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or stomates) in the skin, through breaks in the surface tissue or 

 coating, or directly through the waxy coating. Like other gasses, 

 water vapor moves from areas of higher concentration (the saturated 

 atmosphere within the product) to areas of lower concentration (the 

 surrounding air at less than 100% relative humidity). The drier 

 the surrounding air, the faster will be the movement of water vapor 

 from the product. Since warm air can hold much more water vapor 

 than cold air, this moisture loss occurs faster at warmer temper- 

 atures . 



The rate of water loss is also affected by air movement past 

 the product. In the absence of air movement, water vapor will con^ 

 centrate at the product surface and slowly diffuse outward, thus 

 creating a moist layer of air around the fruit. With increasing 

 air movement, this water vapor is swept away ever more rapidly. 



Methods of shrivel protection begin in the field and carry on 

 to the housewife. These include: 



Temperature . Rapid cooling quickly places the product under 

 an environment that is adaptable to moisture retention. Mainten- 

 ance of a constant low temperature (as low as the commodity will 

 tolerate) will minimize moisture stress between the product and its 

 environment. Prevention of temperature fluctuations protects the 

 product from periodic increases in moisture stress. 



Relative Humidity . A high relative humidity will minimize the 

 gradient in water vapor concentration from the product to the sur- 

 rounding atmosphere. Many fresh commodities can be successfully 

 held at 90 to 95 percent relative humidity. Problems of increased 

 growth of decay organisms during high relative humidity storage are 

 usually associated with too high a holding temperature. 



Air Velocity . The ability to manipulate air velocity during 

 product distribution can aid in reducing moisture loss. A high air 

 velocity is often essential for rapid cooling. However, if con- 

 tinued after cooling, this high air velocity will cause unnecessary 

 moisture loss, even under high relative humidity conditions. Once 

 cooling is completed, the air circulation should be just sufficient 

 to maintain the temperature by sweeping away the heat of respiration 

 and heat leakage into the system. 



Product Waxing . Edible waxes are sometimes used to reduce 

 moisture loss by creating a barrier to water vapor passing through 

 the surface of the product. Since the wax barrier must not inter- 

 fere with the exchange of Op and COg gasses that is essential for 



