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- Author or Editor: S. Ben-Yehoshua x
Abstract
The commercial deterioration of orange fruit of the ‘Shamouti’ and ‘Valencia’ varieties was studied in relation to transpiration, respiratory activity and concentrations of CO2, O2 and ethylene inside the fruit. Loss of commercial value of fruit under various storage conditions was caused by transpiration, which resulted in shriveling of the peel. During storage, respiratory activity declined, and the internal CO2 rose from a range of 2-4% to a range of 5-10%, while the O2 declined from ranges of 17-19% to 10-12%. Drying of the peel caused a rise in resistance to gas diffusion which, in turn, changed the internal atmosphere. The flavedo portion of the peel was the main site of resistance to gas diffusion.
Abstract
A foliar spray of various iron salts induced preferential abscission of citrus fruits over that of leaves. This effect was related to Fe cations rather than to anions, and was enhanced at lower pH. The Fe salts can cause marked phytotoxicity, but fruit loosening was achieved at concentrations that caused little to no defoliation, some rind damage, and light to severe injury to young growth and fruit buds. Effective concentration varied for different species. ‘Valencia’ was more resistant to loosening than the other citrus cultivars tested.
Concentrations of Fe cation in the iron formulations were more than 100-fold that required by cycloheximide, 2 to 10-fold that required by ethephon and about one tenth-fold that required by ascorbic acid to loosen fruit. However, Fe formulations have the following advantages: a) low cost, b) provide essential nutrients to the tree, and c) cause very few problems in registration with the Food and Drug Administration.
The fruit removal force and the sensitivity of ‘Calamondin’ fruit to various looseners during its ontogenical development varied in the order, starting with the most sensitive phase, flowers, fruits just set, mature fruit, immature fruit, and green full-sized fruit.
Abstract
This work describes changes in abscisic acid (ABA) content, membrane permeability, microviscosity, and lipid composition during storage of green and red bell pepper fruit (Capsicum annuum L. cv. Maor). Membrane permeability increased as measured by leakage of electrolytes and ninhydrin-reacting substances, sucb as amino acids. Membrane microviscosity increased initially and then showed a slow decrease. In red peppers, the increase in microviscosity occurred sooner than in green peppers, and the membrane leakage was higher. Examination of the composition of sterol and phospholipid in microsomal membranes revealed a connection between sterol level and membrane microviscosity. Sterol levels increased and then slightly decreased, while phospholipid levels showed no significant change. Abscisic acid levels showed an increase during senescence, followed by a decrease that was more dramatic in green pepper.
Abstract
Yellowing and decay of leaves were reduced when romaine lettuce (Lactuca sativa L. cv. Hazera Yellow) was prepackaged in closed polyethylene (PE) bags in which O2 concentration was reduced by flushing with N2. Similar, but less effective results were obtained when the lettuce was prepackaged in closed PE bags (not flushed with N2 gas), or when open bags were placed in PE-lined cartons, as well as when lettuce was vacuum precooled after packaging in open bags. Vacuum precooling of PE-lined cartons of lettuce did not further delay deterioration, since the process of vacuum cooling eliminated the modified atmosphere previously produced in PE liners. The efficacy of PE-lined cartons and that of closed PE bags in delaying deterioration of lettuce was related to reduction of O2 and accumulation of CO2 in the ambient atmosphere in the package.
Concentrations of CO2 in PE-lined cartons, which reached 8 to 12% at the end of holding at 18 to 20°C following storage at 1°C, had no adverse effect on romaine lettuce. However, about 64% of the heads of ‘Great Lakes’ lettuce packed in similar packages during cold storage showed CO2 damage, even when CO2 was not higher than about 3%.
Abstract
Ascorbic acid (AA) application at relatively high concentration, 1-5% w/v, accelerated abscission of fruit more than of leaves and increased the ethylene production of both organs by about 10 fold. This selective abscission may be related to the following factors: a) the internal ethylene concentration rises in treated fruit up to levels above 1 ppm whereas its concentration in treated leaves is estimated to be lower; b) leaves incorporate less ascorbic acid than fruit; c) A A induces a marked injury to the fruit’s rind and little to no visible injury to leaves.
