Biostimulanten maken opmars in de tuinbouw
Reinders, U. ; Wurff, A.W.G. van der - \ 2014
Kas Magazine / TuinbouwCommunicatie (2014)8. - ISSN 1878-8408 - p. 48 - 51.
gewasbescherming - ziektebestrijdende teeltmaatregelen - chemische bestrijding - gewaskwaliteit - wortelbehandeling - bacteriën - schimmels - mest - extracten - tuinbouw - plant protection - cultural control - chemical control - crop quality - root treatment - bacteria - fungi - manures - extracts - horticulture
Planten sterker maken waardoor ze beter bestand zijn tegen ziekten en plagen. Met dat doel worden biostimulanten of plantversterkers aan het wortelmilieu toegediend. Ze zijn sterk in opkomst, want ze vormen een alternatief voor chemische gewasbeschermingsmiddelen, waarvan het gebruik steeds meer onder druk komt te staan.
Efficient Purification of Ginkgolic Acids from Ginkgo biloba Leaves by Selective Adsorption of Fe3O4 Magnetic Nanoparticles
Li, R. ; Shen, Y. ; Zhang, X. ; Ma, M. ; Chen, B. ; Beek, T.A. van - \ 2014
Journal of Natural Products 77 (2014)3. - ISSN 0163-3864 - p. 571 - 575.
anacardic acids - 6-pentadecylsalicylic acid - shell liquid - acetoacetate - inhibition - apoptosis - extracts - quality - cells
Ginkgolic acids (GAs; anacardic acids; 6-alkylsalicylic acids) are both unwanted constituents in standardized Ginkgo biloba (Ginkgo) extracts and desirable constituents for pharmacological assays. Thus, for the quality control of Ginkgo extracts, the availability of pure GAs is important. In this investigation, inexpensive and easily prepared Fe3O4 magnetic nanoparticles (MNPs) in methanol were used to selectively adsorb GAs from crude petroleum ether extracts of Ginkgo leaves in the presence of various lipids including other alkylphenols (cardanols and cardols). The adsorption capacity of the MNPs is high, at 4–5% (w/w). The moiety responsible for the adsorption is the salicylic acid group, which binds strongly to Fe(III). Desorption with acidified methanol gave an extract with a GA content of 73%. This could be further separated by preparative HPLC on a C8 column. In total, eight different GAs were captured by MNPs. The MNP adsorption step can replace more traditional column chromatography and liquid–liquid extraction steps and is superior in terms of solvent consumption, selectivity, labor, and energy consumption. MNPs might become an efficient separation technique for selected high-value phytochemicals that contain a salicylic acid moiety.
MetIDB: A Publicly Accessible Database of Predicted and Experimental 1H NMR Spectra of Flavonoids
Mihaleva, V.V. ; Beek, T.A. te; Zimmeren, F. van; Moco, S.I.A. ; Laatikainen, R. ; Niemitz, M. ; Korhonen, S.P. ; Driel, M.A. van; Vervoort, J. - \ 2013
Analytical Chemistry 85 (2013)18. - ISSN 0003-2700 - p. 8700 - 8707.
hplc-spe-nmr - structural elucidation - information-system - mass-spectrometry - identification - constituents - ms - products - extracts
Identification of natural compounds, especially secondary metabolites, has been hampered by the lack of easy to use and accessible reference databases. Nuclear magnetic resonance (NMR) spectroscopy is the most selective technique for identification of unknown metabolites. High quality 1H NMR (proton nuclear magnetic resonance) spectra combined with elemental composition obtained from mass spectrometry (MS) are essential for the identification process. Here, we present MetIDB, a reference database of experimental and predicted 1H NMR spectra of 6000 flavonoids. By incorporating the stereochemistry, intramolecular interactions, and solvent effects into the prediction model, chemical shifts and couplings were predicted with great accuracy. A user-friendly web-based interface for MetIDB has been established providing various interfaces to the data and data-mining possibilities. For each compound, additional information is available comprising compound annotation, a 1H NMR spectrum, 2D and 3D structure with correct stereochemistry, and monoisotopic mass as well as links to other web resources. The combination of chemical formula and 1H NMR chemical shifts proved to be very efficient in metabolite identification, especially for isobaric compounds. Using this database, the process of flavonoid identification can then be significantly shortened by avoiding repetitive elucidation of already described compounds
Fast and Robust Method To Determine Phenoyl and Acetyl Esters of Polysaccharides by Quantitative 1H NMR
Neumüller, K.G. ; Carvalho de Souza, A. ; Rijn, J. van; Appeldoorn, M.M. ; Streekstra, H. ; Schols, H.A. ; Gruppen, H. - \ 2013
Journal of Agricultural and Food Chemistry 61 (2013)26. - ISSN 0021-8561 - p. 6282 - 6287.
