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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Gezondheidseffecten onder de loep : weldadig groen
Spijker, J.H. ; Vries, S. de - \ 2017
Stadswerk (2017)6. - ISSN 0927-7641 - p. 34 - 36.
gezondheid - warmtestress - temperatuur - kwaliteit - beplantingen - biodiversiteit - stedelijke gebieden - bevolking - stressfactoren - sociaal welzijn - klimaat - health - heat stress - temperature - quality - plantations - biodiversity - urban areas - human population - stress factors - social welfare - climate
Groen speelt een sleutelrol bij een gezonde leefomgeving. De gezondheidseffecten spelen op diverse manieren, maar vooral door de stressverlagende effecten van groen en de hittedempende werking op warme dagen. Het is daarbij wel belangrijk om niet alleen naar de kwantiteit maar ook naar de kwaliteit van het groen te kijken.
Effecten van gebiedsgrootte op de kwaliteitsbeoordeling van Natuurgebieden : evaluatie begrenzing van beoordelingsgebieden volgens de Werkwijze Monitoring en Beoordeling van het Natuurnetwerk
Sanders, M.E. ; Schippers, P. ; Meeuwsen, H.A.M. - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2805) - 49
natuurgebieden - natuur - kwaliteit - monitoring - natura 2000 - soortenrijkdom - grootte - natural areas - nature - quality - species richness - size
De kwaliteitsbeoordeling van natuurgebieden zoals beschreven in de “Werkwijze Monitoring en Beoordeling Natuurnetwerk en Natura2000/PAS” is onder andere gebaseerd op het aantal kwalificerende soorten per beheertype en de ruimtelijke verspreiding daarvan. Deze beoordeling kan gevoelig zijn voor ruimtelijke keuzes in omvang en ligging van de beoordelingsgebieden. In dit rapport onderzoeken we de relatie tussen de grootte van de beoordelingsgebieden en de kwaliteitscriteria voor Natura 2000-gebied de Nieuwkoopse Plassen en de Veluwe. De resultaten laten zien in welke mate de beoordeling afhankelijk is van de gebiedsgrootte. Daarnaast doen we een voorstel voor een alternatieve methode voor de kwaliteitsbeoordeling die niet afhankelijk is van de gebiedsgrootte. Bij de alternatieve methode kunnen de arealen per beheertype worden opgeteld voor elke gewenst (Natura 2000-) gebied, per provincie of landelijk ongeacht de grootte en ligging van de beoordelingsgebieden.
Natuurbrug Laarderhoogt en woningbouw op Crailo-Zuid : programma van eisen voor woningbouw nabij de Natuurbrug vanuit ecologisch perspectief
Grift, E.A. van der; Lammerstma, D.R. - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2799) - 31
habitatfragmentatie - natuur - kwaliteit - ecologische verstoring - woningbouw - habitatverbindingszones - wildpassages - noord-holland - habitat fragmentation - nature - quality - ecological disturbance - house building - habitat corridors - wildlife passages
Philosophical explorations on energy transition
Geerts, Robert-Jan - \ 2017
Wageningen University. Promotor(en): Bart Gremmen; Guido Ruivenkamp, co-promotor(en): Josette Jacobs. - Wageningen : Wageningen University - ISBN 9789463430487 - 172
philosophy - technology - sustainable energy - renewable energy - social change - energy consumption - quality - society - energy - filosofie - technologie - duurzame energie - hernieuwbare energie - sociale verandering - energiegebruik - kwaliteit - samenleving - energie

This dissertation explores energy transition from a philosophical perspective. It puts forward the thesis that energy production and consumption are so intimately intertwined with society that the transition towards a sustainable alternative will involve more than simply implementing novel technologies. Fossil energy sources and a growth-based economy have resulted in very specific energy practices, which will change in the future. Broader reflection is needed to understand how and in which direction such change is acceptable and desirable.

This reflection is initiated by articulating two pertinent problems with current energy practices that have thus far failed to receive appropriate attention in debates on energy transition: 1) the difficulty of dealing with intermittent sources in relation to the idea of cumulative accounting of energy consumption, and 2) the mismatch between expectations of ethical consumer behaviour in energy systems that discourage engagement.

