Lipophilic extracts from banana fruit residues: a source of valuable phytosterols

The chemical composition of the lipophilic extracts of unripe pulp and peel of banana fruit 'Dwarf Cavendish' was studied by gas chromatography-mass spectrometry. Fatty acids, sterols, and steryl esters are the major families of lipophilic components present in banana tissues, followed by diacylglycerols, steryl glucosides, long chain fatty alcohols, and aromatic compounds. Fatty acids are more abundant in the banana pulp (29-90% of the total amount of lipophilic extract), with linoleic, linolenic, and oleic acids as the major compounds of this family. In banana peel, sterols represent about 49-71% of the lipophilic extract with two triterpenic ketones (31-norcyclolaudenone and cycloeucalenone) as the major components. The detection of high amounts of steryl esters (469-24405 mg/kg) and diacylglycerols (119-878 mg/kg), mainly present in the banana peel extract, explains the increase in the abundance of fatty acids and sterols after alkaline hydrolysis. Several steryl glucosides were also found in significative amounts (273-888 mg/kg), particularly in banana pulp (888 mg/kg). The high content of sterols (and their derivatives) in the 'Dwarf Cavendish' fruit can open new strategies for the valorization of the banana residues as a potential source of high-value phytochemicals with nutraceutical and functional food additive applications.     

Residue levels of ethoxyquin, imazalil, and iprodione in pears under cold-storage conditions.

A gas chromatographic method is presented for the simultaneous determination of the antiscald ethoxyquin and the fungicides imazalil and iprodione in peel and pulp of Blanquilla pears. Fruits were cold-stored in commercial chambers in normal atmosphere and in controlled atmosphere with low oxygen content (oxygen and carbon dioxide were held at 2.5% and 1.5%, respectively). The method uses gas-liquid chromatography (GLC) with an alkaline flame ionization detector (detector of N-P, NPD) and allows the detection of the mentioned compounds to minimum levels of 0.08-0.12 mg/kg in fresh fruit. With this system the evolution of residues in fruit was monitored throughout the period of cold storage. In the surveys carried out the residue levels of these compounds were found to be below the limits allowed by the legislation of European Union. For the three studied products residues in pulp are lower and disappear more quickly than in peel.     

Improved cleanup for gas chromatographic determination of propiconazole residues in soil, wheat grain, straw, and leaves

A simple and sensitive method is described for determination of propiconazole, a new type of broad-spectrum systemic fungicide, in soil, wheat grain, straw, and leaves. Pesticide residues in or on grain and green plant materials are extracted with methanol (or a mixture of methanol and water (4 + 1), for soil), partitioned into methylene chloride, and cleaned up on an alumina column for grain and soil or an activated charcoal column for green plant materials. The amount of residue is quantitatively measured by gas chromatography using an alkali flame ionization detector in the nitrogen-sensitive mode. Recoveries from soil, grain, and green plant materials fortified at 0.1-5 mg/kg are better than 80%. The practical detection limits of this method are 0.01 mg/kg in grain and soil and 0.02 mg/kg in green plant materials.     

Volatile chemicals identified in extracts from newly hybrid citrus,dekopon (Shiranuhi mandarin Suppl. J.)