acids - nmr - spectroscopy - extracts
The acetyl (AcE), feruloyl (FE), and p-coumaroyl (pCE) ester contents of different cereal and grass polysaccharides were determined by a quantitative 1H NMR-based method. The repeatability and the robustness of the method were demonstrated by analyzing different plant polysaccharide preparations. Good sensitivity and selectivity for AcE, FE, and pCE were observed. Moreover, an optimized and easy sample preparation allowed for simultaneous quantification of AcE, FE, and pCE. The method is suitable for high-throughput analysis, and it is a good alternative for currently used analytical procedures. A comparison of the method presented to a conventional HPLC-based method showed that the results obtained are in good agreement, whereas the combination of the optimized sample preparation and analysis by the 1H NMR-based methodology results in significantly reduced analysis time.
Phenolic compound contents and antioxidant activity in plants with nutritional and/or medicinal properties form the Peruvian Andean region
Chirinos, R. ; Pedreschi Plasencia, R.P. ; Rogez, H. - \ 2013
Industrial Crops and Products 47 (2013). - ISSN 0926-6690 - p. 145 - 152.
capacity - extracts - assay - profiles - leaves - fruits
Total phenolic compounds (TPC) and antioxidant activities using different assays (DPPH, ABTS and ORAC) in fruits, grains, leaves, seeds, roots and tubers from 27 different Peruvian Andean plants used in folk medicine or/and as food by the native population were evaluated in order to use these as natural antioxidant compounds. Total flavanoids (TFA), total flavonoids (TFO) and total anthocyanins (TA) were also determined. In general, the samples with the highest TPC values had the highest antioxidant activities. Leaves (e.g., Alnus acuminate, Clinopodium bolivianum, Lepechinia meyenii (Walp) and Mutisia acuminate), fruits (e.g., Sambucus peruviana), tubers (e.g., Tropaeolum tuberosum) and seed (e.g., Lupinus mutabilis) sparked attention due to their high TPC and antioxidant activities. Results from this study highlight the biodiversity of the Andean Region of Peru where plants with high TPC and antioxidant properties grow. Thus, these plants can be considered as promising sources of antioxidant phytochemicals.
Biologische grondontsmetting met Herbie (Bodemresetten)
Ludeking, D.J.W. ; Streminska, M.A. ; Hamelink, R. ; Wensveen, W. van; Groot, E.B. de - \ 2013
biologische grondontsmetting - organische stof - plantenplagen - alternatieve methoden - proeven op proefstations - chrysanthemum - extracten - werkzaamheid - biological soil sterilization - organic matter - plant pests - alternative methods - station tests - chrysanthemum - extracts - efficacy
Poster over biologische grondontsmetting met inzet van 'Herbie". In 2011 zijn goede resultaten behaald tegen wortelknobbelaaltjes ( Meloidogyne ) en Verticillium dahliae. In 10 dagen leverde bodemresetten een beter resultaat dan stomen. Telers geven aan dat er zekerheid, tijd, geld en bemesting een probleem vormen en daarmee een grootschalige toepassing in de weg staan. Daarom is in 2012 gekozen voor het ‘enten’ van Herbie met bedrijfseigen microbiologie (primer) voor toepassing. Doel is om de methode daarmee zeker, sneller en kosteneffectief te maken om een alternatief te laten zijn voor het conventionele stomen.
