(601b) Detailed 3d Evaluation of Oil and Air Dispersion in a Simulated Fermentation Broth, Using a Stereoscopic Vision System

&gamma-Decalactone (peach-like aroma) production by Trichoderma harzianum has been chosen as a model for the microscopic analysis of the organic (castor oil) and gaseous (air) phases dispersion, in order to characterize the multiphase mixing problems occurring in bioreactors. We have studied the dispersion of air (gaseous phase), oil (immiscible liquid phase) and solid phase (fungi of complex morphology) by an advanced image-analysis technique. This technique allowed us to observe the formation of complex oil structures, which are likely to be a multiple dispersion, as some of the air bubbles and aqueous phase droplets remain trapped in the organic phase. However, a two-dimensional observation of this phenomenon may lead to an erroneous evaluation of the extent of the particles trapped since different focal planes may show overlapped. In this work, by the acquisition of stereoscopic images for three-dimensional analysis by coupling two video cameras with a small angle between them, we could calculate the spatial position of air bubbles and oil drops as well as their size as a function of the concentration of fungal biomass. These measurements allowed us to discern accurately whether the air bubbles and water droplets were trapped in the oil drops or if it was only a superposition of particles in different focal planes. Overall, we found that by increasing the mycelial content, a larger proportion of air bubbles and water droplets were located inside the oil drops. 3 D results indicated that 2 D observations can underestimate the inclusion of bubbles and droplets by up to 30 %. This detailed evaluation would allow us to understand with more detail the highly complex interactions of the liquid and gaseous phases in the mixing tank and, in turn, how the fungal biomass affects the mass transfer and the productivity of the process.