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  • Author or Editor: Jinhe Bai x
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Superficial scald of `d'Anjou' pears usually develops after storage of 2 months or longer. MCP application controls scald; however, fruit lose their ripening capacity if the dosage is >30 ppb, but lower dosages cannot control scald substantially. In this study, fruit treated with or without 25 ppb MCP within 2 d after harvest were stored at –1 °C for up to 5 months. After 1, 7, 30, or 70 d of storage, part of the fruit were pulled from storage and treated with 1000 ppm ethoxyquin line spray and immediately returned to the storage, left untreated as non-ethoxyquin control. Incidence of superficial scald along with the concentrations of α-farnesene and conjugated trienes (CTs), and the ripening capacity of fruit were investigated after 3, 4, and 5 months storage. All fruit ripened properly within 7 d of conditioning at room temperature regardless of treatments. Both of MCP or ethoxyquin-1d (ethoxyquin was applied after 1 day storage at –1 °C) alone controlled scald for only 3 months; however, MCP + ethoxyquin controlled scald for 5 months, whenever ethoxyquin was applied between 1 to 70 d after storage. Thus, with 25 ppb MCP treatment, which is simple, with rapid and mass treatment available, a delayed application (up to 70 d) of ethoxyquin becomes effective to control scald. Furthermore, the later application of ethoxyquin within 70 d after MCP treatment, the less incidence of scald was observed. Scald is caused by the CTs oxidation products of α-farnesene. MCP and ethoxyquin inhibited accumulation of CTs of fruit peel by different mechanisms. MCP inhibited the production by influencing ethylene production through control of α-farnesene synthesis; however, ethoxyquin worked by inhibiting the oxidation of α-farnesene to the CTs.

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A study was made to determine if induction of modified atmosphere at the time of packaging would be of a benefit to the quality of fresh-cut honeydew cubes because the desired gas levels are not attained immediately or at all during the short holding period in modified-atmosphere packages. Fresh-cut honeydew cubes (2-cm cube) were placed in a plastic container underlaid with a water absorbent packet and the container was sealed with a film. The film is coextruded polystyrene and polyethylene (Cryovac), which had oxygen transmission rates of 1448 and 1903ml/m2 per day per atm at 5 °C and 10 °C, respectively. The sealed packages were given one of the following three treatments: 1) the packages were allowed to form their own natural modified atmosphere (nMAP), 2) the internal atmosphere of the packages was flushed with a gas mixture of 5% O2 + 5% CO2 (iMAP), 3) the film was perforated with a needle to have ten 1.5-mm holes (PFP). The packages were stored at 5 °C, 2 days at 5 °C, and transferred to 10 °C or at 10 °C for 2, 4, 7, 9, or 11 days. Quality attributes and microbial population were analyzed after each holding period. The average gas mixture equilibrated to 7% O2 and 9.5% CO2 in nMAP, was unchanged from the induced atmosphere in iMAP, and was close to the ambient condition (air) in PFP. Honeydew cubes were marketable on days 11, 4, and 4 when held in nMAP; on days 11, 4, and 7 when held in iMAP; and unsalable on days 9, 4, and 7 when held in PFP at 5 °C, 10 °C or transferred to 10 °C, respectively. Development of water-soaked lesions and sour odor were the main factor affecting marketability of the cubes. The decreasing pH, chroma and `L' values and increasing hue angle, mesophilic aerobic microrganism, and yeast population was retarded in both of nMAP and iMAP.

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Responses of adult pear to the integrated N fertigation and drip irrigation system have not been documented in Oregon. A field trial was conducted on adult pear at the Mid-Columbia Agricultural Research and Extension Center, Hood River, Ore., in 2005. Two N and water management systems (integrated N fertigation and drip irrigation system; and broadcast application of dry N fertilizer to the soil surface and microsprinkler irrigation system) were compared on pear cultivars of Bartlett and Golden Russet Bosc, and rootstocks of OH×F97 and OH×F87. The responses of these cultivars and rootstocks to the integrated N fertigation and drip irrigation system were similar. The integrated N fertigation and drip irrigation system consumed 1450 m3·ha-1 of irrigation water during the entire season from May to September, reducing irrigation water use by 73% compared with 5297 m3·ha-1 under the current system—broadcast application of dry N fertilizer to the soil surface and microsprinkler irrigation system averaged over the four cultivar and rootstock combinations. The fruit yield was statistically similar for the integrated N fertigation and drip irrigation system and the broadcast application of dry N fertilizer and microsprinkler irrigation system on the average of the four cultivars and rootstocks. Differences in fruit size and color were negligible between the two N and irrigation management systems. Overall, our results suggest that adopting the integrated N fertigation and drip irrigation system does not cause significant reduction in yield or quality of adult pear; the integrated N fertigation and drip irrigation system could be a profitable and environmentally sound management alternative for pear production.

