Residue levels and storage responses of nectarines, apricots, and peaches after dip treatments with fludioxonil fungicide mixtures

Mature apricots (Prunus armeniaca), nectarines [Prunus persica var. nectarine (Ait.)], and peaches [P. persica (L.) Batsch.] were subjected to a 2 min dip treatment with warm water at 48 degrees C or with fludioxonil (FLU) at 100 mg L-1 and 20 degrees C or at 25 mg L-1 FLU and 48 degrees C and then stored at 5 degrees C and 90-95% relative humidity (RH) for 1 week plus 1 additional week at 18 degrees C and approximately 80% RH. Fruit residue uptake was determined as a function of fungicide concentration, dip temperature, treatment time (only on nectarines), and fruit storage conditions. FLU residue level was closely related to fungicide concentration and treatment temperatures and was dependent on fruit species. FLU residues showed great persistence over both storage and shelf life. Fruit dipping in water at 48 degrees C effectively reduced decay development in cvs. 'May Grand' nectarines and 'Pelese' apricots but was ineffective in cvs. 'Red Top' and 'Sun Crest' nectarines during 7 days of storage compared with nontreated fruit. Decay rates in cvs. 'Glo Haven' peaches and 'Fracasso' apricots were very low in fruit dipped in water at both 20 and 48 degrees C. Fungicide treatments at 20 and 48 degrees C resulted in the total or almost total suppression of decay in all cultivars. During shelf life, fruit became very prone to decay, averaging 25.7-100% depending on the cultivar. Fruit dipping in hot water effectively reduced decay in 'Pelese' and 'Fracasso' apricots, 'Sun Crest' peaches, and 'May Grand' nectarines as compared to control, but was ineffective in 'Glo Haven' and 'Red Top' peaches. Fungicide treatments at 20 degrees C were more effective than hot water in most cultivars. The combination of FLU with water at 48 degrees C further improved the fungicide performance. Indeed, reduced levels (a fourth) of active ingredient were required to achieve a control of decay comparable to that for treatment at 20 degrees C. Residue levels in fruit after treatment with 100 mg L-1 FLU at 20 degrees C or with 25 mg L-1 FLU at 48 degrees C averaged approximately 0.6-2 mg kg-1, which were notably lower than the maximum residue limit (5 mg kg-1) allowed in the United States for stone fruit.     

Complexation of imazalil with beta-cyclodextrin,residue uptake,persistence, and activity against penicillium decay in citrus fruit following postharvest dip treatments

A method for the inclusion of imazalil (IMZ) in the beta-cyclodextrin (betaCD), structural characterization of the inclusion complex and its antifungal activity against Penicillium digitatum and P. italicum assessed by in vitro and in vivo tests are reported. According to the starting stoichiometry of betaCD with respect to IMZ, an equimolar ratio beta-cyclodextrin-IMZ (betaCD-IMZ) was detected by (1)H NMR. In vitro assays showed that the freshly prepared betaCD-IMZ was as effective as IMZ, although 1- and 4-day-old betaCD-IMZ mixtures were more effective. Studies on Star Ruby grapefruit showed no significant differences in residue uptake between treatments with an IMZ commercially available fungicide (Deccozil) or betaCD-IMZ when equal active ingredient (a.i.) concentrations (250 mg/L) and dip temperatures (20 or 50 degrees C) were used. By contrast, treatments of Tarocco oranges and Di Massa lemons with 250 mg/L betaCD-IMZ at 50 degrees C produced significant differences in residue uptake in comparison with 250 mg/L Deccozil treatments at 50 degrees C. The a.i. degradation rate in grapefruit during postquarantine and simulated marketing period (SMP) at 20 degrees C was not affected by the type of formulation used, whether at 20 or 50 degrees C. Conversely, IMZ in oranges and lemons had greater persistence when applied at 50 degrees C. All fungicide treatments showed a comparable efficacy against decay in grapefruit and oranges, whereas treatment in lemons at 250 mg/L a.i. of heated fungicides had higher suppressive effects against decay than unheated chemicals having equal a.i. concentrations and comparable activity at 1200 mg/L IMZ at 20 degrees C.     

