Testen van stoffen met een mogelijk afwerende werking op trips
Pijnakker, J. ; Leman, A. - \ 2014
Bleiswijk : Wageningen UR Glastuinbouw (Rapport / Wageningen UR Glastuinbouw 1325) - 22
frankliniella occidentalis - plantenplagen - waardplanten - etherische oliën - insectenplagen - lokstoffen - vangmethoden - proeven - frankliniella occidentalis - plant pests - host plants - essential oils - insect pests - attractants - trapping - trials
Secundaire plantenstoffen, zoals essentiële oliën, hebben het vermogen om te interfereren met het selectieproces van een geschikte waardplant door een plaaginsect. In het eerste gedeelte van dit verslag worden de resultaten beschreven van laboratorium- en kasproeven waarin een aantal mogelijk afwerende plantenstoffen zijn getest tegen Californische trips (Frankliniella occidentalis). In het tweede gedeelte van dit verslag is aandacht besteed aan de extrinsieke en intrinsieke factoren die de werking van de commercieel verkrijgbare lokstof Lurem-TR op Californische trips kunnen beïnvloeden
Physiologically based biokinetic (PBBK) models to characterize dose dependent effects, species differences, and interindividual human variation and detoxification of estragole
Punt, A. - \ 2009
Wageningen University. Promotor(en): Ivonne Rietjens; Peter van Bladeren, co-promotor(en): B. Schilter. - [S.l.] : s.n. - ISBN 9789085853718 - 251
toxiciteit - soortverschillen - metabolische detoxificatie - etherische oliën - risicoschatting - carcinogenese - toxicity - species differences - metabolic detoxification - essential oils - risk assessment - carcinogenesis - cum laude
cum laude graduation (with distinction)
Proceedings of the 2nd international symposium on natural preservatives in food, feed, and cosmetics : Amsterdam, the Netherlands, June 7-8, 2006
Havkin-Frenkel, D. ; Dudai, N. ; Mheen, H.J.C.J. van der - \ 2008
Leuven : International Society for Horticultural Science (Acta horticulturae 778) - ISBN 9789066057302 - 110
conserveermiddelen - voedselconserveermiddelen - voer - cosmetica - natuurlijke producten - medicinale planten - antioxidanten - etherische oliën - aromatische gewassen - preservatives - food preservatives - feeds - cosmetics - natural products - medicinal plants - antioxidants - essential oils - aromatic plants
Uitgangsmateriaal & veredeling : beheersing van zilverschurft bij (biologische) aardappelen
Hospers-Brands, M. ; Bus, C.B. - \ 2007
[S.l.] : S.n. - 6
aardappelen - bewaarziekten - helminthosporium solani - schimmelziekten - ziektebestrijdende teeltmaatregelen - etherische oliën - thymus - knoflook - compost - potatoes - storage disorders - helminthosporium solani - fungal diseases - cultural control - essential oils - thymus - garlic - composts
Zilverschurft is een knolziekte die zich in haar verschijningsvorm vooral tijdens de bewaring openbaart en ontwikkelt. Als gevolg daarvan vormt zilverschurft een ernstig cosmetisch probleem in zowel poot- als consumptieaardappelen. Zilverschurft wordt veroorzaakt door een schimmel, Helminthosporium solani. In de biologische pootgoedsector is op dit moment geen effectieve methode voorhanden om deze infectieroute te voorkomen of te beperken. Om de besmettingpotentie van de moederknollen te reduceren moet de schimmel ofwel tijdens de bewaring worden bestreden, ofwel moet de sporenvorming na het poten worden voorkomen.
|Dompelen of gassen werken goed tegen tulpengalmijt
Conijn, C.G.M. ; Lans, A.M. van der - \ 2007
BloembollenVisie 2007 (2007)118. - ISSN 1571-5558 - p. 23 - 23.
tulpen - bloembollen - koudeopslag - forceren van planten - aceria tulipae - aceria - bestrijdingsmethoden - dompelen - etherische oliën - plagenbestrijding - biologische bestrijding - gewasbescherming - tulips - ornamental bulbs - cold storage - forcing - aceria tulipae - aceria - control methods - dipping - essential oils - pest control - biological control - plant protection
Geen uitval meer door tulpengalmijt bij de bewaring en broeierij van tulpen lijkt ook in de toekomst mogelijke door nieuwe alternatieven. Een boldompeling kort na het rooien in en contactmiddel of verdampen van een etherische olie voorkwam tulpengalmijt aantasting in proeven bij PPO Bloembollen. Deze middelen en methoden kunnen in de toekomst mogelijk een volwaardig alternatief zijn voor het nu enige voor dit doel toegelaten middel Actellic
Bulk, R.W. van den; Groot, S.P.C. - \ 2005
Biologisch Onderzoek Bericht (BOB) 26 (2005). - p. 1 - 2.
