Diphenylamine metabolism in 'braeburn' apples stored under conditions conducive to the development of internal browning

Diphenylamine metabolism and ethylene action were evaluated as factors influencing the development of 'Braeburn' apple internal browning and cavitation during cold storage. Apples treated with the antioxidant diphenylamine (DPA) and/or the ethylene action inhibitor 1-methylcyclopropene (1-MCP) were held at 1 degrees C for up to 6 months in air or a controlled atmosphere (CA) containing 1 kPa of O2 and 3 kPa of CO2. Cortex tissues from fruit without disorders as well as from symptomatic and asymptomatic areas of fruit with disorders were analyzed for DPA and DPA derivative content. Internal browning and cavities developed in control and 1-MCP-treated fruit stored in CA, whereas air-stored and CA fruit treated with DPA or with DPA and 1-MCP prior to storage did not develop disorders. Depending on the storage regimen and duration, less DPA was detected in 1-MCP-treated fruit. The 4-hydroxydiphenylamine (4OHDPA) content of control fruit decreased during air storage duration but increased between 2 and 4 months in CA storage. 4OHDPA content in 1-MCP-treated fruit increased with storage duration in CA but not air. N-Nitrosodiphenylamine (NODPA) was detected after 2 months in control fruit stored in air or CA and in 1-MCP-treated fruit stored in CA, and NODPA content in control fruit was higher compared to that in 1-MCP-treated fruit. Accumulation of 4-methoxydiphenylamine (4MeODPA) in control fruit stored in air increased with storage duration, but 4MeODPA content did not change in 1-MCP-treated fruit stored in air or CA. 2-Nitrodiphenylamine content was reduced by prestorage treatment with 1-MCP, but storage environment and duration had no effect on its accumulation. The results indicate that CA storage increases the risk of disorder development in 'Braeburn' apples, that DPA can prevent disorder development, and that the content of DPA and DPA derivatives is influenced by storage environment and ethylene action. A clear relationship between DPA derivative formation and storage conditions that promote internal browning was not apparent.     

Interactive responses of gala apple fruit volatile production to controlled atmosphere storage and chemical inhibition of ethylene action

Gala apples exposed to the ethylene action inhibitor 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C in air or a controlled atmosphere (CA) maintained at 1 kPa O2 and 2 kPa CO2. Volatile compounds were measured after 4, 12, 20, and 28 weeks plus 1 or 7 days at 20 degrees C. Treatment with 1-MCP and then storage in air or CA or storage in CA without 1-MCP treatment reduced volatile production as compared to apples not treated with 1-MCP stored in air. The reduced production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene was observed. Ester production by fruit stored in CA decreased throughout the storage period regardless of previous 1-MCP treatment. The production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene by 1-MCP-treated fruit stored in air plus 7 days at 20 degrees C increased after 20 or 28 weeks of storage. Continuous exposure to 417 micromol m(-3) ethylene for 7 days at 20 degrees C after 12 or 28 weeks of storage stimulated production of many volatile compounds, primarily esters and alcohols, by fruit stored in CA or 1-MCP-treated apples stored in air. However, exposure to ethylene had no effect on the production of aldehydes or acetic acid.     

1-Methylcyclopropene interactions with diphenylamine on diphenylamine degradation, alpha-farnesene and conjugated trienol concentrations, and polyphenol oxidase and peroxidase activities in apple fruit

1-Methylcyclopropene (1-MCP) is a new technology that is applied commercially to inhibit ethylene action in apple fruit, but its interactions with existing technologies such as diphenylamine (DPA) for control of superficial scald development in fruit during and after storage is unknown. To investigate possible interactions between 1-MCP and DPA, Delicious apples were untreated or treated with 2 g L(-1) DPA, and then with or without 1 microL L(-1) 1-MCP. Ethylene production and respiration rates of fruit were measured immediately following treatment, and fruit was stored at 0.5 degrees C for 12 weeks. Internal ethylene concentrations (IEC), alpha-farnesene and conjugated trienol (CTol) concentrations, activities of peroxidase and polyphenol oxidase (PPO), and DPA levels in the skin of the fruit were measured at intervals during storage. 1-MCP reduced the rate of DPA loss from peel tissue so that by 12 weeks of storage concentrations of the chemical were 25% higher than in untreated fruit. 1-MCP, with and without DPA, markedly inhibited ethylene production and respiration rates, maintained low IEC and alpha-farnesene and CTol concentrations, while DPA had little effect on these factors except inhibition of CTol accumulation. Treatment effects on peroxidase and PPO activities were inconsistent.     

