URL below is PDF report on an experiment run by BYO magazine & the internet based "Basic Brewing Radio".
"...In the Basic Brewing podcast of April 14th 2011 a request was made to participate in a brewing experiment. The
experiment aimed to determine the effect of hydration of dry yeast and the way of adding yeast to wort on lag-
time before fermentation starts, krausening, apparent degree of fermentation, the final taste of the beer and other
characteristics..."
"...Discussion / conclusion
For quite some years there is a debate amongst home brewers whether or not dry yeast should be hydrated before
pitching. Some even state that sprinkling dry yeast on wort would lead to a decrease in cell viability by 60 to
70%.
Based on the historic data desktop research and the experiments that were performed using different yeasts I
conclude that hydration of yeast is not needed to make a good beer. It does not lead to higher degrees of
fermentation. On the contrary, the historic data research showed that the average brewer obtained lower degrees
of fermentation upon hydration of dry yeast. The historic data research showed that for 9 out of 12 yeast
hydration lead to significant lower degrees of fermentation..."
http://ec.libsyn.com/p/1/a/e/1aeeb08f8db63...mp;c_id=3529671