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The effects of in-row groundcover and drip irrigation on mineral nutrition and productivity of sweet cherry are largely unknown in the Pacific Northwest. A field experiment was initialized on the Mel Omeg orchard at The Dalles, Ore., in 2005. This orchard had been managed under microsprinkler irrigation and in-row herbicide application since its establishment in 1998. Two irrigation systems (drip irrigation, microsprinkler irrigation) and four in-row ground management systems (straw mulch, white fabric cover, black fabric cover, and no cover with herbicide applications) were evaluated in a split-plot design with four replicates. Drip irrigation reduced irrigation water consumption by 74% relative to microsprinkler during the entire season from May to September. Compared with no cover, black fabric lowered water use by 8%, and straw mulch and white fabric had a 1% to 3% reduction in water use. Fruit yield was similar for drip irrigation and microsprinkler. There was a trend of yield increase with groundcovers relative to no cover. Fruit firmness, size, and sugar content did not differ regardless of irrigation or groundcover systems. Drip irrigation increased marketable fruits by 5% (absolute value) via reducing fruit surface pitting compared with microsprinkler. Differences in soil-available N, P, K, Ca, Mg, S, B, Zn, Mn, Cu, pH, and organic matter were negligible between the two irrigation systems and among the four groundcover treatments. However, drip irrigation resulted in slightly lower concentrations of N, P, K, Ca, B, and Mn in leaf than microsprinkler. Overall, our results suggest that in-row straw mulch and fabric covers and drip irrigation could be feasible management alternatives for sweet cherry production in the Pacific Northwest.

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Pear texture is similar to that of apple—firm and crispy—and is one of the potential alternatives to apple. However, at a crispy stage the taste is flat. Improving the taste of pears is considered the key to the success of pear salad. This study evaluated the effect of harvest maturity on the quality of pear salad. Fruit were harvested at commercial maturity or 1 month delayed. After 2 and 5 months (1 and 4 months for delayed harvested fruit) of storage at –1 °C, fruit were sliced (eight to 10 wedges per fruit), treated with an anti-browning dip, packaged in zip-lock bags (10 pieces per bag), and stored at 1 °C for up to 21 days. Delayed harvested fruit were larger in size (≈12.5% increase in weight), had lower flesh firmness (≈5 N decrease), lower titratable acidity content (≈20% decrease), and a lower phenolic content (≈45% decrease in pulp). There was no significant difference in soluble solids content. After 2 months of storage, ethylene production and respiration rate were initially lower in delayed harvested fruit in either the intact fruit or cut slices, but tended to similar after 7 days in storage. Sensory evaluation results show that about 80% of the panel preferred delayed-harvested fruit over commercial harvest, especially in terms of visual quality (71% to 92%), sweetness (75% to 93%), taste (69% to 92%), texture of skin (61% to 92%), texture of flesh (53% to 92%), and overall quality (73% to 92%) during 21 days of storage at 1 °C. After 5 months of storage, cutting surface was dry-looking in delayed harvested fruit. However, sensory evaluation showed panels still preferred the delayed-harvested fruit. The results indicate that salad quality of pears can be improved by delaying harvest.

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This study evaluated the effects of huanglongbing (HLB) symptom severity on fruit detachment force (FDF) and fruit mechanical properties in sweet oranges (Citrus sinensis) as indicators of potential HLB-influenced preharvest fruit drop and postharvest damage and breakdown. FDF for fruit from HLB-asymptomatic trees (AS) was substantially greater than for fruits from HLB-symptomatic trees or branches. Fruit hardness, resilience, springiness, and cohesiveness values, measured by texture profile analysis (TPA), represent various aspects of fruit firmness and recovery capacity once compressed, and were lower in HLB-symptomatic fruits in comparison with AS fruits. On the other hand, puncture force, toughness, and deformation values, measured by a puncture test and representing peel toughness, were higher in HLB-symptomatic fruits than in the AS fruits. The results indicate that fruits from severely HLB-symptomatic sweet orange trees are more likely to have problems with preharvest fruit drop, and postharvest pressure damage and breakdown, but may have less puncture damage in harvesting, transportation, packing, and juice processing.

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`Bartlett' pears were treated with 300 nL·L-1 1-MCP at 20°C for 24 h shortly after harvest, and were stored at -1 °C in either regular atmosphere (RA) or controlled atmosphere (CA: 1.5 kPa O2 / 0.5 kPa CO2). After 2 and 4 months of RA storage, or 4 months of CA storage, fruit were pre-conditioned at 10 °C, 15 °C or 20 °C for 5, 10, or 20 days, respectively. Pre-conditioned fruit were then held at 20 °C for 14 days to simulate marketing conditions. Flesh firmness (FF) and extractable juice (EJ) were monitored during the marketing period. The optimal stage of ripeness for `Bartlett' pears was defined to be when FF decreases to 27 N and EJ decreases to 55 mL/100 g. The proper pre-conditioning combinations of temperature and duration were 15 °C or 20 °C for 10 d or 10 °C for 20 d if the fruit had been stored in RA for 2 months, 10 °C or 15 °C for 5 d if the fruit had been in RA for 4 months, and 20 °C for 10 d or 10°C for 20 d if the fruit had been in CA for 4 months, for which combinations the fruit ripened within a week and maintained quality for 14 days at 20 °C. The treatment combinations of lower temperature and/or shorter duration times in pre-conditioning delayed the ripening response of the fruit, and combinations of higher temperature and/or longer duration times in pre-conditioning resulted in a shorter marketing life because of senescence breakdown, in comparison the optimal combinations mentioned above. These results indicate that pre-conditioning regimes for 1-MCP treated `Bartlett' pears are storage atmosphere and time dependent. Generally, CA stored fruit needed more preconditioning (in terms of higher temperature and/or longer duration) than did RA stored fruit.