Carbohydrate metabolism as related to high-temperature conditioning and peel disorders occurring during storage of citrus fruit

The aim of this research was to understand the involvement of the carbohydrate metabolism in physiological disorders occurring during the postharvest storage of citrus fruit. These disorders, manifested in the rind, depreciate fruit quality and often originate important losses. There has been increasing interest in the use of nonharmful treatments, such as high-temperature conditioning, to avoid citrus peel damage during fruit storage at low temperature in chilling-sensitive cultivars, but their influence in postharvest disorders occurring at nonchilling temperatures and the mechanisms related to them are poorly understood. The data obtained showed that heat conditioning (3 days/37 degrees C) increases the chilling tolerance of cv. Navelate fruit and favored sucrose, but not hexoses, accumulation and its maintenance after the fruit was transferred to low temperature. This effect was related to heat-induced increase in the activities of the sucrose-synthesizing enzymes sucrose phosphate synthase (SPS) and sucrose synthase (SS). Furthermore, sucrose levels and the activities of both enzymes were higher in cv. Pinalate oranges, a chilling-tolerant spontaneous abscisic acid deficient mutant of Navelate. In contrast, carbohydrates appeared not to be involved in the susceptibility of oranges to rind staining, a physiological disorder different from chilling injury, which mainly occurred at a nonchilling temperature (12 degrees C) and was not reduced by heat conditioning. The effect of low temperature in SS and SPS activities was less than that of high temperature, which might be related to the lower changes occurring in sucrose during fruit storage at 2 degrees C.     

柑橘幼果提取物对猪肉冷藏过程中抗脂质氧化影响

为了研究不同浓度的柑橘幼果乙醇提取物（CE）在新鲜猪肉中的抗脂质氧化和抑菌作用。在冷藏（4℃）条件下对鲜猪肉进行以下5种处理：对照组（不添加保鲜剂）;AC-0.02（添加0.02%抗坏血酸）;CE-0.05（添加0.05%柑橘幼果醇提物,下同）,CE-0.1和CE-0.2。在12 d的冷藏（4℃）过程中,各样品的pH值均显著降低（p＜0.05）,而硫代巴比妥酸值（TBARS）和游离脂肪酸的含量显著增加（p＜0.05）。CE-0.1和CE-0.2处理组的菌落总数在贮藏过程中均低于对照组。CE的加入使猪肉样品的L*值和a*值都显著下降,在贮藏过程中,CE处理组样品的b*值均高于对照组,且随着CE浓度的增加,b*值增大。5组试验样品中,经CE-0.2处理的样品TBARS值和游离脂肪酸含量最低;对照组的过氧化值在第6天达到最大值,随后逐渐减小,而其它处理组的过氧化值在储藏期间均呈上升趋势。在贮藏1 d后,各处理组中的共轭二烯值均小于对照组。结果表明,柑橘幼果醇提物可作为肉制品的保鲜剂,能有效抑制新鲜猪肉贮藏过程中的脂质氧化和腐败微生物的生长。为开发柑橘幼果天然提取物保鲜剂提供理论参考。     

Residue levels and effectiveness of pyrimethanil vs imazalil when using heated postharvest dip treatments for control of Penicillium decay on citrus fruit