Production of volatile compounds by Fuji apples following exposure to high CO2 or low O2

The emission of volatile compounds by Fuji apples following short- or long-term exposure to high CO(2) was studied. The production of ethanol, methyl and ethyl esters, octanal, nonanal, and decanal was enhanced while the production of C(3)-C(6) alcohols, propyl, butyl, pentyl, and hexyl esters and butanal decreased in fruit exposed to 10 kPa O(2) + 20 kPa CO(2) at 20 degrees C for up to 12 days. The impact of high CO(2) exposure on volatile production was dependent on fruit maturity at harvest. Apples stored for 8 months in an ultralow O(2)-controlled atmosphere (CA) (0.5 kPa O(2) + 0.05 kPa CO(2)) or high CO(2) CA (1.5 kPa O(2) + 3 kPa CO(2)) at 0.5 degrees C had reduced production of most volatiles, especially butyl and hexyl esters, as compared to fruit stored in air. Two exceptions were ethanol and ethyl acetate for which the production was enhanced by both CA regimes. Treatment with the antioxidant diphenylamine prior to storage prevented most of the high CO(2)-induced and ultralow O(2)-induced changes in volatile production. The results of this study do not indicate that changes in volatile production following the exposure of Fuji apples to high CO(2) are causally related to the development of CO(2) injury.     

Ester variability in apple varieties as determined by solid-phase microextraction and gas chromatography-mass spectrometry

Solid-phase microextraction (SPME) with a polydimethylsiloxane fiber coupled with gas chromatography-mass spectrometry (GC-MS) was applied to the study of variability in volatiles released by 13 apple varieties. The relative amounts of 40 esters and alpha-farnesene were determined. Principal component analyses of these results clustered the apples into three groups according to skin color: red, green, and red-green. Total ester contents were highest with the red cluster apples, and the green cluster apples had the highest alpha-farnesene levels. This technology was also applied to the monitoring of changes in volatiles for apples removed from controlled-atmosphere storage with subsequent storage at 4 degrees C and room temperature. Total ester contents increased 25-fold, with the greater increases coming at room temperature, whereas alpha-farnesene levels increased only 5-fold. For apples stored at room temperature, after 11 days, the amount of increase was inversely proportional to the size of the ester: levels of smallest esters (molecular weight 116) increased 12.5-fold, and the largest esters (molecular weight 228) increased approximately 1.3-fold.     

Influence of the Fertilisation System on the Mechanical Damage of Apples

Fuji and Gala apples obtained with different fertilisation systems (soil surface application and fertigation) were submitted to drop tests to analyse the possible difference in susceptibility to damage. The tests were carried out by simulating two impacts of different severity that occur in a packing line. For the Fuji apples, a test was also carried out to assess the effect of a long storage period. For the test with the highest impact severity, the apple acceleration was recorded to describe the mechanical behaviour of the fruit and to correlate it with the damage. Logistic and multiple linear regressions were performed to assess the correlations between probability, extent and nature of damage, fertilisation systems and main characteristics of the fruits. The results show that the resistance to damage of Fuji and Gala apples is influenced by the fertilisation system both in probability and in characteristics of damage. Duration of storage can invert the susceptibility to damage, with the apples having a higher resistance to damage after a longer period of storage. Conventional fertilisation induced a high susceptibility to darkening and fracturing of the apples tissue. The parameters to describe the mechanical behaviour of apples were often correlated with the fertilisation system. However, their influence on extent and nature of damage was not significant or substantial while they can have a high effect on probability of damage. Fuji apples were found to be more susceptible to damage than Gala apples.     

