Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Revisiting the Role of Master Regulators in Tomato Ripening
    Wang, Rufang ; Angenent, Gerco C. ; Seymour, Graham ; Maagd, Ruud A. de - \ 2020
    Trends in Plant Science (2020). - ISSN 1360-1385
    CRISPR- mutagenesis - gain-of-function - mutants - ripening - tomato - transcription factors

    The study of transcriptional regulation of tomato ripening has been led by spontaneous mutations in transcription factor (TF) genes that completely inhibit normal ripening, suggesting that they are ‘master regulators’. Studies using CRISPR/Cas9 mutagenesis to produce knockouts of the underlying genes indicate a different picture, suggesting that the regulation is more robust than previously thought. This requires us to revisit our model of the regulation of ripening and replace it with one involving a network of partially redundant components. At the same time, the fast rise of CRISPR/Cas mutagenesis, resulting in unexpectedly weak phenotypes, compared with knockdown technology, suggests that compensatory mechanisms may obscure protein functions. This emphasises the need for assessment of these mechanisms in plants and for the careful design of mutagenesis experiments.

    Methodology for estimating emissions from agriculture in the Netherlands. : Calculations of CH4, NH3, N2O, NOx, PM10, PM2.5 and CO2 with the National Emission Model for Agriculture (NEMA)
    Vonk, J. ; Bannink, A. ; Bruggen, C. van; Groenestein, C.M. ; Huijsmans, J.F.M. ; Kolk, J.W.H. van der; Luesink, H.H. ; Oude Voshaar, S.V. ; Sluis, S.M. ; Velthof, G.L. - \ 2016
    Wageningen : Statutory Research Tasks Unit for Nature & the Environment (WOt-technical report 53) - 164
    air pollutants, greenhouse gases, livestock, crops, animal housing, manure storage, manure application, inorganic fertilizer, enteric fermentation, manure management, agricultural soils, liming, NIR, CRF, IIR, NFR - landbouw - gewassen - landbouwgronden - vee - huisvesting, dieren - dierlijke meststoffen - rundveemest - mestverwerking - begrazing - broeikasgassen - luchtverontreinigende stoffen - emissie - ammoniakemissie - kooldioxide - methaan - anorganische meststoffen - fermentatie - bekalking - nederland - compost - rioolslib - teelt - oogstresten - rijp worden - agriculture - crops - agricultural soils - livestock - animal housing - animal manures - cattle manure - manure treatment - grazing - greenhouse gases - air pollutants - emission - ammonia emission - carbon dioxide - methane - inorganic fertilizers - fermentation - liming - netherlands - composts - sewage sludge - cultivation - crop residues - ripening
    The National Emission Model for Agriculture (NEMA) is used to calculate emissions to air from agricultural activities in the Netherlands on a national scale. Emissions of ammonia (NH3) and other N-compounds (NOx and N2O) from animal housing, manure storage, manure application and grazing are assessed using a Total Ammoniacal Nitrogen (TAN) flow model. Furthermore, emissions from application of inorganic N-fertilizer, compost and sewage sludge, cultivation of organic soils, crop residues, and ripening of crops are calculated. NEMA is also used to estimate emissions of methane (CH4) from enteric fermentation and manure management, particulate matter (PM) from manure management and agricultural soils, and carbon dioxide
    (CO2) from liming. Emissions are calculated in accordance with international guidance criteria and reported in an annual Informative Inventory Report (IIR; for air pollutants) and National Inventory Report (NIR; for greenhouse gases). This methodology report describes the outline and backgrounds of the emission
    calculations with NEMA
    Met ethyleen heb je de afrijping van tomaten beter in de hand : goed alternatief voor de bespuiting met ethrel
    Stijger, H. ; Janse, J. - \ 2015
    Onder Glas 12 (2015)6/7. - p. 24 - 25.
    glastuinbouw - groenten - tomaten - cultuurmethoden - rijp worden - ethyleen - gewaskwaliteit - teeltsystemen - arbeid (werk) - greenhouse horticulture - vegetables - tomatoes - cultural methods - ripening - ethylene - crop quality - cropping systems - labour
    Het goed afrijpen van de laatste tomaten aan het eind van de teelt is veelal een probleem. Met een gecontroleerde toediening van ethyleengas is het rijpingsproces te bevorderen. Tomatenkwekerij Van Heijningen in Maasdijk heeft hier goede ervaringen mee opgedaan.
    Breeding for pepper fruit quality: a genitical metabolomics approach
    Wahyuni, Y. - \ 2014
    Wageningen University. Promotor(en): Raoul Bino, co-promotor(en): Arnaud Bovy; E. Sudarmonowati; A.R. Ballester. - Wageningen : Wageningen University - ISBN 9789461739582 - 193
    capsicum annuum - capsicum frutescens - capsicum chinense - capsicum baccatum - plantenveredeling - metabolomica - gewaskwaliteit - secundaire metabolieten - gezondheid - genetische kartering - rijp worden - capsicum annuum - capsicum frutescens - capsicum chinense - capsicum baccatum - plant breeding - metabolomics - crop quality - secondary metabolites - health - genetic mapping - ripening

    A diverse collection of 32 pepper accessions was analysed for variation in health-related metabolites, such as carotenoids, capsaicinoids, flavonoids and vitamins C and E. For each of the metabolites analysed, there was a lot of variation among the accessions and it was possible to identify accessions with high amounts of specific metabolites. While all accessions contained high levels of vitamin C, accession C. chinenseAC2212 was found to be an excellent source of vitamin E, whereas C. annuumLong Sweet accumulated high levels of the flavonoid quercetin. A genetical metabolomics approach was used to study the genetic basis of metabolic traits in a segregating F2 population based on a cross between two contrasting pepper genotypes. This led to the identification of several metabolites QTL hotspots. The genetic basis for the accumulation of several flavonoids in pepper fruit was further investigated, by combining metabolic, gene expression and candidate gene-based marker data. This provided valuable insight into the key genes important for flavonoid accumulation in pepper fruit. The results of this study will help breeders to assist future breeding programs aimed at optimizing the levels of nutritional compounds in pepper fruit.

