Sorry if this gets technical :ugeek:
shearclass said:
I see conflicting arguments on the forum,
Its not just on the forum, it's the interweb in general. There are a lot of people on here, who offer advice that is quite frankly dangerous (as far as it can be said in a brewing context), and is basically half understood stuff form something they saw on Youtube or read on a blog, which has very little in the way of experience, or research behind it.
shearclass said:
but I'm just trying to figure out what is the best way to use the dired yeast that comes with a kit.
Don't
Unless it is a named variety of yeast, I wouldn't touch it with a barge pole . . . Unless I was to boil it up with a little bit (100ml) of water and add it to the beer as yeast nutrient. Yeast provide 80% of the flavour compounds in beer, using a named variety at least moves you away from some random general purpose yeast.
Another reason for using a different yeast (not necessarily liquid there are plenty of good dried yeast out there) is that the little silver foil packets of yeast included with a kit often contain as little as 5g of yeast. If you consider that there are around 10 billion yeast cells in a gram of dried yeast, and we need to pitch a minimum of 1 million cells per ml of wort (Minimum homebrew pitching rate for beers up to 1.060), you can see that 5g only gives us 500,000 cells per ml . . . . half the homebrew pitching rate, and around 1/4 of the commercial pitching rate. . . . and that assumes that all the yeast cells are viable following pitching! The other dried yeasts on the market are 11.5 or 12g packets and if treated properly will yield the correct pitching rate. Some people will say that the yeast will reproduce so it's not to critical . . . but there is a limit to the number of times a cell can bud or fission, and if a wort is low in nutrients this will further limit the amount of reproduction, and lead to the formation of distorted cells that do not ferment wort correctly . . .producing sluggish fermentations and off flavours.
shearclass said:
3 options I have seen so far are
1 - mixing it with the wort as per packet instructions
2 - making a yeast starter
3 - mixing it with water at about 35 degrees as described by unclepumble (similar to the instructions on brupacks kits)
4 - buy yeast separate to the kit (liquid yeast?) - however i want to keep the process as cheap as possible
What is wrong with option 2? i've never done this.
If you pitch the correct amount of dried yeast (11.5g for 5 gallons) into a 1L starter you will be over pitching by a factor of 23 to 1 . . . The yeast will wake up, utilise their reserves (that the manufacturer has carefully encouraged them to build up prior to drying), use all the sugar in the starter, and then go dormant again . . . At which point you then pour them into the main wort and they have to get going all over again . . .only this time the reserves that they had are not there, so rather than a healthy population of yeast ready to go, you are pitching yeast that are half asleep, and you will extend the 'lag' phase, rather than doing what you intend which is shorten it.
shearclass said:
Can anyone tell me what 3 actually achieves?
this process is known as rehydration, and doing it achieves the highest viable cell count compared to other methods of getting dry yeast ready to work. When yeast are first pitched into liquid, the cell membrane isn't fully formed, and there is nothing to stop all sorts of chemicals/sugars/water rushing across the cell membrane, potentially damaging the yeast cell. By using warm water (And the temperature is strain dependant . . . Danstar yeasts use 35C fermentis yeasts use 27C) only water passes across the membrane and when you pitch into the wort the cell membrane is fully formed and working correctly, and you have a much higher number of viable cells ready to go to work.
shearclass said:
Is it just the high temperature that wakes the yeast up and makes it ferment as soon as it's added to the brew? i have been told by another forumite that i should not do this as it's too hot.
Well the method that UP and I have described, was given to my by Dr Clayton Cole of Lallemand yeasts . . . He ran the research and production division, and is more than qualified to give a method that ensures we as home brewers pitch sufficient yeast in the best possible condition to ferment our beers. I cannot comment on the qualifications or experience of 'another forumite'. The important thing to remember is that the rehydration temperature is strain dependent so you need to ensure that you are using the correct temperature for the yeast you are using. You also need to measure the temperature properly and not guess it.
Brewers make wort . . . . Yeast make beer, it makes sense to pitch enough yeast in a fit state to make our beer. . . . pinching pennies at this stage can be self defeating.