Fruit antioxidant activity, ascorbic acid, total phenol, quercetin, and carotene of Irwin mango fruits stored at low temperature after high electric field pretreatment

Greenhouse-grown tree ripe (TR) and mature green (MG) mangoes (cv. Irwin) were exposed to high electric field treatment before 20 and 30 days of storage at 5 degrees C. MG fruits were allowed to ripen at room temperature after low-temperature storage. Fruit physical quality attributes, ascorbic acid, carotene, quercetin, total phenols, and antioxidant capacity were estimated before and after the storage period. Antioxidant capacity of fruit juice was estimated using the ferric reducing antioxidant power (FRAP) assay. Fruit firmness decreased significantly during storage. Titratable acidity decreased 20 days after storage. Total soluble solids did not change during storage. Antioxidant capacity of fruits remained unchanged up to 20 days of storage period and decreased thereafter. Total phenol and carotenes increased during storage. Antioxidant capacity of fruits was significantly correlated only to ascorbic acids. Peel color and carotenes were higher in TR fruits, whereas titratable acidity and firmness were higher in MG fruits. There was no significant difference in other parameters between the stages of picking. Electric field pretreatment affected the respiration and antioxidant capacity of TR fruits and did not have any significant affect on other parameters. TR mangoes of cv. Irwin are more suitable for low-temperature storage and can be successfully stored for up to 20 days at 5 degrees C without any significant losses in functional properties and quality attributes.     

Postharvest variation in apple (Malus x domestica Borkh.) Flavonoids following harvest, storage, and 1-MCP treatment

The impact of 1-methylcyclopropene (1-MCP) on the synthesis and retention of flavonoid compounds during storage and ripening of red Delicious (Malus x domestica Borkh.) apples was investigated. Numerous anthocyanins, flavonols, flavan-3-ols, and a hydroxycinnamic acid from three different fruit harvest maturities were monitored after a 120 day storage and 1 week shelf life period using high-performance liquid chromatography/diode array detector analysis. The total flavonoid concentration was 5% greater in fruit treated with 1-MCP, whereas chlorogenic acid levels were 24% lower. All compounds analyzed increased in concentration during fruit harvest; however, the anthocyanins generally declined after storage, while chlorogenic acid levels increased. 1-MCP treatment resulted in the retention of anthocyanins in the latter stages of storage but did not affect the flavonols and flavan-3-ols. Chlorogenic acid biosynthesis from early and optimal fruit harvest maturities was greatly inhibited by 1-MCP during storage and the 1 week shelf life period. However, 1-MCP did not affect chlorogenic acid concentrations in late-harvested fruit. Results suggest that 1-MCP may inhibit the activity of phenylalanine ammonia-lyase and subsequent biosynthesis of flavonoid compounds. However, because very little postharvest biosynthesis of flavonoids occurs in apples, 1-MCP treatment may be useful for maintaining some of the intrinsic flavonoid levels of red Delicious apples, if applied at the proper harvest maturity.     

Monitoring residues of carbendazim (applied as benomyl) and thiabendazole in Wellspur apples

Residues of benomyl (determined as carbendazim, widely accepted as MBC) and of thiabendazole in Wellspur apples were monitored after the apples were treated postharvest by immersion in a bath with each of the fungicides separately and stored under refrigeration. Whole fruit and pulp analyses were conducted over the period beginning 1 day after treatment and lasting up to 200 days afterwards. Under the conditions described, both benomyl (expressed as parts per million of carbendazim) and thiabendazole were found in the fruits in the following average amounts: 0.44 +/- 0.03 and 0.11 +/- 0.03 ppm benomyl (as carbendazim) in whole fruit and in pulp, respectively; 0.98 +/- 0.10 and 0.39 +/- 0.10 ppm thiabendazole in whole fruit and in pulp, respectively.     

不同纳米改性LDPE膜对枇杷保鲜效果的影响

为探讨不同纳米改性低密度聚乙烯(LDPE) 膜对枇杷果实采后保鲜效果的影响,本试验分别研究了普通LDPE膜与纳米改性LDPE膜在室温条件下(20℃)对采后枇杷品质和生理特性的影响。结果表明,与普通LDPE膜相比,纳米Ag、纳米TiO₂和纳米SiO₂改性LDPE膜可显著抑制采后贮藏过程中枇杷果实的腐烂指数、褐变指数、失重率和硬度的上升及出汁率的下降;延缓其可溶性固形物、可滴定酸和Vc含量的降低;保持其贮藏后期较高的总酚、总黄酮含量和抗氧化能力;提高了对枇杷果实DPPH自由基和羟自由基的清除能力,有效延长了枇杷保质期,表明不同纳米改性LDPE膜可显著提高枇杷果实的保鲜效果。其中,纳米SiO₂改性LDPE膜包装处理能够更好地抑制枇杷果实品质的下降,保持更好的抗氧化能力,其作为枇杷果实采后保鲜包装具有潜在的市场前景。本研究结果为纳米改性LDPE膜在果蔬保鲜中的应用提供了理论参考。     

