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Rooms, Amer. Soc. Hort. Sci. Proc. 55:239-249. 
88. Varner, J. E. 
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89. Workman, M., and Patterson, M. E. 
1959, The Value of an Alkalone Potassium Permanganate Air Scrubber to 
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RIPENING AND COMPOSITION 
Ripening of apples involves the transformation of a hard nearly inedible 
object into a succulent delicious treat to the palate. Ripening may be con- 
fined entirely to the after-harvest period, or it may occur to some extent on 
the tree before harvest and be confused with maturation. However, maturation 
ends when the apple is harvested, and only ripening and senescence follow (7/7). 
Ripening involves changes in firmness and texture, color, flavor, odor, and 
composition, These changes are preceded by or begin with a rapid increase in 
respiration frequently referred to as the climacteric. Hulme (29) considers 
ripening as embracing all those processes which take place from the onset of 
the respiration climacteric until the fruit has assumed the color and texture 
at which it is normally consumed. 1/ The ripening processes continue beyond 
this point, however, causing overripeness and lead to reactions related to 
senescence. The activities in the ripening process are recognized as being 
largely enzyme mediated and involve various oxidative and glycolytic reactions, 
Respiration and the Climacteric 
Respiration in apples, like most chemical reactions, is sensitive to 
temperature and, within limits, increases in rate with rise in temperature. It 
is also sensitive to the concentration of oxygen and carbon dioxide as well as 
to the presence of other gases such as ethylene in the surrounding atmosphere. 
As the oxygen concentration is reduced and the carbon dioxide concentration in- 
creased from that in normal air, respiration is depressed. The presence of 
small quantities of ethylene may, under some conditions, induce an added incre- 
ment to respiration, the climacteric. This is usually followed by a sequence 
of ripening processes. Kidd and West (39) indicated some years ago that the 
climacteric may occur while the fruit is still on the tree. It may be in pro- 
gress during harvest or take place after harvest. A number of factors including 
variety, location, and climatic conditions appear to affect the timing of the 
climacteric. The use of the climacteric for determining the time to harvest is 
discussed under another section in this review entitled, "Harvest Maturity." 
1/ Underscored numbers in parentheses refer to Literature Cited, p. 117. 
111 
