COMMERCIAL STORAGE OF FRUITS AND VEGETABLES 6 



iure in storage rooms be held fairly constant. Variations of 2° or 3° 

 above or below the desired temperature are in most cases too large. 

 They can usually be avoided if the storage rooms are well insulated 

 throughout and are furnished with adequate refrigeration and equipped 

 either with reliable, accurate thermostats or with means for manual 

 control which are given frequent personal attention by somec/ne 

 charged with that duty. Even when reliable automatic controls 

 are used, periodic visits to storage rooms should be made by some 

 responsible person. 



In commercial cold-storage rooms thermometers are usually placed 

 at about the level of the eyes of a man of ordinary height, sometimes 

 slightly lower. It is important, however, to take temperatures fre- 

 quently at the floor and the ceiling also, or at any other places where 

 they might be expected to be undesirably high or low. If the air 

 in certain locations seems always to be too warm or too cold it may 

 be necessary to install fans to increase the rate of air movement and 

 so bring about a better equalization of the temperature in various 

 parts of the room. 



Most varieties of apples keep best and longest if held constantly 

 at 31.5° to 32° F.; the best temperature for Bartlett pears is between 

 30° and 31°. If the air temperature where either of these fruits is 

 stored rises 2° or 3° above the upper limit mentioned, there is danger 

 of increased decay and undue ripening, the danger being greater the 

 longer the period during which the temperature is above 32°. For 

 example, 3 or 4 days at 35° usually would have little or no effect, 

 partly because of a slower rise in the temperature of the fruit than 

 in that of the air; but 10 days at this temperature would probably 

 shorten the life of the fruit by about a week and possibly result in 

 more decay. On the other hand, if the temperature goes a degree 

 or two below 30°, there is a chance that freezing will occur. Celery 

 and cabbage allowed to remain too warm in storage may show yellow- 

 ing and decay; potatoes are likely to begin to sprout if the tempera- 

 ture is too high and usually become undesirably sweet if it is too 

 low. Other commodities undergo these or other kinds of deteriora- 

 tion if the temperature variations throughout long storage periods 

 exceed the limits given for them in this circular. In addition, there 

 is always the possibility that fluctuations in temperature will cause 

 condensation of moisture on stored products, which in itself is unde- 

 sirable because it favors the growth of mold and the development of 

 decay. 



Control of temperature is usually easier in large rooms than in 

 small ones if both are filled to capacity. This is because of the 

 "flywheel" effect produced by the larger mass of material, including 

 both the commodity and the building material. Refrigeration is 

 thus stored up, so to speak, and temperature changes occur more 

 slowly. For this reason small storage rooms generally will require 

 closer attention than large ones. 



HUMIDITY OP STORAGE ROOMS 



The relative humidity of the air in storage rooms has a direct rela- 

 tion to the keeping quality of the products held in them. If it is too 

 low, wilting is likely to occur in most fruits, vegetables, cut flowers, 