Extracts from the peel and flesh of a citrus fruit, dekopon (Shiranuhi mandarin Suppl. J.), were obtained under reduced pressure followed by dichloromethane extraction. A total of 127 volatile chemicals were identified in the extracts using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). They included 11 monoterpenes, 32 monoterpenoids, 9 sesquiterpenes, 5 sesquiterpenoids, 20 aliphatic alcohols, 14 aliphatic esters, 15 aliphatic aldehydes and ketones, 7 aliphatic acids, and 10 miscellaneous compounds. The major volatile constituents of the extract from the peel were d-limonene (2380.33 mg/kg), myrcene (36.54 mg/kg), bisabolene (30.03 mg/kg), sabinene (21.12 mg/kg), trans-beta-ocimene (16.96 mg/kg), valencene (12.84 mg/kg), decanal (8.14 mg/kg), beta-phellandrene (4.53 mg/kg), citronellol (4.51 mg/kg), 4-terpineol (4.50 mg/kg), linalool (4.13 mg/kg), and citronellyl acetate (3.63 mg/kg). The major volatile constituents of the extract from the flesh were ethyl acetate (21.54 mg/kg), acetoin (7.23 mg/kg), 3-methylbutanol (2.79 mg/kg), p-mentha-cis-2,8-dien-1-ol (1.01 mg/kg), 3-methylbutanoic acid (0.95 mg/kg), isobutanol (0.59 mg/kg), trans-isopiperitenol (0.58 mg/kg), p-mentha-trans-2,8-dien-1-ol, and trans-carveol (0.44 mg/kg). Compositions of volatile chemicals in peel and flesh extract were considerably different: the peel extract was rich in terpenes, whereas the flesh extract was rich in aliphatic compounds.     

Effect of a pilot washing system on dicofol levels in orange matrix

An efficient analytical method is described for the analysis of dicofol residues in pulp and orange peel. Samples are mixed with Celite and transferred to chromatographic columns prepacked with silica gel. Dicofol is eluted with ethyl acetate, and the extracts are analyzed by gas chromatography with electron capture detection. Mean recoveries for dicofol at levels of 0.5, 2.0, 5.0, and 10 mg/kg ranged from 87 to 95% with relative standard deviation values between 2.6 and 9.0%. To investigate the effect of a pilot washing system on dicofol residues in oranges, the analytical procedure was applied to samples submitted to different treatments with commercial formulations under field and laboratory conditions. The orange samples with and without washing were analyzed in duplicate, and the results indicated that washing under the described conditions did not allow a complete removal of dicofol residues from orange peel.     

Residue level, persistence, and storage performance of citrus fruit treated with fludioxonil

The potential of postharvest dip treatments with fludioxonil (FLU) (a synthetic analogue of the bacterial metabolite of pyrrolnitrin), in controlling postharvest decay caused by Penicillium digitatum and Penicillium italicum of citrus fruit was investigated in comparison with the conventional fungicide imazalil (IMZ). The ultrastructural changes of fruit epicuticular wax was investigated as a function of water dip temperature, and the possible role of these changes was related to residue accumulation under FLU treatment. Residues retained by fruit were determined as a function of fungicide concentration, dip temperature, and fruit storage conditions. Scanning electron microscopy analysis revealed that fruit dipping in water at 30 or 40 degrees C did not cause differences in cuticular wax's ultrastructure in comparison to control fruit, while treatments at 50, 55, or 60 degrees C caused the disappearance of wax platelets, resulting in relatively homogeneous skin surface, due to partial "melting" of epicuticular wax. Residues of FLU in fruit treated at 20 or 50 degrees C were significantly correlated with the doses of fungicide applied. When equal amounts of fungicide were employed, the residue concentrations were notably higher (from 2.6- to 4-fold) in fruit treated at 50 degrees C than in fruit treated at 20 degrees C. The dissipation rate of FLU in "Salustiana" and "Tarocco" oranges was lower in fruit subjected to treatment at 50 degrees C. The minimal FLU concentration for almost complete decay control in artificially wounded fruit during 7-d storage at 20 degrees C was 400 mg/L active ingredient (ai) in fruit treated at 20 degrees C and 100 mg/L ai in fruit treated at 50 degrees C. Results on nonwounded Tarocco oranges subjected to 3 weeks of simulated quarantine conditions at 1 degrees C, plus 6 weeks of standard storage at 8 degrees C and an additional two weeks of simulated marketing period (SMP) at 20 degrees C revealed that almost complete decay control with FLU applications of 100 mg/L at 50 degrees C and 400 mg/L at 20 degrees C resulted in ca. 0.8 mg/kg FLU fruit residues, in agreement with results on wounded citrus fruit. When equal concentrations and temperatures were applied, FLU treatments were as effective as IMZ. In vitro trials showed a low sensitivity to FLU against P. digitatum and P. italicum isolates. MIC values for the complete inhibition of mycelium growth were >or=100 microg/mL, while ED(50) values ranged from 0.1 to 1 microg/mL for P. digitatum and from 1 to >100 microg/mL for P. italicum. The latter result suggests that care should be taken to avoid exclusive application of FLU in a sustainable program for management of fruit decay. However, integrating fungicide application and hot water dip may reduce the possibility of selecting fungicide-resistant populations of the pathogen, by increasing the effectiveness of the treatment.     