biologische landbouw - zaadkwaliteit - zaadreinigers - thymus vulgaris - etherische oliën - stoom - zaadbehandeling - zaadproductie - organic farming - seed quality - seed cleaners - thymus vulgaris - essential oils - steam - seed treatment - seed production
Dit biologisch onderzoekbericht laat enkele resultaten en plannen zien van het onderzoeksprogramma Biologisch uitgangsmateriaal, dat van 2005 tot en met 2007 loopt. Een Zweedse sauna om zaad te ontsmetten of een bad met thijmolie lijken succesvol.Het programma gaat in nauwe samenwerking met de sector werken aan gezonder uitgangsmateriaal voor de biologische sector.
Etherische oliën als alternatief voor conventionele fungiciden
Griepink, F.C. ; Cegiela-Carlioz, P. ; Förch, M.G. ; Bouwmeester, H.J. - \ 2005
gewasbescherming - fungiciden - plantenziekteverwekkende schimmels - schimmelbestrijding - etherische oliën - plantaardige oliën - kaneel - onderzoeksprojecten - biobased economy - plant protection - fungicides - plant pathogenic fungi - fungus control - essential oils - plant oils - cinnamon - research projects - biobased economy
Plant Research International heeft 200 commercieel verkrijgbare essentiële oliën getest op hun effect op drie belangrijke plaagschimmels: Botrytis elliptica, Phytophthora infestans and Pythium aphanidermatum. Dit onderzoek moet uitwijzen of etherische oliën in bepaalde toepassingen een alternatief kunnen zijn voor de nu toegepaste conventionele fungiciden.
Quality, energy requirement and costs of drying tarragon (Artemisia dracunculus L)
ArabHosseini, A. - \ 2005
Wageningen University. Promotor(en): J. Mueller, co-promotor(en): W. Huisman; Ton van Boxtel. - Wageningen : - ISBN 9789085042976 - 115
dragon - artemisia dracunculus - energieproductiekosten - drogen - voedselbewaring - droogkwaliteit - luchtdroging - extractie - etherische oliën - keukenkruiden - medicinale planten - iran - nederland - tarragon - artemisia dracunculus - energy cost of production - drying - food preservation - drying quality - air drying - extraction - essential oils - culinary herbs - medicinal plants - iran - netherlands
Tarragon ( Artemisia dracunculus L.) is a favorite herbal and medicinal plant. Drying is necessary to achieve longer shelf life with high quality, preserving the original flavor. Essential oil content and color are the most important parameters that define the quality of herbal and medicinal plants. Hot air batch drying is the most common drying method for these plants but affects the essential oil content and color. The drying conditions affect essential oil content and color as well as the energy consumption and costs. Process engineers and farmers need to know how they have to dry to obtain the best quality. The objective of this work is to investigate the conditions for optimal drying in terms of quality, energy consumption and costs.
Adsorption and desorption experiments were done to find the equilibrium moisture content and water exchange between the material and surrounding air during drying and storage at temperatures of 25ºC to 70ºC and relative humidities of 5% to 90%. Drying of tarragon leaves and chopped plants was investigated separately and the best model was selected from the drying equations in literature. The effect of drying temperature and relative humidity on the essential oil content and color change was studied. Experiments were done at temperatures of 40ºC to 90ºC and the optimal conditions were. Long‑term effects of the drying conditions were also investigated during the storage time. Material dried at 45, 60 and 90ºC was stored and the essential oil content and color of the material was measured after 15, 30, 60 and 120 days of storage. Drying at 45ºC was found as the best condition based on the changes of essential oil and color during drying and storage.
