Design Space Estimation in the Freeze-drying of Instant Soup Product

Abstract

A mathematical model that could simulate multi-dimensional freeze-drying operated by radiative heat was developed and applied to a freeze-drying process of instant soup. A model product (precooked soybean paste soup) set in a cuboidal plastic cup was freeze-dried where drying progressed multi-dimensionally, that is, the surface area of the sublimation interface changed as a progress of drying. In order to simplify model equations, the relationship between the sublimation surface area and degree of drying was empirically estimated and applied to the model calculation. The simulation results of the present mathematical model were in good accordance with the experimental results. Based on the mathematical model, a method was shown to calculate the design space where rational choice in better drying conditions can be selected.