The influence of fungicide concentration and treatment temperature on residue levels of pyrimethanil (PYR) in comparison with the commonly used fungicide imazalil (IMZ) was investigated in orange fruits following postharvest dip treatments. The dissipation rate of PYR residues was recorded as a function of storage conditions. The fungicide efficacy against green and blue molds caused by Penicillium digitatum and Penicillium italicum, respectively, was evaluated on different citrus varieties following the fungicide application at 20 or 50 degrees C. Residue levels of PYR in Salustiana oranges were significantly correlated with the fungicide dosage, but residue concentrations were notably higher (ca. 13-19-fold) after treatment at 50 degrees C as compared to treatments at 20 degrees C. After treatment at temperatures ranging from 20 to 60 degrees C, PYR and IMZ residues in Salustiana oranges were significantly correlated with dip temperatures. Dissipation rates of PYR during storage were negligible in both Salustiana and Tarocco oranges. Results obtained on wounded, noninoculated Miho satsumas revealed that when treatments were performed at 50 degrees C, PYR or IMZ concentrations needed to achieve the complete control of decay were 8- and 16-fold less than by treatment at 20 degrees C. When fruits were inoculated with either P. digitatum or P. italicum, the application of 400 mg L(-1) PYR at 20 degrees C or 100 mg L(-1) PYR at 50 degrees C similarly reduced green and blue mold development. These results were corroborated by storage trials on Marsh grapefruits and Tarocco oranges. The lowest concentration of PYR required to achieve almost total protection of the fruit against decay accounted for 100 mg L(-1) at 50 degrees C and 400 mg L(-1) at 20 degrees C, respectively. Treatments did not affect fruit external appearance, flavor, and taste. It is concluded that postharvest PYR treatment represents an effective option to control green and blue mold in citrus fruit and that integration of fungicide applications and hot water dips may reduce the possibility of selecting fungicide-resistant populations of the pathogen, as a consequence of increased effectiveness of the treatment.     

A fast method coupling ultrahigh performance liquid chromatography with diode array detection for flavonoid quantification in citrus fruit extracts

Flavonoids are a widely distributed group of polyphenolic compounds present in an extensive range of edible plants, notably Citrus species. This article reports a rapid, optimized, and validated method for the separation and quantification of flavonoids in three Citrus fruit extracts by ultrahigh performance liquid chromatography (UHPLC) using a photodiode array detector. This new procedure allowed the simultaneous separation and quantification of 11 selected flavonoids in 5.5 min, 8.2 times faster than that by HPLC analysis. The solvent consumption for each individual analysis was also reduced almost 6.2-fold. The most abundant component in the analyzed samples was naringin (299.06-544.36 mg 100 g?1), followed by rutin (116.60-256.33 mg 100 g?1) and quercetin (7.78-251.49 mg 100 g?1). Isoquercitrin was found in a lower proportion (60.05-81.88 mg 100 g?1). The method was completely validated, providing a sensitive analysis for flavonoid detection and showing satisfactory data for all the parameters tested. This methodology is cheaper, more environmentally friendly, and easier to perform than others previously described.     

Gas chromatographic determination of fenpropimorph residues in citrus fruit

A rapid gas chromatographic method for determining fenpropimorph residues in citrus fruit is reported. The fungicide is extracted with hexane after pH adjustment of the fruit homogenate. A short liquid-liquid partitioning process is performed before gas chromatography on an OV-17 column with nitrogen-phosphorus specific detection. The limit of detection of the method was 0.01 mg/kg, based on a 25 g sample. Recovery was always higher than 70%. Fenpropimorph residues in "Washington Navel" oranges and "Hernandina" clementine fruits dipped in a 1500 mg/L fungicide solution were determined. The fungicide remains mainly in the peel, with levels less than 0.1 mg/kg in the pulp. Fungicide residues in the peel decrease during storage, mainly in Washington Navel peel, where values decreased from 5.2 to 2.8 mg/kg.     

Orthophenylphenol and phenylhydroquinone residues in citrus fruit and processed citrus products after postharvest fungicidal treatments with sodium orthophenylphenate in California and Florida

Sodium orthophenylphenate (SOPP) has been used extensively for >40 years to control postharvest diseases of citrus fruits. Studies of the metabolism of [(14)C]SOPP have identified orthophenylphenol (OPP) as the major metabolite with phenylhydroquinone (PHQ) as a minor metabolite. The whole-fruit tolerance in the United States for OPP is 10 ppm. This study was conducted to quantify terminal OPP and PHQ residues in whole Navel oranges, grapefruit, and lemons following SOPP applications at maximum application rates and following commercial application and fruit storage practices. OPP and PHQ residues also were determined in products processed from treated Navel oranges. OPP residues in lemons, Navel oranges, and grapefruit treated with SOPP using foamer wash and shipping wax applications remained below the 10 ppm tolerance, and PHQ residues were all < or =0.439 ppm. PHQ residues in whole fruit increased with time in commercial storage. OPP residues in all Navel orange matrices except oil remained relatively stable with time in commercial storage; residues in oil declined substantially while in storage.     

