SUMMARYA method was developed for the determination of water activities of flour at high moisture contents. In this method a flour sample was allowed to equilibrate with water contained in a porous membrane while under a certain constant mechanical pressure. The cell was fitted with a porous membrane which allowed the transfer. of moisture from and to the sample. After equilibrium was achieved the sample was analyzed for moisture content. A thermodynamic relationship enabled calculation of the water activity corresponding to the pressure used in the cell. Results obtained with this method were in agreement with those obtained with the constant‐relative‐humidity desiccator technique in the over‐lapping range of water activities. The two methods were also in agreement that the water activity of flour was not affected by the particle size distrib
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