Determination of polycyclic aromatic hydrocarbons in coffee brew using solid-phase extraction     

Houessou JK  Benac C  Delteil C  Camel V 《Journal of agricultural and food chemistry》2005,53(4):871-879

The presence of polycyclic aromatic hydrocarbons (PAHs) in coffee has been reported and is suspected to be due to the degradation of coffee compounds during the roasting step. Due to the high toxicity of these compounds, among which benzo[a]pyrene is known to be the most carcinogenic, their presence in the coffee, especially the coffee brew that is directly ingested by the consumer, is of prime importance. However, due to the low solubility of these compounds, their concentrations are expected to be rather low. As a consequence, reliable and sensitive analytical methods are required. The aim of this study was to develop a reliable and fast analytical procedure to determine these organic micropollutants in coffee brew samples. PAHs were retained on a 0.5 g polystyrene-divinylbenzene cartridge before being eluted by a mixture of methanol/tetrahydrofuran (10:90 v/v), concentrated, and directly analyzed by reversed-phase high-performance liquid chromatography coupled to a fluorescence detector. Application to the determination of PAHs in several coffee brew samples is also given, with mean estimated concentrations in the range of 0-100 ng L(-1) for suspected benzo[b]fluoranthene and benzo[a]pyrene, whereas no fluoranthene could be detected. Tentative identification was made on the basis of UV spectra. However, identification of the suspected traces of PAHs could not be achieved due to matrix effects, so that the presence of coeluting compounds may not be excluded.  相似文献   

Improvement of table grapes quality and safety by the combination of modified atmosphere packaging (MAP) and eugenol, menthol, or thymol   总被引：1，自引：0，他引：1  

Valverde JM  Guillén F  Martínez-Romero D  Castillo S  Serrano M  Valero D 《Journal of agricultural and food chemistry》2005,53(19):7458-7464

Table grape is a nonclimacteric fruit that shows a rapid loss of quality during storage and is very susceptible to colonization by fungi, especially Botrytis cinerea, which is considered the most important disease of this commodity. To solve this problem, synthetic fungicides have been used, although legal restrictions and consumer's concern demand the search of other safe means. In the present paper, and as an alternative of synthetic fungicides, an active packaging to improve MAP effectiveness on preserving table grape (cv. Crimson Seedless) quality and safety was developed by the addition of 0.5 mL of eugenol, thymol, or menthol inside the packages. Packages were stored at 1 degree C for 35 days. The final gas composition inside the packages was 1.4-2.0 and 10.0-14.5 kPa of CO(2) and O(2), respectively, with no significant slight differences among treatments. Results showed that the addition of eugenol, thymol, or menthol improved the beneficial effect of MAP in terms of delaying weight loss and color changes, retarding degrees Brix/acidity ratio evolution, and maintaining of firmness. Thereafter, these treatments showed additional benefit in terms of delayed rates of rachis deterioration and berry decay. Finally, the total viable counts for both mesophilic aerobics and especially yeast and molds were significantly reduced in the grapes packaged with the natural antimicrobial compounds. All of the above effects led to maintenance of table grape quality and safety for longer storage periods (3 additional weeks as compared to controls under MAP only).  相似文献   

Capillary electrophoresis and high-performance liquid chromatography determination of polyglutamyl 5-methyltetrahydrofolate forms in citrus products   总被引：2，自引：0，他引：2  

Matella NJ  Braddock RJ  Gregory JF  Goodrich RM 《Journal of agricultural and food chemistry》2005,53(6):2268-2274

The 5-methyltetrahydrofolate (5mTHF) polyglutamates in citrus products were analyzed by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Folate species were purified from citrus products and concentrated from 2- to 100-fold using combined folate-affinity chromatography and C18 extraction. Seven polyglutamyl 5mTHFs were found in most not-from-concentrate (NFC) orange juices (OJ) in total amounts of approximately 1 nmol/mL, with varying distributions of individual polyglutamates. Folate amounts and distributions were also measured in orange fractions, single-strength OJ from concentrate, NFC grapefruit juice, and citrus peel molasses. Models containing ascorbic acid had folate thermal degradation rates one-seventh that of models without ascorbic acid. Pasteurization studies demonstrated that folate loss was <2% for commercial OJ pasteurization conditions (i.e., 93 degrees C for 5 s, 88 degrees C for 15 s, and 82 degrees C for 30 s). Both methods were precise, reproducible, and potentially faster than traditional analytical procedures requiring enzymatic deconjugation and microbial assays.  相似文献   

Chemical composition and antifungal activity of essential oil of Chrysactinia mexicana gray   总被引：1，自引：0，他引：1  

Cárdenas-Ortega NC  Zavala-Sánchez MA  Aguirre-Rivera JR  Pérez-González C  Pérez-Gutiérrez S 《Journal of agricultural and food chemistry》2005,53(11):4347-4349

The chemical composition of the essential oil of Chysactinia mexicana was analyzed by gas chromatography-mass spectrometry. Seventeen compounds were characterized; eucalyptol (41.3%), piperitone (37.7%), and linalyl acetate (9.1%) were found as the major components. The essential oil of leaves and piperitone completely inhibited Aspergillus flavus growth at relatively low concentrations (1.25 and 0.6 mg/mL, respectively).  相似文献   

Procyanidin fractions from pine (Pinus pinaster) bark: radical scavenging power in solution, antioxidant activity in emulsion, and antiproliferative effect in melanoma cells     

