Little information is available about moisture loss behavior of respiring commodities at humidities approaching saturation.  Experiments were performed with tomatoes, apples, and mushrooms at three different constant temperature levels and high humidities in the range of 91-99% RH. Transpiration coefficient showed a decrease with increasing water vapor pressure difference except for a few cases. No evidence was found to support the observation of van Beek and Ficek (1979) that at high RH, transpiration rate may increase with decreasing water vapor pressure difference. In some cases, tomatoes and apples showed moisture gain at very high humidity, but mushrooms always showed moisture loss. No observable microbial decay of the selected commodities occurred during these studies.

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