Optimization of drying of tarragon was studied based on the results of the sorption isotherms, drying equations and the changes of essential oil content and color during drying and storage. Models were made for the drying process, energy consumption and cost calculation. The current conditions in The Netherlands and
Repellence and toxicity of plant essential oils to the potato aphid, Macrosiphum euphorbiae
Munneke, M.E. ; Bruin, A. de; Moskal, J.R. ; Tol, R.W.H.M. van - \ 2004
In: Proceedings of the section Experimental and Applied Entomology of the Netherlands Entomological Society (NEV). - Amsterdam : Nederlandse Entomologische Vereniging (NEV) - ISBN 9789071912252 - p. 81 - 85.
plantenplagen - macrosiphum euphorbiae - insectenpathogenen - etherische oliën - insectenafweermiddelen - plant pests - macrosiphum euphorbiae - entomopathogens - essential oils - insect repellents
Several plant essential oils were tested for their effect on behaviour and mortality of M. euphorbiae. Olfactory and contact experiments were performed to study these effects. We found that host plant and formulation of the different oils have a strong influence on repellence and mortality of the aphids. Three out of ten tested oils show potential for control of this aphid in greenhouses and field crops
Gewasbeschermingsmiddelen van natuurlijke oorsprong voor behandeling van biologisch zaad
Wolf, J.M. van der; Birnbaum, Y.E. - \ 2003
zaadbehandeling - gewasbescherming - plantenziektebestrijding - etherische oliën - fytochemicaliën - natuurlijke producten - biologische zaden - seed treatment - plant protection - plant disease control - essential oils - phytochemicals - natural products - organic seeds
Poster met onderzoeksresultaten: In de biologische landbouw wordt gezocht naar fysische methoden en gewasbeschermingsmiddelen van natuurlijke oorsprong (GNO’s) waarmee effectief zaadovergaande ziekteverwekkers op het zaad kunnen worden bestreden. Hierna kan het gedesinfecteerde zaad effectief worden gecoat met antagonisten. We laten hier de effectiviteit van tijmolie zien voor bestrijding van bacteriën en schimmels op zaad.
Use of controlled atmospheres to enhance essential oil fumigant toxicity against Western Flower Thrips, Frankliniella occidentalis
Woltering, E.J. ; Janmaat, A.F. ; Kogel, W.J. de; Oosterhaven, J. ; Peppelenbos, H.W. - \ 2003
Acta Horticulturae 600 (2003). - ISSN 0567-7572 - p. 155 - 159.
gasbewaring - bloemen - frankliniella occidentalis - thrips - opgeslagen producten - fumigeermiddelen - etherische oliën - controlled atmosphere storage - flowers - frankliniella occidentalis - thrips - stored products - fumigants - essential oils
The fumigant toxicity of selected essential oils was assessed against the Western Flower Thrips, Frankliniella occidentalis. Adult females and larvae were exposed to combinations of essential oil doses and increased carbon dioxide and decreased oxygen levels. Application of such combinations were found to significantly increase the fumigant toxicity against thrips. An increase in exposure time also led to an increase in mortalities in both essential oil alone and combined treatments. These results indicate that by combining applications of the essential oils with e.g. moderately increased carbon dioxide levels (2 to 10%), it may be possible to achieve toxicity levels similar to those of standard chemical fumigants
Crina Piglets als alternatief voor AMGB's bij gespeende biggen
Krimpen, M.M. van; Lierop, A.H.A.A.M. van; Binnendijk, G.P. - \ 2003
Lelystad : Praktijkonderzoek Veehouderij (Praktijkboek / Praktijkonderzoek Veehouderij : Varkens 23) - 14
biggen - spenen - groeibevorderaars - antimicrobe-eigenschappen - diervoedering - etherische oliën - experimenten - piglets - weaning - growth promoters - antimicrobial properties - animal feeding - essential oils - experiments
In de veehouderij maakt men op dit moment veelvuldig gebruik gemaakt van antimicrobiële groeibevorderaars (AMGB's) in voeders voor landbouwhuisdieren. Het gebruik van AMGB's wordt vanaf 2005 wellicht volledig verboden, omdat het gebruik van antibiotica resistentie van bacteriepopulaties tot gevolg kan hebben. Met dit vooruitzicht is de mengvoersector bezig met het ontwikkelen van voerconcepten als alternatief voor AMGB's. In opdracht van bedrijf Crina s.a. (Gland, Zwitserland) is op het Praktijkcentrum Sterksel nagegaan wat het effect is van de etherische olie Crinae Piglets als alternatief voor AMGB's op technische resultaten en gezondheid van gespeende biggen. In dit experiment zijn drie proefbehandelingen met elkaar vergeleken: voer zonder AMGB, voer met AMGB en voer met Crinae Piglets. Op een leeftijd van gemiddeld 4 weken zijn de biggen gespeend en ingedeeld voor de proef. De biggen zijn vanaf spenen 34 dagen gevolgd. In totaal zijn 630 biggen gevolgd. De behandelingen zonder en met AMGB zijn elk 22 keer herhaald, de behandeling met Crinae Piglets 19 keer.
