148 HARVESTING, STORING, AND MARKETING 



be anticipated. With certain varieties, concentrations of carbon dioxide 

 as low as 2 percent are toxic at a temperature of 32® F. Because of 

 this toxicity factor, with many varieties of fruit the temperature must 

 be as high as 40° F. Different apple varieties have different specific 

 atmospheric and temperature requirements for long-time keeping. This 

 necessitates the use of different chambers with varieties of different 

 atmospheric requirements. 



5. With apples the scald hazard is increased because of the restricted 

 ventilation. For this reason, all apples stored in gas-tight chambers 

 must be treated with oiled papers. 



Applications of Modified-Atmosphere Storage, At Cornell the only 

 apple varieties studied in detail to date are Mcintosh, Cortland, and 

 Northwestern Greening. Of these three, Cortland is the only od3 which 

 has not offered real promise in modified-atmosphere storage. The 

 scald hazard is so great with this variety even with oiled papers in the 

 container that it is not recommended for trial in this system of storage 

 till a better method of scald control is found. Preliminary work indi- 

 cates that there may be such a control. With both Mcintosh and North- 

 western Greening the best atmospheres have proved to be 5 percent 

 carbon dioxide and 2 percent oxygen, with a temperature of 40° F. Of 

 course, the remainder of the atmosphere was nitrogen. To attain such 

 an atmosphere, it is necessary to reduce the carbon dioxide concentra- 

 tions with an atmospheric scrubber or washer which contains sodium 

 hydroxide solution. Such a system is in use with certain varieties in 

 England. 



Pears seem eminently adapted to this type of storage, according to 

 studies in England and California. Just what are the best atmospheres 

 for our American-grown varieties for longest keeping is not clear. None 

 of the stone fruits seems adapted to long-time storage in modified 

 atmospheres, it would seem from California investigations. 



V. FROZEN FRUIT 



Freezing methods of fruit preservation make it possible for a house- 

 wife to serve a wide variety of fruits with fresh qualities on very short 

 notice at any season of the year. Frozen fruit may be purchased for less 

 than out-of-season fresh produce of equal quality. Consequently a large 

 industry has been built up which caters to the discriminating housewife, 

 confectioner, and dining room. 



To produce a good frozen product, it is important to select fruit 

 of proper quality and maturity, and in many cases the proper variety. 

 Klondike, Blakemore, Marshall, and Dunlap strawberries; Eclipse, 



