Measuring Yeast CO2 Production with the Risograph
G. E. Rattin, J. M. Faubion, C. E. Walker, and A. L. Mense. Kansas State University, Department of Grain Science and Industry, Manhattan, KS, U.S.A. Cereal Foods World 54(6):261-265.
The Risograph is an electronic instrument that measures gas generated by fermenting dough or chemical leavening. It was originally manufactured and distributed by R-Design Co, Pulman, WA, U.S.A., but has been purchased by the National Division of TMCO, Lincoln, NE, U.S.A., and the software and hardware have both been greatly updated. It rapidly and accurately determines the milliliters of CO(2) per minute evolved (rate) as well as the cumulative gas released. Although it is widely used for testing yeast in bread doughs, little has been published about the current model, and there has not been a standard analytical method established specifically for the instrument. This study utilized two instruments and two operators to measure the effects of factors likely to affect results/performance including: machine, operator, mixer size, and the relationship between yeast level, dough rest time, and sugar level. The method was shown to be repeatable when a 35-g mixer was used. Significant differences were observed when a 100-g mixer was used, a result of different post-mixing fermentation times. The method showed good repeatability for different operators and Risographs, but the mixers used resulted in different results.