Listeria monocytogenes - inactivation by essential oils and high pressure, and contribution of genetic variation to stress resistance
Karatzas, K.A.G. - \ 2002
Wageningen University. Promotor(en): F.M. Rombouts; M.H.J. Bennik. - S.l. : S.n. - ISBN 9789058086303 - 86
voedselmicrobiologie - listeria monocytogenes - inactivatie - etherische oliën - druk - genetische variatie - stressreactie - food microbiology - listeria monocytogenes - inactivation - essential oils - pressure - genetic variation - stress response
A variety of non-thermal mild preservation techniques have lately been introduced in food production, or are currently being investigated thoroughly for potential use in food processing. Two of these novel preservation techniques are the use of essential oil compounds isolated from plants and of High Hydrostatic Pressure (HHP) treatment. Applications of these preservation methods, alone or combined, have shown to reduce the viable numbers of microorganisms occurring in foods, and in addition, are able to preserve the nutritional and sensory characteristics of the product. The objectives of this thesis were to asses the antimicrobial potential of these combined processing techniques against the foodborne bacterium Listeria monocytogenes , which can cause serious disease with a relatively high mortality rate. In addition, to get more insight in the primary cellular targets that are affected upon HHP treatment of L. monocytogenes , we examined the mechanism underlying increased HHP tolerance of an isolate of this organism.
Chapter 1gives a short introduction on L. monocytogenes. Furthermore, mild and novel preservation techniques in food processing are addressed, with special emphasis on the use of essential oil compounds from plants, and the use of High Hydrostatic Pressure (HHP). General characteristics and the mode of action of these preservation techniques are described, followed by resistance mechanisms that bacteria use to counteract their potentially lethal action. This chapter is concluded with the combined use of these preservation methods, and an outline of this thesis.
In Chapter 2 , it is demonstrated that various plant-derived volatiles, namely, S-carvone, carvacrol, cinnamaldehyde, thymol, and decanal, have the ability to reduce the viable numbers of L. monocytogenes if used in combination with mild heat treatment, while these treatments alone were not affecting the viability of this pathogen. These findings show that essential oil compounds can play an important role in minimally processed foods, and can be used in the concept of Hurdle Technology to reduce the intensity of heat treatment or possibly other individual hurdles.
In Chapter 3 , the combined antimicrobial action of carvacrol or thymol in combination with HHP was investigated at different temperatures. These treatments showed a synergistic action, with greater antimicrobial effects upon pressurisation at 1 oC than at 8°C or 20°C. Furthermore, addition of carvacrol to cells after exposure to sub-lethal HHP treatment showed reductions in viable numbers that were similar to those using simultaneous treatment with carvacrol and HHP. Synergism was also observed between carvacrol and HHP in semi-skimmed milk that was artificially contaminated with L. monocytogenes . The study demonstrates the synergistic antimicrobial effect of essential oils in combination with HHP. Together with the results described in Chapter 2, these data indicate the potential of essential oils to be employed in food processing if combined with other techniques.
A major problem that successful application of HHP treatment faces is the variable piezotolerance of bacterial species, strains within a species, and even cells within pure cultures that are not homogenous. In Chapter 4 , we investigated the characteristics of a L. monocytogenes ScottA isolate, named AK01, that was derived from a wild type (wt) culture after a single pressurisation treatment. The survival of exponential and stationary phase cells of AK01 was at least 2 logs higher than that of the wt over a broad range of pressures (150-500 MPa), while both strains showed higher piezotolerance in the stationary than in the exponential phase of growth. In semi-skimmed milk, exponential phase cells of both strains showed lower reductions upon pressurisation than in buffer, but again, AK01 was more piezotolerant than the wt. The piezotolerance of AK01 was retained for at least 40 generations in rich medium, suggesting a stable phenotype. Interestingly, cells of AK01 lacked flagella and were elongated, and this strain showed slightly lower maximum specific growth rates at 8°C, 22°C and 30°C than the wt. Moreover, the piezotolerant strain AK01 showed increased resistance to heat, acid, and H 2 O 2 compared with the wt. The difference in HHP tolerance between the piezotolerant strain and the wt strain could not be attributed to differences in membrane fluidity, since strain AK01 and the wt had identical in situ lipid melting curves, as determined by Fourier Transfer Infrared spectroscopy.