Recovery and concentration of phenolic compounds in blood orange juice by membrane operations
Destani, F. ; Cassano, A. ; Fazio, A. ; Vincken, J.P. ; Gebriele, B. - \ 2013
Journal of Food Engineering 117 (2013)3. - ISSN 0260-8774 - p. 263 - 271.
osmotic distillation - antioxidant activity - bioactive compounds - citrus flavonoids - anthocyanins - cancer - evaporation - inhibition - extracts - kinetics
Cross-flow ultrafiltration (UF) and osmotic distillation (OD) were implemented on laboratory scale to obtain formulations of interest for food and/or pharmaceutical industry starting from the blood orange juice produced in the Calabria region. The freshly squeezed juice, after a depectinization step, was submitted to an UF process in order to recover natural antioxidants, such as hydroxycinnamic acids, hydroxybenzoic acids, flavanones, flavan-3-ols, and anthocyanins. The UF permeate, with an initial total soluble solids (TSS) content of 10.5°Brix, was concentrated by OD up to a final concentration of 61.4°Brix. The performance of both processes was analyzed in terms of productivity (permeate fluxes in UF and evaporation fluxes in OD) and quality of clarified and concentrated samples through the identification and quantization of phenolic compounds. The UF membrane showed a rejection towards the identified phenolic compounds in the range 0.4–6.9% and a little decrease of the TAA (8.2%) was observed in the UF permeate in comparison with the fresh juice. Phenolic compounds were also well preserved in the retentate of the OD process as demonstrated by the constant value of the ratio between the concentration of phenolic compounds in the OD retentate and the concentration of these compounds in the UF permeate stream (in the range 5.54–6.39).
Virulence of ‘Dickeya solani’ and Dickeya dianthicola biovar-1 and -7 strains on potato (Solanum tuberosum)
Czajkowski, R.L. ; Boer, W.J. de; Zouwen, P.S. van der; Kastelein, P. ; Jafra, S. ; Haan, E.G. de; Bovenkamp, G.W. van den; Wolf, J.M. van der - \ 2013
Plant Pathology 62 (2013)3. - ISSN 0032-0862 - p. 597 - 610.
soft-rot erwinias - carotovora subsp atroseptica - plant-pathogenic bacteria - host-range - pectobacterium - israel - extracts
Studies were conducted to explain the relative success of ‘Dickeya solani’, a genetic clade of Dickeya biovar 3 and a blackleg-causing organism that, after recent introduction, has spread rapidly in seed potato production in Europe to the extent that it is now more frequently detected than D. dianthicola. In vitro experiments showed that both species were motile, had comparable siderophore production and pectinolytic activity, and that there was no antagonism between them when growing. Both ‘D. solani’ and biovar 1 and biovar 7 of D. dianthicola rotted tuber tissue when inoculated at a low density of 103 CFU mL-1. In an agar overlay assay, D. dianthicola was susceptible to 80% of saprophytic bacteria isolated from tuber extracts, whereas ‘D. solani’ was susceptible to only 31%, suggesting that ‘D. solani’ could be a stronger competitor in the potato ecosystem. In greenhouse experiments at high temperatures (28°C), roots were more rapidly colonized by ‘D. solani’ than by biovar 1 or 7 of D. dianthicola and at 30 days after inoculation higher densities of ‘D. solani’ were found in stolons and progeny tubers. In co-inoculated plants, fluorescent protein (GFP or DsRed)-tagged ‘D. solani’ outcompeted D. dianthicola in plants grown from vacuum-infiltrated tubers. In 3 years of field studies in the Netherlands with D. dianthicola and ‘D. solani’, disease incidence varied greatly annually and with strain. In summary, ‘D. solani’ possesses features which allow more efficient plant colonization than D. dianthicola at high temperatures. In temperate climates, however, tuber infections with ‘D. solani’ will not necessarily result in a higher disease incidence than infections with D. dianthicola, but latent seed infection could be more prevalent
Eikenprocessierups op verkeerde spoor
Bergervoet, J.H.W. ; Raaij, H.M.G. van; Stevens, L.H. - \ 2012
[S.l.] : YouTube
thaumetopoea processionea - quercus - plantenplagen - plagenbestrijding - natuurlijke producten - biologische bestrijding - extracten - gedrag - innovaties - landbouwkundig onderzoek - thaumetopoea processionea - quercus - plant pests - pest control - natural products - biological control - extracts - behaviour - innovations - agricultural research
Eenvoudig, milieuvriendelijk en goedkoop de eikenprocessierups bestrijden. Dat komt dichterbij nu onderzoekers van Plant Research International (PRI), onderdeel van Wageningen UR, een natuurproduct hebben gevonden waarmee de rupsen om de tuin geleid kunnen worden. In samenwerking met gemeenten en groenbeheerders moet verder onderzoek uitwijzen welke stoffen voor deze reactie zorgen en hoe ze geproduceerd kunnen worden. De verwachting is dat dit onderzoek twee jaar zal duren. Deze film is gemaakt doorJan Bergervoet. Deze film hoort bij het persbericht van Wageningen UR die op 13 november 2012 verschenen is onder de titel: Wageningse onderzoekers leiden eikenprocessierups om de tuin. Voor meer informatie zie de website: www.wageningenur.nl/eikenprocessierups
An on-line high performance liquid chromatography-crocin bleaching assay for detection of antioxidants
Bountagkidou, O. ; Klift, E.J.C. van der; Tsimidou, M.Z. ; Ordoudi, S.A. ; Beek, T.A. van - \ 2012
Journal of Chromatography. A, Including electrophoresis and other separation methods 1237 (2012). - ISSN 0021-9673 - p. 80 - 85.