Touriño S  Selga A  Jiménez A  Juliá L  Lozano C  Lizárraga D  Cascante M  Torres JL 《Journal of agricultural and food chemistry》2005,53(12):4728-4735

Pine (Pinus pinaster) bark is a rich source of procyanidin oligomers. From a total polyphenolic extract, we have generated fractions of different procyanidin composition. The mixtures, devoid of gallate esters, were active as free radical scavengers against ABTS(*+), DPPH, and HNTTM. Pine bark fractions were tested for antioxidant activity in solution (hydrogen donation and electron transfer) and emulsion (inhibition of lipid peroxidation) and compared with their galloylated counterparts from grape origin. While galloylation clearly influenced the free radical scavenging efficiency in solution, it did not seem to play a determinant role in protection against lipid peroxidation in emulsion. The fractions were very mild inhibitors of cell proliferation. Because gallate esters appear to interfere with crucial cell functions, gallate free pine procyanidins may be the innocuous chemopreventative agents of choice for many applications in food and skin protection.  相似文献   

Effect of storage temperature and water activity on the content and profile of isoflavones, antioxidant activity, and in vitro protein digestibility of soy protein isolates and defatted soy flours     

Pinto Mda S  Lajolo FM  Genovese MI 《Journal of agricultural and food chemistry》2005,53(16):6340-6346

The aim of this work was to study the effect of 1 year of storage at different temperatures and 1 month of storage at different water activities on the content and profile of isoflavones, antioxidant activity, and in vitro protein digestibility of defatted soy flours (DSF) and soy protein isolates (SPI). The storage for up to 1 year, at temperatures from -18 to 42 degrees C, had no effect on the total content of isoflavones, but the profile changed drastically at 42 degrees C, with a significant decrease of the percentage of malonylglucosides with a proportional increase of beta-glucosides. A similar effect was observed for SPI stored at a(w) = 0.87 for 1 month. For DSF, however, there was observed a great increase in aglycons (from 10 to 79%), probably due to the action of endogenous beta-glucosidases. The antioxidant activity decreased after storage at 42 degrees C, but the in vitro protein digestibility did not change.  相似文献   

Evaluation of the antioxidant capacity of individual phenolic compounds in virgin olive oil     

Carrasco-Pancorbo A  Cerretani L  Bendini A  Segura-Carretero A  Del Carlo M  Gallina-Toschi T  Lercker G  Compagnone D  Fernández-Gutiérrez A 《Journal of agricultural and food chemistry》2005,53(23):8918-8925

Virgin olive oil has a high resistance to oxidative deterioration due to its tryacylglycerol composition low in polyunsaturated fatty acids and due to the presence of a group of phenolic antioxidants composed mainly of polyphenols and tocopherols. We isolated several phenolic compounds of extra virgin olive oil (phenyl-ethyl alcohols, lignans, and secoiridoids) by semipreparative high-performance liquid chromatography (HPLC) and identified them using ultraviolet, atmospheric pressure chemical ionization, and electrospray ionization MS detection. The purity of these extracts was confirmed by analytical HPLC using two different gradients. Finally, the antioxidant capacity of the isolated compounds was evaluated by measuring the radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical, by accelerated oxidation in a lipid model system (OSI, oxidative stability instrument), and by an electrochemical method.  相似文献   

Effect of high-intensity pulsed electric fields processing and conventional heat treatment on orange-carrot juice carotenoids     

Torregrosa F  Cortés C  Esteve MJ  Frígola A 《Journal of agricultural and food chemistry》2005,53(24):9519-9525

Liquid chromatography (LC) was the method of choice for quantification of carotenoids (including geometrical isomers) to evaluate the effects of high-intensity pulsed electric field (HIPEF), a nonthermal preservation method, with different parameters (electric field intensities and treatment times), on an orange-carrot juice mixture (80:20, v/v). In parallel, a conventional heat treatment (98 degrees C, 21 s) was applied to the juice. HIPEF processing generally caused a significant increase in the concentrations of the carotenoids identified as treatment time increased. HIPEF treatment at 25 and 30 kV/cm provided a vitamin A concentration higher than that found in the pasteurized juice.  相似文献   

ITS1-rDNA-based methodology to identify world-wide hake species of the Genus Merluccius     

Pérez M  Vieites JM  Presa P 《Journal of agricultural and food chemistry》2005,53(13):5239-5247

Species-specific DNA-based tags are valuable tools for the management of both fisheries and commercial fish products. In this study, we have developed a two-step molecular tool to detect the presence of hake DNA (Merluccius spp.) and to identify the exact hake species present in an blind sample. The first test involves PCR amplification of an ITS1-rDNA fragment of 193 bp using nested primers that are interspecifically conserved in Merluccius spp. and Atlantic cod, Gadus morhua. The second test consists of the PCR amplification of a 602-659 bp DNA fragment spanning part of the ribosomal cluster 18S-ITS1-5.8S and digesting it with four restriction enzymes whose targets map at interspecifically nonconserved sites of the ITS1. Alternatively, the identification of hake species can be achieved by FINS or BLAST, using the nucleotide sequence of either the whole ITS1 sequence or its nested fragment of 193 bp. Because of their high reproducibility and ease of execution, these procedures allow for routine analysis and constitute high reliable tools for the rapid identification of 12 species of hake.  相似文献   

Validation of a semi-quantitative food-frequency questionnaire for use among adults in Guatemala     

Rodríguez MM  Méndez H  Torún B  Schroeder D  Stein AD 《Public health nutrition》2002,5(5):691-699

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