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  • Author or Editor: Krista C. Shellie x
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An instrumented sphere (IS) was used to identify high-impact areas on seven grapefruit (Citrus paradisi Macf.) packing lines in the Rio Grande Valley of Texas. The packing-line unit operations having the greatest percentage of high impacts were 1) the sizer, 2) when #2 fruit were separated by hand at the grading table, 3) when fruit were dumped from the harvest bin onto the packing line, and 4) when fruit dropped into a collection bin at the end of the packing line. The number of high impacts and the amount of cushioning in high-impact areas varied among the seven packing sheds. The amount of red dye visible on the surface of fruit collected from the end of each shed's packing line did not correspond with each shed's percentage of high impacts or with incidence of decay during fruit storage. The severity of impacts and degree of cushioning provided in these Texas packing sheds were comparable to that reported for 39 Florida packing houses. This study illustrates the usefulness of the IS for enhancing individual packing-line operations and for comparing individual shed performance to packing-line operations in other agricultural production regions.

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A collection of 23 red and six white wine grape (Vitis vinifera) cultivars were evaluated for viticultural performance in Parma, ID. Vine yield, fruit composition, and vegetative growth were measured over four growing seasons, and data were used to compare relative cultivar performance based on yield to pruning ratio and fruit maturity. Relative differences among cultivars in budbreak day of year [96 (6 Apr.) to 122 (2 May)] and days from budbreak to harvest (143 to 179 days) varied from year to year. The earliest and latest maturing cultivars in 3 of 4 years were ‘Blauer Portugieser’ (143 days), ‘Nebbiolo’ (177 days), ‘Barbera’ (179 days), ‘Orange Muscat’ (144 days), ‘Flora’ (149 days), ‘Muscat of Alexandria’ (166 days), and ‘Viognier’ (168 days). Cultivars differed in yield (2.4 to 7.0 tons/acre), vegetative vigor (4.6 to 20.4 yield/pruning weight), and harvest soluble solids concentration (21.1 to 26.5), but differences in harvest pH (3.0 to 4.1) and titratable acidity (2.48 to 13.03 g·L−1) varied from year to year. Average heat unit accumulation (1646) was 160 units higher than the 78-year site average. Few (less than 150) units accumulated in April and October, most units accumulated in July, and diurnal difference in air temperature was ≈15 °C. Performance results from this study can assist cultivar site selection by comparing climate data for an intended site with that of Parma. For example, the low acidity and earliness of ‘Blauer Portugieser’ suggests it is best suited to a site with less heat unit accumulation than Parma, and the high acidity and late maturity of ‘Barbera’, ‘Nebbiolo’, and ‘Carignan’ suggest these cultivars are best suited to a site with more heat unit accumulation than Parma. The inconsistent relationship between onset of budbreak and earliness observed in this study suggests opportunity to match short-season cultivars late to break bud such as Flora to short-season growing sites prone to late-season frost.

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Green mold, a predominant disease of citrus fruit, develops when spores of Penicillium digitatum infect extant wounds in fruit epidermal tissue. Development of green mold during shipping limits the distance grapefruit can be surface transported. The objective of this research was to evaluate whether altering the atmosphere during refrigerated storage could suppress development of green mold. In the first two experiments, growth of green mold was evaluated after fruit were stored in ultra-low oxygen (0.05 or 1 kPa) at 14, 16, or 18 °C for up to 21 days. In the last two experiments, grapefruit were stored for 14 or 21 d at 12, 13, or 14 °C in atmospheres containing 2, 5, or 10 kPa oxygen with or without 2, 5, 10, or 20 kPa carbon dioxide. In all experiments, grapefruit were inoculated with 10 or 20 μL of a spore suspension of P. digitatum. Decay progression after storage was monitored by measuring the diameter of the lesion in cm at the demarcated site of inoculation or by subjectively rating percent decayed fruit surface area. Grapefruit not inoculated with P. digitatum had no visible symptoms of green mold. Grapefruit stored under controlled atmosphere had less fruit surface covered with mycelium (5% to 64%) than grapefruit stored in air. Inoculated grapefruit stored in 0.05 kPa oxygen for up to 14 d at 14 or 18 °C had no visible symptoms of green mold upon removal from cold storage, but developed a characteristic green mold lesion after 5 additional days of storage in air at ambient temperature. Results suggest that refrigerated controlled-atmosphere storage combined with wax and a fungicide can enhance control of green mold during shipping.

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Export and domestic marketing of grapefruit (Citrus paradisi Macf.) can be limited by phytosanitary barriers against fruit fly species and growth of decay organisms, especially green mold (Penicillium digitatum Sacc.), during the marketing process. The objective of this research was to identify whether the dose of high-temperature forced air that providing quarantine security against Mexican fruit fly could also beneficially control the growth of green mold during subsequent storage. `Rio Red' grapefruit were harvested four times in 1995 and nine times in 1996 and challenge-inoculated with 10 L of a 1 × 106 spores/ml spore solution (10,000 spores) of green mold before or after exposure to 46°C forced air for 300 min. Control fruit were challenge-inoculated but not exposed to the heat treatment. The growth of green mold was quantified by measuring lesion diameter after 3 days of storage at 23°C, 80% RH. Grapefruit inoculated prior to the heat treatment developed significantly smaller lesions than fruit inoculated after the heat treatment or fruit not exposed to a heat treatment. The average lesion diameter of fruit inoculated prior to the heat treatment was 2.5 and 0.9 cm, respectively, in 1995 and 1996. The average lesion diameter of fruit inoculated after the heat treatment was similar to non heat-treated, control fruit. Lesion diameter of control and post heat-challenged fruit were 6.4 and 6.1 cm in 1995 and 5.7 and 5.3 cm in 1996. Results suggest reduction in decay be attributed to alteration in the pathogenicity of green mold after exposure to the heat treatment rather than an altered resistance of the fruit to the pathogen.