采后红光处理对芥蓝芽菜生物活性物质的影响

为研究采后红光处理对不同贮藏温度下芥蓝芽菜中生物活性物质含量的影响,本试验设置了米后红光、白光和黑暗处理芥蓝芽菜试验,分析了不同贮藏时间其芥子油苷、维生素C、花青素和总多酚的含量及抗氧化能力的变化.结果表明,25℃贮藏时,芥蓝芽菜中芥子油苷含量在采后贮藏过程中逐渐降低,采后红光处理可显著延缓芥子油苷含量的下降.在贮藏1...     

Carbohydrate and acid contents of Gala apples and Bartlett pears from regular and controlled atmosphere storage.

Gala apples and Bartlett pears were harvested over two crop seasons at different maturities and growing sources then stored in refrigerated storage alone and in controlled atmosphere storage (1% O(2) plus 1% CO(2) or 2% O(2) plus 3% CO(2)). Before and after storage of 45 or 90 days, the juice from the fruit was examined for carbohydrate and acid compositions and contents. For Gala apples, the type and length of storage had no significant effect on juice carbohydrate and acid contents and compositions, whereas the time of harvest greatly influenced both parameters. Storage atmosphere did not affect the carbohydrate and acid contents and compositions of Bartlett pear juice; however, the source of the fruit and subsequent amount of ripening did appear to significantly cause changes in the same parameters. The carbohydrate and acid compositions and contents of Gala apple juice were within the compositional range for worldwide apple juice. Bartlett pear juice contained significantly greater concentrations of citric acid than shown in previously published studies.     

干雾湿度控制系统的组建及果蔬贮藏保鲜应用试验

为了实现果蔬贮藏所需环境恒定高湿度的精准自动控制,该文作者以净化水和压缩空气为原料,采用特殊的雾化器、湿度传感器及微电脑控制终端等组件,设计组建了干雾湿度控制系统,可喷发2~10μm的水雾离子均匀扩散到环境空气中,提供90%~98%的精确高湿度。加湿性能及加湿效果测试证明该系统可有效实现果蔬贮藏库内恒定湿度的精准自动控制。果蔬贮藏保鲜应用试验表明,干雾湿度控制系统可有效防止未包装果蔬在贮藏过程中的失水失质量,延长其贮藏保鲜期1倍以上。作为采后果蔬贮运保鲜加湿的技术,干雾湿度控制系统具有低温下高湿度不会凝露滴水,库内呈"干爽"状态,节能环保,节约劳动力等优点,可替代采用聚乙烯薄或袋的保湿保鲜方法。     

Activity and concentration of polyphenolic antioxidants in apple: effect of cultivar, harvest year, and storage conditions

Consumers' increasing interest in the relationship between diet and health is a sign for food producers to pay more attention to potential health-protecting compounds in new product development and food processing. From a production chain perspective the choice of the raw material that is used is important for the health-protecting potential of the end product. Four apple cultivars (Jonagold, Golden Delicious, Cox's Orange, and Elstar), which can be used as fresh apples or in processed apple products, were compared with regard to flavonol, catechins, phloridzin, and chlorogenic acid concentrations and antioxidant activity. Jonagold apples possessed the highest flavonoid concentration and the highest antioxidant activity. To study seasonal differences, apples from three different harvest years were analyzed, but in three cultivars no effect on flavonoid concentration and antioxidant activity was observed. Long-term storage, both at refrigerator temperature and under controlled atmosphere conditions, was found not to influence flavonoid concentration or antioxidant activity.     

