growth rate and harvesting

[BR_]

What I have read says adding more wort to an existing starter would result in the yeast continuing to follow the growth rates as shown on the charts we've all seen ... so at some point the replication slows. But, if I harvest the yeast, say by rinsing, when I begin a new starter the rates "reset" and the growth is higher. I guess the same action is seen when stepping up a starter as long as you replace the wort.

So, what is happening that they yeast increases it's replication with new wort but not by just adding new wort to existing? Why can't you just keep adding wort to a starter to step it up instead of decanting?

I'm sure I don't understand so enlighten me, please!

 

[flars]

Adding a 1.040 starter wort to the previous wort will dilute the newly added wort since the fermentables in the first wort have been used up. One liter of new 1.040 wort added to one liter of the previous starter wort will result in a total wort volume of 1.020. Growth rate will quickly diminish.

 

[day_trippr]

At some point the ever increasing alcohol content becomes a growth inhibitor.
Probably fairly early, I'd guess...

Cheers!

 

[sky4meplease]

I build up starters from plates so I start with roughly 10 million cells in 25ml wort and step up four or five times during the course of a week pouring new wort into old at each step.
If it is practical to cold crash and decant I would but otherwise I would try to maintain a respectable inoculation rate so you have enough sugar present to promote growth and don't worry too much about the alcohol present unless it is over the tolerance threshold of the yeast.
I would recommend cold crashing and decanting prior to brewing since your not making yeast anymore but instead making beer.