22 STUDIES ON PEACHES. 



in. EFFECT OF STORAGE ON THE COMPOSITION OF PEACHES. 



The effects of three kinds of storage on the composition of peaches 

 were studied, the fruit being stored at the time of market ripeness: 

 First, at the ordinary room temperature in the summer time, the 

 temperature ranging from 25 to 30 C. (77 to 86 F.), the results 

 being recorded in Table VIII; second, in cold storage at 0. (32 F.), 

 (see Table IX); third, in an ordinary refrigerator at a temperature of 

 from 12 to 15 C. (53.6 to 59 F.), (see Table X). In all forms of 

 storage the weight of the peaches decreased. This loss in weight was 

 not entirely due to evaporation of water, for a diminution of solids in 

 the flesh occurs in all cases. 



In certain respects the changes in composition during storage sug- 

 gest the changes that take place in apples under similar conditions. 

 Unfortunately the experiments could not be prolonged sufficiently to 

 follow these changes through as wide a range as is possible in the case 

 of apples. The peach is short lived and at best remains in good 

 condition, in fact remains alive, but a comparatively short period of 

 time, whereas the apple may be kept for months, or even for a couple 

 of years, in such condition that the cells are apparently able to per- 

 form their natural functions, though to a somewhat diminished extent. 



The nature of the peach changes obviously even within two or three 

 days at summer heat and its life can be prolonged only by reducing 

 the temperature quickly after picking. It is apparent that the gain in 

 reducing sugar to a large extent compensates for the loss in weight of 

 sucrose, and the total loss of invert sugar is comparatively small. At 

 the same time the loss in weight of marc can not be accounted for by 

 the figures obtained in this experiment. It is probable that this loss 

 is largely occasioned by the conversion of the insoluble pectin bodies 

 into soluble pectins which, while they were a part of the marc of the 

 peach, were not determined separately. Therefore we might expect 

 the weight of the undetermined matter to increase somewhat propor- 

 tionally with the disappearance of the marc. On the contrary, a 

 decided decrease of undetermined matter has occurred. This can only 

 be accounted for by the loss in total solids, and it is suggested that 

 this loss is probably partly due to the consumption of invert sugar in 

 the respiration of the peach, and that a portion of the marc may be 

 converted into sugar in the life processes of the fruit. At the same 

 time it seems possible that some of the pectin bodies may be consumed 

 in the respiration. It is also possible that a portion of the loss in marc 

 may be explained by the following fact: When after storage the 

 sample was partially decayed and it became necessary to cut away the 

 rotten parts, the proportion of skin sacrificed was probably relatively 

 greater than that of the flesh, the skin being notably richer in marc 

 than the flesh. 