    DCS en ethyleen verminderen schilvlekjes
    Schoorl, F.W. ; Schaik, A.C.R. van - \ 2012
    De Fruitteelt 102 (2012)38. - ISSN 0016-2302 - p. 6 - 7.
    appels - opslag met klimaatbeheersing - ethyleen - rijp worden - landbouwkundig onderzoek - opslagkwaliteit - houdbaarheid (kwaliteit) - apples - controlled atmosphere stores - ethylene - ripening - agricultural research - storage quality - keeping quality
    Bewaring onder DCS-condities van Elstar vermindert het optreden van schilvlekjes in Elstar. Een experiment bij PPO Fruit te Randwijk toonde in 2011/`12 het positieve effect aan van DCS™ op het terugdringen van schilvlekjes. Dit was niet nieuw, maar werd niet eerder zo sterk vastgesteld als in dit experiment. Ook zagen we een goed resultaat van toegediend ethyleen bij bewaring onder ULO-condities. Onder ULO trad wél enig hardheid- en kleurverlies op bij continue toediening van ethyleen.
    TILLING & EcoTILLING in tomato : harvesting artificial and natural genetic diversity
    Gady, A.L.F. - \ 2011
    Wageningen University. Promotor(en): Richard Visser, co-promotor(en): Christian Bachem. - [S.l.] : S.n. - ISBN 9789085859352 - 141
    solanum lycopersicum - tomaten - mutatieanalyse - mutaties - rijp worden - vruchten - metabolisme - genetische diversiteit - plantenveredeling - solanum lycopersicum - tomatoes - mutational analysis - mutations - ripening - fruits - metabolism - genetic diversity - plant breeding

    Mutations in genes controlling specific traits of interest are widely used in plant breeding to introduce particular characteristics in commercial varieties. The establishment of a large mutant collections and the identification of mutations in candidate genes controling traits of interest represents an important resource for plant breeding. Chemical mutagenesis with EMS produces G/C to A/T transitions and is a well-characterized method to generate a saturated mutant population. The TILLING (Targeting Induced Local Lesions IN Genomes) process enables the identification of mutations in specific genes of interest and produces heteromorphic as well as knock-out alleles.

    In order to apply the TILLING strategy to tomato, we have created two new populations of 8025 M2 and 6600 M3 lines respectively derived from seed treatment with 1% EMS of Solanum esculentum (var. TPAADASU). To screen the collection for mutations in selected genes, two novel high-throughput SNP detection technologies were adapted. Firstly, Conformation Sensitive Capillary Electrophoresis (CSCE) and secondly, high resolution DNA-melting analysis (HRM). Our results indicate a mutation frequency of 1,1 mutation per 1kb per 1000 plants.

    Mutations in genes involved in carotenoid biosynthesis and tolerance to salinity stress, Psy1 and ProDh, were identified. Characterisation of the mutant lines, carrying knock-out or amino acid substitution alleles, using plant growth assays, metabolic profiling and gene expression studies allowed the demonstration of the TILLING strategy as an efficient method for plant breeding purposes and plant biology research.

    EcoTILLING was set up using the HRM based SNP screening method to screen the EU-SOL and CBSG tomato core collections for candidates genes involved in sugar metabolism. 13 haplotypes over 6 target genes were identified and related to the studied trait, total soluble sugars. We show that HRM is a fast and cost effective method to unravel natural genetic diversity in candidate genes.

    Rijping tomatenvruchten: alternatieven voor ethrel
    Boer-Tersteeg, P.M. de; Janse, J. ; Slootweg, G. ; Lee, K.M. ; Marcelis, L.F.M. - \ 2009
    Bleiswijk : Wageningen UR Glastuinbouw (Nota / Wageningen UR Glastuinbouw 606) - 39
    tomaten - solanum lycopersicum - rijp worden - plantengroeiregulatoren - teelt onder bescherming - kasgewassen - tomatoes - ripening - plant growth regulators - protected cultivation - greenhouse crops
    Het doel van dit onderzoek was het vinden van alternatieven voor het gebruik van Ethrel in de tomatenteelt. Ethrel wordt gebruikt om aan het einde van het teeltseizoen de laatste trossen versneld te laten afrijpen. Onduidelijkheid over een mogelijk negatief effect van de consumptie van tomaten met ethephon (de werkzame stof in Ethrel) op de gezondheid heeft geleid tot discussie over het gebruik van Ethrel. In 2007 heeft de EU besloten de MRL (Maximum Residue Level) voor ethephon te verlagen van 3,0 naar 1,0 mg/kg tomaat. In 2008 dreigde het gebruik van Ethrel zelfs verboden te worden. Inmiddels is door de Europese Commissie besloten dat de verlaagde MRL van 1,0 mg/vrucht in principe gehandhaafd kan blijven. De kans is dus groot dat het gebruik van Ethrel in de tomatenteelt in Nederland wel toegelaten blijft.
    Het onderzoek van Martin van Dam : 'Nieuw licht op rol ethyleen' : een interview met Martin van Dam
    Dwarswaard, A. ; Dam, M.F.N. van - \ 2009
    BloembollenVisie 2009 (2009)161. - ISSN 1571-5558 - p. 37 - 37.
    bloembollen - fusarium - oogsten - verwerking - ethyleen - rijp worden - ornamental bulbs - fusarium - harvesting - processing - ethylene - ripening
    De serie : Het onderzoek.. van laat onderzoekers vertellen waar zij op dit moment mee bezig zijn. In deze aflevering PPO-onderzoeker Martin van Dam over ethyleen en zuur in tulpen
    Rambutan cultivation techniques
    Knol, J.J. ; Yuliani, S. ; Buddendorf, C.J.J. ; Schaik, A.C.R. van - \ 2008
    Wageningen : Wageningen UR (HORTIN-II research report nr. 2)
    nephelium lappaceum - ramboetans - landbouwplantenteelt - oogsttijdstip - rijp worden - indonesië - nephelium lappaceum - rambutans - crop husbandry - harvesting date - ripening - indonesia
    The application of transcriptomics in the comparative safety assessment of (GMO-derived) plant products
    Kok, E.J. - \ 2008
    Wageningen University. Promotor(en): Ivonne Rietjens; Michael Muller, co-promotor(en): Harry Kuiper; Jaap Keijer. - [S.l. : S.n. - ISBN 9789085049296 - 200
    risicoschatting - transgene planten - genexpressie - tomaten - rijp worden - voedselveiligheid - transcriptomics - eiwitexpressieanalyse - risk assessment - transgenic plants - gene expression - tomatoes - ripening - food safety - transcriptomics - proteomics
    National and international organizations have discussed current approaches to the safety assessment of complex (plant) food products in general and the safety assessment of GMO-derived food products in particular. One of the recommendations of different expert meetings was that the new analytical techniques, in particular the ‘omics’ approaches, need to be explored for their potential to improve the analysis and thereby the toxicological and nutritional assessment of complex (GMO-derived) plant products. This thesis aims to further explore this approach in general and, more specifically, has evaluated the potential added value of transcriptomics to assess unintended side effects in a newly bred (genetically modified) plant variety. As one of the first initiatives in this area a small food safety–related tomato-array was developed with pathway-selected cDNAs on the basis of two subtractive cDNA libraries. This tomato array was used to hybridise mRNA derived from tomatoes in five subsequent ripening stages from green, via breaker, turning, and light red, to red, to obtain a background library of gene expression profiles of different ripening stages for future comparisons. At the same time these initial series of experiments were aimed to assess the potential of the approach with respect to its sensitivity and specificity. In addition the tomato array was used to hybridise mRNA derived from GM tomato transformant lines and the traditionally bred parent line and the results were analysed for the presence of differential expression patterns in both transformant lines, that have incorporated the same genetic construct, compared to the parent line. A similar study was performed in Arabidopsis to assess the extent of unintended effects in GM lines that have incorporated different numbers of the introduced genetic construct. The resulting data show that the methodology of transcriptomics has the potential to detect large as well as small differences in gene expression. The first was primarily shown in the comparative study on the developmental stage, the latter in the comparison of transcriptomics profiles of the two transformant lines vs the parent variety. It was also shown that, for direct comparison, plants to be sampled need to be grown under very similar conditions and the sampling needs to be performed in a structured way taking into account the developmental stage of the selected plant organs and/or tissues. All experiments illustrated the necessity to establish the bandwidth of natural variation for comparative purposes in order to determine the biological as well as toxicological and/or nutritional significance of differences detected in GM lines or in lines resulting from other breeding procedures. Finally, the results of the international debate on the assessment of complex (GMO-derived) plant products, the knowledge on current breeding strategies, and the results of the first publications on experiments that aim to detect unintended effects in plant breeding strategies using ‘omics’ technologies, including the experiments described here, are combined to review current approaches. A new overall approach for the safety evaluation of complex plant products, including GMO-derived products, is proposed. This approach applies currently available tools, including the ‘omics’ technologies, to assess food safety aspects of newly developed plant varieties already during the plant breeding process. Undesired effects of the breeding procedures for the plant’s physiology, can thus be traced at an early stage and this will help to further guarantee the safety of the final plant-derived food products. Observed differences in the final plant product will form part of the comparative safety assessment. It can be envisioned on the basis of the data presented in this thesis as well as in other studies described in the scientific literature that in general few differences will be observed between GM lines and the WT counterparts that fall outside of the bandwidth of natural variation of commercial counterparts. The toxicological and nutritional evaluation of the final plant products will need to focus on the limited number of differences that are outside of this bandwidth and may affect the product’s food safety characteristics. To avoid inequalities in food safety assessment procedures that do not have a sound scientific basis, it is argued that these developments should have an impact on all novel plant varieties, not just on GMO-derived food plant products.

