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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    Een kwestie van smaak
    Smit, G. - \ 2007
    Wageningen : Wageningen UR - 31
    smaak - geur en smaak - geurstoffen en smaakstoffen - receptoren - smaakonderzoek - taste - flavour - flavour compounds - receptors - taste research
    The formation of fat-derived flavour compounds during the ripening of Gouda-type cheese
    Alewijn, M. - \ 2006
    Wageningen University. Promotor(en): J.T.M. Wouters, co-promotor(en): E.L. Sliwinski. - Wageningen : - ISBN 9789085043812 - 136
    goudse kaas - geurstoffen en smaakstoffen - vetten - vetzuren - lactonen - esters - ketonen - kaasrijping - gouda cheese - flavour compounds - fats - fatty acids - lactones - esters - ketones - cheese ripening
    Cheese flavour is an important quality attribute, and is mainly formed during cheese ripening. Besides compounds that are formed from protein and carbohydrates, milk fat-derived compounds are essential for cheese flavour. Before, but mainly during ripening, free fatty acids, lactones, ketones, esters, alcohols and aldehydes can be formed from milk fat, compounds that all contribute their own special character to the final cheese flavour. The formation mechanisms that lead to these compounds are not completely understood, and therefore cheese flavour formation is not under full control.
    Sensory and instrumental analysis of food aromas
    Bult, J.H.F. - \ 2006
    Wageningen University. Promotor(en): J.H.A. Kroeze; Fons Voragen, co-promotor(en): H.N.J. Schifferstein; J.P. Roozen. - [S.l.] : S.n. - ISBN 9789085045236 - 172
    aroma - aromatische verbindingen - geur en smaak - geurstoffen en smaakstoffen - zintuiglijke waarneming - sensorische evaluatie - gaschromatografie - aroma - aromatic compounds - flavour - flavour compounds - organolepsis - sensory evaluation - gas chromatography

    Food aromas are generally perceived as unitary aromas, i.e. fried potatoes smell like fried potatoes and roasted coffee smells like roasted coffee. Nonetheless, nearly all food aromas are produced by a multitude of volatile components that contribute to an extensive collection of aromas in various compositions. Of the hundreds of volatiles released from fried potatoes and roasted coffee a major se!ection does not produce an odour, many others do produce an odour that contributes to one of both aromas, many others contribute to both. In spite of this, food aromas are not being perceived as collections of discernable odours.

    Central theme of this thesis is a method used to fractionate, identify and characterise the odorous components in mixtures of odorants: gas chromatography olfactometry (GCO). GCO entails the pressurised transfer of volatiles through a capillary column, after capturing these from the headspace of a foodstuff. Since the column delays volatiles differentially, panellists may sniff these volatiles sequentially on their release from the capillary. This allows the separate sensory evaluation of components in the aroma mixture.

    A well-established practice in technological studies is that measurement reliability of instruments is estimated and minimised. Although sniffing panels are generally employed as instruments that assess the odour impact of chemical components in food aromas, reliability assessment is generally not applied to their application. Paradoxically, there are no practically available valid methods that may assess the reliability of panel responses. In addition, studies of systematic bias of panel responses in GCO studies are not available, although some common assumptions in GCO studies are not valid psychologically. For instance, intense odorants that arc qualitatively similar to the aroma quality are generally identified as character impact components. However, perception studies showed that odorants may affect (viz. suppress) each others odour contribution in a mixture. Therefore, assumptions regarding the contribution of singular odorants to aromas on basis of GCO, is premature.

    This thesis introduces methodology to estimate GCO response reliability and reports the empirical testing of this methodology (chapters 2, 3 and 4). In addition, several GCO assumptions considered psychologically disputable, are evaluated in empirical studies. These studies entail the effect of stimulus context on the estimated reliability of GCO results (chapter 4), the evaluation of the contribution of GCO-identified 'character impact components' to an apple model aroma (chapter 5), the effects of task instruction on the identification of odorants in food aromas (chapter 6), the effects of peri-threshold components on a supra-threshold food aroma (chapter 7) and the effects of sequentially presented odorants on their mutual odour intensities as a function of qualitative odour similarity (chapter 8). The general conclusions of this thesis are, that panel responses in the temporary absence of odorants must be used to estimate the reliability of panel odour detections, and that mechanisms that systematically affect response variation should be known and considered m GCO.

