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Water Activity of a Component Mix Program 

This page is from the Water Activity of a Component Mix Program on-line help.

Program Description

This program estimates the water activity and individual moistures of a mix of up to 5 components after they have reached equilibrium. If diffusion data is available, it will also estimate the time taken to reach equilibrium.

Based on initial moistures and water activities, the program estimates the final aw using the weighted average method. If the GAB isotherm parameters are available for all components, the program then uses non-linear regression to refine the estimate, calculates the GAB parameters and plots the isotherm of the mix at equilibrium.

For information on diffusion data, refer to the sections on the drying and sorption programs.

An example of the use of this program is to determine the final aw of a breakfast cereal blend of cereal flakes and dried fruits.

Input requirements

  • Component names
  • Product name (optional)
  • Total weight of each component
  • Initial moisture (wb) of each component
  • Isotherm GAB constants for each component
    OR initial water activity of each component
  • Diffusion data for each component (optional):
    • half thickness or radius
    • diffusion coefficient
    • critical moisture content
    • equilibrium moisture content

The original demonstration data can be restored by selecting the menu item "Program menu" - "Demo. data".

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Last modified: 10-Aug-2008