    Measuring compounds in fruits using spectral image analysis
    Zedde, H.J. van de; Heijden, G.W.A.M. van der; Polder, G. - \ 2007
    rijp worden - rijpheid - multispectrale beelden - chemische samenstelling - vruchten - voedseltechnologie - chemische verbindingen - beeldvormende spectroscopie - ripening - maturity - multispectral imagery - chemical composition - fruits - food technology - chemical compounds - imaging spectroscopy
    In a greyvalue (black&white) image, a pixel contains a single value, representing light intensity. In an RGB color image, a pixel contains three values, corresponding with the light intensity at the red, green and blue band of the electromagnetic spectrum. In a spectral image, each pixel consists of an array of intensity values corresponding with small bands (
    Efficiënt gebruik van snijmaïs. Deel 5: invloed afrijpingstype en oogststadium op opname en melkproductie = Efficient use of silage maize. Part 5: effect of maturity type and harvest stage on intake and milkproduction
    Zom, R.L.G. - \ 2006
    Lelystad : Animal Sciences Group / Praktijkonderzoek (PraktijkRapport / Animal Sciences Group : Rundvee ) - 43
    maïs - zea mays - rassen (planten) - cultivars - maïskuilvoer - gewasopbrengst - rijp worden - melkveehouderij - melkproductie - rundveevoeding - maize - varieties - maize silage - crop yield - ripening - dairy farming - milk production - cattle feeding
    In the period 2003-2005 effects of genotypes and maturity stage on yield, quality, conservation and nutrition have been investigated. This research was focusing on the effects of maturity type and energy type on intake and milk performance. There was no influence of maturity type (stay green and dry down) on intake and milk performance. The starch energy type caused a higher milk performance than the cell wall energy type
    Applying prior knowledge to model batch keeping-quality of cucumber batches
    Schouten, R.E. ; Tijskens, L.M.M. ; Kooten, O. van; Jongbloed, G. - \ 2004
    In: Bayesian statistics and quality modelling in the agro-food production chain : proceedings of the Frontis workshop on Bayesian statistics modelling in the agro-food production chain, Wageningen, The Netherlands 11 - 14 May 2003 / van Boekel, M.A.J.S., Stein, A., van Bruggen, A.H.C., Wageningen : Frontis (Wageningen UR Frontis series Vol. 3) - ISBN 9781402019166 - p. 71 - 80.
    komkommers - houdbaarheid (kwaliteit) - variatie - chlorofyl - rijp worden - cultivars - bewaartijd - bewaarfysiologie - kleur - cucumbers - keeping quality - variation - chlorophyll - ripening - cultivars - storage life - postharvest physiology - colour
    Keeping-quality of individual cucumbers is limited by the green colour; the keeping-quality of batches of cucumbers is limited by the time it takes before 5␘f the cucumbers in the batch reach a predefined colour limit. From literature concerning the synthesis and degradation of chlorophyll and a published colour model (Schouten, Tijskens and Van Kooten 2002) it is known that colour behaviour of individual cucumbers depends on the concentration of protochlorophyllide (Pchl), at harvest. Here a model for the synthesis and degradation of Pchl is proposed for individual cucumbers, assuming that light conditions during growth are a major factor for Pchl synthesis. Subsequently, this individual Pchl model is expanded to a batch model that describes the variation in the Pchl concentration by assuming that differences between cucumbers of the same batch are primarily caused by differences in light conditions during growth. Pchl data were obtained from colour data from six batches from three cultivars (¿Volcan¿, ¿Beluga¿ and ¿Borja¿) over two growing seasons. Pchl data were gathered per batch and compared with the proposed batch model. The variation in the Pchl concentration per batch could be described satisfactorily in terms of the parameters of the proposed Pchl batch model: batch maturity, batch variation (due to differences in light conditions during growth on a batch level) and a cultivar-dependent factor. Estimating this cultivar-dependent factor for new cultivars could be a tool for cucumber-breeding companies to obtain cultivars with an increased keeping-quality. Keywords: Biological variation; postharvest; preharvest; precursor
    Automatic produce quality monitoring in Reefer containers
    Lukasse, L.J.S. ; Sanders, M.G. ; Kramer, J.E. de - \ 2003
    In: International Conference on Quality in Chains. An Integrated View on Fruit and Vegetable Quality / L.M.M. Tijskens, L.M.M., Vollebregt, H.M., [S.l.] : ISHS - p. 313 - 322.
    appels - ethyleenproductie - rijp worden - ademhaling - containertransport - voedselkwaliteit - apples - ethylene production - ripening - respiration - container transport - food quality
    Current day perishable supply chains require intermediate points for manual produce quality inspection. Over the last decade international seatransport of fruit and vegetables in reefer containers has grown tremendously. Reefer containers may completely close the cold chain only if produce quality inspection is automated. The observation of this growing need for automatic produce quality monitoring has triggered this research. The aim is twofold: to reveal a correlation between fruit gas exchange rates and actual produce quality aspects (1) and to automatically monitor fruit's gas exchange rates in containers from one-point gas concentration measurements only (2). Large experimental datasets have been collected to assess the correlation between respiration, ethylene production and ripeness-related firmness for Elstar apples. Both simulations and experiments have been done to test the feasibility of monitoring (variations in) respiratory activity over time. On the one hand the results prove that both objectives are feasible, at least for Elstar apples. On the other hand some uncertainties remain: 1. Uncertainty in the observed correlation between gas exchange rates and apple firmness, 2. On-line monitoring of gas exchange rates in reefer containers may be hampered by e.g. unknown leak rates, 3. To what extend may the observed correlation between quality aspects and gas exchange rates be generalised to other perishable commodities.
    Strawberry and beyond: a novel and comprehensive investigation of fruit maturation and ripening
    Aharoni, A. - \ 2002
    Wageningen University. Promotor(en): J.N.M. Mol; W.J. Stiekema; A.P. O'Connell. - S.l. : s.n. - ISBN 9789058087256 - 250
    fragaria - aardbeien - rijp worden - rijpen - genexpressie - genexpressieanalyse - fragaria - strawberries - ripening - maturation - gene expression - genomics - cum laude