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`Manila' mangoes (Mangifera indica) were immersed in 46C water for 65 or 75 minutes, or exposed to 45, 50 or 52C moist, forced-air (MFA) for 240, 100, and 98 minutes, respectively Mangoes exposed to 50 or 52C MFA had a significantly higher incidence of internal cavitation than mangoes exposed to 45C MFA; mangoes immersed in 46C water for 65 or 75 minutes, or control fruit. Shrink wrapped and nonshrink wrapped mangoes were exposed to 45C MFA for 240 minutes or 52C MFA for 98 minutes to evaluate whether the concentration of oxygen and carbon dioxide inside the fruit influenced cavitation development. Shrink wrapping per se had no significant effect on cavitation development Mangoes heated in 45C MFA for 240 minutes, 52C MFA for 98 minutes, or 46C water for 65 minutes were hydrocooled in 23C water or air cooled at 23C to evaluate whether heat dose influenced cavitation development. Hydrocooling had no significant effect per se on cavitation development though it significantly reduced the heat dose. The above results suggest that tolerance of 'Manila' mango to disinfestation heat treatments is more influenced by a maximum flesh temperature threshold than the heating method, heat dose, or fruit internal atmosphere.

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Navel orange [Citrus sinensis (L.) Osbeck] was exposed to moist, forced air at 46 °C for up to 4.5 hours or 50 °C for 2 hours, or immersed for 3 hours in water at 46 °C. Quality attributes of heated and nonheated fruit were compared after 4 weeks of storage at 7 °C and 1 week at 23 °C. The flavor of oranges immersed in water was rated significantly inferior to fruit heated in air and fruit that were not heated. Oranges immersed in hot water also developed a higher incidence of decay during storage than oranges heated in air or nonheated control fruit. The flavor of oranges exposed to moist, forced air at 46 °C for up to 4.5 hours was rated by preference panelists as similar to nonheated controls, even though heated fruit had a significantly lower amount of titratable acidity and a higher ratio of sugar to acid. Fruit exposed to high-temperature forced air developed less decay during subsequent storage than nonheated control fruit. Texas `N33' navel oranges tolerated exposure to forced air at 46 °C for up to 4.5 hours without deleterious effects on fruit market quality.

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`Dancy' tangerines (Citrus reticulata Blanco) were harvested after color break and exposed to high-temperature forced air (HTFA) at 45C for 3.5 or 4 h to kill Mexican fruit fly [Anastrepha ludens (Loew)] larvae. Heat-treated and control fruit were stored subsequently for 2 weeks at 4C. Tangerines harvested after color break (naturally degreened) tolerated exposure to HTFA in a similar fashion as tangerines harvested before color break and degreened by postharvest exposure to ethylene. Titratable acidity (TA) was significantly lower after heat treatments. Flavor, soluble solids concentration, external appearance, incidence of decay, percent juice yield, percent weight change, and flavedo color of heat-treated fruit were not different from nonheat-treated, control fruit. Exposure to HTFA is a viable alternative to methyl bromide for disinfestation of `Dancy' tangerine.

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Genetic and environmental interactions for bean cooking time, water absorption, and protein content were estimated with 10 dry bean (Phaseolus vulgaris L.) cultivars grown at three locations in Rwanda, Africa, during five consecutive harvests. The genotypic variance component was larger than genotype × environment variance components for the cooking time index and percent water absorption. No significant genotypic effect was observed for seed protein content. The phenotypic correlation (-0.37) between the cooking time index and percent water absorption was not strong enough to justify the use of water absorption as an indirect selection method for cooking time. The most efficient allocation of resources to evaluate the cooking time of common bean cultivars with a 25-pin bar-drop cooker was four field replications over two harvests at two locations. Water absorption was evaluated most efficiently with four field replications over two harvests at a single location.

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`Valencia' oranges [Citrus sinensis (L.) Osbeck] were exposed to moist, forced air (MFA) at 46, 47, or 50C for 1, 2, 3, or 4 hours to identify the maximum temperature and duration of exposure for which there was no detectable reduction in fruit quality. The flavor of oranges exposed to MFA at 47 or 50C was rated significantly inferior to that of oranges exposed to 46C. The degree minutes that accumulated in the center of the fruit between 2 and 4 hours and the maximum fruit center temperature during the heat treatment were associated with inferior fruit flavor. Oranges exposed to MFA at 46C for up to 4 hours could not be distinguished from the nonheated fruit. MFA at 46C is a promising quarantine treatment for `Valencia' oranges.

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Physicochemical and sensory attributes of fully mature honey dew melon (Cucumis melo L. var. inodorus Naud.) fruits were evaluated 10 days after storage for eight commercial cultivars grown in two locations. Cultivars varied in degree of pref- erence expressed by panelists' ratings for overall fruit preference, flavor, and shape and for physicochemical measurements of soluble solids concentration (SSC), flesh firmness, and fruit weight. The sensory attribute that correlated most strongly with overall fruit preference was fruit flavor (r = 0.97). The whiteness of epidermal tissue (rind L value) and SSC correlated more highly with overall fruit preference (r = 0.54 and r = 0.52, respectively) than other physicochemical attributes, such as fruit firm- ness (r = -0.24) and fruit weight (r = -0.12). Epidermal L value correlated more strongly with panelists' ratings for fruit shape (r = 0.69) than with fruit flavor (r = 0.35), but SSC correlated more strongly with fruit flavor (r = 0.61) than with fruit shape (r = 0.30). Superior honey dew melon quality at harvest was associated with high SSC, white epidermal tissue, and round fruit shape.

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