To move forward, instead of assuming that all consumption is equivalent and that more is better, we must develop a better informed and more nuanced idea of 'good' energy practices that actually contribute to our quality of life. One often overlooked aspect of this may be 'embodied engagement', which would suggest that automation of tasks through energy-consuming technologies may be convenient, but also tends to lead to a loss of appreciation for both the task and its result. Some things, like creating a cozy environment around a fireplace, or climbing a mountain, are better partly because they take effort. In such cases, the 'efficiency' of the technology (e.g. the heat-pump, or the automobile) is besides the point - the question is whether it gives us anything of value at all.

Eindrapport Fruitkwaliteit Continu op Niveau : voorspelling bewaarkwaliteit van Elstar en Conference 2014-2015
Schaik, Alex van; Wenneker, Marcel - \ 2016
Wageningen : Wageningen Plant Research (Wageningen Plant Research rapport 2017-01) - 31
appels - peren - kwaliteit - gewaskwaliteit - opslagkwaliteit - apples - pears - quality - crop quality - storage quality
Verkenning indicatoren voor de beoordeling van terrestrische natuurkwaliteit op provinciaal schaalniveau
Greft-van Rossum, J.G.M. van der; Zee, F.F. van der; Knegt, B. de; Pouwels, R. - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2750) - 27
natuur - provincies - natuurbeheer - ecologische beoordeling - kwaliteit - indicatoren - nature - provinces - nature management - ecological assessment - quality - indicators
Provincies in Nederland zijn na de decentralisatie meer verantwoordelijk voor de natuurkwaliteit in de provincies. Om de outcome van het natuurbeleid te kunnen monitoren en hierover de Provinciale Staten te kunnen informeren, hebben provincies behoefte aan indicatoren die de kwaliteit van de natuur in de provincie weergeven. De afgelopen jaren is deze kwaliteit in Nederland op verschillende wijzen beoordeeld. Ook zijn enkele provincies gestart met het ontwikkelen van provinciale indicatoren. Het is echter onbekend of alle provincies dezelfde indicatoren willen gebruiken en in hoeverre deze samenhangen met indicatoren op landelijk schaalniveau. In dit project wordt een overzicht gegeven van indicatoren voor de terrestrische natuur en op basis van enkele schema’s wordt de samenhang van de indicatoren weergegeven. Deze schema’s geven inzicht waar provinciale indicatoren mogelijk goed aansluiten bij nationale indicatoren en waar eventuele knelpunten liggen voor een uitwerking op provinciaal niveau. Aandachtspunt daarbij is optimaal gebruik van monitoringssystemen. Naast de indicatoren die momenteel gebruikt worden, is er behoefte aan indicatoren voor het agrarisch gebied en het stedelijk gebied.
Examining growth, yield and bean quality of Ethiopian coffee trees : towards optimizing resources and tree management
Bote, Adugna - \ 2016
Wageningen University. Promotor(en): Niels Anten, co-promotor(en): Jan Vos; F.L. Ocho. - Wageningen : Wageningen University - ISBN 9789462578319 - 138
coffea - coffea arabica - trees - growth - yields - quality - radiation - nitrogen - agroecosystems - coffea - coffea arabica - bomen - groei - opbrengsten - kwaliteit - straling - stikstof - agro-ecosystemen

Coffee (Coffeaarabica L.)bean production and quality are determined by a diversity of interacting factors (e.g. shade, nitrogen, crop traits). Bean yield increases with increase in radiation, but adequate fertilizer suppliesare needed to sustain the productivity. This thesis analysed coffee tree growth, bean production and bean quality in relation to different degrees of exposure to radiation and nitrogen supply. Growth of leaves and branches and properties of leaves such as specific leaf area, nitrogen content per unit leaf area and light-saturated rate of photosynthesis were determined. Radiation interception and nitrogen uptake were also determined as were radiation use efficiency and apparent nitrogen recovery. Tree biomass and coffee bean yield responded positively to both radiation and nitrogen supply. Abundant bean yield to the detriment of vegetative growth, however, resultedin biennial bearing in coffee trees. Effects of fruit load on coffee treegrowth and productivity were studied for two consecutive years and the resultshowed that competition between fruit growth and vegetative growth predisposed the trees for biennial bearing. Reduced vegetative growth when fruit load is high reduces the number of flower bearing nodes and hence yields in the next season. Coffee quality is a sum of favourable characteristics that satisfies requirements of different actors in the coffee chain and is the factor determining the price on the coffee market. This study has also examined coffee quality attributes in relation to radiation and nitrogen, fruit load manipulation, and genotype by environment (different altitudes) interactions. The result indicated that factors and conditions that support non-limiting supply of resources for bean to grow and a sufficient long period of maturation promote coffee bean quality. Overall, the study gained further understanding of coffee tree growth, yield and bean quality responses to aforementioned factors and explored traits that underlie the patterns. Further works are required to use the traits and describe the behaviour of coffee trees in different agro-ecosystems.