    Functional-genomics tools such as Expressed Sequence Tags (ESTs) and whole genome sequencing, gene expression using macro and micro arrays and generation of mutant populations contributed largely to the research on model plants, mainly Arabidopsis thaliana . A substantial portion of this "tool-box" can also be utilized successfully for research on non-model plants, which are more difficult and time consuming to deal with, but allow investigations of unique biological processes such as fruit flavour biogenesis. As a first phase in a strategy to investigate strawberry fruit maturation and to identify key genes associated with fruit quality traits (in particularly aroma and flavour), we generated a collection of more than 1000 ESTs from ripe fruit cDNA library (cv. Elsanta ). Combining information on the putative identity of the ESTs and gene expression studies was subsequently used to select candidate genes for further investigation. In early studies we used RNA gel-blots to analyse levels of 50 selected genes (selected based on homology). More than 15 transcripts showed ripening - regulated expression pattern and included FaMYB1 , a member of the R2R3 MYB family of transcription factors. The FaMYB1 gene was subjected to a more profound investigation, and the results suggested it to function as repressor of late flavonoid biosynthesis genes in the ripe strawberry fruit. To perform a more comprehensive study of gene expression we constructed DNA microarrays representing 1700 strawberry cDNAs and compared gene expression both during fruit development and between receptacle and achene tissues. A major finding in this study was the identification of the SAAT gene encoding the ester-forming enzyme from strawberry. Volatile esters are major components of the aroma profiles of most fruit, including strawberry. We also generated a second, dedicated set of arrays, comprising only 384 probes selected on the basis of the first hybridisation results including mainly ripening regulated and receptacle associated cDNAs. This set was used to analyse gene expression in fruit treated with auxin and fruit under oxidative stress conditions. Taken as a whole, microarray experiments have provided us with an extensive and novel insight into the transcriptional programs active in strawberry fruit during maturation. They also led to the identification of several other flavour associated genes which are currently being characterised. As a complementary step for the large-scale analysis of gene expression using microarrays we conducted a set of experiments aimed at identifying key metabolic changes in strawberry fruit during development using a Fourier Transform Ion Cyclotron Mass Spectrometry (FTMS)-based method. The analysis identified changes in the levels of a large range of masses corresponding to known fruit metabolites and revealed novel information on the metabolic transition from immature to ripe fruit. The integration of emerging functional genomic practices will be an invaluable approach both for gene discovery and for understanding the biology of non-model plant species such as strawberry.

    Structural characteristics of polysaccharides from olive fruit cell walls in relation to ripening and processing
    Vierhuis, E. - \ 2002
    Wageningen University. Promotor(en): A.G.J. Voragen; H.A. Schols. - S.l. : S.n. - ISBN 9789058085948 - 135
    voedselchemie - olijven - celwandstoffen - polysacchariden - rijp worden - voedselverwerking - food chemistry - olives - cell wall components - polysaccharides - ripening - food processing

    Key words: Olive fruit; olive oil; pectic polysaccharides; xyloglucans; xylans;

    enzyme preparations; phenolic compounds; processing; ripening

    Technical enzyme preparations can be used as processing aids in the olive oil industry to obtain a higher yield and a better quality of the oil. These technical enzyme preparations degrade the plant cell wall, thus enhancing the permeability for oil. However, still very little is known about the specific role of the various constituent enzymes present in the preparations towards the polysaccharides in the plant cell wall. This study deals with this subject and describes the structural characteristics of the polysaccharides in the cell wall of olive fruit in relation to processing for oil extraction.