Residues of spiroxamine in grapes following field application and their fate from vine to wine

Dissipation of the fungicide spiroxamine in grapes of two vine varieties, Roditis and Cabernet Sauvignon, exposed to field treatments was evaluated. Vines of a grape vineyard located in central Greece were sprayed once or twice with a commercial formulation of the fungicide at 30 g a.i./hL. Residues in grapes, must, and wine were determined by gas chromatography/IT-MS after extraction with cyclohexane-dichloromethane (9:1), with a limit of quantitation 0.02 mg/kg in grapes and 0.012 mg/kg in wine. Under field conditions, spiroxamine dissipation on grapes was faster during the first 2 weeks and then slower to the sixth week. About 7 days after application, half of the initial spiroxamine concentration remained on the grapes; the respective proportion at 42 days was about 10%. At 14 and 35 days, residues were lower than 0.44 and 0.22 mg/kg, respectively, values below the maximum residue levels set by the European Union (1 mg/kg). Spiroxamine residues transferred from grapes into the must and through the vinification process into the wine were also studied. Mean transfer factors of 0.26 and 0.55 were found from grapes into wine for the wines obtained without maceration and with maceration, respectively. Residues in wine, prepared from grapes with a spiroxamine content of 0.11-0.20 mg/kg, varied from <0.026 to 0.09 mg/kg. Spiroxamine diastereomer B was found to dissipate slower than diastereomer A in the field as well as during the vinification process.     

Analytical study of trichlorfon residues in Kaki fruit and cauliflower samples by liquid chromatography-electrospray tandem mass spectrometry

A detailed analytical study on trichlorfon residues in selected vegetables samples has been carried out, focused on the reliable quantification and confirmation of this compound, and on stability of residues under storage. As a consequence, a rapid and sensitive LC-ESI-MS/MS method has been developed for the determination of residues of this insecticide in kaki fruit (flesh and peel) and cauliflower samples. Extraction was performed with acetonitrile using a high-speed blender. After 4-fold dilution of the extract with water, 20 microL was directly injected in the LC-ESI-MS/MS system (triple quadrupole), using matrix-matched standards calibration for quantification. Under optimized MS/MS conditions, limit of detections between 0.006 and 0.013 mg/kg were reached, and a limit of quantification of 0.05 mg/kg was established, with a runtime of only 15 min. Recoveries from spiked blank samples at 0.05 and 0.5 mg/kg were in the range 83-101% with relative standard deviations lower than 10%. The method was applied to treated and untreated samples collected from field residues trials, using quality control samples analysis for the evaluation of the method. Despite the acquisition of two MS/MS transitions in selected reaction monitoring mode, the analysis of treated samples revealed the presence of a chromatographic peak close to the analyte that corresponded to a trichlorfon isobaric compound that shared the same MS/MS transitions. This unusual situation in LC-MS/MS-based procedures required the application of an efficient chromatographic separation to avoid this interference. All experiments have been made in compliance with the principles of Good Laboratory Practices (GLP) and following the European SANCO guidelines for pesticides residue analysis (PRA).     

