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  • Author or Editor: P.M. Chen x
  • Journal of the American Society for Horticultural Science x
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Abstract

‘d’Anjou’ pears (Pyrus communis L.) harvested at optimum maturity with flesh firmness of 6.4 kg were stored at -1.1°C for 3 months before being subjected to different intermittent and simulated transit temperatures. Fruit held for 3 days at 1.7 or 7.2°C did not soften significantly at transit temperature of -1.1°C for 4 weeks, whereas fruit held for 3 days at 12.8°C softened from 6.0 kg to 4.0 kg after 4 weeks at -1.1°C. After 4 weeks at 1.7°C, fruit held for 3 days at all intermittent temperatures softened 5.0-3.5 kg. Simulated transit temperatures above 7.2°C caused softening to less than 2.5 kg within 3 weeks. The additive effects of brief intermittent and 4-week simulated transit temperatures indicated that the higher the temperature, the more softening of ‘d’Anjou’ pears occurred. Fruit held for 3 days at 1.7, 7.2, or 12.8°C and 4 weeks at -1.1 or 1.7°C softened rapidly to 1 kg within 8 days in the ripening environment at 20°C, in conjunction with accelerated rates of respiration and ethylene production. However, softening preceded climacteric rises in ethylene and respiration of fruit kept 4 weeks at -1.1°C.

Open Access

Abstract

’D‘Anjou’ pears (Pyrus communis L.) were harvested at weekly intervals for a 3-week period beginning at the start of commercial harvest in the Hood River Valley, Oregon. Late-harvested fruit at flesh firmness of 5.9 to 5.4 kg ripened with fair to good quality following 30 days storage at -1.1°C. Fruit harvested at optimum flesh firmness of 6.4 to 6.1 kg required 60 days of postharvest chilling to ripen with quality. The development of ripening capacity corresponded to the increase in internal ethylene to 1.5—2.0 ppm during cold storage. Dessert quality of late-harvested fruit declined after 90 days of storage while quality of optimum-harvested fruit continued to improve until 150 days in storage. Flesh firmness and ethanol-soluble matters indicated that fruit harvested over the 3-week period were of different maturities. Concentrations of titratable acids and soluble solids varied among different harvest groups.

Open Access
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Abstract

‘Bosc’ pears (Pyrus communis L.) harvested at an optimum maturity, based on flesh firmness (about 62 N), were stored either in air or 1% O2 (plus <0.03% CO2) at −1°C. Fruit stored in air for 1 to 3 months softened rapidly after 2 days of ripening at 20°C and reached ripeness with flesh firmness of 20 N or lower by the 9th day. Ripening was associated with a reduction in extractable juice (EJ) and an apparent increase in water soluble polyuronides (WSP). Fruit stored in air for 4 to 5 months also softened rapidly after 2 days of ripening, but flesh firmness was still between 26 and 30 N after 9 days; however, EJ and WSP of fruit did not change appreciably during 9 days of ripening. The WSP content in fruit stored in either air or 1 % O2 increased substantially during 6 months of storage at −1°C. Increased WSP content during storage did not affect the quantity of EJ. Fruit stored at 1% O2 showed a reduction in EJ and an increase in WSP during the 9-day ripening period, whereas, in long-term air-stored fruit, EJ did not decline while WSP was degraded. Correlation of EJ and WSP during each ripening period provided an estimation of storage life. Increased WSP after ripening might be responsible for the increase in hygroscopic binding capacity of the ripened pulp tissue.

Open Access

Abstract

Stem-end decay caused by several several fungi was less in ‘d’Anjou’ pears (Pyrus communis L.) stored in a low O2 (1% O2 + 0.05% CO2, −1.1°C) room than in ones stored in −1.1° air. Ethylene concentration in the low O2 room was about 120 times higher than in the air room hut did not cause fruit softening or peel degreening after 8 months storage at −1. 1°. The 1% O2-stored fruit softened faster than the air-stored fruit during ripening and also ripened with better dessert quality. Juice binding capacity of ripened fruit pulp from 1 % O2-stored pears was greater than that of air-stored fruit; the texture of ripe fruit from the 1% O2 storage was buttery and juicy while that of air-stored fruit was coarse and dry. The high performance liquid chromatographic analysis revealed that organic acids in 1% O2-stored and air-stored fruits were qualitatively identical.

Open Access

Abstract

‘d’Anjou’ pears (Pyrus communis L.) harvested at optimum maturity, 6.4 kg flesh firmness, were stored in 0.5, 1.0, 1.5, 2.0, 2.5 and 5.0% O2 with CO2 concentration were maintained at 0.01 to 0.03%. Other samples were stored in commercially recommended concentrations of 2-2.5% O2 and 0.8-1.0% CO2 (i.e., regular CA), and conventional air storage. Temperatures of −1.1°C (30°F) were maintained in all cabinets throughout the 8 month storage. Oxygen concentration below 1.5% maintained the dessert quality of fruit and reduced the incidence of superficial storage scald after 8 months of storage. Fruit stored at 1.0% O2 for 8 months did not develop scald even after returning to air storage for 30 days. Oxygen concentration above 2% without CO2 had no beneficial effect on dessert quality or scald control. Regular CA storage also maintained dessert quality, but had only slight effect on scald control. Fruit stored below 2% O2 softened slower, lost titratable acids and free amino acids more slowly, and accumulated protein more slowly than samples stored at higher O2 levels for 8 months. Regular CA fruit changed similarly to those from the 1.0% and 1.5% O2 treatments. Overall fruit metabolism in 0.5% O2 was markedly retarded during the 5 to 8 month storage period.