柑橘果实发育中果胶酸钙、草酸钙和果胶动态的研究

以单性结实的龟井蜜柑和自花结实的鄂柑1号橘为试材,对整个果实发育期的子房(幼果)、果皮和果肉的果胶酸钙、草酸钙和果胶含量变化进行了测定。结果表明,1)两品种子房(幼果)果胶酸钙含量呈类似的下降趋势;草酸钙则相反,龟井花后趋下降,而鄂柑1号却明显上升;而且鄂柑1号子房(幼果)果胶酸钙、草酸钙和果胶含量均相对较高。2)在果实增大期内,两品种果皮和果肉的果胶酸钙含量均出现显著上升,对应果皮草酸钙含量虽有波动但居相对较高水平,而果肉草酸钙则趋明显下降。3)两品种果皮和果肉水溶性果胶含量均在增大期内呈显著上升,对应原果胶含量均相对较高,进入增大后期均明显下降。     

Risk assessment of repetitive movements in the citrus fruit industry

Musculoskeletal disorders are injuries of the muscles, nerves, tendons, ligaments, joints, cartilage, or spinal discs and are often classified as soft tissue injuries. They are the result of chronic or gradual development and are not caused by acute incidents such as slips, trips, or falls. The significance of this phenomenon prompted us to carry out a broader study of pathologies attributable to repetitive movements in the upper limbs within the citrus growing industry. Calabria, a very important region for citrus fruit growing in Italy, was chosen as the study area. The study analyzed the risks of repetitive movements for 180 workers on 35 different farms using the OCRA (Occupational Repetitive Actions) checklist method By analyzing the scores obtained in the different work phases, it was possible to determine the tasks that incur more risk in the citrus fruit industry. The OCRA checklist considers all the repetitive tasks involved in a complex job and estimates the level of exposure to each worker. In support of the specific aims of the present study, it is possible to identify a series of working conditions for which the level of risk may be reasonably estimated and for which it is possible to adopt a checklist system. The results of this study suggest that there must be a significant increase in the use of effective ergonomic interventions in the workplace in order to attain reductions in the number of local musculoskeletal complaints.     

Determining multifumigants in whole grains and legumes, milled and low-fat grain products, spices, citrus fruit, and beverages

Whole grain and legumes, milled and low-fat products, spices, citrus fruit, and dry beverage ingredients are leached with purified, acidified acetone-water solutions. Portions of these leachates are then back-extracted with purified isooctane. Liquid beverages are directly extracted with the isooctane. Six to 10 microL of each isooctane extract is then screened for 11 fumigant residues by gas chromatography (GC) using electron-capture and Hall electroconductivity detectors, and dual 20% OV-101 columns. Further confirmation of residue identity is done on 20% OV-225/20% OV-17 (2.5 + 1 mixed-bed) and 10% SP-1000 columns. The analytes determined include methyl bromide, methylene chloride, carbon disulfide, chloroform, ethylene dichloride, methyl chloroform, carbon tetrachloride, trichloroethylene, chloropicrin, ethylene dibromide, and tetrachloroethylene, using mixed-component reference solutions. Average recoveries from fortified grain range from 25 to 85%; methyl bromide and chloropicrin were recovered the least. Recoveries from the other kinds of food samples range from 43 to 111%. Advantages of this procedure are (1) clean sample extracts, (2) ppb detection limits, (3) residue stability, (4) relative speed, quality control, and safety of the analysis, and (5) results which gave an accurate picture of residual fumigants in grain and food products.     

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.     