Deep frying : from mechanisms to product quality
Koerten, K.N. van - \ 2016
Wageningen University. Promotor(en): Maarten Schutyser, co-promotor(en): Remko Boom. - Wageningen : Wageningen University - ISBN 9789462576476 - 119
deep fat frying - quality - chips (french fries) - evaporation - crusts - moisture meters - fried foods - crisps - frituren - kwaliteit - patates frites - evaporatie - korsten - vochtmeters - gebakken voedsel - aardappelchips

Deep frying is one of the most used methods in the food processing industry. Though practically any food can be fried, French fries are probably the most well-known deep fried products. The popularity of French fries stems from their unique taste and texture, a crispy outside with a mealy soft interior, but also because of the ease and speed of preparation. However, despite being a practical and easy method, the fundamental phenomena that occur during frying are very complex. This thesis aimed at gaining a deeper understanding of the frying of French fries. This was done at the product level, with regards to heat transfer, moisture loss, oil uptake and crust formation, and at the process level, which encompasses the oil movement in a frying unit and the consequent oil-fry interactions.

Firstly a numerical model was developed to describe the water evaporation during frying (Chapter 2). Though various models exist for describing moisture loss, they all use constant values for the heat transfer coefficient. However, the heat transfer coefficient actually varies greatly due to the varying degrees of turbulence, induced by the vapour bubbles escaping from the fry surface. Therefore, the model in this thesis incorporated an evaporation rate dependent heat transfer coefficient. Other than the varying heat transfer coefficient, the model was heat transfer dependent, with a sharp moving evaporation boundary and Darcy flow describing the flow of water vapour through the crust. The model was successfully validated against experimental results for moisture loss and temperature profiles in the fry.

For oil uptake during frying, a pore inactivation model from membrane technology was adopted (Chapter 3). In membranes, pores will inactivate when the transmembrane pressure becomes too low. In fries, this can be translated as pores in the crust inactivating when the evaporation rate becomes too low. As pores stop expelling water vapour, oil can migrate into the fry. The model also took into account the lengthening of the pores with increasing crust thickness, allowing for more oil uptake in inactivated pores. The model fitted well with experimental data for oil uptake during frying. Also, the pore inactivation model better described oil uptake during the initial stages of frying, where the evaporation rate is still relatively high, compared to the linear relation between oil uptake and moisture content, which is usually assumed in literature.

Both the influences of frying temperature and moisture content on crust structure and consequent textural properties were studied (Chapter 4). The crust structure was visualized and quantified using X-ray tomography (XRT), which uses multiple 2D X-ray pictures of a rotated sample to reconstruct a 3D density map. Textural properties, like hardness and crispness, were quantified using force deformation curves from a texture analyser. Moisture loss was shown to greatly increase porosity and pore size in fries. More crispy behaviour was also shown for higher moisture loss, though not significantly at moisture contents close to the initial moisture content. Though increased frying temperatures also showed an increased porosity and pore size, there was no significantly observed increase in crispness. This is most likely because the texture analysis was not sensitive enough to discern any increased crispness for porosities below a certain degree. Strikingly, for frying temperature around 195 °C, a decrease in crispness was observed. These samples visually also showed more plastic behavior. The most likely cause for this is degradation of sucrose, which happens around 186 °C, and consequent caramelization of glucose, thus increasing the glass transition temperature.

At the process level, oil flow and fry quality distribution were investigated using a pilot scale cross-flow fryer (Chapter 5). Oil circulation velocities were varied to observe the initial fluidization behavior of the fry bed through an observation window. This fluidization behavior was well described by the Ergun equation, modified for non-spherical particles. The distribution in moisture content of the fries was used as an indicator for quality distribution. Though increased oil circulation initially increased the homogeneity of the moisture content, upon fluidization the homogeneity actually decreased. Image analysis of fries before and after frying showed local packing of fries around their fluidization point. This was due to the non-spherical shape of the fries, making them more sensitive to channelling.