Linalool in orange juice: origin and thermal stability

Linalool concentrations were determined in juice from three groups of 60 Valencia oranges using pentane:ether extraction and high-resolution capillary GC. The outer peel (flavedo) was removed from one group. The other two groups retained their peel intact. Juice was extricated from the halved fruits of the flavedo-less group and from one of the peel-intact groups using a hand reamer. A peel-cutting/macerating juice extractor was used for the other peel-intact group. Linalool concentrations were 0.004 mg/L in peeled fruit juice and 0.020 and 0.106 mg/L for hand-reamed and mechanically extracted peel-intact juice, respectively. Juice from peeled fruit contained significantly (P < 0.05) less linalool than peel-intact juice. Approximately 80% of the total juice linalool content was associated with peel using reamer design, and 96% was associated with peel-cutting/macerating design. Linalool increased with increasing peel oil levels; however, the increases were not proportionate. Since all commercial juices are mechanically extracted, the vast majority of linalool in commercial orange juice originates from the peel and not from the juice vesicle cytoplasm. Juice from peel-macerated, mechanically extracted fruit increased from 0.106 to 0.134 mg/kg after thermal processing, whereas juice from reamer extraction was essentially unchanged.     

Simple and sensitive determination of o-phenylphenol in citrus fruits using gas chromatography with atomic emission or mass spectrometric detection

In this work, a simple and sensitive method for the analysis of the pesticide o-phenylphenol (OPP) on citrus fruits was developed. OPP is extracted with dichloromethane by ultrasonication and derivatized with ferrocenecarboxylic acid chloride. Using ferrocene as a label, residues of OPP are determined by gas chromatography with atomic emission detection in the iron selective mode or with mass spectrometric detection. Sample cleanup is simple and rapid and merely involves a removal of excess reagent on an alumina minicolumn. The method detection limit is 2 ng of OPP/g of fruit, and recoveries from lemon samples fortified at levels of 35 and 140 ng/g are 101 and 106%, respectively. The citrus fruits analyzed (oranges, grapefruits, lemons) contained between 60 ng/g and 0.37 microg/g OPP (RSD = 8-13%), and the results were in good agreement with results obtained when OPP was analyzed using an established HPLC-FLD method. Several alcohols could also be identified in the fruit peel.     

LC/ESI/MS method for the quantitative detection of guazatine residues in cereals

Guazatine is a fungicide used in agriculture to control a wide range of seed-borne diseases of cereals and other vegetable foods. In this work, a LC-ESI-MS method was developed for the quantitative detection of guazatine residues in maize and hard wheat. Quantitative data were determined for the residues of the main diamines, triamines, and tetramines that cover more than 87% of the total contents of the mixture. The mean recoveries from the fortified cereals at 0.050 mg/kg ranged from 81 to 86%, with the coefficients of variation (CVs) ranging from 0.9 to 5.5% (n = 5). At 0.025 mg/kg, the recoveries ranged from 78 to 87%, with the CVs ranging from 0.8 to 6.3% (n = 5). The limits of quantification have been estimated to be 0.010, 0.004, 0.002, 0.002, 0.005, and 0.002 mg/kg, respectively, for GN, GG, GNG, GGN, GGG, and GGGG in maize and hard wheat (S/N ratio >10).     

Gas chromatography-mass spectrometry determination of phosphine residues in stored products and processed foods

A gas chromatography-mass spectrometry (GC-MS) method was used for the quantitative confirmation of phosphine residues in stored products and processed foods. An established extraction technique was utilized for the preparation of headspace samples, which were analyzed by GC-MS and gas chromatography-nitrogen-phosphorus detection (GC-NPD). Wheat, oats, maize, white rice, brown rice, cornflakes, tortilla cornchips, groundnuts, and raisins were validated, showing excellent agreement between detectors when spiked at levels equivalent to 0.001 and 0.01 mg/kg phosphine and for samples containing incurred residues. The GC-MS method was reproducible and accurate when compared to the GC-NPD method and allowed five samples to be quantified in a working day. Subambient GC-MS oven temperatures were most suitable for phosphine residues ranging from 0.001 to 0.005 mg/kg, and a GC oven temperature of 100 degrees C was appropriate for residues >0.005 mg/kg. The method was sufficiently robust to be evaluated for other similar commodities as the need arises.     