Open Access

Abstract

Studies of low-O2 storage of ‘Delicious’ apple fruit (Malus domestica Borkh.) were conducted in Oregon (1981), Washington (1982), and British Columbia (1981 and 1982). A combination of 1% O2 with 1% CO2 was the most promising for control of storage scald and quality preservation of ‘Delicious’ apple fruit grown in Oregon. A combination of 1% O2 with <0.03% CO2 effectively reduced or eliminated the incidence of storage scald and preserved dessert quality of apples grown in Washington. Early-harvested apples from British Columbia developed a high incidence of storage scald after 7 months of storage in 1% O2 with 0.05% CO2. Apples harvested at commercial maturity, however, developed only slight or minimal storage scald symptom after 7 months of storage in 1 and 0.5% O2 with 0.05% CO2. A high incidence of low-O2 injury (i.e., ribbon-like, depressed skin browning) was found in fruit from Oregon stored for 9 months in 0.5% O2 (with or without CO2) and in 1.0% to 1.5% O2 with <0.03% CO2. No low-02 injury was found in fruit from Washington or British Columbia after low-O2 storage.

Open Access

Abstract

A comparative study in 1979 and 1980 between ‘Anjou’, a long-keeping winter pear and ‘Bose’, a shorter keeping winter pear (both Pyrus communis L.) revealed that ethanol-insoluble matter, titratable acids, soluble solids, proteins, and free amino acids in fruit of both cultivars during fruit development, maturation, and storage period fluctuated from season to season and were not associated with their difference in postharvest life. Malic acid was the major fraction of organic acids in both cultivars, and it declined at a faster rate in ‘Bosc’ than in ‘Anjou’ during storage at −1.1°C. The amounts of citric, oxaloacetic, and fumaric acids were higher in ‘Bosc’ than in ‘Anjou’ and were maintained at constant levels throughout the storage period. Internal ethylene in both cultivars early in fruit development was about 0.3 ppm and decreased rapidly to below 0.07 ppm during late fruit development and harvest period. For 2 seasons, ‘Bosc’ was capable of ripening after less than 20 days of chilling at −1.1°C when its internal ethylene increased to 0.2 ppm, while ‘Anjou’ required at least 50 days of chilling to develop the ripening capacity coincident with an internal ethylene above 2.0 ppm. Internal ethylene accumulated in ‘Bosc’ about 8 times faster than in ‘Anjou’ during the first 60 days of storage at −1.1° and reached an equilibrium at 40 ppm for ‘Bosc’ and only 5 ppm for ‘Anjou’ during the remaining storage period. After any corresponding period of cold storage, both ethylene and CO2 productions of ‘Bosc’ at ripening temperature of 20° were higher than those of ‘Anjou’, and ‘Bosc’ also required fewer days to reach the climacteric peaks than did ‘Anjou’.

Open Access

Abstract

Low temperatures (LT) exotherms were found by differential thermal analysis (DTA) at −30°C in ‘Siberian C’ peach (Prunus persica [L.] Batsch) and −39° in ‘Starkrimson Delicious’ apple (Malus domestica Borkh. Nuclear magnetic resonance (NMR) spectrometry of intact stems and isolated bark and wood revealed that the LT exotherm was produced by freezing of deep supercooled water which was detected in the wood but not the bark. Freezing processes of the wood and bark appeared to be independent. In both species, xylem injury occurred at the same temperature as the LT exotherm and was closely, if not causally related to freezing of the supercooled water. Bark injury also occurred at the same temperature as the LT exotherm and may have been caused by dehydration stress or freezing of a small amount of supercooled water which remained undetected by NMR spectrometry. The dehydration resistance of apple wood on desiccation at 70 to 90% relative humidity was greater than that of the peach wood which in turn was greater than that of the bark of both species. The dehydration resistance of apple and peach wood may involve both nonliving and living elements of the wood because pulverizing the tissue destroyed the effect, whereas heat killing only lowered it. Both supercooling and dehydration resistance may be related to microcapillary pore structure which restricts heterogeneous nucleation and sublimation of supercooled water from the ray parenchyma cells.

Open Access

Abstract

‘Bing’ sweet cherries (Prunus avium L.) harvested at commercial maturity were commercially packed and stored in 6 low-02 and 1 high-C02 controlled atmospheres (CA) at −1.1°C for 35 days and in a second study were stored in either 1.5% 02 and 0.8% C02 or 12% 02 and 10% C02 at 5.6°, 3.3°, or 1.1°C for 23 days. Fruit stored at 0.5–2.0% 02 with 0.03% C02 maintained a higher percentage of very green stems, brighter fruit color, and higher levels of titratable acids than those stored in air at −1.1°C for 35 days. High C02 atmospheres conserved fruit brightness and TA level but did not prevent stem discoloration. The only effect of lowering temperature from 5.6° to 1.1° was a slight increase in fruit firmness after storage.

Open Access

A proportion of `d'Anjou' pear fruit (Pyrus communis L.) developed a disorder, “black speck” or “skin speckling”, after prolonged controlled atmosphere (CA) storage (1% O2, - 0.5 C). A comparative study of biochemical components revealed that there was no significant difference in succinic, citric, fumaric, and pyruvic acids between the speckled' and normal skin tissues. The content of malic acid in the affected tissue was almost three times lower than that in the normal tissue. The specific activity of NADP-malic enzyme (EC 1.1.1.40) in the affected tissue was also lower, but the total activities were similar. The affected tissue contained higher percentages of dry matter and soluble proteins than the normal tissue. Two-dimensional gel electrophoresis of proteins showed that two groups of novel polypeptides appeared only in the affected skin tissue. This study indicated that a certain proportion of `d'Anjou' pear fruit might have been exposed to unfavorable preharvest environmental stresses, and, therefore, could no longer tolerate the subsequent semi-anaerobic and chilling stresses during prolonged CA storage.

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