短波紫外线处理对采后草莓果实腐烂和抗氧化能力的影响

以"凤冠"草莓为材料,研究了0、1.5、3.0和4.5kJ.m-2UV-C处理对草莓果实在10℃,12d贮藏期间腐烂和果实抗氧化能力的影响。结果表明,3kJ.m-2UV-C处理能显著抑制草莓果实采后腐烂的发生和MDA的积累,延缓果实失重、硬度和可溶性固形物含量的降低,促进果实CIRG值的提高,增强果实采后着色能力,从而保持果实的感官和食用品质。同时,3kJ.m-2UV-C处理能促进贮藏期间果实总花色苷、总酚含量和DPPH自由基清除能力的增加,减少草莓果实中抗氧化组分含量的下降,维持果实较高的营养品质。说明适宜剂量的UV-C处理(3kJ.m-2)在草莓果实采后后贮运保鲜和抗氧化能力调控中具有潜在的应用前景。     

Volatile emission after controlled atmosphere storage of Mondial Gala apples (Malus domestica): relationship to some involved enzyme activities

Mondial Gala apples were harvested at commercial maturity and stored at 1 degrees C under either air or controlled atmosphere (CA) conditions (2 kPa O2/2 kPa CO2 and 1 kPa O2/1 kPa CO2), where they remained for 3 or 6 months. Data on emission of selected volatile esters, alcohol precursors, and activity of some aroma-related enzymes in both peel and pulp tissues were obtained during subsequent shelf life of fruit and submitted to multivariate analysis procedures. CA storage caused a decrease in the emission of volatile esters in comparison to storage in air. Results suggest that lessened ester production was the consequence of modifications in activities of alcohol o-acyltransferase (AAT) and lipoxygenase (LOX) activities. For short-term storage, inhibition of lipoxygenase activity in CA stored fruit possibly led to a shortage of lipid-derived substrates, resulting in decreased production of volatile esters in spite of substantial ester-forming capacity that allowed for some recovery of fruit capacity for ester emission during the shelf life. For long-term storage, strong inhibition of AAT activity in CA stored fruit in combination with low LOX activities resulted in unrecoverable diminution of biosynthesis of volatile esters.     

Effect of reddening-ripening on the antioxidant activity of polyphenol extracts from cv. 'Annurca' apple fruits

Apple is among the most consumed fruits worldwide, and several studies suggest that apple polyphenols could play a role in the prevention of degenerative diseases. 'Annurca' apple fruit undergoes, after harvest, a typical reddening treatment to turn the apples' skin red, and it is noted for its high firmness. This paper reports the effect of reddening-ripening treatment on polyphenol concentration and antioxidant activity of both peel and flesh extracts. The in vitro antioxidant properties have been compared with the protective effect against the cytotoxic effects of reactive oxygen species using Caco-2 cells as model system. Pretreatment of cells with different polyphenolic apple extracts provides a remarkable protection against oxidative damage. This effect seems to be associated with the antioxidant activity of 'Annurca' apple polyphenolic compounds. The flesh has antioxidant properties comparable to those possessed by the peel. Neither the reddening nor the fruit conservation causes changes in the antioxidant properties possessed by this apple variety. The data indicate that polyphenolic compounds in 'Annurca' apples are relatively stable in the peel and also in the flesh; therefore, the health benefits of polyphenols should be maintained during long-term storage. Finally, a diet rich in apple antioxidants could exert a beneficial effect in the prevention of intestinal pathologies related to the production of reactive oxygen species.     

Comparison of the volatile profile and sensory analysis of 'Golden Reinders' apples after the application of a cold air period after ultralow oxygen (ULO) storage

All efforts to improve fruit quality are rewarded when consumers are satisfied after tasting the fruit. Apples are often stored under controlled atmosphere conditions to preserve them over time, but this frequently results in a loss of flavor. The aim of this work, which was based on two seasons, was to evaluate the influence of a period of short-term air storage (periods of 2 and 4 weeks) after removal from ultralow oxygen (ULO) storage (1 kPa of O(2)/1 kPa of CO(2)) with respect to increases in volatile compound emissions and the effect on standard and sensory quality in 'Golden Reinders' apples. The results showed that emissions of 26 volatile compounds increased as a result of ULO + 2 weeks or ULO + 4 weeks of storage. However, the results of tastings involving a panel of consumers and trained experts revealed that this increase was not matched by corresponding increases in either the degree of consumer preference or flavor attributes.     