The results obtained in this thesis were finally discussed, together with the possibility to also model the process scale of the frying process (Chapter 6). The possibility of modelling the oil flow through a packed bed of fries, and the free-convective heat transfer during frying, using a CFD software package (STARCCM+) was shown. Additionally, the possibility of linking oil flows computed using CFD to the general models developed in this thesis was discussed. Modelling the momentum transfer of the expelled vapour bubbles to the oil, but also the movement of the fries themselves is still a faraway goal. However, a multiphase model that can describe both the entire frying setup as the consequent individual fry parameters would be invaluable.

Kwaliteitsbeoordeling verse schol : Vergelijking hand- en mechanisch gestripte schol van de MDV-1
Schelvis-Smit, A.A.M. - \ 2016
IMARES (Rapport / IMARES C003/16) - 36 p.
schol - verse producten - visproducten - kwaliteit - visverwerking - plaice - fresh products - fish products - quality - fish processing
Rietdekkers rietkwaliteit en levensduur
Dam, J.E.G. van; Kolk, J.C. van der; Putten, J.C. van der - \ 2015
Wageningen UR - Food & Biobased Research (Rapport / Wageningen UR Food & Biobased Research 1578) - 28 p.
bouwmaterialen - dakstro - phragmites - kwaliteit - duurzaamheid (durability) - building materials - thatch - quality - durability
Riet als dakbedekking kan bogen op een eeuwenoude traditie en wordt nog steeds veelvuldig toegepast bij renovatie maar ook gewaardeerd voor nieuwbouw. In de praktijk echter doen zich tegenwoordig regelmatig problemen voor, waarbij het rietdek vroegtijdig sporen van aantasting vertoont en al na enkele jaren reparatie of vervanging nodig is. Dit verslag beschrijft de “state of the art”, waarin wat er al bekend is uit de wetenschappelijke en vakliteratuur over rietkwaliteit en de factoren, die mogelijk de vroegtijdige achteruitgang veroorzaken, onder de loep worden gelegd. De tweede stap was het systematisch analyseren van een aantal geoogste rietsoorten en twee monsters afkomstig van gerepareerde rieten daken van factoren die mogelijk kunnen verklaren waarom de kwaliteit goed dan wel slecht is.
Audit Basisregistratie Topografie 2014 : resultaten van de tweede wettelijk vereiste externe controle op de kwaliteit van de BRT
Storm, M.H. ; Knotters, M. ; Schuiling, C. ; Clement, J. - \ 2015
Alterra, Wageningen-UR (Alterra-rapport 2640) - 25 p.
geodata - topografie - luchtfotografie - kwaliteit - registratie - topography - aerial photography - quality - registration
Tussen november 2014 en april 2015 voerde Alterra een audit uit op de Basisregistratie Topografie. Deze audit is uitgevoerd op de november 2014-release van TOP10NL in file geodatabase formaat. De TOP10NL-data zijn vergeleken met de luchtfoto’s van het jaar van herziening. Deze luchtfoto’s zijn ook gebruikt in het productieproces. In aanvulling op de luchtfoto’s is gebruikgemaakt van cyclorama’s voor zover zaken niet of niet duidelijk zichtbaar waren op de luchtfoto. Bij de controle is gekeken of de data voldoen aan wat beschreven staat in het document Basisregistratie Topografie: Catalogus en Productspecificaties versie 2.2 (Kadaster, 2014a).
Big data dringen door in de tuinbouw. Naar een volledig begrip van plantgedrag en productkwaliteit
Kierkels, T. ; Zedde, H.J. van de - \ 2015
Onder Glas 12 (2015)11. - p. 24 - 25.
tuinbouw - glastuinbouw - innovaties - landbouwkundig onderzoek - kunstmatige intelligentie - gewaskwaliteit - plantenveredeling - sorteren - kwaliteit - teeltsystemen - 3d analyse - metabolomica - genomica - transcriptomica - horticulture - greenhouse horticulture - innovations - agricultural research - artificial intelligence - crop quality - plant breeding - sorting - quality - cropping systems - 3d analysis - metabolomics - genomics - transcriptomics
