The effect of post-harvest temperature on fresh fruits is a matter of plant physiology rather than of engineering, but a knowledge of the principles involved is desirable for the engineering of temperature control. The tissues of these products remain alive after harvest and normal life processes continue. With some exceptions the longest life and the best quality can be obtained by checking the life processes by low temperature as soon and as completely as possible. Moisture loss and the action of enzymes and microorganisms also cause deterioration that can be checked by low temperature. The rates of these various changes are commonly doubled or tripled with each 10° F rise in temperature. It may be estimated roughly that fresh fruits and vegetables deteriorate as much in an hour at 90°F as in a day at 50 or in a week at 32°E. ___________________________________________________________________________________ Keywords: Post-Harvest Temperature, Plant Physiology, Moisture Loss, Enzymes & Microorganisms