The interior oil fraction in a microcapsule, defined as the ratio of the volume of oil isolated from the microcapsule surface to the whole volume of the microcapsule, was statistically calculated based on a two-dimensional percolation model. As the entire oil fraction increased, the interior oil fraction first increased and then sharply declined after reaching a maximum value. It was demonstrated that reduction of the oil-droplet size was effective in the preparation of microcapsules with a high interior oil fraction.
The application examples of PTR-MS which measures volatile organics forming flavor or quality of foods in real-time were introduced focusing on breath-by-breath analysis of retronasal aroma. Time variations of multiple low concentration flavor compounds at each exhalation events after swallowing food or drink could be tracked simultaneously by using PTR-MS instruments. With this approach, the aroma perception was analyzed in view of mass transfer processes, especially remarking interfacial mass transfer which determined liquid–gas partitioning. Physicochemical properties related with retronasal aroma were complicated and could not be interpreted only by the differences of simple Henry’s law constants.