APPLES AS FOOD 19 



size of fruit is improved by good pruning and soil fertility practices. Good mois- 

 ture conditions are also required. 



After reviewing the "spray residue" problem, Clague and Fellers (1936) 

 stated that "arsenic and lead residues often persist on apples after picking. 

 Only a small part of these toxic substances is removed by ordinary fruit washing 

 methods. Commercially, apples are often washed in solutions containing from 

 0.5 to 1 percent hydrochloric acid. This treatment is effective in residue re- 

 moval." In the East the normal rainfall removes most of the spray before har- 

 vest. Furthermore, orchardists are refraining from using lead or arsenic sprays 

 during the latter part of the season. It is not believed that spray residue on apples 

 constitutes a health hazard in the non-irrigated sections of the United States. 



Water Supply 



The dessert and keeping qualities of the apple are not adversely afifected when 

 the moisture supply varies enough to permit it to fall temporarily to the wilting 

 point, according to Gourley and Howlett (1941). They point out, however, 

 that extremes of moisture are undesirable. Pressure tests indicated that fruits 

 growing under a higher degree of moisture were softer and more susceptible to 

 soft scald. Drier plots produced fruits more acid and better flavored. The gen- 

 eral consensus of opinion is that excessive irrigation may have a detrimental 

 effect. Apple trees, as a result of their deeper rooting system, have access to a 

 much larger water reserve than herbaceous plants, and therefore any moisture 

 changes are not quickly apparent in the fruit. 



Storage 



Gunness, Cole and Roberts (1939) have described the effect of storage on apples 

 as follows: 



An apple grows as a part of a living organism — the tree. Before harvest it 

 continues to receive materials from the tree and the net result of these 

 life processes is growth and increased weight. After removal from the 

 tree, life must be sustained on food stored in the apple. Life processes are 

 destructive, and when they have run their course, the apple dies. This 

 natural breakdown of the apple is marked by a gradual darkening of the 

 flesh beginning at the core, and may occur without rotting. Frequently, 

 decay organisms attack the apple and it rots before its food reserves are 

 completely exhausted. 



The changes that take place within the apple are the result of chemical 

 reactions. The important constituents affecting the quality of an apple 

 are starch, sugars, acids, tannins, pectins, and esters which are compounds 

 responsible for the characteristic odor and flavor of a particular variety. 

 Quality in an apple depends chiefly upon the proportions of sugars and 

 acids. Prior to harvest, an apple contains a relatively large quantity of 

 starches. In the process of ripening, the starches change to sugars and the 

 acids and tannins diminish, thus making the apple more agreeable to eat. 

 Changes in the character of the pectins are believed to be responsible for 

 the "meah'" or granular condition of the flesh as apples become overripe. 

 Chemical changes within the apple are accompanied by the utilization of 

 oxygen and the evolution of carbon dioxide. This process is known as 

 respiration and is a measure of the speed of ripening. These chemical 

 changes are hastened by heat and retarded by cold. If left in the orchard, 

 an apple may reach its maximum quality for human consumption in 

 early autumn. If exposed to low temperatures before that maximum is 

 reached, development may be retarded and a condition of prime eating 

 quality reached in February or March instead of September or October. 