In Chapter 5 , the mechanisms underlying the altered phenotypic characteristics of AK01 are further examined. In this chapter, high piezotolerance, immobility, and reduced virulence were conclusively linked to a single amino acid deletion in the highly conserved glycine-rich region of the regulatory protein CtsR ( C lass t hree s tress gene r epressor). CtsR negatively regulates the expression of Class III heat shock genes ( clpP , clpE and the clpC operon). The Clp proteins prevent the accumulation of misfolded proteins that might be toxic to the cell. In the mutant strain AK01, expressing the CtsRΔGly protein, we observed upregulation ofclpP , which demonstrates the involvement of Class III heat shock genes in increased survival upon HHP treatment and other stresses. Replacement of the wt ctsR gene with the ctsRΔGly gene in a wt background resulted in a mutant strain that also lost its motile character, and importantly, also showed attenuated virulence. The deletion of three base pairs in the region of ctsR that normally encodes four glycines is seemingly not an isolated incident, since we detected the same mutation in the majority of other spontaneous piezotolerant isolates of L. monocytogenes . This suggests a functional role for this mutation in L. monocytogenes to survive unforeseen events that do not allow for adaptation of normal cells, but require genetic diversity.
In conclusion, this work demonstrated some of the potentials that novel techniques, like the use of essential oils and HHP, can offer alone or combined with other novel or traditional techniques, like heat treatment. We furthermore investigated risks that could emerge from the use of those novel techniques. The occurrence of the piezotolerant strain AK01 of L. monocytogenes demonstrated the existence of bacterial heterogeneity within a supposedly pure wt population with regard to HHP resistance. The variance of piezotolerance within a microbial population, but also between different strains, is an important parameter that determines successful application of HHP treatment. This will be an important aspect for risk assessment of HHP treated foods that are, or will become, available on the market. Tailored HHP treatments, possibly in combination with additional mild preservatives, will be required for different products, and increased knowledge about the effects of these treatments will enable the food industry to produce safe foods at minimal costs.
Ropadiar als alternatief voor een antimicrobiele groeibevorderaar in voer voor gespeende biggen
Krimpen, M.M. van; Binnendijk, G.P. - \ 2001
Lelystad : Praktijkonderzoek Veehouderij (Rapport / Praktijkonderzoek Veehouderij 205) - 14
varkens - spenen - voedertoevoegingen - groeibevorderaars - antimicrobe-eigenschappen - etherische oliën - plantaardige oliën - origanum vulgare - pigs - weaning - feed additives - growth promoters - antimicrobial properties - essential oils - plant oils - origanum vulgare
Op verzoek van Ropapharm B.V. te Zaandam heeft het Praktijkonderzoek Veehouderij een onderzoek uitgevoerd naar de effectiviteit van Ropadiar e , een etherische olie van de oreganoplant, als alternatief voor AMGB. Oregano-olie heeft antibacteriële eigenschappen
Olie- en carvonproductie van winterkarwij bij schermen- en zaadoogst
Mheen, H.J.C.J. van der - \ 2000
PPO-bulletin akkerbouw 4 (2000)3. - ISSN 1385-5301 - p. 31 - 33.
karwij - carum carvi - etherische oliehoudende planten - oogsttijdstip - oogsten - opbrengsten - etherische oliën - caraway - carum carvi - essential oil plants - harvesting date - harvesting - yields - essential oils
De afgelopen jaren is bij PAV-proeven in dille, zomer- en winterkarwij gebleken dat oogst en destillatie van de zaadschermen, juist voor de volledige rijping van het zaad, resulteert in een 40% hogere olieopbrengst in vergelijking met destillatie van het rijpe zaad geoogst met de maaidorser
Bactericidal action of carvacrol towards the food pathogen Bacillus cereus : a case study of a novel approach to mild food preservation
Ultee, A. - \ 2000
Agricultural University. Promotor(en): F.M. Rombouts; E.J. Smid. - S.l. : S.n. - ISBN 9789058082190 - 96
voedselvergiftiging - bacillus cereus - voedselbewaring - anti-infectieuze middelen - secundaire metabolieten - etherische oliën - food poisoning - bacillus cereus - food preservation - antiinfective agents - secondary metabolites - essential oils
A new trend in food preservation is the use of mild preservation systems, instead of more severe techniques such as heating, freezing or addition of chemical preservatives. Carvacrol, a phenolic compound present in the essential oil fraction of oreganum and thyme, is known for its antimicrobial activity since ancient times. This thesis describes a study of the antimicrobial activity of carvacrol towards the foodborne pathogen B. cereus . Carvacrol shows a dose-related inhibition of growth of B. cereus . Concentrations of 0.75 mM and higher inhibit growth completely at 8°C. Below 0.75 mM, carvacrol extends the lag-phase and reduces the specific growth rate as well as the final population density. Exposure to 0.75-3 mM carvacrol decreases the number of viable cells of B. cereus exponentially. Spores are approximately two fold more resistant towards carvacrol than vegetative cells.