radical scavenging compounds - chemiluminescence detection - natural antioxidants - complex-mixtures - identification - capacity - extracts - inhibition - plant
An on-line HPLC (high performance liquid chromatography) method for the rapid screening of individual antioxidants in mixtures was developed using crocin as a substrate (i.e. oxidation probe) and 2,2'-azobis(2-amidinopropane dihydrochloride (AAPH)) in phosphate buffer (pH 7.5) as a radical generator. The polyene structure of crocin and AAPH-derived peroxyl radicals resemble the lipidic substrates and radicals found in true food more closely than the popular, albeit artificial, DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS+ (2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate)) do. After separation by a C18 (octadecyl silica) column and UV (ultraviolet) detection, antioxidative analytes react with peroxyl radicals at 90 °C and the inhibition of crocin oxidation (i.e. bleaching) is detected as a positive peak by an absorbance detector at 440 nm. The method is simple, uses standard instruments and inexpensive reagents. It can be applied for isocratic HPLC runs using mobile phases containing 10–90% organic solvent in water, weak acids or buffers (pH 3.5–8.5). With baseline correction, gradient runs are also feasible. The radical scavenging activity of several natural antioxidants and a green tea extract was studied. After optimisation of conditions such as reagent concentrations and flows, the limit of detection varied from 0.79 to 7.4 ng, depending on the antioxidant. --------------------------------------------------------------------------------
Speciation of Se and DOC in soil solution and their relation to Se bioavailability.
Weng, L.P. ; Vega, F.A. ; Supriatin, S. ; Bussink, W. ; Riemsdijk, W.H. van - \ 2011
Environmental Science and Technology 45 (2011)1. - ISSN 0013-936X - p. 262 - 267.
donnan membrane technique - ion-chromatography - selenium uptake - trace-metals - extracts - translocation - spectrometry - adsorption - sorption - samples
A 0.01 M CaCl2 extraction is often used to asses the bioavailability of plant nutrients in soils. However, almost no correlation was found between selenium (Se) in the soil extraction and Se content in grass. The recently developed anion Donnan membrane technique was used to analyze chemical speciation of Se in the 0.01 M CaCl2 extractions of grassland soils and fractionation of DOC (dissolved organic carbon). The results show that most of Se (67-86%) in the extractions (15 samples) are colloidal-sized Se. Only 13-34% of extractable Se are selenate, selenite and small organic Se (
Direct photothermal techniques for quantification of anthocyanins in sour cherry cultivars
Doka, O. ; Ficzek, G. ; Bicanic, D.D. ; Spruijt, R.B. ; Luterotti, S. ; Toth, M. ; Buijnsters, J.G. ; György Végvári, G. - \ 2011
Talanta 84 (2011)2. - ISSN 0039-9140 - p. 341 - 346.
cancer prevention - prunus-cerasus - tart cherry - l. - antioxidant - flavonoids - extracts - rat - ldl
The analytical performance of the newly proposed laser-based photoacoustic spectroscopy (PAS) and of optothermal window (OW) method for quantification of total anthocyanin concentration (TAC) in five sour cherry varieties is compared to that of the spectrophotometry (SP). High performance liquid chromatography (HPLC) was used to identify and quantify specific anthocyanins. Both, PAS and OW are direct methods that unlike SP and HPLC obviate the need for the extraction of analyte. The outcome of the study leads to the conclusion that PAS and OW are both suitable for quick screening of TAC in sour cherries. The correlation between the two methods and SP is linear with R2 = 0.9887 for PAS and R2 = 0.9918 for OW, respectively. Both methods are capable of the rapid determination of TAC in sour cherries without a need for a laborious sample pretreatment.