    The major polysaccharides in the cell wall of olive fruit were found to be the pectic polysaccharides and the hemicellulosic polysaccharides xyloglucan and xylan. The pectic polysaccharides were highly methyl esterified and rich in arabinose. The xyloglucans had a backbone with three out of four glucose residues substituted with xylose residues and had a very specific substitution pattern, because galactose as well as arabinose residues could be linked to the xylose residues. The presence of arabinose residues linked to xylose residues is a common feature of xyloglucans produced by solanaceous plants, but has not been demonstrated for other dicotylodonous plants. Incubation of the cell wall material from olive fruit with pectin degrading enzymes in combination with endo-glucanases revealed that O -acetyl groups were not only linked to pectic material in olive fruit but also to xyloglucan. It was established that the arabinose residues of the xyloglucan could carry one or two O -acetyl groups. The cell wall material of olive fruit contained besides xyloglucan also considerable amounts of the hemicellulose xylan. These xylans appeared to be very low in substitution. Less than 10% of the xylose residues were mono substituted, mainly with 4- O -methyl-glucuronic acid residues.

    The use of technical enzyme preparations during processing affected only a relatively small part of the polysaccharides in the cell wall. About 8-10% of the cell wall polysaccharides were extracted with cold and hot buffer and appeared to be modified during enzymatic processing. The changes of the buffer soluble pectic material were reflected by an increase in yield, a change in molecular weight distribution, a decrease in methyl esterification and a degradation of the (1®4)-linked galactan chains. No differences were observed in the composition of the arabinan chains during enzymatic processing. Analysis of the olive oil revealed that the use of enzyme preparations increased the concentration of phenolic compounds in the oil. Especially, the contents of secoiridoid derivatives such as the dialdehydic form of elenolic acid linked to 3,4-dihydroxyphenylethanol and an isomer of oleuropein aglycon increased significantly. These two phenolic compounds have high antioxidant activities.

    The effect of enzyme treatment during the mechanical extraction of olive oil depends on the stage of maturity of the olive fruit. From this perspective the structural characteristics of the cell wall polysaccharides during ripening have also been investigated. During ripening the degree of methyl esterification and acetylation decreased and the solubility of the pectic polymers in buffer markedly increased. No distinct differences could be noticed with regard to the sugar composition and the profile of the molecular weight distribution of the pectic and hemicellulosic polymers during fruit development.

    Suicidal tomato cells: programmed cell death in suspension-cultured tomato cells and ripening fruit
    Hoeberichts, F.A. - \ 2002
    Wageningen University. Promotor(en): L.H.W. van der Plas; E.J. Woltering. - S.l. : S.n. - ISBN 9789058087157 - 168
    solanum lycopersicum - tomaten - apoptose - cellen - dood - celsuspensies - rijp worden - veroudering - genexpressie - kwaliteit - plantenfysiologie - solanum lycopersicum - tomatoes - apoptosis - cells - death - cell suspensions - ripening - senescence - gene expression - quality - plant physiology

    Tomato fruit ripening involves a series of highly organised biochemical, physiological and structural changes that are under strict genetic control. The plant hormone ethylene (C 2 H 4 ), in synergy with certain developmental cues, regulates fruit ripening by initiating and co-ordinating the expression of genes responsible for different aspects of the ripening process, such as the respiratory rise, chlorophyll degradation, carotenoid biosynthesis, conversion of starch to sugars, and cell wall degradation. The economical importance of tomato as a crop has resulted in substantial research efforts aimed at the improvement of fruit quality traits, such as shelf life. Inhibition of ethylene action or perception, either by the use of inhibitors or by transgenic approaches, has been proved to be a powerful means to control ripening.

    In this thesis, research aimed at providing new tools to further improve tomato fruit quality is described. It was hypothesised that fruit quality could be improved if (further) ripening was inhibited only after the fruit had reached a certain degree of maturity, including the associated stages of coloration and taste development. Genes that encode for proteins involved in ethylene biosynthesis or perception are potential targets for a transgenic approach within this strategy. It was believed that ethylene acts as a rheostat rather than a trigger during tomato fruit ripening, which means that ethylene signalling is required throughout the complete course of ripening. Indeed, treatment of tomato fruit with 1-MCP, a potent inhibitor of ethylene action, delayed colour development, softening, and ethylene production not only in tomato fruit harvested at the mature green stage, but also in the breaker, and orange stages. 1-MCP treatment decreased the mRNA abundance of PSY1 , EXP1 , and ACO1 , three ripening-related tomato genes, in mature green as well as in breaker, orange, and red ripe fruit. These results demonstrate that the ripening process can be inhibited both on a physiological and molecular level, even at very advanced stages of ripening.

    In plant transgenic approaches, the most widely used promoter is the CaMV 35S promoter. It expresses the corresponding transgene constitutively and at high levels in all plant cells. A number of endogenous, fruit-specific tomato promoters, such as the 2A11 , ACO1 , E8 , E4 , and polygalacturonase (PG) promoter, have also been successfully used to obtain transgenic fruit. These promoters are generally active throughout ripening. To obtain DNA sequences that potentially could direct expression of a transgene towards the later stages of ripening, two new promoters were cloned. CEL2 (encoding an endo-ß-1,4-glucanase) and EXP1 (an expansin) are specifically and highly expressed during the advanced stages of ripening. The 1341 bp long EXP1 promoter fragment contains a 19 bp stretch also present in the promoter of fruit-specific polygalacturonase (PG) gene, and two putative ethylene-responsive elements (EREs). The 660 bp long CEL2 promoter fragment does not contain any putative EREs. Several promoter deletion constructs were transiently expressed in fruit tissue by particle bombardment, using firefly luciferase as a reporter gene. Some positively and negatively regulating regions could be identified, but it was concluded that this method is not very suitable to determine promoter activity in tomato fruit tissue.

    In addition to disrupting ethylene biosynthesis or perception, new possibilities to inhibit tomato fruit ripening were searched for. It was postulated that programmed cell death (PCD) might play a role during the advanced stages of ripening and postharvest senescence. PCD is a process aimed at eliminating unnecessary or harmful cells during growth and development of multicellular organisms. It is indispensable for normal development and survival of plants. To study a possible role for PCD in tomato fruit ripening and postharvest senescence, first, a model system of suspension-cultured tomato cells was established. These cells can be induced to undergo PCD by treatment with chemicals that are known to induce a specific form of PCD in animal cells, named apoptosis. This chemical-induced cell death in tomato is accompanied by characteristic features of animal apoptosis, such as typical changes in nuclear morphology, the fragmentation of the nucleus and genomic DNA degradation. Moreover, inhibitor studies suggest that, like in animal systems, caspase-like proteases are involved in this apoptotic-like cell death pathway.