Quantification of carotenoids in citrus fruit by LC-MS and comparison of patterns of seasonal changes for carotenoids among citrus varieties

To quantify the 18 carotenoids on the basic routes of the carotenoid biosynthesis in plants simultaneously, a method for liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionization was developed. With this method, the seasonal changes of carotenoids in the flavedo and juice sacs of 39 citrus varieties were analyzed. On the basis of the patterns of seasonal changes of carotenoids in both flavedo and juice sacs, 39 citrus varieties were classified. In flavedo, 39 varieties were classified into 5 clusters, in which the carotenoid profiles were carotenoid-poor, phytoene-abundant, violaxanthin-abundant, violaxanthin- and beta-cryptoxanthin-abundant, and phytoene-, violaxanthin-, and beta-cryptoxanthin-abundant, respectively. In juice sacs, they were classified into 4 clusters, in which the carotenoid profiles were carotenoid-poor, violaxanthin-abundant, violaxanthin- and phytoene-abundant, and violaxanthin-, phytoene-, and beta-cryptoxanthin-abundant, respectively. In flavedo, many citrus varieties, except for the carotenoid-poor and phytoene-abundant varieties, massively accumulated beta,epsilon-carotenoids (e.g., lutein), beta,beta-carotenoids (e.g., beta-cryptoxanthin and violaxanthin), and phytoene, in that order. In juice sacs, the accumulation order among beta,beta-carotenoids was observed. Violaxanthin accumulation preceded beta-cryptoxanthin accumulation in violaxanthin-, phytoene-, and beta-cryptoxanthin-abundant varieties. In each variety, the carotenoid profiles of the flavedo and juice sacs on the basis of the concentration in violaxanthin and beta-cryptoxanthin were similar, with the exception of a few varieties.     

Influence of mitochondria origin on fruit quality in a citrus cybrid

Sugar, organic acid, and carotenoid are the most important indicators of fruit taste and nutritional and organoleptic quality. These components were studied on fruit pulp of the cybrid between Willow leaf mandarin ( Citrus deliciosa Ten.) and Eureka lemon [ Citrus limon (L.) Burm.] and the two parents. The cybrid possessed nuclear and chloroplast genomes of Eureka lemon plus mitochondria from Willow leaf mandarin. The impact of new mitochondria on fruit quality was studied during the mature period. Levels of organic acids were slightly higher in the cybrid fruit pulp than in Eureka lemon. No significant difference in sugar and carotenoid content was observed between the cybrid and the lemon. Results confirm that the main genetic information for the biosynthesis of sugars, organic acids, and carotenoids is contained in the nucleus. In Citrus, cybridization can be used as a strategy to breed specific traits associated with mitochondrial genomes, such as male sterility, without affecting the main organoleptic and nutritional qualities.     

Dissipation rates of cyprodinil and fludioxonil in lettuce and table grape in the field and under cold storage conditions

Two fungicides (cyprodinil and fludioxonil) have recently been used in southeast Spain to control disease in lettuce and grape. Gas chromatography with a nitrogen-phosphorus detector (GC-NPD) was used to study the disappearance of these compounds from crops under field conditions and during refrigeration. Residual values 21 days after application were below the maximum residue limit (MRL = 0.05 mg kg(-1)) established by Spanish law in the field experiment for both compounds. However, with the exception of fludioxonil in lettuce, residues were above the MRL in the refrigerated farm produce for both fungicides. The half-lives were 3-6 times greater under refrigeration.     

有机无机复混肥对柑橘产量和品质的影响

采用田间小区试验研究了有机无机复混肥对柑橘产量和品质的影响.结果表明,施有机无机复混肥能增加柑橘产量,改善果实品质,提高经济效益.柑橘产量以施有机无机复混肥处理最高,施有机无机复混肥能增加柑橘果实的Vc含量、可溶性总糖含量、糖酸比和可溶性固形物百分比,降低可滴定酸含量.     

基于彩色信息的树上柑橘识别研究

为正确识别自然环境中的树上水果,从而为机械手的运动提供参数并完成水果的自动采摘,研究了基于彩色信息的树上柑橘识别方法。在对53幅含有各种背景情况的可见光彩色图像进行颜色特征提取和理解的基础上,建立了利用柑橘、树叶、树枝在R-B颜色指标上的差异进行树上柑橘识别的颜色模型,并利用动态阈值法,根据图像特征动态产生阈值T,将柑橘从背景中分割出来。分别在顺光条件和逆光条件下进行了试验分析,试验结果表明该识别模型可以实现对树上可见的柑橘的识别,并适用于单个和多个果实的识别,正确识别率较高。