Changes in fruit antioxidant activity among blueberry cultivars during cold-temperature storage

Antioxidant activity, total phenolic content, anthocyanin content, and six other fruit characters including titratable acid concentration, soluble solids, firmness, and percentage of bruised berries were determined for nine blueberry (Vaccinium L. sp.) cultivars at harvest and at various postharvest intervals after storage at 5 degrees C. Berries from MSU-58, Brigitta, and Legacy stored successfully for 7 weeks, Bluegold stored for 3-5 weeks, Bluecrop, Elliott, and Nelson stored for 3 weeks, and Jersey and Little Giant stored for fewer than 3 weeks. During the time they retained marketable quality, one cultivar (MSU-58) demonstrated a 29% increase in antioxidant activity. None of the cultivars showed a significant decrease from the harvest antioxidant activity value during storage. Antioxidant activity, total phenolic content, and anthocyanin content were strongly correlated with each other (r = 0.87-0.99, P < 0.01). All three parameters were moderately correlated with soluble solids (r = 0.47, P < or =0.05; r = 0.44, P < or = 0.05; and r = 0.64, P < or = 0.01, respectively), and antioxidant activity and total phenolic content were both moderately correlated with pH (r = 0.53 and 0.49, respectively; P < or = 0.05). However, antioxidant activity, total phenolic content, and anthocyanin content showed no correlation with firmness, percent severely bruised berries, or weight loss. Antioxidant activity and total phenolic content at harvest both correlated with titratable acidity at harvest (r = 0.68, P < or = 0.05 and r = 0.70, P < or = 0.05, respectively) on a cultivar mean basis. Berries from Elliott were also harvested from plants at two levels of bush ripeness (30-50% and 60-80% ripe berries on plants) and separated into three fruit maturity classes on the basis of percent blue color. The level of bush ripeness had no significant effect on antioxidant activity, total phenolic content, or anthocyanin content; however, fruit maturity had a significant effect on antioxidant activity, total phenolic content, and anthocyanin content, and bush ripeness x fruit maturity interactions were significant for these three traits. Berries with 50-75% blue coloration harvested from bushes with 60-80% mature fruit showed a significant increase in antioxidant activity, total phenolic content, and anthocyanin content during the first 3 weeks in storage. Our results demonstrate that increases in antioxidant activity, total phenolic content, and anthocyanin content may occur in the blueberry during cold storage and are cultivar-dependent. The increases that occur in immature fruit, such as in Elliott, may be advantageous for producers who wish to delay marketing of the fruit.     

Loss of ripening capacity of pawpaw fruit with extended cold storage

The fruit ripening traits of pawpaw [ Asimina triloba (L.) Dunal] were examined after harvest and after cold storage at -2, 2, 4, and 6 degrees C for up to 12 weeks. Generally, fruits stored at 2-4 degrees C for 4 weeks ripened normally, but those stored at -2 degrees C did not ripen normally, those stored at 6 degrees C were overripe, and by 6-8 weeks those stored at 2-4 degrees C had a lower respiration rate and ethylene production, lower firmness, and lower pH than fruit cold-stored for 4 weeks or less. These changes, and the occasional development of brown discoloration in the pulp once the fruits were moved back to room temperature, were evidence of chilling injury by 6 weeks. After harvest and through 4 weeks of cold storage, the main volatile compounds produced by fruit were methyl and ethyl octanoates and hexanoates. Volatile production significantly increased >5-fold in fruit ripened for 72 h after harvest or after removal from up to 4 weeks of cold storage. Fruit cold-stored for 6 weeks or more produced fewer total volatiles and esters but increased levels of such off-flavor compounds as ethyl acetate, ethyl propionate, and hexanoic and decanoic acids. Alcohol acyltransferase (AAT) activity declined in cold-stored fruit but was not correlated with either total volatile production or total ester production. Alcohol dehydrogenase activity did not change during ripening after harvest or cold storage. Lipoxygenase activity was highest just after harvest or after 2 weeks of cold storage, but was low by 4 weeks. Thus, ripening of pawpaw fruit seems to be limited to 4 weeks at 2-4 degrees C with loss of ability to continue ripening and chilling injury symptoms evident at colder temperatures and after longer periods of cold storage.