Yeast Propagation

[SUSHIL]

Hi everyone,

I have confused about the meaning of following sentences regarding with yeast propagation,

1] When we give proper inputs to propagation process then every stage of yeast propagation gives four times more yeast cell count.

2] When we give proper inputs to propagation process then every stage of yeast propagation gives four doublings of yeast cell count.

The meaning of above sentences are same or different.basically I have confused with Four times and four doublings.
Please reply me.I know it is every easy but I can't differentiate it.

[Scott M]

From Jean de Clerck's A textbook of Brewing, vol. 1 p. 425.....

"To multiply up a culture, flasks containing 3 liters of sterile wort are pitched with the culture yeast and allowed to ferment at the appropriate temperature of a brewery fermentation, or a little higher (8-10^o C for bottom yeasts and 18-20^o c for top yeasts). With bottom yeasts, when fermentation in the flasks is over, the contents of the flasks are pitched into 20 liters of brewery wort taken from the refrigerator in the 50 liter vessel. When fermentation is well under way by the next day, the vessel is filled with fresh wort and 24 hours later the contents are transferred to the 3-4 hectorliter vessel and 50 liters of fresh wort added. After 24-48 hours the volume is again doubled by the addition of fresh wort. On the following day the fermenting wort is transferred to the 30 hectoliter vessel and the volume doubled with fresh wort. This process of doubling up the volume is continued in the large vessel until sufficient yeast is obtained to pitch to the brewery vessel."

I believe this is the doubling being referred to.