Isolation of antioxidative secoiridoids from olive wood (Olea europaea L.) guided by on-line HPLC-DAD-radical scavenging detection
Pérez-Bonilla, M. ; Salido, S. ; Beek, T.A. van; Waard, P. de; Linares-Palomino, P.J. ; Sánchez, A. ; Altarejos, J. - \ 2011
Food Chemistry 124 (2011)1. - ISSN 0308-8146 - p. 36 - 41.
liquid-chromatography - natural antioxidants - jasminum polyanthum - phenolic-compounds - mill wastewaters - by-products - glucosides - identification - extracts - plants
The woody portion of olive tree pruning is a source of natural antioxidants of potential interest for the food industry. This work deals with the isolation and identification of further antioxidants present in an ethyl acetate extract of olive (Olea europaea L.) wood. Thus, a new secoiridoid, oleuropein-3¿-methyl ether (1), together with six known secoiridoids, 7¿S-hydroxyoleuropein (2), jaspolyanoside (3), ligustroside 3'-O-ß-d-glucoside (4), jaspolyoside (5), isojaspolyoside A (6) and oleuropein 3'-O-ß-d-glucoside (7) were isolated by combining HPLC with fast on-line post-column radical scavenging activity evaluation. The structures of these compounds were determined by spectroscopic methods. The antioxidant activity of the pure compounds was determined by measuring the radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Compounds 2, 5 and 7 displayed a higher antioxidative effect than the synthetic antioxidant BHT and lower than rosmarinic acid, whereas compounds 3 and 4 showed weak DPPH scavenging activity.
Isolation, identification and activity of natural antioxidants from costmary (Chrysanthemum balsamita) cultivated in Lithuania
Pukalskas, A. ; Venskutonis, P.R. ; Dijkgraaf, I. ; Beek, T.A. van - \ 2010
Food Chemistry 122 (2010)3. - ISSN 0308-8146 - p. 804 - 811.
radical scavenging compounds - chlorogenic acid isomers - liquid-chromatography - caffeic acid - online - plants - l. - derivatives - extracts - phenols
The sweet, minty-lemony leaves of costmary (Chrysanthemum balsamita) are used for salads and tea, and as flavourings in meats, sausages, cakes and ale. In this study, the extracts isolated from costmary aerial parts were investigated as antioxidants in rapeseed oil and as free radical-scavengers in DPPH and ABTS(+) assays. It was found that costmary extracts and their fractions were weak antioxidants in rapeseed oil; however, some fractions were active in scavenging synthetic free radicals. Crude methanol-water extract, its tertbutyl methyl ether and butanol fractions were the most effective in DPPH assay by scavenging 87.0%, 86.9% and 86.4% of radicals present in the reaction, respectively. Several active compounds were detected in these fractions, using HPLC with on-line radical-scavenging detection. After multi-step fractionation of these fractions, four radical-scavenging constituents were isolated and their properties were assessed by DPPH (antiradical power, ARP, calculated as an inverse value of the effective concentration, 1/EC50) and ABTS(+) (Trolox equivalent antioxidant capacity, TEAC(6min)) free radical-scavenging assays. The following structures were elucidated by NMR and MS: 5-O-caffeoylquinic acid (ARP = 3.85: TEAC(6min) = 0.60), 3,5-O-dicaffeoylquinic acid (ARP = 6.25: TEAC(6min) = 1.16), 5,7,4'-trihydroxy-3',8-dimethoxyflavone (ARP = 0.03) and 5,7,3',4'-tetrahydroxy-3,8-dimethoxyflavonol (ARP = 3.79; TEAC(6min) = 1.50).