    To identify genes potentially involved in plant PCD, changes in gene expression during chemical-induced PCD were studied. Tomato homologues of DAD1 and HSR203 , two genes that had been implicated in PCD previously, were isolated. LeDAD1 mRNA levels are reduced by approximately 50%, whereas LeHSR203 mRNA levels increase 5-fold during chemical-induced PCD tomato. A differential display approach, used to identify novel genes, resulted in isolation of two up-regulated (CTU1 and CTU1 shows high homology to various gluthatione S-transferases, whereas CTU2 shows homology to human PIRIN . CTD1 is highly similar to early-auxin-responsive Aux/IAA genes. CTD2 corresponds to the tomato RSI-1 gene, CTD4 is an unknown clone, and CTD5 shows limited homology with a proline-rich protein from maize. A tomato metacaspase gene, designated LeMCA1 , that encodes a protein homologous to mammalian caspases was also cloned. Caspases are cysteinyl aspartate-specific proteases that constitute the core component of animal apoptosis. Southern analysis indicates that there is at least one more metacaspase present in the tomato genome. Unexpectedly, LeMCA1 gene expression is constitutive in suspension-cultured tomato cells. However, LeMCA1 is rapidly induced upon infection of tomato leaves with the fungal pathogen Botrytis cinerea , suggesting a possible role in disease-related cell death.

    Taken together, the data derived from the model system of tomato suspension cells suggest that plants make use of cell death pathways that share homology with animal apoptotic pathways. These conserved mechanisms, however, can be activated and regulated by plant-specific factors such as plant hormones

    The occurrence of PCD during fruit ripening and postharvest senescence was investigated using DNA laddering and the expression of several genes as markers. No DNA laddering could be detected in tomato fruit tissue. The tomato homologue of a putative negative regulator of apoptosis, LeDAD1 , is constitutively expressed during ripening of wildtype, rin , and Nr tomato fruit. LePIRIN(a tomato homologue of a human gene encoding a putative nuclear factor that is believed to be involved in NF-κB/IκB signalling) mRNA could not be detected in fruit tissue.LeHSR203 (correlated with HR-like cell death) transcripts were clearly detectable in tomato fruit and significantly increased during postharvest senescence of MG, BR, OR, and RR fruit. CTD1 (IAA/Aux factor) mRNA was detected at very low levels in ripening tomato fruit, but, unlike during chemical-induced PCD, transcript levels did not decrease during the course of ripening.

    In conclusion, these data do not support the hypothesis that PCD occurs during postharvest senescence of tomato fruit. Although LeHSR203 gene expression patterns during postharvest senescence of tomato fruit were similar to those observed during various forms of plant PCD, those of the other genes under investigation were not. In addition, the degradation of genomic DNA (DNA laddering) could not be detected. The results up to now did not lead to novel opportunities for the improvement of tomato fruit quality by targeting plant PCD signalling pathways. However, improvement of tomato fruit quality through inhibition of ethylene biosynthesis or perception at the later stages of ripening seems feasible.

    Gebruiksmogelijkheden ReTain in de fruitteelt - Literatuuronderzoek
    Wenneker, M. ; Maas, F.M. - \ 2001
    Randwijk : PPO Fruit (Rapport PPO 2001-21) - 25
    ethyleen - rijp worden - vruchten - nederland - ethylene - ripening - fruits - netherlands
    The apple skin: colourful healthiness : developmental and environmental regulation of flavonoids and chlorogenic acid in apples
    Awad, M.A.G. - \ 2001
    Wageningen University. Promotor(en): W.M.F. Jongen; L.H.W. van der Plas; A. de Jager. - S.l. : S.n. - ISBN 9789058084255 - 146
    malus - appels - chemische samenstelling - plantenpigmenten - flavonoïden - chlorogeenzuur - rijp worden - plantenontwikkeling - houdbaarheid (kwaliteit) - gasbewaring - malus - apples - chemical composition - plant pigments - flavonoids - chlorogenic acid - ripening - plant development - keeping quality - controlled atmosphere storage

    The ultimate objective of the production, handling and distribution of fresh fruits and vegetables is to satisfy consumers requirements. In general the attractiveness of fruits and vegetables to consumers is determined both by visible (e.g. colour) and invisible (e.g. healthiness) quality attributes. Flavonoids and hydroxycinnamic acid derivatives, secondary metabolites, contribute largely to both fruit colour and, through fruit consumption, to human health and it is, therefore, very useful to study factors that affect these substances with the aim of further improving the relevant fruit attributes. Flavonoids and hydroxycinnamic acid derivatives are widespread in the plant kingdom, comprise a large group of naturally occurring antioxidants that form part of the human diet. There is considerable evidence for the role of antioxidant constituents of fruits and vegetables in the maintenance of health and disease prevention. Recent studies have shown that the majority of the antioxidant activity of a fruit or vegetable may originate from the flavonoids and other phenolic compounds. Apple fruit are rich in flavonoids such as flavonols (quercetin 3-glycosides), flavanols (catechin, epicatechin, gallocatechin, procyanidins and its polymers), dihydrochalcone glycosides (phloritin glucoside (phloridzin) and phloritin xyloglucoside), and cyanidin 3-glycoside (anthocyanins). Apple fruits also contain considerable amounts of hydroxycinnamic acid derivatives mainly represented by chlorogenic acid. The red colour of apples is primarily a consequence of the flavonoid pigments anthocyanins which are located in the vacuole. Despite the importance of flavonoids for the intrinsic quality of apples very little is known of their regulation in fruit. The aim of the work described in this thesis was therefore, to obtain knowledge on the extent to which the contents of flavonoids and chlorogenic acid in the skin of apples varies, how they develop during fruit growth phase, ripening phase and post harvest phase and how they can be manipulated.

    Chapter 1 contains a review of the literature. It appears that the accumulation of flavonoids and phenolic acids in plants is under control of many internal and external factors.

