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Author Topic: Heat Produced During Lag Phase  (Read 1020 times)

Offline HighVoltageMan!

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Re: Heat Produced During Lag Phase
« Reply #15 on: September 19, 2023, 03:04:20 pm »
I need to do some more reading to re-familiarize myself with the exact workings of the Crabtree Effect.  Unless I am way off base here, during the growth phase (maybe incorrectly called the "lag phase") my recollection from reading previous articles on the fermentation process is that during this phase which is aerobic, the yeast cells take up oxygen in the wort and build cell walls and biomass.  Then the yeast changes to the the anaerobic phase where it ferments glucose, maltose, etc. to produce alcohol.  If the yeast is over-pitched, then fermentation begins much faster because the growth phase is reduced (Crabtree Effect)
Correct me if I am interpreting this incorrectly.
Because of the Crabtree effect, the yeast will always be in an anaerobic state, even in the presence of oxygen. In an aerobic state, the yeast will produce very little alcohol or co2. Most of the carbon (sugar) will be used to create biomass. As brewers, we want yeast in an anaerobic state to produce alcohol and co2

The oxygen needed during a "lag" phase is used by the yeast to produce lipids for cell wall production. It's nearly impossible to get the yeast in aerobic state during beer brewing. The gravity of the wort must be below 1.012 or so and have constant aeration to achieve aerobic respiration. This is the method used by dry yeast manufacturers to produce yeast. Yeast manufacturers also "feed" the yeast to keep in this state which produces maximum biomass from the available carbon.

For all practical purposes, there is a lag phase. To argue otherwise is the pointless splitting of hairs.
« Last Edit: September 19, 2023, 03:06:51 pm by HighVoltageMan! »