Vijftien onderzoeksgroepen van Wageningen UR hebben de handen ineengeslagen om te komen tot het beter meten, begrijpen en voorspellen van plantgedrag en productkwaliteit. Het vakgebied heet ‘Plant phenomics’ en maakt gebruik van innovatieve technieken en sensoren. Het doel is een betere beheersing van teelt- en veredelingsproces en productkwaliteit. Toepassingen voor de praktijk liggen nog vooral op het terrein van sorteren en automatische kwaliteitsbeoordeling.
Logistics network design & control : managing product quality in a blooming sector
Keizer, M. de - \ 2015
Wageningen University. Promotor(en): Jack van der Vorst, co-promotor(en): Jacqueline Bloemhof-Ruwaard; Rene Haijema. - Wageningen : Wageningen University - ISBN 9789462576025 - 239
logistiek - netwerkanalyse - sierteelt - kwaliteitszorg - kwaliteit - productie - tuinbouw - verse producten - voedselproducten - simulatiemodellen - simulatie - logistics - network analysis - ornamental horticulture - quality management - quality - production - horticulture - fresh products - food products - simulation models - simulation
Natriumgevoeligheid en recirculatie bij Cymbidium. Tussenrapport na 1e teeltjaar : Behoud plantgezondheid en voorkomen groeiremming bij hergebruik drainwater
Kromwijk, J.A.M. ; Voogt, W. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1371) - 24
teelt onder bescherming - glastuinbouw - cymbidium - recirculatiesystemen - emissie - natrium - drainagewater - groei - kwaliteit - gewaskwaliteit - protected cultivation - greenhouse horticulture - recirculating systems - emission - sodium - drainage water - growth - quality - crop quality
In the Netherlands, the government and horticultural industry have agreed to lower the emission of nutrients to the environment. Until recently no drain water was reused in the cultivation of Cymbidium orchids as growers were allowed to discharge the drain water when a sodium level of more than 0 mmol/l was reached. As reusing drain water is a new phenomenon for Cymbidium, growers are now faced with a lack of knowledge on the effects of drain water reuse. Therefore a trial was started to investigate the effect of sodium accumulation on crop growth and flowering in two varieties of Cymbidium. Different sodium concentrations are given while maintaining the EC at 0.8. These sodium treatments have a lower “nutritional EC” than the control treatment without sodium. As of February 2015 unusual symptoms in the leaves emerged at the two highest levels of sodium resulting in dead leaf tips / leaves. This is potassium deficiency, induced by the lower potassium concentration in the nutritional solution and by inhibition of the potassium uptake by a high sodium concentration. In the first year of cultivation, sodium accumulation had no effect on production as the flower stalks were already induced before the start of the treatments. Cymbidium is a perennial crop in which negative effects on production and quality take a long time to become visible, so the experiment will be continued into a second year of cultivation. This research is funded by the Cymbidium growers in the Netherlands, Product Board for Horticulture and Top Sector Horticulture and Propagation Materials.
Lichtspectrum als middel voor energiezuinige rozenteelt : praktijkproef bij Van der Arend Roses
Garcia Victoria, N. ; Pot, S. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1368) - 68
teelt onder bescherming - glastuinbouw - rozen - kunstlicht - led lampen - lichtsterkte - productie - kwaliteit - energiebesparing - energy economics - protected cultivation - greenhouse horticulture - roses - artificial light - led lamps - light intensity - production - quality - energy saving