The incubation and exposure temperature have a significant influence on the sensitivity of B. cereus to carvacrol. An increase of the growth temperature from 8°C to 30°C decreases the fluidity of the membrane of vegetative cells and as a consequence, B. cereus becomes less sensitive to carvacrol. The change in membrane fluidity is probably the result of a higher percentage of lower melting lipids in the membranes at 8°C (chemical process) as an adaptation to lower temperature. Cells need to maintain an adequate proportion of the liquid-crystalline lipid in the membrane, as this is the ideal physical state of the membrane. On the other hand, an increase of the exposure temperature from 8 to 30°C, reduces the viability again. This can be explained by an increase of the membrane fluidity at a higher temperature as a result of melting of the lipids (physical process). At a higher membrane fluidity, relatively more carvacrol can dissolve in the membrane and the cells will be exposed to relatively higher concentrations than at a lower membrane fluidity.
Not only the temperature plays a role in the activity of carvacrol, also pH is an important factor. The sensitivity of B. cereus to carvacrol is reduced at pH 7, compared to other pH-values between pH 4.5 and 8.5.
Carvacrol interacts with the cytoplasmic membrane by changing its permeability for cations such as K +and H +. Consequently, the dissipation of the membrane potential (Δψ) andΔpH leads to inhibition of essential processes in the cell, such as ATP synthesis, and finally to cell death. At carvacrol concentrations as low as 0.15 mM,Δψis completely dissipated, however the viable count of B. cereus is not affected.
Vegetative cells of B. cereus can adapt to carvacrol when the compound is present at concentrations below the MIC-value. Compared to non-adapted cells, lower concentrations of carvacrol are needed to obtain the same reduction in viable count of adapted cells. Adapted cells were found to have a lower membrane fluidity, caused by a change in the fatty acid composition and head group composition of the phospholipids in the cytoplasmic membrane. Adaptation to 0.4 mM carvacrol increases the phase transition temperature of the lipid bilayer (T m ) from 20.5°C to 28.3°C. Addition of carvacrol to cell suspensions of adapted B. cereus cells decreases T m again to 19.5°C, approximately the same value as was found for non-adapted cells in the absence of carvacrol.
Incubation of cooked rice in the presence of different carvacrol concentrations results in a dose-related reduction of the viable count of B. cereus . Concentrations of 0.15 mg/g and above, reduce the viable count, leading to full suppression of growth at 0.38 mg/g. The influence of carvacrol on the viable count is dependent on the initial inoculum size. Although carvacrol is an effective inhibitor of growth of B. cereus in rice, it could affect the flavour and taste of the product at concentrations where full suppression of growth is observed. However, strong synergistic activity is observed when carvacrol is combined with the biosynthetic precursor cymene or the flavour enhancer soya sauce. This makes it possible to use lower carvacrol concentrations and consequently a smaller influence on the sensoric properties of the rice is expected.
Besides its influence on the viability of vegetative cells, carvacrol also shows inhibition of diarrhoeal toxin production by B. cereus at concentrations below the MIC-value. Addition of 0.06 mg/ml carvacrol to the growth medium, inhibits the toxin to 21% of the control (no carvacrol added). The inhibition correlates with the reduction of the viable count of B. cereus in the presence of carvacrol. At the same time, the total amount of cells did not change. In mushroom soup, also an inhibition of the toxin production was observed, however, the viable count did not change. This effect on the toxin production is most probably caused by a lack of sufficient metabolic energy, since carvacrol affects ATP synthesis. The cell will use its low levels of ATP to maintain its viability, rather than using it for toxin production or excretion. It could also be possible that the decreased toxin synthesis in BHI was the result of the lower amount of viable cells. The inhibition of toxin production at carvacrol concentrations which do permit growth of B. cereus , reduces the risk of food intoxication by this pathogen.
In conclusion, carvacrol may play an important role in future as a natural antimicrobial compound. However, its application will most probably be in combination with other natural antimicrobial systems.
