So the standard pitching rate that gets quoted all the time is 1 million cells/mL/(degree Plato) plus or minus 25% or so depending on what reference you read and if you're brewing an ale or lager.
Qualitatively I've usually heard this explained as 'high gravity wort is more stressful to the yeast so you need more cells for a healthy ferment', but does any know (or care to speculate about) the actual mechanisms that stress yeast in higher gravity wort? Also, any other reasons for needing more yeast in high gravity wort besides stressed out yeast?
Off the top of my head I could think of osmotic stress, less dissolved oxygen in the wort, higher ABV towards the end of the ferment, maybe a larger buildup of waste products due to more fermentation..... It would seem like some big breweries or brewing scientists would have looked at this and that's what guided the pitching rate guidelines.
Qualitatively I've usually heard this explained as 'high gravity wort is more stressful to the yeast so you need more cells for a healthy ferment', but does any know (or care to speculate about) the actual mechanisms that stress yeast in higher gravity wort? Also, any other reasons for needing more yeast in high gravity wort besides stressed out yeast?
Off the top of my head I could think of osmotic stress, less dissolved oxygen in the wort, higher ABV towards the end of the ferment, maybe a larger buildup of waste products due to more fermentation..... It would seem like some big breweries or brewing scientists would have looked at this and that's what guided the pitching rate guidelines.