Continuous estimation of viscosity, fluid density, surface tension, and heat output during fermentations

Abstract

Currently, sensors for measuring fluid density, surface tension, viscosity, and heat output are rarely if ever used in estimating conditions continuously in microbial cultures. Measurement of fluid density and surface tension can be accomplished with differential air pressure-based sensors. Fluid viscosity can be estimated by measuring differential fluid pressures. These three sensors, as tested with cultures, were comprised of glass and rubber tubing, a gas supply for density and surface tension and a peristaltic pump for viscosity. The heat output was estimated with an infrared detector spaced two inches from the bottom surface of a solid-state culture flask.