During the winter 2014-2015 a research was conducted at a commercial rose nursery to learn more about the influence of a special lamp light spectrum on the production and quality of the rose Avalanche. A “hybrid” lighting system was installed with 103 µmol /m2s PAR from High Pressure Sodium and from Valoya LED lamp G1 in two different intensities: 57 or 103 µmol /m2s PAR. Compared with the conventional installation of the company (191 micromol SON-T), the spectrum of the hybrid installation allowed, depending on the intensity of the added LED, a 7.2% to 9% higher light use efficiency (LUE) by the crop. This offers possibilities for energy saving, but therefore the energy efficiency of the lamps used (Valoya G1) needs to increase to an output of 1.7 µmol PAR per watt electric. Valoya is already working on this improvement. The performed plant measurements (SPAD, bud temperature, photosynthesis, leaf area, etc.) do not contribute to explain this positive effect. More research about the effects of light colour on the rose production is needed. Remaining questions are if other rose varieties react the same to the combined spectrum, if the crop can grow more compact in winter when there is more blue in the spectrum, and if a larger proportion of far-red light could make the flowers even heavier, with a larger flower bud. The research was funded by the program “Greenhouse as Energy Source” (Ministry of Economy and the Horticultural Product Board) and Valoya.
Uiensector werkt samen aan kwaliteit
PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2015
Boerderij 100 (2015)28. - ISSN 0006-5617 - p. 24 - 27.
akkerbouw - uien - kwaliteit - rassen (planten) - economische samenwerking - proefboerderijen - nederland - arable farming - onions - quality - varieties - economic cooperation - experimental farms - netherlands
Door kordate ketensamenwerking heeft de uiensector kwaliteitsonderzoek in de benen gekregen. Met ook als resultaat: de rassenlijst blijft bestaan. De plannen zijn groter dan ooit.
Camera vervangt ervaren selecteur
Kamp, J.A.L.M. - \ 2015
Boerderij 100 (2015)36. - ISSN 0006-5617 - p. 50 - 53.
akkerbouw - aardappelen - vermeerderingsmateriaal - detectie - monitoring - diagnostische technieken - fotometrie - pootaardappelen - kwaliteit - kunstmatige selectie - gewasbescherming - precisielandbouw - arable farming - potatoes - propagation materials - detection - diagnostic techniques - photometry - seed potatoes - quality - artificial selection - plant protection - precision agriculture
Selecteren van pootaardappelen kost de teler veel tijd en vergt een hoge mate van vakmanschap. Wellicht kan een machine dat sneller en beter. Daarom start dit jaar het vierjarige project Smart Ziekzoeken Pootaardappelen om te testen of het automatisch opsporen van zieke aardappelplanten haalbaar is. Het project wordt uitgevoerd door Praktijkonderzoek Plant en Omgeving (PPO) en specialisten van Plant Research International (beide onderdeel van Wageningen UR)
Facility management in Dutch higher education
Kok, H.B. - \ 2015
Wageningen University. Promotor(en): Onno Omta, co-promotor(en): Mark Mobach. - Wageningen : Wageningen University - ISBN 9789462573499 - 133
facilitaire diensten - gebouwen - onderwijs - hoger onderwijs - universiteiten - kwaliteit - ontwerp - voorzieningen - bedrijfsvoering - nederland - facility management - buildings - education - higher education - universities - quality - design - facilities - management - netherlands
This book discusses whether, and if so, how facility management can contribute to educational achievements at Dutch higher education institutions.
Daqu : a traditional fermentation starter in China: microbial ecology and functionality
Zheng, X. - \ 2015
Wageningen University. Promotor(en): Marcel Zwietering; E.J. Smid, co-promotor(en): Rob Nout. - Wageningen : Wageningen University - ISBN 9789462572805 - 175
fermentatieproducten - fermentatie - optimalisatie - starterculturen - micro-organismen - kwaliteit - china - fermentation products - fermentation - optimization - cultured product starters - microorganisms - quality - china
Abstract

