VIEW ARTICLE    DOI: 10.1094/ASBCJ-38-0142

A Rapid Method for the Determination of Yeast Dry Weight Concentration. James F. Rice, Timothy R. Sullivan, and J. Raymond Helbert, Miller Brewing Company, Milwaukee, WI 53201. J. Am. Soc. Brew. Chem. 38:0142, 1980.

A rapid method using membrane filtration and microwave drying was developed for measuring yeast dry weight concentration. It permits the determination of yeast dry weight in about 0.5 hr and has the same precision as a conventional method utilizing centrifugation and hot air drying. The microwave method gives dry weight measurements about 5% greater than those obtained by the conventional method. Correlation between the methods is good over the concentration range normally found in beer fermentations. The following variables in methodology do not affect precision: microwave time in excess of 5 min, sample location in microwave oven, use of plastic (vs glass) weighing vessels, and sample size within a fixed dry weight range. Use of a mechanical pipet reduces precision.

Keywords: Analytical method, Dry weight, Microwave drying, Moisture content, Yeast