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Jeffery K. Brecht - One of the best experts on this subject based on the ideXlab platform.
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Effects of Low-dose Electron Beam Irradiation on Respiration, Microbiology, Color, and Texture of Fresh-cut Cantaloupe
HortTechnology, 2005Co-Authors: B.b. Boynton, Charles A. Sims, M. O. Balaban, M. R. Marshall, Bruce A. Welt, Jeffery K. BrechtAbstract:Cantaloupes (Cucumis melo) in three separate trials were cut into 1-inch cubes and irradiated at 0, 0.25, 0.5, 0.75, 1.0, 1.25, or 1.5 kGy; 0, 0.1, 0.2, 0.3, 0.4, 0.5, or 0.7 kGy; and 0, 0.3, 0.6, or 0.9 kGy, respectively. They were then stored in air at 3 °C for up to 20 days, and respiration rate, measured as carbon dioxide (CO2) production, microbiological counts [total plate count (TPC) and yeast and molds], texture, and color were measured during storage. Respiration rates were initially higher in irradiated cantaloupe. After 8 days, respiration was similar between irradiated and control Fruit. Irradiation moderated increases in respiration in a dose-dependent manner. Highest Irradiation doses resulted in initial TPC reductions of 1.5 log compared to the non-irradiated controls, and also prevented the 2.5 to 3 log TPC increases seen in controls after 10 to 11 days of storage. Texture differed on day 1, when controls were most fi rm, but Irradiation maintained greater fi rmness than controls after day 7. Irradiation of fresh-cut cantaloupe has potential for shelf life extension and for integration with modifi ed atmosphere packaging systems.
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Irradiation-INDUCED CHANGES IN TOMATO Fruit AND PERICARP FIRMNESS, ELECTROLYTE EFFLUX, AND CELL WALL ENZYME ACTIVITY AS INFLUENCED BY RIPENING STAGE
Journal of the American Society for Horticultural Science, 1997Co-Authors: Najib El Assi, Donald J. Huber, Jeffery K. BrechtAbstract:Mature green and pink tomato (Lycopersicon esculentum Mill.) Fruit were subjected to ionizing Irradiation in the range of 0.7 to 2.2 kGy from gamma-or X-ray sources. Firmness of whole Fruit and pericarp tissue, pericarp electrolyte leakage, and pericarp cell wall hydrolase activities were measured following Irradiation and during postIrradiation ripening at 20 °C. Irradiation-induced softening was evident in mature-green and pink Fruit within hours following Irradiation, and differences between irradiated and control Fruit persisted throughout postIrradiation storage. Trends of firmness loss were much more consistent and showed much greater dose dependency in pericarp tissue than whole Fruit. Irradiation enhanced electrolyte efflux in Fruit of both maturity classes. Fruit irradiated at the mature-green stage softened during postIrradiation storage but exhibited an apparently irreversible suppression in polygalacturonase activity, with levels remaining <10% of those of nonirradiated Fruit. Polygalacturonase activity was less strongly affected in irradiated pink Fruit than in mature-green Fruit, but activity remained reduced relative to the controls. Pectinmethylesterase and β-galactosidase activities were significantly enhanced in irradiated Fruit of both ripening stages in the early period following Irradiation, but reductions were noted after prolonged storage.
J. K. Brecht - One of the best experts on this subject based on the ideXlab platform.
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926 PB 497 SOFTENING OF GAMMA-IRRADIATED TOMATO FruitS
HortScience, 1994Co-Authors: N. El-assi, D. J. Huber, J. K. BrechtAbstract:The use of Irradiation to increase longevity and quality of horticultural commodities often results in undesirable softening. The biochemical basis of Irradiation-induced softening is not well understood. In this study, we investigated the role of the pectic polysaccharides in Irradiation-induced textural changes of `Sunny' tomato Fruit. `Sunny' mature-green and pink Fruit subjected to 84 or 240 Krad experienced a dosage-dependent decrease in firmness, an increase in electrolyte leakage, and an increase in chelator-soluble pectins. Additionally, pectins prepared from 240 Krad-irradiated Fruit were of markedly lower mol wt compared to those from nonirradiated Fruit. Irradiation-induced downshifts in pectin mol wt were also noted for preripe Fruit that lack PG activity. Mol wt decreases noted for pectins from 240 Krad-treated Fruit exceeded those observed for fully ripe, nonirradiated Fruit The role of other cell wall polymers in Irradiation-induced textural changes is currently being addressed.
James H. Moy - One of the best experts on this subject based on the ideXlab platform.
