22 



CIRCULAR 



U. S. DEPARTMENT OF AGRICULTURE 



was not found on the other varieties, of which ozonized and non- 

 ozonized lots were indistinguishable except when ozone injury was 

 noticeable. A similar stickiness of the cuticle as a result of ozone 

 treatment was observed on Rhode Island Greening apples by Smock 

 and Watson (2^). 



Physiological Properties 



Apparently ozone has little effect upon the rate of ripening of 

 apples in storage. A number of investigators (7, 17) reported that 

 ozone does not accelerate the rate of ripening; and some (£, 11, 21j) 

 maintained that there is a tendency for ozone to retard the rate because 

 it oxidizes ethylene, which is liberated by the ripening fruit and 

 hastens ripening. Although a slight increase in carbon dioxide pro- 

 duction (a measure of respiration) has been reported (1. 11. 12) . this 

 increase did not result in any hastening of maturity. Pressure tests 

 and chemical analyses by Baker (I) showed no differences in hardness 

 or in sugar and starch contents of ozonized and nonozonized fruit. 

 Because of the sticky, varnishlike surface of the ozonized Arkansas 

 and Winesap varieties and its possible effect on the permeability of 

 the cuticle and on the rate of ripening. pH. total-acidity, and internal- 

 atmosphere determinations were made. The differences between the 

 ozonized and nonozonized fruit were small, however, and had no 

 significance. 



The findings in these physiological tests are summarized in table 11. 



Table 11. — Effect of 3.25 p. p. in. of ozone for a storage season on some 

 physiological properties of apples 





Fruit 

 waxed or 



unwaxed 



Stor- 

 age 



period 

 at 



31° F. 



Sub- 

 se- 

 quent 

 pe- 

 riod 



at 

 70° 



F. 



pH 



Total 

 acid- 

 ity as 

 malic 

 acid 



Internal atmosphere 



Variety and 

 ozone treat- 

 men t 



Total 

 gas 



Car- 

 bon 



dioxide 



Oxy 



gen 



Arkansas : 



3.25 p. p. m_ _ 







3.25 p. p. m_ _ 

 



Winesap : 



In waxed _ 



___do___ 



___do 



___do 



Waxed 



__. do 



Unwaxed. 

 _._do 



Months 

 5 



5 



7 



7 



7 

 7 

 7 



7 



Days 



{ I 

 { I 





 



{ ? 

 { ? 

 { ? 



{ ? 



3. 63 



3.80 

 3. 83 

 3. 96 

 3. 63 

 3. 70 



Per- 

 cent 

 0. 39 

 . 27 

 . 40 

 .30 

 .38 

 .36 



Cubic 

 centi- 

 meters 

 per kilo- 

 gra m 

 306. 2 

 282. 

 287.0 

 296.0 

 305. 7 

 297. 6 



316.0 

 301. 

 326. 6 

 328. 3 

 312. 6 

 314. 5 

 312. 6 

 333. 3 



Per- 

 cent 

 7.3 

 10. 2 



6. 8 

 12. 8 



3. 6 



4. 6 



10. 

 8.6 



11. 4 

 8.0 



7. 6 

 8.2 



11. 9 

 8.0 



Per- 

 cent 

 18. 7 

 13.4 

 18. 2 

 11. 3 

 19.8 

 18. 6 



13. 6 



3.25 p. p. m_ _ 



3. 78 



.31 



15. 6 

 12. 2 







3. 78 



. 29 



12. 4 

 16. 4 



3.25 p. p. m__ 



3.78 



. 30 



15. 2 

 12. 9 







3. 73 



. 31 



14. 4 