Fermented products have high nutritional value and constitute an important part of the Chinese dietary profile; they are also gaining popularity throughout the world. Daqu is a traditional natural fermentation starter culture that has a significant impact on the quality and flavour of Chinese liquor and vinegar.

A review of the literature was conducted focusing on the classification, composition, and manufacture of Daqu. The review provided a preliminary understanding of the link between the fermentation process and the characteristics of the final Daqu product. Then the occurrence, levels, and diversity of microorganisms were studied in different types of Daqu produced by various fermentation processes. The results showed that Bacillus licheniformis and Saccharomycopsis fibuligera were present in all the tested samples of Daqu. Regional comparisons showed Staphylococcus gallinarum and Staphylococcus saprophyticus in southern Daqu. The fungi Sm. fibuligera and Lichtheimia ramosa were found in low/medium-temperature Daqu and Thermomyces lanuginosus occurred in high-temperature Daqu.

In order to study the functionality of Daqu and the contribution of the predominant microorganisms to alcoholic fermentation, the mesophilic and thermophilic bacteria and spores, Enterobacteriaceae, lactic acid bacteria, yeasts, and moulds present in the core and outer portions of Fen-Daqu were isolated. The isolates were identified by culture-dependent sequencing of rRNA genes (16S rRNA for bacteria; 18S rRNA, 26S rRNA, and ITS rRNA for fungi). A succession of fungi, lactic acid, and Bacillus spp. was associated with prevailing acidity, moisture content, and temperature during Daqu fermentation. The predominant species in fermentation were B. licheniformis, Pediococcus pentosaceus, Lactobacillus plantarum, Pichia kudriavzevii, Wickerhamomyces anomalus, Sacchromyces cerevisiae, and Sm. fibuligera.

One strain of the each of the above-mentioned predominant species, with the highest starch degrading ability and alcohol tolerance, was selected and used in different combinations to perform alcoholic fermentation. Metabolite composition differed significantly between various fermentation trials. S. cerevisiae provided superior ethanol production. Sm. fibuligera and B. licheniformis provided the amylolytic activity that converted starch and polysaccharides into fermentable sugars. Finally, W. anomalus was found to be an important contributor to formation of the liquor aroma.

Understanding the microbial diversity and functional activity, as well as the production dynamics and safety of Daqu will enable commercial producers to improve and/or scale-up traditional processes and enhance product quality and safety, thus facilitating entry into international markets.

Quality of traditionally processed shea (Vitellaria paradoxa) kernels and shea butter
Honfo, G.F. - \ 2015
Wageningen University. Promotor(en): Tiny van Boekel; M.M. Soumanou, co-promotor(en): Anita Linnemann. - Wageningen : Wageningen University - ISBN 9789462572737 - 237
sheaboter - voedselbereiding - plantaardige vetten - warmtebehandeling - extractie - inheemse kennis - kwaliteit - achteruitgang (deterioration) - benin - vitellaria paradoxa - shea butter - food preparation - plant fats - heat treatment - extraction - indigenous knowledge - quality - deterioration - benin - vitellaria paradoxa

Abstract

The shea tree is an endogenous and multipurpose tree from the Savanah zone of Africa, mostly used for its fruits and the fat extracted from its kernels, commonly known as shea butter. The butter is used for cooking and medicinal purposes by local populations, and in cosmetic products as well as a cocoa butter substitute in chocolate in others areas of Africa and at the international level. The butter is generally extracted by traditional methods, which vary throughout the production zones but involve some common processing operations viz. boiling of the fresh nuts, sun drying, shelling, crushing, roasting, milling, churning, and heating. This thesis investigated the influence of traditional processing of shea on quality attributes of shea kernels and butter.

The results showed that 2 mains techniques (differing in the heat treatment applied to the fresh nuts) are used to process shea fruits after their collection: the boiling followed by sun drying technique and the smoking technique. Boiled and sundried kernels contained a higher fat content (48 % dw) and yielded more butter (30 % of kernel mass) than smoked kernels that had a fat content of 39 % dw. The butter extracted from the boiled kernels had a better quality than the butter from smoked kernels with respect to the unsaponifiable fraction (7 %), tocopherol compounds (125 mg/g), peroxide value (8 meq O2/kg), and FFA (2 %). Some processing operations, namely the storage of fresh nuts as related to their boiling time and the roasting of kernels, were optimized using the response surface method to design the experiments. The conditions to obtain an optimal quality of kernels are to store the nuts for 3 days and boil them for 28 ± 3 min. Subsequently, optimal roasting conditions for kernels were found to be 15 min at 171 ºC, which resulted in kernels with a fat content of 49 % dw, a butter yield of 32 %, and butter with a FFA of 1.2 %. The results also revealed that shea butter extracted from roasted kernels contained more volatile compounds (58) than that from unroasted kernels (27). Additionally, storage temperature and storage duration significantly affected some quality characteristics of shea butter, whereas the influence of local packaging materials was less pronounced

Shea processors are advised to process shea fruits by integrating the optimal conditions of storage of fresh nuts, boiling and roasting found in this research, then pack the butter in clean and opaque plastic and store it in a relatively cool area to maintain the quality of the product during prolonged storage periods. Areas for future research were identified for further improvements of local shea processing.

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