    Flavour aspects of pea and its protein preparations in relation to novel protein foods
    Heng, L. - \ 2005
    Wageningen University. Promotor(en): Fons Voragen; Tiny van Boekel, co-promotor(en): Jean-Paul Vincken. - Wageningen : Wageningen University - ISBN 9789085041986 - 152
    erwten - pisum sativum - peulvruchteiwit - geur en smaak - aroma - vluchtige verbindingen - geurstoffen en smaakstoffen - saponinen - nieuwe voedingsmiddelen - peas - pisum sativum - legume protein - flavour - aroma - volatile compounds - flavour compounds - saponins - novel foods
    This research is part of the multidisciplinary program, PROFETAS (PROtein Foods Environment Technology And Society), which aimed to feasibly shift from animal proteins to pea proteins for the development of Novel Protein Foods (NPFs) with desirable flavour. The aim of this research is to investigate the flavour aspects of peas and its protein fractions, as being potential ingredients for NPFs. To achieve this objective, the type and amount of flavour compounds from pea flour and pea protein preparations, as well as the stability and sensory characteristics of some of these compounds were investigated. The interactions of flavour compounds and pea protein fractions, as well as the effect of heating and presence of non-protein components on these interactions were also studied. With the results obtained, PROFETAS will be able to provide essential information for food industries and research institutes, to aid in the production of food with superior quality. Food manufacturers can better manipulate their ingredients and processing, optimising production conditions, which in turn lead to cost saving.
    Comments of RIVO to the report "Bromophenols: cause off-flavour in marinated herring and other foods"
    Schelvis-Smit, A.A.M. ; Kotterman, M.J.J. - \ 2005
    onbekend : RIVO Milieu en Voedselveiligheid (Report / RIVO-Netherlands Institute for Fisheries Research no. C002/05) - 8
    geur en smaak - geurstoffen en smaakstoffen - visproducten - haringen - zuren - marineren - flavour - flavour compounds - fish products - herrings - acids - marinating
    In commission of GAB Robins Scully Tyrrell Ltd RIVO has evaluated the report of Jan W. Henfling. Identified in the documentation with nr: 1740-1747 + 1749-1756 + 1758-1759 RIVO has dealt mainly with those topics and opinions that are plainly not correct, not justifiable or misleading. Topics or opinions raised by Jan W. Henfling, which are not discussed in this RIVO report, do not necessarily reflect the opinion of RIVO. In this evaluation, the report will be discussed page by page. Again, it has never been scientifically proven that phenol in acetic acid was the cause of off-flavour in fishery products. To the opinion of RIVO the final conclusion in the Henfling-report is not stated by any solid evidence.
    Formation of Amino Acid Derived Cheese Flavour Compounds
    Smit, B.A. - \ 2004
    Wageningen University. Promotor(en): J.T.M. Wouters; Gerrit Smit, co-promotor(en): W.J.M. Engels. - Wageningen : S.n. - ISBN 9789058089960 - 127
    geurstoffen en smaakstoffen - aldehyden - kazen - melkzuurbacteriën - aminozuren - aroma - fermentatieproducten - flavour compounds - aldehydes - cheeses - lactic acid bacteria - amino acids - aroma - fermentation products
    Lactic acid bacteria (LAB), among them Lactococcus lactis, are often used for the fermentation of milk into various products, such as cheeses. For their growth and maintenance LAB metabolise milk sugar, protein and fat into various low molecular compounds, which sometimes have strong flavour characteristics. This thesis focuses on the production of one class of these compounds as a model system: aldehydes, in particular the key-flavour compounds 3-methylbutanal and 2-methyl propanal, which are enzymatically derived from the amino acids leucine and valine. Comparing several strains belonging not only to the genus Lactococcus , but also to the genera Lactobacillus , Streptococcus , Leuconostoc , Bifidobacterium , Propionibacterium , Brevibacterium , Corynebacterium and Arthrobacter with regard to various enzyme activities involved in the conversion pathway of leucine to 3-methylbutanal, revealed a large variation between and within species. In particular,a-keto acid decarboxylase activity, leading to 3-methylbutanal was identified as a rate-limiting step in this pathway.

    Identification of thea-keto acid decarboxylase gene was obtained by screening of mutant libraries of the decarboxylase-positive strain L. lactis B1157 with a newly developed method for high throughput analysis (HTS) of volatiles, present in the headspace of miniaturised fermentations. The gene had a very high homology with a (most probably) truncated gene in the genome of L. lactis IL1403 annotated as ipd . The molecular weight of the TPP dependant enzyme was 60.9 kDa, its estimated pI is 5.03. The enzyme activity was hardly affected by high salinity and activity was found to be optimal at pH=6.3. Moreover, of all potential substrates tested, the activity towards branched-chaina-keto acids was the highest, for which reason it is proposed to be annotated as BcKAD (branched-chain keto acid decarboxylase).