Aroma of some plants cultivated in Lithuania : composition, processing and release
Bylaite, E. - \ 2000
Agricultural University. Promotor(en): A.G.J. Voragen; R.P. Venskutonis; J.P. Roozen. - S.l. : S.n. - ISBN 9789058082329 - 182
plantkunde - aroma - etherische oliën - asteraceae - etherische oliehoudende planten - litouwen - aromatische gewassen - botany - aroma - essential oils - asteraceae - essential oil plants - lithuania - aromatic plants
In this study, some factors affecting the aroma of some plants of the families Umbelliferae and Asteraceae were evaluated. The composition of the aromas is influenced by several factors: plant family, harvesting time, anatomical part of plant, method used to isolate volatiles, cultivar, fertilisers used for the growing of plant, cultivation site. The yield of caraway fruits varies over a wide range depending on fertiliser content, cultivation area and the cultivar itself. The trends for the accumulation of essential oils differ between the families in yield and composition. Seeds and flowers of lovage ( Umbelliferae ) possess the highest yields of oil. In the leaves of lovage seasonal changes are less significant than in the stems. In leaves and flowers of costmary ( Asteraceae ) the highest oil content is obtained before full flowering, while their stems possess only negligible amount of volatiles. Various anatomical parts of lovage showed differences in flavour release measured by the dynamic headspace method. The effluents from a gas chromatography column were characterised by a sniffing panel, which attributed descriptors to the recognised constituents.
Liquid essential oils can be processed by emulsification and encapsulation with milk proteins. Stability of essential oil-in-water emulsions can be improved either by adding soybean phosphatidylcholine and/or by increasing its protein concentration. Adsorption of the protein from the aqueous phase at the oil/water interface was studied by applying ellipsometry. Essential oil of caraway was encapsulated by milk derivatives either alone or combined with carbohydrates. Partial replacement of whey protein concentrate increases the retention of volatiles during spray drying and enhances the protective properties of solidified capsules against oxidation and the release of volatiles during the timed period. The structural features of spray- dried capsules indicated that good physical protection is provided to the caraway essential oil.
Different aspects of S-carvone, a natural potato sprout growth inhibitor
Oosterhaven, J. - \ 1995
Agricultural University. Promotor(en): J.J.C. Scheffer; L.H.W. van der Plas. - S.l. : Oosterhaven - ISBN 9789054854357 - 152
carum carvi - karwij - solanum tuberosum - aardappelen - behoud - opslag - bestraling - diterpenoïden - sesquiterpenoïden - terpenen - etherische oliën - sesquiterpenen - carum carvi - caraway - solanum tuberosum - potatoes - preservation - storage - irradiation - diterpenoids - sesquiterpenoids - terpenoids - essential oils - sesquiterpenes
After harvest, potato tubers are usually stored at a temperature of 6-8°C in combination with the application of a synthetic sprout inhibitor. Frequently used sprout inhibitors are isopropyl N-phenyl-carbamate (propham or IPC), isopropyl N-(3-chlorophenyl)carbamate (chlorpropham or CIPC) or a combination of both compounds. There are several reasons for the development of alternative, natural sprout inhibitors. First, the Scandinavian market, for example, requires potato tubers free of (C)IPC residues, and the so-called "green" market, for which no or very little synthetic chemicals are allowed, does not yet have alternative sprout inhibitors. Secondly, governmental policy is directed towards a reduction of the amount of synthetic pesticides used in agricultural practice (Meerjarenplan Gewasbeschermingsmiddelen, MJPG).
Natural potato sprout inhibitors were already used in the ancient Inca cultures. After harvest, the potato tubers were stored in boxes or bins together with the twigs of muña plants (Minthostachys species). Treating the tubers in this way controlled sprouting as well as insect attack during a prolonged storage. Volatiles emanating from the muña leaves during the storage were responsible for the insect repellent and sprout inhibitory effects.
The monoterpene S-carvone is a related volatile compound which can be isolated from the seeds of caraway (Carum carvi L.) or dill ( Anethum graveolens L.), for example; also this compound has good potato sprout growth inhibitory effects. Application of S-carvone, derived from caraway seed, as a potato sprout inhibitor can stimulate the demand for caraway and therefore the need to grow it. This can be beneficial for Dutch growers, since cultivation of caraway is suitable on heavy clay soils in which crop rotation is limited to only a few crops. The research described in this thesis has been performed within the Dutch Caraway Research Programme in which nine research groups were amalgamated with the objective to reduce the problems with respect to the cultivation of caraway and to stimulate possible new applications of its essential oil or of S-carvone.
