Fermentation and Yeast

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Loic

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Hi all,

I've just read the book "yeast : the practical guide to beer fermentation" and I would like to share with you my notes and my experiences as homebrewer about fermentation

So please feel free to make any correction or share your experience :)

I would like to start by this tow following points really important for me:
  • All yeast will produce most of their flavours in the first 72h.
  • Brewer make the work, yeast make the beer.
How to choose the yeast :
  • Be creative ! Exploring new strains ! It is like cooking a cake without recipe
  • Attenuation
  • Flavour profile
  • Temperature range
  • Flocculation
My experience : in accordance with the beer I want to brew, I read every information provided by the yeast supplier, flavours, dry or not...

Firstly how do we rehydrate dry yeast:
  1. Use a sanitised container
  2. Water ? wort? both ? Sterile tap water (I boil tap water or I use bottled water)
  3. how musg water ? 10ml of water /g of yeast - I have to try thisaunsure....
  4. Between 35 and 41°C :thumba:
  5. Sprinkle the yeast on the top and wait 15 min
  6. Stir and wait another 5 min
  7. Adjust the temperature of the yeast within 8°C of the wort ( I prefere to be within 4 or 5 °C)

What next ? I've just cooled down my wort ! what about oxygen ?
  • Prior to fermentation, chill and aerate the wort, it is necessary to promote yeast growth.
  • Lager and high in alcohol beer require more oxygen
  • Yeast need 10 ppm of oxygen - 5min of shaking aeration is 2,7ppm of oxygen in the wort
Personlly I'm alway afraid by oxydation !!!!!!!!ashock1aheadbutt

What's happen in fermentation vessel ?
Lag phase :
  • 0 to 15 hours
  • 20°C for ale and 13°C for lager
  • Acclimating to their environment
  • During this phase the yeast will absorb the oxygen to produce compound
  • For high gravity beer a second addition of oxygen can make a better attenuation
Exponential growth phase :
  • 4 hours to 4 days
  • Production of CO2
  • Yeast will consume
    • Glucose 14% of the sugar in the wort
    • Fructose
    • Sucrose
    • Maltose 59% of sugar in the wort
  • high kraeusen activity
Stationary phase :
  • 3 to 10 days
  • The beer has not reached the balance of flavours but it I nearly their
  • Yeast reabsorb much of the diacetyl and acetaldehyde
  • Hydrogen sulphite continue to escape
  • At this point we can cool the beer down about 2 to 4°C to force the yeast to floccule and settle

an option if we have a big spare fridge is the Lagering
Process:
  • Process to improve beer flavours by cold period conditioning at 4 °C
  • Do not drop the temperature more than 5 °C per hour otherwise the yeast can release more ester than usual.
Advantages
  • Flocculation
  • Improve flavours
  • Prevent oxidation
Temperature :
  • If we can control the temperature is it interesting to start fermenting the beer at 1 to 2 °C below the final target and raise the temperature over the course of 18 to 36h.
  • It is interesting to control the temperature during the first 72 when the yeast make most of their flovours.
Note1 : If we want to cool down the wort, wait until the end of the fermentation net before 4 days
Note2 : at 24 °C acetaldehyde s 10 time higher than the perception threshold.

Ale Yeast : top fermeting between 18 and 21°C
Usually ale fermentation in complete in 4 days and then 4 to 5 more days for the yeast to settles.

Lager Yeast : bottom fermeting between 10 and 13°C

Et voila !:beer1:

Please forgive my english I've just moved in UK so I'm still learning both brewing and english:rolleyes:

Loic
 
WOW! That's a lot to read!

In view of the many thousands of variables in brewing, I have made a conscious decision to use just two yeasts:
  1. Wilco Ale Yeast (aka Nottingham Yeats & Gervin -12 Yeast)
  2. Youngs Lager Yeast.
I have often used harvested yeast and also recovered yeast from bottles for experimental purposes.

It's a minefield out there - but good luck with your brewing odyssey!
 
Personlly I'm alway afraid by oxydation !!!!!!!!ashock1aheadbutt
oxidation (not good in this environment) is different from aeration,very important to aerate the wort, the yeast needs to grow & multiply, this needs aerobic respiration, once that is complete then it starts the (alcohol producing) anaerobic respiration. I just make sure that the chilled wort splashes into the fermenter from a height, (normally creating a head on the wort showing that it has been aerated?)
 
Yeast nutrient is a good idea for new pitches of yeast. (Although who knows, I'm no scientist)
Liquid yeast will often need a starter for high strength/old packets. Starters are a minefield but plenty info out there.
Mr malty will keep you right.
 
oxidation (not good in this environment) is different from aeration,very important to aerate the wort, the yeast needs to grow & multiply, this needs aerobic respiration, once that is complete then it starts the (alcohol producing) anaerobic respiration. I just make sure that the chilled wort splashes into the fermenter from a height, (normally creating a head on the wort showing that it has been aerated?)

That is correct :). Without oxygen your year won’t produce desired flavours.

By afraid, I mean, I try to be carefully when I’m transferring beer to another vessel for filtration.

Good idea I will try to pitch my next batch with yeast from the previous bottles batch.

Have you ever try yeast from cider or wine ?

I tried to pitch apple juice with beer yeast, actually the result was quite good. But don’t pu to much yeast otherwise you will get to mush gaz !! :)

Cheers

Loïc
 
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