There's something rather satisfying about a yeast starter, the flask quietly whirring away in the corner of my home office turning from a dark brown, to foamy cloudy amber then lastly light gold with settled yeast. This one is the Omega OYL-107 for another batch of the red festbier which I'm vacillating between discouraging upset and determination to improve, after the LAB feedback. Anyway, this was a comment about yeast starters I thought would be helpful to share, as I'd wondered whether I could economise by using a blend of dextrose and malt extract, or even increase the OG with dextrose to improve the yeast cell count yield.
So I've read these two papers which really helped
How Glucose additions to yeast with maltose rapidly suppresses the genes to allow maltose digestion, within half an hour. It's not clear though how quickly the ability to digest maltose can recover though.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC215083/pdf/jbacter00239-0311.pdf
This shows how even small additions of glucose to starter wort depresses yeast growth and attenuation. Though annoyingly the data charts shown aren't complete and don't fully explain the text narrative.
http://braukaiser.com/blog/blog/2013/07/07/yeast-growth-on-malt-and-sugar/
All of which is consistent with John Palmers' statement in How to Brew that
"Yeast that has been eating a lot of sucrose, glucose, and fructose will quit making the enzyme that allows it to eat maltose—the main sugar of brewer’s wort."
Long way of saying don't add glucose to your starter, and it's really making me think that using brewing sugar to increase gravity is not a great idea either - not that I've done so for a long time but it is a thought.
A
So I've read these two papers which really helped
How Glucose additions to yeast with maltose rapidly suppresses the genes to allow maltose digestion, within half an hour. It's not clear though how quickly the ability to digest maltose can recover though.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC215083/pdf/jbacter00239-0311.pdf
This shows how even small additions of glucose to starter wort depresses yeast growth and attenuation. Though annoyingly the data charts shown aren't complete and don't fully explain the text narrative.
http://braukaiser.com/blog/blog/2013/07/07/yeast-growth-on-malt-and-sugar/
All of which is consistent with John Palmers' statement in How to Brew that
"Yeast that has been eating a lot of sucrose, glucose, and fructose will quit making the enzyme that allows it to eat maltose—the main sugar of brewer’s wort."
Long way of saying don't add glucose to your starter, and it's really making me think that using brewing sugar to increase gravity is not a great idea either - not that I've done so for a long time but it is a thought.
A