Isotopic analysis of dissolved organic nitrogen in soils
Ros, G.H. ; Temminghoff, E.J.M. ; Groenigen, J.W. van - \ 2010
Analytical Chemistry 82 (2010)18. - ISSN 0003-2700 - p. 7814 - 7820.
inorganic nitrogen - persulfate oxidation - microbial biomass - diffusion methods - n-15 analysis - amino-acids - mason jars - extracts - nitrate - water
Determination of the isotopic signature of dissolved organic nitrogen (DON) is important to assess its dynamics in terrestrial ecosystems. Analysis of 15N-DON, however, has been hindered by the lack of simple, reliable, and established methods. We evaluate three off-line techniques for measuring the 15N signature of DON in the presence of inorganic N using a persulfate digestion followed by microdiffusion. The 15N-DON signature is calculated from the difference between total dissolved 15N (15N-TDN) and inorganic 15N. We quantified the 15N recovery and signature of DON, NH4+, and NO3- in a series of inorganic N/DON mixtures (with a TDN concentration of 10 mg N L-1) for three lab protocols. Phenylalanine was used as a model compound for DON. The best lab protocol determined the concentration of inorganic N and TDN prior to diffusion using improved spectrophotometric techniques. An accuracy of 88% for 15N-DON should be routinely possible; coefficient of variation was
High molecular weight glucan of the culinary medicinal mushroom Agaricus bisporus is an a-glucan that forms complexes with low molecular weight galactan
Smiderle, F. ; Sassaki, G.L. ; Arkel, J. van; Lacomini, M. ; Wichers, H.J. ; Griensven, L.J.L.D. van - \ 2010
Molecules 15 (2010)8. - ISSN 1420-3049 - p. 5818 - 5830.
beta-glucans - flammulina-velutipes - edible mushroom - in-vitro - polysaccharide - pleurotus - extracts - glycogen - purification - spectroscopy
An a-glucan was isolated from the culinary medicinal mushroom A. bisporus by hot water extraction, ethanol precipitation and DEAE-cellulose chromatography. The resulting material showed a single HMW peak excluded from a Sephadex G50 column that could completely be degraded by a-amylase treatment. After heating in 1% SDS a small additional peak of low MW eluted from the G50 column. The monosaccharide composition of the main peak was evaluated by HPLC, and was found to consist of a majority of glucose (97.6%), and a minor proportion of galactose (2.4%). Methylation analysis and degradation by a-amylase indicated the presence of an a-glucan with a main chain consisting of (1®4)-linked units, substituted at O-6 by a-D-glucopyranose single-units in the relation 1:8. Mono- (13C-, 1H-NMR) and bidimensional [1H (obs.),13C-HSQC] spectroscopy analysis confirmed the a-configuration of the Glcp residues by low frequency resonances of C-1 at d 100.6, 100.2, and 98.8 ppm and H-1 high field ones at d 5.06, 5.11, and 4.74 ppm. The DEPT-13C-NMR allowed assigning the non-substituted and O-substituted –CH2 signals at d 60.3/60.8 and 66.2 ppm, respectively. Other assignments were attributed to C-2, C-3, C-4, C-5 and C-6 of the non-reducing ends at d 71.8; 72.8; 70.0; 71.3 and 60.3/60.8 ppm, respectively. The minor proportion of galactose that was demonstrated was probably derived from a complex between the a-glucan and a low molecular weight galactan
Culinary-medicinal mushrooms: must action be taken?
Griensven, L.J.L.D. van - \ 2009
International Journal of Medicinal Mushrooms 11 (2009)3. - ISSN 1521-9437 - p. 281 - 286.
agaricus-bisporus - fungal metabolites - cancer-therapy - extracts - immunochemotherapy - polysaccharides
In the Western world, the mushroom industry suffers from overproduction. Expectations are stronger than reality, and as a result, production is too high and prices are too low. Because bulk production has taken the lead, which not only happens in the West, overproduction occurs regularly. Low pricing influences the quality concept of consumers and hence their appreciation of mushrooms. This cannot continue without doing great harm to the socioeconomic structure of the industry. Therefore, measures have to be taken to introduce mushrooms as a true health food in the Western world. This may form a first step in the acceptance of mushroom extracts and mushroom-derived compounds as medicine in the prevention and cure of disease. The present review discusses the acceptance of mushrooms as health food and medicine and suggests pathways for necessary action
An on-line normal-phase high performance liquid chromatography method for the rapid detection of radical scavengers in non-polar food matrixes
Zhang, Q. ; Klift, E.J.C. van der; Janssen, H.G. ; Beek, T.A. van - \ 2009
Journal of Chromatography. A, Including electrophoresis and other separation methods 1216 (2009)43. - ISSN 0021-9673 - p. 7268 - 7274.