S-carvone inhibits the sprouting of potato tubers and the sprout growth reversibly: removal of S-carvone allows sprouting and regrowth of the individual sprouts. A high dosage leads to necrosis, but the side buds remain their viability and they start to sprout again when the concentration of S-carvone in the atmosphere comes below a threshold value. The enantiomer of S-carvone, R- carvone, can be isolated from spearmint ( Mentha spicata L.) and possesses almost the same sprout growth inhibitory properties as S-carvone. Current research is focussed on the practical application of S-carvone to seed potatoes as a reversible sprout growth inhibitor.
In addition to the inhibitory effects just mentioned, the growth of several storage pathogens is also reduced by S-carvone. However, the susceptibility of fungi to S-carvone, e.g. Fusarium species that cause dry-rot, differs between (sub)species. F.solani var. coeruleum is able to grow on tubers treated with S- carvone, whereas F . sulphureum cannot withstand it. This difference was not found in vitro; both fungi were susceptible to the same range of S-carvone concentrations, they were both able to convert S-carvone with the same rate, and into almost the same conversion products. Therefore, the difference in susceptibility in situ must be found in, for example, a specific interaction of the fungi with the potato tubers.
Carvone is stereoselectivily converted into other compounds by potato tissue: R-carvone mainly into neodihydrocarveol, and S-carvone into neoisodihydrocarveol. The bioconversion only takes place in easily accessible tissues, such as sprouts and tuber wound tissue. More than 90% of the amount of S-carvone found in intact tubers, is located on or in the skin. In addition to the chloroform-soluble bioconversion products, water-soluble carvone derived compounds were detected in potato tissue, using 13C-labelling studies. The identity of the conjugated compounds has not been established yet, but S-carvone is found after addition of HCl to the aqueous phase containing the conjugates. The induction of glutathione S-transferase may point to the conjugation of S-carvone to glutathione. Conjugation to saccharides may be an alternative explanation.
The sprout growth inhibition is correlated strongly with a decreasing 3- hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity, a key enzyme providing building blocks for the synthesis of various essential plant metabolites. Using specific potato HMGR antibodies, it was found that the decrease of activity correlated well with the disappearance of HMGR protein signals on Western blots derived from samples of proteins from organelle fractions and microsomal membranes.
S-carvone inhibits the healing of wounded tubers temporarily; in particular, suberization is delayed for about 10 days. The formation of a cambium layer is almost completely inhibited, which indicates that S-carvone interferes with cell division processes during the healing of wounded tissue. The suberization is correlated with the activity of phenylalanine ammonia Iyase (PAL). This enzyme catalyses the first step that leads to the synthesis of suberin, and in S-carvone treated wound tissue, the induction of PAL is delayed for about 10 days. This implies that tuber wound tissue is able to adapt to the exposure to S-carvone.
In conclusion, based on the research described in this thesis, it can be stated that S-carvone is a compound with a great potential because of its sprout growth inhibitory effect, possibly partly due to an inhibition of HMGR. Since S-carvone inhibits sprouting reversibly, it may also be useful as a temporary inhibitor of seed potatoes. In addition, S-carvone reduces the development and growth of several storage pathogens. These effects make the chances of an application of S-carvone as a natural potato sprout growth inhibitor even better.
Onderzoeksprogramma ter verbetering van karwij als akkerbouwgewas en ter introductie van nieuwe afzetmogelijkheden : eindverslag 1990 - 1994
Anonymous, - \ 1994
Wageningen etc. : CPRO-DLO [etc.]
carum carvi - karwij - diterpenoïden - sesquiterpenoïden - terpenen - etherische oliën - sesquiterpenen - vluchtige verbindingen - carum carvi - caraway - diterpenoids - sesquiterpenoids - terpenoids - essential oils - sesquiterpenes - volatile compounds
|De geurtocht van Marcel Dicke.
Beekman, W. - \ 1994
Ekoland 14 (1994)11. - ISSN 0926-9142 - p. 12 - 13.
dieren - lokstoffen - biologische bestrijding - etherische oliën - gastheer parasiet relaties - geurstoffen - feromonen - gewasbescherming - planten - terpenen - animals - attractants - biological control - essential oils - host parasite relationships - odours - pheromones - plant protection - plants - terpenoids
Interview with Marcel Dicke who is involved in research on the relationship between phytophagous insects and mites, their predators and the host plants. Plants produce attractants, mostly terpenes, to attrack the predators. Possible applications of this mechanism for pest control are discussed