A classification scheme for interfacial mass transfer and the kinetics of aroma release

Background: The study of aroma release has gained popularity in food science. Nowadays, experiments become increasingly more complex. However, an application of theories on mass transfer, which may help to better explain the results, is lagging behind on these developments. Scope and approach: The goal of this review is to get together, in a concise way, the state of the art on fundamental knowledge of mass transfer in aroma release plus creating an extension of theory with a comprehensible classification that is useful for food scientists. The existing mathematical model is simplified and points that have received little attention are identified. Key findings and conclusions: An overview of experimental studies that focus on the influence of viscosity on aroma release show that there is heterogeneity in results and no consensus exists on the influence of viscosity. Such heterogeneity may be better understood with the effects of mass transfer. These effects are summarized by describing three implications based on non-proportional relationships between the partition coefficient and (A)the overall mass transfer coefficient, (B)the depletion and saturation time-scales, and (C)the peak value of the aroma concentration in the head space. A classification scheme is made to enable food scientists and technologists to apply the complex description in shorter and simpler terms that can be communicated and compared more easily. The scheme depends on a classification in two dimensions based on a thermodynamic factor, the partition coefficient, and a kinetic factor which divides aroma's and experiments into four different classes.