Effect of Moisture on Mass Transfer in Spray-Dried Powder

Abstract

Microencapsulation of flavor is an important technology whereby liquid flavor is enclosed in a carrier matrix by spray drying. In this review, the flavor release from spray-dried powder is discussed. Flavor release from the spray-dried powder could be correlated using the Avrami (Weibull) equation. In the analysis of flavor release from the powder, the unknown parameters were: the diffusion coefficient of flavor in the matrix, D_out, diffusion coefficient of flavor in the flavor droplet, D_in, and mass transfer coefficient from the powder, κ_L, which were estimated to fit d-limonene release behavior by using the partial differential equation model. First, the parameters were determined by fitting with the experimental database, assuming that the release in the matrix was the rate limiting step (D_in»D_out). The diffusion model could explain well the release characteristics of encapsulated d-limonene. For the release of encapsulated d-limonene from the spray-dried powder at 51% RH and 50°C, diffusion of flavor inside the matrix was the rate-limiting step. The encapsulated flavor powder with vacuoles showed greater release than powder without vacuole formation.