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.     

Residues of azoxystrobin from grapes to raisins

Azoxystrobin, a fungicide of the strobilurin group, has an European Union maximum residue level (MRL) of 2 mg/kg for grapes. This work aimed to assess residues on fresh and washed grapes and on raisins following processing with (i) alkali treatment and sun drying and (ii) sun drying only. QUADRIS 25% SC was applied according to good agricultural practice for two consecutive years on a typical cv. Thomson seedless and a seed-producing clone. Samples were collected 0, 15, and 21 days postapplication and analyzed using gas chromatography/electron capture detection; recoveries were 86 +/- 12% for grapes and 99 +/- 15% for raisins. Residues on grapes were 0.49-1.84 mg/kg, and washing removed 75% of the residue. Residues in raisins produced from seedless grapes were 0.51-1.49 (treatment 1) and 1.42-2.08 mg/kg (treatment 2), with residue transfer factors sometimes >1, even following alkali treatment, which reduced residues considerably. To avoid trade problems, a higher MRL for raisins is necessary.     

Determination of fungicide residues in field-grown strawberries following different fungicide strategies against gray mold (Botrytis cinerea)

In a 2 year experiment, residues in field-grown strawberries were investigated from the fungicides fenhexamid, pyrimethanil, tolylfluanid, and kresoxim-methyl resulting from different strategies, as regards the dose, number, and time of fungicide applications. Kresoxim-methyl was only used the first year and in full or no dose to control powdery mildew. In the first year, the highest concentrations analyzed were 0.66 mg kg(-1) for pyrimethanil and 0.63 mg kg(-1) for fenhexamid resulting from the use of recommended dose rates and a preharvest interval (PHI) of 10 days, thus not exceeding the Danish maximum residue limit (MRL) of 1 mg kg(-1). Tolylfluanid was used no later than 21 days before harvest, which left residue contents in the berries of 0.48 mg kg(-1), a value well below the MRL of 5 mg kg(-1). In the second year, fungicide residues found in the samples were generally lower, 0.39 and 0.03 mg kg(-1) for pyrimethanil and fenhexamid, respectively. No residues of kresoxim-methyl were found in any of the samples from the field trials, indicating that kresoxim-methyl residues had declined to a level well below the detection limit within the 28 day period between the last application and the harvest.     

Determination of ethylenethiourea in grapes and wine

Residues of ethylenethiourea (ETU) in grapes and wine were determined by capillary gas chromatography and paper chromatography, without a cleanup step, and after derivatization to S-benzyl-ETU. The detection limit was 0.0002 mg/kg for flame ionization detection, 0.008 mg/kg for paper chromatography with photodensitometric evaluation of the detected spot. Results were compared with a generally used GC method specifying electron capture detection of trifluoroacetylated S-benzyl-ETU. The recoveries of ETU in grapes and wine at different concentration levels were determined. ETU residues were determined in treated grapes but no residues were detected in wine.     

民勤蜜瓜产品特性与质量评价

为明确民勤蜜瓜相对于同类产品的存在优势,促进民勤蜜瓜的健康快速发展。从产地环境、生产过程、果品安全质量和果实品质等方面对其进行系统评价。结果表明,民勤的气候生态符合蜜瓜最适宜生产区条件,土壤、灌溉水中有害金属含量均符合标准规定。果实样品中11 种重金属和农药残留量未检出或小于最低检测临界值,果实安全性达到标准要求。民勤蜜瓜可溶性固形物含量为167.4 g/mg,可溶性总糖含量为81.7 g/kg,蛋白质含量为38.0 g/kg,维生素C含量为2.43 mg/kg。民勤蜜瓜成熟阶段糖酸比较高,且富含钙、镁、锌等元素。综合民勤蜜瓜产地环境、生产过程、果实安全质量、品质营养等,综合评价为优。     