antioxidant capacity - tocopherols - plant - oils - galvinoxyl - products - extracts - phenols - assays
An on-line method for the rapid pinpointing of radical scavengers in non-polar mixtures like vegetable oils was developed. To avoid problems with dissolving the sample, normal-phase chromatography on bare silica gel was used with mixtures of hexane and methyl tert-butyl ether as the eluent. The high performance liquid chromatography-separated analytes are mixed post-column with a solution of stable free radicals in hexane. Reduced levels of the radical as a result of a reaction with a radical scavenger are detected as negative peaks by an absorbance detector. After investigating a number of different reagents, solvents, concentrations and solution flow rates an optimized instrumental set-up incorporating a superloop for pulse-free delivery of the reagent solution is presented. Both 2,2’-diphenyl-1-picrylhydrazyl (DPPH) and 2,6-di-tert-butyl-a-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-p-tolyloxy (galvinoxyl) were used as stable free radicals. The method is suitable for both isocratic and gradient HPLC operation. The method has a simple experimental protocol, uses standard instruments and inexpensive and stable reagents, and accepts any hexane-soluble sample. It can also be used for semi-quantitative analysis. The method was applied to several pure, non-polar natural antioxidants, vegetable oils and lipid-soluble rosemary extract. The limits of detection varied from 0.2 to 176 µg/ml, depending on the compound tested.
Microbial fermented tea - a potential source of natural food preservatives
Mo, H.Z. ; Yang Zhu, Yang ; Chen, Z.M. - \ 2008
Trends in Food Science and Technology 19 (2008)3. - ISSN 0924-2244 - p. 124 - 130.
pu-erh tea - solid-state fermentation - antimicrobial activity - kombucha fermentation - fungus metabolites - oxidative damage - polyphenols - catechins - extracts - beverage
Antimicrobial activities of microbial fermented tea are much less known than its health beneficial properties. These antimicrobial activities are generated in natural microbial fermentation process with tea leaves as substrates. The antimicrobial components produced during the fermentation process have shown inhibitory effects against several food-borne and pathogenic bacteria. With the trend of increasing use of natural and biological preservatives in food products, natural antimicrobial agents from microbial fermented tea may offer an innovative and interesting measure for such applications. However, a breakthrough in this field can only be realised after several critical aspects are clarified and further studied. Only then, the application of these potential, novel and natural antimicrobial substances from microbial fermented tea can be industrialized. The present review describes some unique microbial fermentation of tea and the antimicrobial activities formed during the fermentation process. Moreover, future needs in research and development of these antimicrobial compounds from microbial fermentation of tea are discussed for potential industrial applications.
Culicoides species attracted to horses with and without insect hypersensitivity
Rijt, R. van der; Boom, R. van den; Jongema, Y. ; Sloet van Oldruitenborgh-Oosterbaan, M.M. - \ 2008
The Veterinary Journal 178 (2008)1. - ISSN 1090-0233 - p. 91 - 97.
sweet-itch - intradermal challenge - icelandic horses - british-columbia - ceratopogonidae - diptera - extracts - trap - dermatitis - mosquitos
The aims of this study were to determine (1) which species of Culicoides is most commonly attracted to horses, (2) whether horses suffering insect hypersensitivity attract more Culicoides spp. than unaffected horses, and (3) the times when Culicoides spp. are most active. Horses affected by insect hypersensitivity and unaffected horses were placed inside mosquito netting tents for 30 min at different times of the day. All Culicoides spp. trapped inside the tents were collected and identified. C. obsoletus was the most common species found, followed by C. pulicaris. Healthy horses attracted slightly more midges than horses that were affected with insect hypersensitivity. All of the Culicoides species were most active at sunset, less so at sunrise and very few or no midges were trapped in the afternoon or at night.