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The development of tissue translucency of fresh-cut honeydew cubes adversely affects product quality and primarily occurs in cubes that have been sanitized by dipping in chlorine water (sodium hypochlorite solution) following processing. Chlorine water dips containing calcium propionate as an antimicrobial salt were tested to decrease tissue translucency and extend the marketable shelf life of honeydew (2-cm cubes) sealed in a rigid container with a film overlap and stored at 10 °C for 7 days. Honeydew cubes not dipped following processing had higher respiration rates and microbial populations than cubes that had been dipped, and lost their marketability on day 5 due to off-odor development. Dipping in chlorine water decreased the initial population and growth of microorganisms on the cubes, compared to dipping in water or not dipping. However, translucency developed in cubes dipped in water, with or without chlorine, and became unsalable by day 5. Chlorine water dips containing calcium propionate were devised that maintained excellent antimicrobial characteristics and prevented translucency in honeydew cubes kept 7 days at 10 °C. Quality analyses revealed that calcium propionate treatments decreased respiration and ethylene production rates, maintained tissue firmness, the lightness and brightness of cube surfaces, melon aroma and overall visual quality through 7 days of storage. The calcium propionate dips did not impart or induce any detectable off-flavors or off-odors to the cubes.

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Zein, starch, polyvinyl acetate (PVA), carnauba, and carnauba-polysaccharide (CPS) coatings were compared with a commercial shellac coating using controlled atmosphere stored 'Delicious' apples (Malus ×domestica Borkh). Coated apples were stored in air at 2 °C for 2 weeks and then removed to 21 °C for an additional two weeks to simulate marketing conditions. Gloss, internal O2 and CO2 partial pressures, weight loss, flesh firmness, and contents of sugars, acids and volatiles were measured on 0, 2, and 4 weeks after coating treatment. Starch- and carnauba-coated apples had high initial gloss, similar to that found for shellac-coated fruit. Gloss of all coated fruit decreased similarly during the 4-week evaluation period, although all of the coated fruit were glossier than uncoated controls. For uncoated apples, the differences of O2 and CO2 partial pressure between internal and ambient atmosphere were ≈1 kPa at 2 °C, and these increased by a further 2 kPa after transfer to 21 °C. Fruit coated with shellac and starch had >10 kPa CO2, and <10 kPa O2 at 21 °C. Zein-, PVA- and carnauba-coated apples showed a less modified internal atmosphere (6-7 kPa CO2, 11-15 kPa O2). Internal partial pressures of O2 and CO2 were inversely related for most coatings, except for the CPS coating, for which partial pressures of both CO2 and O2 were low. Carnauba-, PVA-, and shellac-coated fruit lost less weight than uncoated fruit. Starch-, shellac-, and CPS-coated fruit were firmer than those from other coating treatments, and all coated fruit were firmer than uncoated control. Titratable acidity was higher in the fruit coated with CPS, starch, and shellac than in uncoated control. Ethyl alcohol and ethyl esters accumulated in starch-, shellac-, and CPS-coated fruit kept at 2 °C, but, levels of these volatiles decreased after transfer of fruit to 21 °C. Carnauba, PVA and zein coatings compared favorably to shellac for gloss and other quality characteristics.

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Warm field temperatures can often result in poor peel color of some citrus varieties, especially early in the harvest season. Under these conditions, Florida oranges, temples, tangelos, and K-Early citrus fruit are allowed to be treated with Citrus Red No.2 dye (CR2) to help produce a more acceptable peel color. Unfortunately, CR2, the commercial colorant used in Florida, has been listed as a group 2B carcinogen by the European Union (EU) and the International Agency for Research on Cancer (IARC). Although not likely dangerous at levels used on citrus, and on a part of the fruit that is not ingested, there is a negative health perception, and thus, a need for natural or food grade alternative colorants to replace CR2 for use on citrus. This research demonstrated that three out of five oil-soluble natural red/orange colorants resulted in peel colors somewhat similar to the industry standard CR2. These three (annatto extract, paprika extract, and paprika oleoresin) were selected for further in vivo studies. The stability of the natural colorants along with CR2 was evaluated by applying them on test papers and then on fresh ‘Hamlin’ oranges. All natural colorants were found to be easily oxidized and faded when applied on test papers. However, coating the colored surfaces with carnauba wax apparently inhibited oxidation and the subsequent discoloration of the surface. When applying the natural colorants to ‘Hamlin’ oranges before waxing, the treatments retained the improved color after storage in the dark at 5 °C, simulating cold storage. However, only annatto extract maintained a stable color when subsequently stored in a simulated market condition, at 23 °C exposed to 300 lx of standard fluorescent white light.

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