Physical and chemical changes in the ripening of deciduous fruits

Abstract

circumference measurements of from 20 to 40 individual fruits from several trees. During the season of 1924, increase in size was determined by measuring representative fruits of a given color stage as they were harvested. During 1925 and 1926 the individual fruits were tagged and measured on the tree at frequent intervals during the period of greatest color change. In presenting the results, emphasis is placed on the relative increase in volume rather than on actual gain as ascertained by. measurement.Plums.-The attention given the trees, the water content of the soil, and the size of the crop on the tree are all important factors influencing size changes. As pointed out in a previous publieation'"" instances were found where plums made practically no increase in size after losing their original green color. The greatest gain over a period of ten to fifteen days immediately preceding or during the period of harvest was found to be 4.5 per cent in volume per day, while in most instances the daily increase varied between 1.5 and 2 per cent. Increase in size of plums was usually slightly greater in the early stages of ripening-c-from the time the fruit changed from a decided green to slight pink or blue-than it was in' the later color stages. Growth does not altogether cease until the fruit attains or closely approaches its full color-a greater degree of maturity than most varieties are allowed to reach before being harvested for eastern shipment. Late-ripening varieties made a smaller daily gain in size than early sorts. Early varieties, however, are the ones most often picked prematurely a.nd a five or six days' delay in harvesting would in many instances not only result in fruit of more desirable size but in an approximate 10 per cent increase in the number of crates produced.Peaches.-The measurements and observations shown in table 1 taken on the growth and color of peaches from several orchards in Placer County from the time of 'breaking color' 'until completely colored, show in most instances even a more marked increase in growth during their late development than was. found with plums. Peaches are characterized by a decided 'filling out' or 'swelling' after they begin to show some of their characteristic color. Owing to the firmness of the flesh and the fact that they are primarily used locally for canning, clingstone varieties are usually permitted to attain practically their full growth before harvesting. Freestone varieties, grown for shipment to the eastern markets as fresh fruit, are usually harvested while still somewhat immature a.nd undersized. It is recognized that soft fruits such as peaches must be harvested sufficiently early to withstand the necessary physical handling and the delay in transit. On the other hand, the possibility of attaining better

Effect of Ethylene on Certain Chemical Changes Associated With the Ripening of Pears

“…The decrease in effect of ethylene treatment in relation to the increase in maturity of fruit has been observed by ALLEN (1). He found that this gas was more effective in influencing sugar, acid, and starch changes in Gravenstein apples collected early in the season than in those picked at later dates.…”

“…In other cases (1,27) maturity of the fruit has evidently been a factor. It is apparent, however, that in many of these previous experiments the fact has been overlooked that during maturation and after storage, fruits naturally undergo progressive physiological changes which may greatly modify the response shown to ethylene treatment.…”

INFLUENCE OF YEAR, CULTIVAR AND FRUIT MATURITY ON QUALITY OF PEACH PUREE1

“…Contrary to reports indicating an increase in SS or sugars as peach fruits reach advanced stages of maturity (Allen 1932;Rood 1957;Deshpande and Salunkhe 1964;Kader er al. 1982;Sistrunk 1985;Moriguchi et d. 1990;and Robertson et d. 1990), the results of this study showed small or no changes in SS from maturity 1 to 7, indicating that maturity in the cultivars studied had a small impact on the levels of SS (Fig.…”

Viscosimetric and Other Physical Methods

“…The Magness pressure tester is used widely for the determination of the maturity of deciduous fruits, see Allen (1932). The Magness pressure tester is used widely for the determination of the maturity of deciduous fruits, see Allen (1932).…”