BETTER FRUIT 



AN ILLUSTRATED MAGAZINE PUBLISHED MONTHLY IN THE INTEREST OF MODERN, PROGRESSIVE FRUIT GROWING AND MARKETING 



Essentials of Air-Cooled Storage Houses 



THE term "air-cooled storage" is 

 used to designate that method of 

 storage which utilizes the natural 

 atmospheric temperature for cooling. 

 It differs essentially from cold storage 

 in that no mechanical means of refrig- 

 eration is supplied to cool the fruit or 

 to maintain it at storage temperature. 

 It does not and cannot take the place of 

 cold storage, but it does supply a satis- 

 factory method for the keeping of cer- 

 tain varieties of apples which go onto 

 the winter market. 



Having in mind the recent car short- 

 age which the country has experienced, 

 I think it is not necessary for me to 

 point out the pressing need for storage 

 facilities in the apple producing regions. 

 I do want to call your attention in pass- 

 ing, however, to the use that can be 

 made of the air-cooled storage in solv- 

 ing our labor difficulties at harvest time. 

 The shortage of labor has been serious 

 during the past two years and promises 

 to become more serious with the con- 

 tinuance of the war. Air-cooled storage 

 will help to solve the problem in this 

 way: 



Fruit can be stored loose in boxes, 

 thereby deferring the labor of packing 

 from the rush of harvest time when 

 laborers are scarce to the dull months 

 of winter when laborers are compara- 

 tively plentiful. Where the storage 

 house is situated on the ranch, the labor 

 of packing is often performed by the 

 rancher and his family or hired man at 

 a time when they would otherwise be 

 unemployed. The plan, therefore, has 

 the double advantage of releasing pack- 

 ers for other work during the busy har- 

 vest season and of furnishing employ- 

 ment for the rancher and fruit laborers 

 during the dull season. 



The Department of Agriculture began 

 an investigation of air-cooled storage 

 houses in the Northwest in 1915. Be- 

 lieving that apples keep best at a tem- 

 perature of 32 degrees, we hoped to 

 learn what lype of storage house could 

 be cooled most rapidly in the fall, what 

 provisions are necessary for the main- 

 tenance of storage temperatures, and 

 what provisions are necessary to pre- 

 vent shriveling of the apples in conse- 

 quence of dry atmospheric conditions. 

 In order to learn about the necessity 

 for ventilation, we placed recording 

 thermometers in a number of storage 

 houses. These instruments were placed 

 in a representative part of the storage 

 room, neither in the coldest nor in the 

 warmest part. The instruments were 

 left from the lime the fruit was put into 

 storage until it was taken out in the 

 spring, and they kept for us a contin- 

 uous record of the air temperature 

 within the house. Some of the thermo- 



W. C. Quick, Yakima, Washington 



graphs had humidity recorders attached 

 to them. We have used electrical ther- 

 mometers for recording fruit tempera- 

 tures within large blocks of fruit. They 

 were necessary to determine whether 

 there was a uniformity of temperature 

 throughout the storage room. 



But we wanted to compare the fruit 

 stored in one house with the fruit stored 

 in some other houses which were built 

 after a different plan. This we did by 

 placing comparable lots of fruit in dif- 

 ferent houses and making withdrawals 

 from storage at three times during the 

 winter for the purpose of comparison. 



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From the investigations we have con- 

 cluded that the three features of para- 

 mount importance in the construction 

 of air-cooled storage houses are ample 

 provision for ventilation, for insulation, 

 and for humidity control. In order to 

 emphasize the necessity for such pro- 

 visions let me call your attention to the 

 condition which existed in some poorly 

 constructed basements on December 10 

 of the past year. At that time we in- 

 spected the fruit and took temperature 

 records in a number of storage houses. 

 In poorly constructed basements we 

 found the temperature ranging from 47° 

 to 52° in the greater part of the fruit. 

 Needless to say, the apples were riper, 

 softer, greasier and in some cases more 

 shriveled than they should have been. 

 It is evident that such condition was 

 avoidable, because on the same date, in 

 the same valley, the apples in well ven- 

 tilated houses were firm and bright. 



The one feature that we have found 

 most important, and at the same time 

 least understood, is ventilation. In the 

 Yakima Valley in 1915 I think there 

 was one house with adequate ventila- 

 tors. The greatest misconception was 

 held in regard to the capacity required 

 in the ventilation system, probably be- 

 cause the builders had not considered 

 the amount of air necessary In cool a 

 house full of fruit. At best the fruit in 

 air-cooled storage cools very slowly. 

 The statement has been made that 

 apples in this type of storage ripen 

 more during the first three or four 

 weeks than they do in all the rest of the 



storage period, lasting ordinarily until 

 March 1. Probably such is the case; at 

 least it is true of poorly ventilated stor- 

 age houses. The New Hampshire Ex- 

 periment Station reports indicate that 

 the ripening processes of apples go on 

 about three times as fast at tempera- 

 tures of 45° to 50° as they do at 32°. 

 In general, the quicker the cooling and 

 the lower the temperature at which the 

 fruit is held, provided it is not below 

 freezing, the more effectively are these 

 life processes retarded, and the longer 

 the fruit can be held at maximum des- 

 sert quality. 



Another object of quick cooling is to 

 prevent the germination of fungus 

 spores and to retard the growth of 

 fungus organisms which cause the de- 

 cay of fruit. Quick cooling also retards 

 the development of scalds and spots 

 which occur in storage and which 

 greatly depreciate the value of the fruit. 

 We must, therefore, conclude that rapid 

 cooling is desirable. To cool a large 

 mass of fruit requires the circulation 

 of immense volumes of air. The amount 

 of course varies with the temperature 

 of the incoming air and with the tem- 

 perature and amount of fruit. The air 

 must pass through the building in such 

 a way as to come in contact with all the 

 fruit. In order to secure a free and 

 abundant flow, a free and unobstructed 

 passage must be provided. A free and 

 uniform distribution of air throughout 

 the storage room demands that the 

 house be supplied with numerous large 

 windows in all four walls for the ad- 

 mission of air, a false (slat) floor under 

 which the air can spread, and one or 

 more outlet flues leading up from the 

 ceiling and out through the roof. Large 

 doors in the walls of an above-ground 

 storage are beneficial on windy nights. 

 The same principles are applied in the 

 ventilation of a storage house by the 

 gravity method as are employed in 

 securing a draft through a furnace. 

 Warm apples take the place of the fire, 

 windows take the place of dampers, 

 and a flue takes the place of the smoke 

 slack. The cold air outside the build- 

 ing is heavier than the warm air inside, 

 and pressing in through the intake win- 

 dows it crowds the warm air out 

 through the flues. The difference in the 

 weight of the incoming and outgoing 

 air is not great and the circulation is 

 slow. It is therefore necessary that the 

 windows be large and direct. The 

 necessity for capacious ventilators can- 

 not be over-emphasized. 



In the fall of the year, when it is 



desirable to cool the fruit rapidly and 



the atmospheric temperatures are not 



below 29°, often much higher, an ideal 



Continued <>n page 23 