    In Chapter 2 the extent of natural variation in flavonoids and chlorogenic acid concentration due to within fruit, within tree, between orchards, between cultivars and among mutants was determined. Considerable variation was observed among these variables. Individual flavonoids and chlorogenic acid concentrations were not equally distributed within the fruit. Quercetin 3-glycosides and anthocyanin were almost exclusively found in the skin. The sun-exposed skin of individual fruit had much higher cyanidin 3-galactoside (anthocyanin) and quercetin 3-glycoside concentrations than the shaded skin, while phloridzin, catechins and chlorogenic acid were similar in the skin of both sides (Chapter 2). Significant genotypic variation was observed for the concentration of flavonoids and chlorogenic acid. 'Jonagold' apples contain significant higher concentrations (about 30% higher) (Chapters 2 and 6) and amounts (about 2-fold higher) (Chapter 6) of the total flavonoids than 'Elstar' apples. Chlorogenic acid concentration was about 3-fold higher in 'Jonagold' than in 'Elstar' apples. However 'Elstar' apples contained significant higher concentrations of some quercetin glycosides types as quercetin 3-rhamnoglucoside (about 2-fold higher) and quercetin 3-glucosides (about 30% higher) than 'Jonagold' apples. This might be relevant with respect to differences in bio-activity and antioxidant capacity of various flavonoid compounds. As far as the potential maximum concentration of flavonoids in apple is genetically determined breeding would be an important tool for increasing healthiness of apples. The differences between basic forms and coloured mutants within a given cultivar (for example Jonagold-Jonaprince; Elstar-Elshof) show that the potential anthocyanin accumulation (but only that) may increase several fold without influencing the concentrations of other flavonoid classes (Chapter 2). Microscopic study showed that the most blushed mutants had a higher number of red cells per cell layer and more cell layers containing red cells than the standard cultivar and the less blushed mutants. It is striking to observe coloured and completely uncoloured cells as neighbours. Since the selection of coloured mutants is inherently based on the amount of red coloration, selection of mutants for higher levels of other potential healthy flavonoid classes e.g. quercetin 3-glycosides could be considered, providing that such characteristics can be relatively easily determined. The concentrations of anthocyanin, quercetin 3-glycosides and total flavonoids were highest in fruit borne in the top of the tree followed by fruit from the outer tree parts, whereas the lowest concentrations were found in fruit from the inner tree. Terminal fruit contained the highest concentrations of these compounds, including catechins, compared to lateral and spur fruit. Phloridzin and chlorogenic acid were not affected by the position of the fruit in the tree nor by the bearing wood type. The maximum possible difference in flavonoid concentrations, based on difference between top fruit (optimal light conditions) and inner fruit (minimal light conditions) may be 3-fold for quercetin 3-glycosides and 2-fold for total flavonoids (Chapters 2 and 3). There were significant differences in flavonoid and chlorogenic acid concentrations in 'Elstar' fruit between two normally productive orchards differing mainly in growth vigour and internal shading. All these results show that light conditions are a main regulatory factor in the biosynthesis of flavonoids in apples.

    In Chapter 3 the natural distribution of light within the tree canopy in relation to the concentration of flavonoids and chlorogenic acid in fruit skin was analysed. The concentrations of cyanidin 3-galactoside and quercetin 3-glycosides and the percentage of blush in the fruit skin were directly related to light level in the direct vicinity of the fruit. Light in the interior of the canopy was poorer in UV-A, blue, green and red (R) but richer in far-red (FR) light than at all other positions. Consequently, the FR/R ratio (with large influence on formative processes) was much larger at the interior of the canopy than at all other positions. There was a critical FR/R ratio of about 1 above which no anthocyanin and only low amounts of quercetin 3-glycosides were formed.

    In Chapter 4 the relationships between the fruit nutrients N, P, K, Ca and Mg and concentrations of flavonoids and chlorogenic acid in fruit skin were studied with two types of 'Elstar'. In an experiment with the mutant 'Elshof' with the 5 nutrients applied at 5 rates in 4 replications, only N and Ca applications resulted in higher concentration of these nutrients in the fruit, but sufficient variation was present among treatments to correlate the concentration of the other nutrients with those of flavonoids and chlorogenic acid. Negative correlations were frequently found between the concentration of N and Mg and the N/Ca ratio in fruit during growth, and anthocyanin and total flavonoids concentration at maturity in 1996, 1997 and 1998. In 1997, these correlations were weakest but still significant. In that season, P and K concentration were frequently negatively correlated with the concentration of anthocyanin and total flavonoids. The concentration of Ca was not related to the concentration of anthocyanin and total flavonoids. In a study in 1996 with standard 'Elstar', we used the variation in nutrient concentration due to differences in fruit position on tree. The concentrations of N and K and the N/Ca ratio in fruit at maturity were negatively and that of Ca was positively correlated with the concentration of anthocyanin and total flavonoids. Magnesium concentration was negatively correlated with anthocyanin concentration but not with total flavonoids. As a consequence of the relation with position of the fruit in the tree an interaction with the influence of light may, however, be expected. Multiple regression models mainly containing N as factor accounted for up to 40% and 30% of the variance in anthocyanin and total flavonoids concentration of 'Elshof' mutant apples, and for up to 70% and 65% of the variance in anthocyanin and total flavonoids concentration of standard 'Elstar' apples. The relationships between plant nutrients and chlorogenic acid concentration in apples were not consistent and further study is required. It is concluded that, in addition to improving light conditions, the concentration of flavonoids in fruit skin could be further increased by optimising fertilization especially that of N, directed at preventing excess N accumulation.

    In Chapter 5 we tested the concept that under condition of high carbon supply, plants may increase the formation of their secondary metabolites, like phenolic compounds. In field experiments crop load was manipulated by applying flower or fruit thinning at different stages of development and at different severity. At a low crop load, fruit weight, soluble solids, acidity and firmness were significantly higher than at high and moderate loads. However, the concentrations of flavonoid and chlorogenic acid were similar at the different levels of crop load. Time of thinning had no significant influence on the concentration of flavonoids and chlorogenic acid in fruit skin and had no further effect on fruit quality characteristics such as weight, soluble solids, acidity and firmness. Removal of only the interior fruits (about one-third of total fruit) at about 4 weeks before expected commercial harvest had no influence on the concentration of flavonoids and chlorogenic acid or on the quality characteristics of the remaining exterior fruits of either 'Elstar' or 'Jonagold'. The results indicate that, within the 'normal' range of conditions, assimilate availability is not a major regulatory factor in flavonoids and chlorogenic acid formation in apples. These results are in agreement with the lack of any influence of the supply of precursors in the orchard (Chapter 7).

