Monitoring yeast activation with sugar and zero-calorie sweetener using terahertz waves

We report for the first time the use of terahertz waves (0.75 THz-1.1 THz) to monitor activation of yeast cells in solutions containing normal sugar and artificial sucralose sweetener. We observed that the yeast solution with regular sugar and artificial sweetener each showed 14 dB of variation in the terahertz reflection over 42 minute. The solution with sweetener was in particular very active and generated CO2 bubbles more vigorously than sugar. The control solution containing only yeast and water had a nearly constant terahertz reflection coefficient over time. This finding is quite surprising and we did not expect any activations of yeast with sweetener.