeast (or maybe just the mystery of fermentation).

Exam Questions
Yeast questions (numbers are from the interim study guide) pertaining to the exam are:
T7. Describe the stages of yeast development and give five considerations in selecting the appropriate yeast strain for a given beer style.
• Answer should include the lag phase, respiration, krausen (fermentation), and settling. Lagering phase may be mentioned for depth.
• Considerations are listed above.
T6. Describe the role of yeast in beer production and the positive and negative effects on the finished product of oxygen introduction during the various stages of fermentation.

[brianc]

Unless I am doing something that really requires a specialized yeast, all I am use anymore is the Fermentis products. I have had great success with not rehydrating and progressively sprinkling the yeast across the surface area of the wort (the Fermentis recommendations). I usually do not go back and stir the yeast in later. It seems to take care of itself pretty well. Lag times are pretty minimal. S-04 is a beast and in my experience takes off the quickest (sometimes within a couple hours of pitching). S-05/US-56 seems to take a little longer, but I have had it consistently going within 12 hours using this method.

--Brian

[Rezzin]

Hey Brian - are you gonna be available Sunday afternoon / evening? I was planning on calling you tonight but the wife is going to Disney on Ice with her half sister tonight so I'm on baby sitter duty. I need to pick up some ingredients and some beverage line tubing.

[Rezzin]

Mike - American or Belgian Blonde? I got some T-56 that I am going to try out on a Tripel this Tuesday...

American Blonde - I had a pint of some tasty brew when I last visited Brian and he was kind enough to share the recipe. It's been a while since I've brewed so I figured a nice light, tasty, easy drinking brew was in order to get the rust off. Not to mention the short turn around time.

Thanks for the offer but I'll just pick up a pack when I get the rest of my stuff from Brian. If he's out, I'll give you a jingle.

[brahn]

I'm like Brian, I very rarely use liquid yeast these days. The only one in recent memory was a batch of saison where I used a liquid strain. The dry is just so much easier. I just sprinkle it over the top of the wort and seal up the bucket. Unless I screw up and chill the wort down to 39F I've usually got signs of active fermentation within 6-12 hours.

Brew Captain, do you mean US-56 (US-05) or T-58? In a Tripel I assume you mean T-58 and I think that will make a pretty nice beer. I used T-58 once when I pitched a tube of WL that didn't take off (this was quite a while ago and I hadn't started making starters yet). It had a real nice spicyness to it.

[brew captain]

OK. Sounds like just toss it in without rehydration.

Have any of you harvested the slurry and reused it on a subsequent batch??? I assume you can, but it would be good to know it has been done with success by someone here before I try it.

Cheers!

[Rezzin]

I don't see why not but I think most just pitch new yeast since it's so cheap...

[lars]

I've converted to Us 05 for most of my brews. Like others I just sprinkle it on top of my wort and let 'er rip! I haven't noticed any long lag times... A few things I have noticed about US 05 is that it has a tendency to ferment to a lower fg than either WLP001 or 1056. The other thing about US 05 is that it is ultra clean, even more so than 001. Robert recently tried my Choc Haselnut Porter brewed with US 05 and commented that the yeast profile was too clean. I had another homebrewer comment that it was ultra clean too. For future brews I'm going to raise my mash tem up a bit to compensate for the low fg.

[brahn]

I've noticed that US-05 ferments to a really low fg as well and have been playing around with mash temps to see how it reacts.

I've used the yeast cake from US-05 a few times for really big beers, but for the most part it's so cheap that I don't really worry about it.

[BrewMasterBrad]

I haven't used dry yeast since January 1, 2005. That was my first batch ever. Dry yeasts have come a long way since then and there is more variety, so I may have to start experimenting with them as well. That one time I did use the dry yeast, I did rehydrate it because that is what the B3 kit instructions said to do.

Brad

[jward]

OK. Sounds like just toss it in without rehydration.

My last batch I tried to experiment with rehydration. I calculated the water wrong and didn't use enough. So I haven't formed an opinion yet. The idea is that the yeast cannot control what they let in through their cell walls so well as they rehydrate. I read something that said as many as half die from taking in too much sugar et al when rehydrating in wort but "there is still more then enough cells to ferment the beer". I ask, then why dump 2 packets if I can get the same cell count from one? Pete and I discussed using the mead regime of rehydrating with goferm but I have not done any of that yet. I would suggest you try it both ways and and say what you think.

The other issue was how do you pour the dry yeast into the batch. I'd swear that I have read in the Fermentis directions to pour the yeast into a pile to slow rehydration and another time to spread it around the surface to avoid clumping. I have not gotten to the bottom of that. It may have been for different yeasts or old and new directions.

Have any of you harvested the slurry and reused it on a subsequent batch??? I assume you can, but it would be good to know it has been done with success by someone here before I try it.

Cheers!

I have repitched just fine when brewing batch to batch but don't recall storing any.