Thermal Death time of Yeast

National Canners Association thermaldeath-time tubes are not as convenient for studying thermal-death time above 60°C as are capillary tubes. Capillary-tube data indicate that Saccharomyces cerevisiae var. ellipsoideus (No. 508) is slightly more heat-sensitive than Saccharomyces cerevisiae (No. 522). No. 522 is killed in one minute at 57.5°C and in 0.1 minute at 62°C. The temperatures are 1°C lower for No. 508. The death of No. 522 produced by radiofrequency treatments was by heat and occurs at time-temperature combinations predictable from thermal-death data obtained by more conventional techniques. Synergistic effects were noted in the case of addition of alcohol to the buffer, but the yeast death time was not lowered enough to account for the results of Yang (16).