The effect of trub on fermentation.

Siebert, K.J., Blum, P.H., Wisk, T.J., Stenroos, L.E. and Anklam, W.J.

Abstract
Wort containing trub in suspension undergoes a more vigorous fermentation than bright wort giving higher attenuation and a larger, more viable yeast crop. This effect has usually been attributed to the stimulation of yeast growth by nutrients particularly unsaturated lipids. Although the addition of some lipids to bright wort produced this stimulation it could also be observed when activated charcoal or diatomaceous earth was added. This indicates that particles in suspension irrespective of their nature act as nucleation sites for CO₂ evolution and so reduce the concentration of dissolved CO₂, partially relieving the inhibition known to be caused by CO₂. It follows that the difficulties sometimes found when bright worts are fermented are probably caused by a high degree of CO₂ inhibition.
Keywords : carbon dioxide fermentation growth stimulation turbidity wort yeast