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Tropical Fruit Irradiation - From Research to Commercial Application
2005Co-Authors: James H. MoyAbstract:Food Irradiation is an emerging technology for the 21st century. Extensive research and development worldwide in the past 40 years have proved the versatility and efficacy. With low, medium to high dose, and using either a gamma, electrons, or x-ray source, radiation can: 1) disinfest plant products and spices; 2) extend shelf life of tubers, bulbs, and selected tropical Fruits; 3) decontaminate meats and seafood; 4) sterilize spices and special meals; and 5) improve product utilization. Criteria for testing its efficacy include effectiveness, efficiency, and the ability to retain product quality. The use of Irradiation as a quarantine treatment of tropical Fruits is potentially attractive to countries growing these Fruits. A two-prong research plan should aim at proving radiation’s effectiveness in preventing emergence of all insect pests that might be on a Fruit, and determining that all quality attributes of a host Fruit are retained after Irradiation, subsequent storage and shipment. Commercial application involves conducting an economical feasibility study; market research and testing; selection of radiation source and irradiator type; training of personnel for plant operations, radiation safety and dosimetry monitoring; designing of packages and choosing the most cost-effective means of transporting treated Fruits to market destinations. When all of these are achieved, it should lead to a continuous and profitable operation. Researchers at the University of Hawaii using a gamma irradiator from the mid-1960s to early 2000s had amassed a volume of data to prove the efficacy of radiation disinfestations. And installation of a commercial x-ray irradiator in 2000 on the Island of Hawaii has enabled Fruit farmers and packers to use this technology for exporting tropical Fruits to distant markets.
N. El-assi - One of the best experts on this subject based on the ideXlab platform.
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926 PB 497 SOFTENING OF GAMMA-IRRADIATED TOMATO FruitS
HortScience, 1994Co-Authors: N. El-assi, D. J. Huber, J. K. BrechtAbstract:The use of Irradiation to increase longevity and quality of horticultural commodities often results in undesirable softening. The biochemical basis of Irradiation-induced softening is not well understood. In this study, we investigated the role of the pectic polysaccharides in Irradiation-induced textural changes of `Sunny' tomato Fruit. `Sunny' mature-green and pink Fruit subjected to 84 or 240 Krad experienced a dosage-dependent decrease in firmness, an increase in electrolyte leakage, and an increase in chelator-soluble pectins. Additionally, pectins prepared from 240 Krad-irradiated Fruit were of markedly lower mol wt compared to those from nonirradiated Fruit. Irradiation-induced downshifts in pectin mol wt were also noted for preripe Fruit that lack PG activity. Mol wt decreases noted for pectins from 240 Krad-treated Fruit exceeded those observed for fully ripe, nonirradiated Fruit The role of other cell wall polymers in Irradiation-induced textural changes is currently being addressed.
T. G. Mccollum - One of the best experts on this subject based on the ideXlab platform.
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Canopy Position and Heat Treatments Influence Gamma-Irradiation-induced Changes in Phenylpropanoid Metabolism in GrapeFruit
Journal of the American Society for Horticultural Science, 2000Co-Authors: Roy E. Mcdonald, William R. Miller, T. G. MccollumAbstract:Irradiation is being evaluated as a quarantine treatment of grapeFruit (Citrus paradisi Macf. 'Marsh'), but it can cause damage to the Fruit. Research was conducted to determine if preIrradiation heat treatments would improve Fruit tolerance to Irradiation as they improve tolerance to low temperature injury and to determine if canopy position influenced Fruit tolerance to Irradiation. Initially, grapeFruit were irradiated at 0 or 2.0 kGy at a dose rate of 0.14 kGy·min -1 and selected biochemical changes were monitored over time. There was a marked increase in phenylalanine ammonia-lyase (PAL) activity following Irradiation. Maximum activity (≈18-fold increase) was attained 24 hours after Irradiation. Subse- quently, grapeFruit were harvested from interior and exterior canopy positions and irradiated at 0 or 1.0 kGy at a dose rate of 0.15 kGy·min -1 before storage for 4 weeks at 10 °C. Following storage, pitting of flavedo was the most evident condition defect noted as a result of Irradiation. Pitting was observed on 27% and 15% of irradiated exterior and interior canopy Fruit, respectively, whereas there was no pitting on nonirradiated Fruit. Heat treatment before Irradiation decreased susceptibility of Fruit to damage. Pitting was 26%, 19%, and 17% when Fruit were held 2 hours at 20 (ambient), 38 or 42 °C, respectively. Irradiation-induced PAL activity was reduced by temperature conditioning at 38 or 42 °C. Exterior canopy Fruit flavedo contained higher levels of total phenols, including flavanols and coumarins compared with interior canopy Fruit. Deposition of lignin was not related to canopy position. Neither Irradiation nor heat treatment had an effect on total phenols or lignin deposition. Generally, cholesterol, campesterol, stigmasterol, β β β β β-sitosterol, and isofucosterol were found to be higher in four steryl lipid fractions in exterior canopy Fruit compared with interior canopy Fruit. Irradiation increased campesterol in the free sterol and steryl glycoside fractions and decreased isofucosterol in the free sterol fraction. Heat treatments had no effect on individual sterol levels. It seems that Irradiation causes a stress condition in the Fruit, which leads to pitting of peel tissue. Heat treatment before Irradiation reduced damaging effects of Irradiation.
