Evaluation of Light Scattering and Autofluorescent Properties of Brewer's Worts for Flow Cytometric Analysis of Yeast Viability

Flow cytometric methods for determining yeast viability are currently available. For effective analysis of yeast in breweries it is important that the light scattering properties of the sample medium (wort) do not interfere with that of target yeast cells. For this reason, a number of wort samples were analysed for their light scattering and auto fluorescent properties, as well as their ability to bind the yeast viability dye, oxonol. Worts were found to produce light scattering that was sufficiently different from yeast, such that the two were clearly distinguishable by flow cytometry. Although oxonol bound to wort particles, computer software techniques allowed determination of yeast viability in worts.