in Australia (75) indicates that borax sprays hasten maturity and ripening. | 
Hormone sprays for the control of preharvest drop frequently hasten ripening | 
and shorten the storage life (18, 34, 48, 68). 
Radiation in excess of 10,000 rads from a gamma source was found by 
Massey et al. (47) to cause an immediate softening and a transient stimulatien 
of oxygen consumption. However, the irraidated fruit softened at a much lower 
rate in storage, which gave a net result of somewhat firmer fruit than normal. 
Smock and Sparrow (66) reported earlier that Greening and Cortland apples 
treated with 40,000 rads softened more at 74° F. than untreated fruit. A 
Russian report (57) states that apples treated with 400,000 rads showed a drop 
in monosaccharides and a rise in starch content. Reports from the Danish Atomic 
Energy Commission (50, 74) state that apples treated with 50,000 to 100,000 rads 
developed no storage rots at 12° C. (53.6° F.), but quality deteriorated. At 
20,000 to 40,000 rads the apples were firmer with less rotting in storage, and 
respiration was significantly reduced. 
Compositional Changes During Ripening and Storage 
Esselen et al. (14) gave the average composition of the edible portion 
of fresh apples as 84.1 percent water, 0.3 percent protein, 0.4 percent fat, 
0.29 percent ash, 14.9 percent total carbohydrates, and 0.47 percent acid. 
Strachan et al. (70) conducted a comprehensive study of the proximate composi- 
tion of several varieties of apples grown in British Columbia. Kenworthy and 
Harris (36) obtained several varieties of apples from widely scattered areas of 
the U. S. for 3 years and analyzed them for 26 constituents. More significant 
differences were found for years than for any other variable. Neither of the 
above studies considered changes during ripening or storage. Some of the 
changes occurring in the various groups of constituents during ripening and 
storage are discussed in the following paragraphs. 
Carbohydrates 
Kertesz et al. (38) investigated firmness and cellulose content of 17 
varieties of apples at commercial harvest and after 102 to 135 days of storage. 
Although cellulose is considered a factor in firmness, changes in the amount or 
quality of cellulose were not found to be involved in the softening that occurs 
during ripening and storage. However, Wiley and Stembridge (80) noted an in- 
crease in cellulose content during storage and with softening of the tissue. 
Perhaps the greatest change in carbohydrates occurring during ripening 
involves the pectic constituents. Softening, one of the most noticeable 
characteristics associated with ripening, appears to be closely related to a 
decrease in insoluble pectins (protopectins) and an increase in soluble pectins. 
As apples pass their peak of eating acceptability and become mealy, the soluble 
pectins decrease again and the insoluble protopectins may increase (28). A 
very close direct relation between hardness and protopectin content has been 
observed (78). The degree of softness as measured by a penetrometer, such as 
the Magness-Taylor pressure tester, or with a mechanical thumb instrument (60) 
provides an index of ripeness that guides the producer and storage operator in 
timely marketing of apples for better quality. Storage temperatures profoundly 
affect the formation of soluble pectic constituents (37). All ripening re- 
actions, including the pectin transformations, proceed at a much lower rate at 
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