Evaluation of residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple pulp and bagasse (Smooth cayenne)

The objective of this research was to study the residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple bagasse and pulp. Benomyl (benlate), methyl parathion (Folidol 600), diuron (Krovar), and Vamidothion (Kilval 300) were applied pre-harvest to pineapples (smooth cayenne). After harvesting, the fruits were washed (100 ppm sodium hypochlorite) and the pulp was separated from the sub-products (peel, core, tops, and tails). The pulp was not submitted to any heat treatment. The sub-products and the juice expressed from them, were submitted to a blanching process (95 degrees C for 1 min). After separating the juice, the bagasse and pulp were analyzed for residues of diuron and benomyl by high performance liquid chromatography, and for residues of vamidothion and methyl parathion by gas chromatography using a TSD detector. No residues of benomyl, diuron, vamidothion, or methyl parathion were detected in the pulp within the quantification limits of the methods (0.1 mg/kg, 0.1 mg/kg, 0.005 mg/kg, and 0.005 mg/kg, respectively). Only methyl parathion (0.052 mg/kg) and vamidothion (0.021 mg/kg) were detected in the bagasse. The presence of these residues in the bagasse was probably due to the action of the wax found in the peel, which prevented the methyl parathion and vamidothion from dissolving in the juice. According to these results, the pulp was fit for human consumption, as far as pesticide residues were concerned, and the bagasse was fit for animal feed and similar applications, because the residual levels found were below the limits established for these compounds.     

Analysis of alternariol and alternariol monomethyl ether on flavedo and albedo tissues of tangerines (Citrus reticulata) with symptoms of alternaria brown spot

A method was developed for the quantification of alternariol and alternariol monomethyl ether on tangerines with and without symptoms of Alternaria brown spot disease. The method employs solid-phase extraction for cleanup, followed by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for detection. This method was validated on flavedo (exocarp or epicarp, exterior yellow peel) and on albedo tissue (mesocarp, interior white peel). An excellent linearity over a range of 0.50-20.0 mg/kg was achieved, with r2 >or= 0.997. The limits of detection (LOD) and quantification (LOQ) were fewer than 0.13 and 0.50 microg/kg, respectively. The relative standard deviations (RSDs) were 相似文献   

Dissipation of propiconazole and tebuconazole in peppermint crops (Mentha piperita (Labiatae)) and their residues in distilled oils

The broad-spectrum, systemic fungicides propiconazole (1) and tebuconazole (2) are used to control rust in peppermint (Mentha piperita L.). An analytical method, using gas chromatography combined with detection by high-resolution mass spectrometry, was developed to allow for the simultaneous monitoring of both pesticides in peppermint leaves and oil. Field trials were established to determine the rate of dissipation of tebuconazole and propiconazole in peppermint crops. Three applications of each fungicide were trialed at two rates (125 and 250 g of active ingredient (ai)/ha). At harvest, 64 days after the final application, propiconazole was detected at levels of 0.06 mg/kg and 0.09 mg/kg of dry weight, and tebuconazole was detected at 0.26 and 0.80 mg/kg dry weight, in identical trials. Rates of dissipation of propiconazole and tebuconazole were lower at a second trial site, where three applications of 125 g/ha ai for each fungicide resulted in residue levels of 0.21 mg/kg for both pesticides, detected 89 days after the last application. Propiconazole and tebuconazole were detected in the distilled oil at levels between 0.02 and 0.05 mg/kg and between 0.011 and 0.041 mg/kg, respectively. Propiconazole had a higher tendency to co-distill with the peppermint oil, with 0.7% of that present in the vegetative material ending up in the oil, compared to 0.09% of tebuconazole.