    In Chapter 6 the changes that take place in the concentration and the amount of individual flavonoids and chlorogenic acid in the skin of 'Elstar' and 'Jonagold' apples during development and ripening were investigated. In both cultivars, the concentration on a dry weight basis of quercetin glycosides, phloridzin and chlorogenic acid was highest early in the season but decreased at different rates during fruit development to reach a steady level during maturation and ripening. Catechins (catechin plus epicatechin) concentration showed a similar pattern, but a temporary increase was observed in an early stage of development. The concentration of cyanidin 3-galactoside (anthocyanin) was relatively high early in the season, gradually decreased to a very low steady level during growth, but started to increase near maturation, especially in the outer fruit. On a fruit basis the amount of quercetin glycosides increased during development and was about two times higher in 'Jonagold' compared to 'Elstar', both in outer and inner fruit. These compounds were the most abundant flavonoids in the skin of both cultivars and their accumulation showed a strong dependency on fruit position on tree. The amount of the second most abundant flavonoid type, catechins, increased during development to a maximum and then showed some decrease by mid season which was independent of fruit position on tree. The amount of phloridzin increased only early in the season reaching a steady level during development and ripening, and was independent of fruit position on tree. The amount of chlorogenic acid in both cultivars initially increased, but subsequently decreased to reach a low steady level and was slightly higher in outer than in inner fruit. The latter phenomenon is the only direct evidence for (net) breakdown of any of the studied phenolics. Although anthocyanin concentration was relatively high at early stages of development, significant accumulation on a fruit basis only occurred during maturation and ripening. The accumulation of anthocyanin, similar to that of quercetin glycosides, showed a strong dependency on fruit position on tree. The results indicate that, in general, the overall production of total flavonoids, with the exception of anthocyanin, and chlorogenic acid in apple skin is completed during fruit development before the onset of maturation.

    Chapter 7 reports the influence of exogenous application of a number of chemicals that are precursors of flavonoids or are known to affect ripening on the accumulation of flavonoids and chlorogenic acid in 'Jonagold' apple skin with emphasis on anthocyanin. One aim was to identify a possible substrate limitation and another to separate the formation of anthocyanin from other related maturity/ripening events. Since the occurrence of the second peak in anthocyanin formation more or less parallels the maturation and ripening phase (like starch degradation and aroma production), anthocyanin formation itself is often considered as a ripening phenomenon triggered by ethylene. Our results suggest, however, that there is no simple relation to ripening and consequently to ethylene production (though we did not measure ethylene). This is concluded from the promotion of anthocyanin formation by ethephon (an ethylene releasing compound) and the retardation of anthocyanin formation by ABG and GA 3 (known to lower or counteract endogenous ethylene), without significantly altering starch degradation and changes in streif index (combination of starch index, firmness and sugar concentration). Our results have also shown that the other flavonoid classes quercetin 3-glycosides, catechins and phloridzin and chlorogenic acid do not respond to any of the applied chemicals. It is concluded that anthocyanin formation is dependent on developmental signals and independent of both fruit maturity/ripening and of the synthesis of other flavonoid classes and responds in a complicated way to ethylene.

    In Chapter 8 the changes in individual flavonoids and chlorogenic acid during regular (RS) or ultra low oxygen (ULO) storage conditions at 1°C are reported in both 'Jonagold' and 'Elstar' apples. It could convincingly be shown that during storage of both 'Jonagold' (3, 6 and 8 months) and of 'Elstar' (2, 4 and 6 months) and during 1 or 2 weeks shelf life, the concentrations of cyanidin 3-galactoside and quercetin glycosides were relatively constant, while the concentrations of catechins, phloridzin and chlorogenic acid showed only minor decreases. Moreover there were no significant differences in the concentration of flavonoids and chlorogenic acid between fruits stored under ULO compared to RS conditions. It is concluded that, following harvest, flavonoids present in apples are stable. There is no direct or indirect proof for breakdown (net metabolic turnover) during storage and shelf life.

    In Chapter 9 the practical applications of the findings made in this study were discussed. Our results show that there is much room for increasing the level of potential health phytochemicals in apples. The first step would be cultivar selection either from already available genotypes or by developing new cultivars through classical breeding or molecular biology and gene technology. We showed that light has a significant impact on the final level of flavonoids in fruit. Therefore, the second and more proximate option would be the optimisation of light conditions within tree canopy by measures such as choice of root stocks, planting system, row orientation and training and pruning systems or covering the orchard floor with reflecting films (though the latter is not promoting the visual aspect of the orchard). A third step could be optimisation of the fertilization programme especially avoiding excess N and better timing of N-application. A further possibility is to sort fruit in healthiness classes. As long as a simple method to detect non-destructively quercetin 3-glycosides is lacking, sorting of fruit based on their blush might be a way to make healthiness classes, since blush is a good marker for exposure to light during growth and thus to some extent for the quercetin 3-glycosides level. Even when cultivar choice and cultivation methods succeed in getting high levels of flavonoids in fruit still the treatment by the consumer determines how much of these substances will be consumed. Many consumers still peel the fruit before consumption thereby removing almost all anthocyanin and quercetin 3-glycosides (Chapter 2). Promotion of fruit on the basis of healthiness is, in our opinion, however, only useful if it is accompanied with a guarantee of absence of pesticides, as is most credible, at least to the public, in organic farming.

    Because of the large influence of a number of factors at several steps of the production chain, a quantitative model e.g. integrated with light distribution models, would offer a practical and effective tool for estimating the effect of certain measures and to predict and maximise the final level of healthy compounds in apples enabling the development of more accurate intake data and dietary recommendations.

    Lange bewaring van fritesaardappelen : afgerijpt produkt biedt goede perspectieven
    Hak, P. ; Hoof, M. van - \ 2000
    Aardappelwereld 54 (2000)4. - ISSN 0169-653X - p. 13 - 15.
    aardappelen - solanum tuberosum - opslag - koelen - houdbaarheid (kwaliteit) - opslagkwaliteit - rijpheid - rijp worden - aardappelproducten - temperatuur - chemische analyse - chemische samenstelling - monosacchariden - potatoes - storage - cooling - keeping quality - storage quality - maturity - ripening - potato products - temperature - chemical analysis - chemical composition - monosaccharides
    Rubrieken binnen dit artikel: invloed op bewaarresultaat; het ras; fysiologisch stadium; zorgvuldige handling; drogen en wondhelen; afkoelen; beheersing CO2 concentratie; beheersing spruiting; temperatuurbeleid tijdens bewaring
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