Ascorbic acid treatment increased the sensitivity of both leaves and fruit to external ethylene and increased the respiratory activity of both. This rise in fruit respiration might be related to the increase in internal ethylene and injury.
Abstract
Curing of sealed lemons of normal and decay-prone types [Citrus limon (L.) Burm.f] and of sealed Goliath pomelo [Citrus grandis (L.) Osbeck] inhibited postharvest decay without deleterious effects on fruit quality and prevented the development of Penicillium digitatum on inoculated fruit. Curing of nonsealed fruit was less effective in reducing decay than curing sealed fruit and caused prohibitive weight loss, shrinkage, and softening. Curing of sealed and waxed ‘Shamouti’ and ‘Valencia’ oranges (C. sinensis), in comparison to only sealed fruit, resulted in some CO2 injury of the peel and off-flavor.
Abstract
The physiological changes occurring in green and red bell pepper fruit (Capsicum annuum L. ‘Maor’) before and after harvest were investigated. Red pepper at harvest was less firm and had lower water potential, lower insoluble pectins, and higher water-soluble pectins than green bell pepper. However, the changes occurring in both types of peppers after harvest were similar. Postharvest weight loss was accompanied by a decrease in firmness, decrease in water potential, decrease in insoluble pectin, and an increase in soluble pectin in the cell wall. The production of CO2 showed that there was a slight decrease and a significant but small increase of ethylene after harvest. If weight loss was retarded by holding pepper in a water-saturated atmosphere, then all of these physiological changes were prevented or markedly slowed. It appears that water stress hastens and possibly triggers the onset of senescence in harvested bell pepper fruit.
Abstract
Seal-packaging of individual fruits of ‘Shamouti’ and ‘Valencia’ oranges (Citrus sinensis L. Osbeck), grapefruit (C. paradisi Macf cv. Marsh) and lemons (C. limon Burm. f. cv. Eureka) with a film of high-density polyethylene (0.01 mm) markedly delayed their deterioration as measured by peel shrinkage, softening, deformation and loss of flavor. This film was applied to fruit that had received conventional treatments of disinfection with sodium orthophenylphenate and waxing. Sealed fruit maintained their fresh appearance more than twice as long as conventionally handled fruit. Weight loss of fruit was reduced about five-fold. Sealed fruit at 20° were firmer and lost less weight than non-sealed fruit at the lowest optimal temperature. Sealing various citrus fruits in high density polyethylene reduced both their respiratory activity and ethylene production. CO2 and O2 content in the internal atmosphere of the sealed and control fruit were similar but ethylene content was lower in the sealed fruit.
Abstract
Seal packaging of orange [Citrus sinensis (L.) Osbeck cvs. Valencia and Shamouti], grapefruit (Citrus paradisi Macf. cv. Marsh) and lemons (Citrus limon Burnt, f. cv. Eureka) with high-density polyethylene (HOPE) film (0.01 mm in thickness) delayed softening and inhibited weight loss and deformation of the fruit more than cooling. Sealed fruit at 20°C and 85% relative humidity (RH) had better appearance and were firmer than non-sealed fruit at their lowest temperature possible without chilling injury and 85–90% RH. HOPE seal-packaging also inhibited chilling injury of grapefruit and lemons stored at 5° and 2°C, respectively. The C02 content of grapefruit was unaffected by seal-packaging, hut it was lower at cooler temperatures. Decay of citrus fruit depended more on the storage temperature than on the type of packaging. However, in storage up to 1 month, no significant difference was found in most experiments in decay percentage between orange, grapefruit, and lemon sealed with HOPE and stored in a packing house (13 to 25°C), and non-sealed fruits, at the lowest temperatures possible without chilling injury of 2, 10 and 14°C, respectively.