| Studies on toxic substance in wheat and barley against
brewing yeast Tsutomu OKADA, Hajime YOSHIZUMI and Yutaka TERASHIMA The Central Research Institute, Suntory Limited, Kita-Ku, Osaka, Japan It has been reported by many authors that certain strains of beer yeast of bottom fermentation which was often used for making dough was not suitable because of its poor quality of CO2 gas formation as summarized by LECOURT.1,2,3 Since ever, however, this phenomenon has not been extensively studied. In the present studies, the amounts of the toxic substance against yeast in the grains of different species of cereals, especially wheat and barley, were measured. 1. Material and Method Grain was ground to 100 mesh powder with a roller mill. The powder was suspended in five fold volume of 0.05N H2SO4 which was agitated for 3 hours at 30C. After the above procedure, insoluble material was precipitated by centrifugation (8,000 rpm. 10 min.) and the supernatant was used for further experiment. Various amounts (0.1-1.0 ml) of the supernatant were added to a series
of tubes containing 9 ml of beer wort, and total volume in each tube was
made to 10 ml with distilled water.* Then, beer yeast (5 x
106 cells of strains BH 10 belonging to Saccharomyces cerevisiae
subcultured in beer wort) was inoculated. After incubating at 30C for
24 hours, the propagation response of the yeast cells was measured by
the turbidity and gas volume. |
| * It is estimated that about 0.005N H2SO4 is contained in the wort medium but it was assured that such concentration of H2SO4 does not affect the propagation of the yeast. |
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