    The newly developed method for analysis of volatiles was also applied for monitoring the non-enzymatic conversion of the leucine-derived keto acid to the branched chain aldehyde 2-methylpropanal. 2-Methylpropanal is the aldehyde, which was believed to be a product of the enzymatic conversion of valine. The non-enzymatic reaction proceeded in the presence of manganese ions and oxygen, the products were the aldehyde and either carbon oxides or oxalate. The conversion was maximal at pH 5.5 and pH>8. A range ofa-keto acids were converted under the sameconditions,and keto acids with an electron-pulling side chain had the highest conversion rates.

    The results described in this thesis add to the understanding of the control of flavour formation in fermented products like cheese. The thesis focuses mainly on the existence and relevance of some of the amino acid converting pathways of certain bacterial strains. In addition to this, further research on regulation and/or complementation of these pathways in/by several strains is recommended. The HTS-method also enables the selection of strains from large culture collections for production of certain volatiles and for application of this property in cheese making.

    Smaakstof verbetert bezoekgedrag niet
    Biewenga, G. - \ 2004
    Praktijkkompas. Rundvee 18 (2004)1. - ISSN 1570-8586 - p. 4 - 5.
    melkveehouderij - diergedrag - rundveevoeding - geurstoffen en smaakstoffen - melkkoeien - machinaal melken - robots - proefboerderijen - dairy farming - animal behaviour - cattle feeding - flavour compounds - dairy cows - machine milking - robots - experimental farms
    De koeien op het High-techbedrijf blijven het hele jaar binnen. In de afgelopen jaren was er zowel vrij als gestuurd koeverkeer. In april 2003 startten we hier een proef met vrij koeverkeer. Daarin keken we ook naar het effect van toedienen van smaakstof in het automatisch melksysteem op het bezoek. We kunnen echter geen effect aantonen.
    Production of natural flavour compounds: bioconversion of monoterpenes by spores of Penicillium digitatum
    Wolken, W.A.M. - \ 2003
    Wageningen University. Promotor(en): Hans Tramper. - [S.I.] : S.n. - ISBN 9789058088055 - 128
    geurstoffen en smaakstoffen - biologische productie - monoterpenen - penicillium digitatum - natuurlijke producten - flavour compounds - biological production - monoterpenes - penicillium digitatum - natural products
    Consumers prefer natural over artificial additives. Consequently natural flavour-compounds fetch higher prices than the corresponding artificial compound. Various natural means of flavour production are discussed in this dissertation. The major part is focused on the biotransformation of geraniol into the flavour-compound methylheptenone by spores of the fungus Penicillium digitatum. The biotransformation pathway was elucidated and a unique enzyme in this pathway, citral lyase, was purified from the spores. This cofactor-independent enzyme, combining the actions of a hydratase with that of an aldolase, converts citral, an intermediate of the geraniol conversion, in addition to other a ,b -unsaturated aldehydes. Furthermore, spores were found to be on average 2.5 times more resistant to the toxic effects of the substrates, intermediates and products of the geraniol conversion. Finally, this dissertation describes the use of amino acids as catalysts in the production of natural flavour compounds. They can for instance be used to catalyse the conversion of cinnamaldehyde into the second most applied flavour compound, benzaldehyde
    Effects of flavour absorption on foods and their packaging materials
    Willige, R.W.G. van - \ 2002
    Wageningen University. Promotor(en): A.G.J. Voragen; J.P.H. Linssen. - S.l. : S.n. - ISBN 9789058086402 - 140
    geurstoffen en smaakstoffen - absorptie - verpakkingsmaterialen - voedselverpakking - eiwitten - koolhydraten - vetten - membraanpermeabiliteit - smaakpanels - modellen - flavour compounds - absorption - packaging materials - food packaging - proteins - carbohydrates - fats - membrane permeability - taste panels - models

    Keywords: flavour absorption, scalping, packaging, food matrix, lldpe, ldpe, pp, pc, pet, pen,b-lactoglobulin, casein, pectin, cmc, lactose, saccharose, oil, modelling, storage, oxygen permeability, taste perception, sensory quality.

    Absorption of flavour compounds by linear low-density polyethylene (LLDPE) was studied in model systems representing differences in composition of the food matrix. Proteins,b-lactoglobuline and casein, were able to bind flavours, resulting in suppression of absorption of flavour compounds. Polysaccharides, pectin and carboxymethylcellulose, increased viscosity, and consequently decreased absorption. Disaccharides, lactose and saccharose, increased absorption, probably caused by a "salting out" effect of less apolar flavour compounds. The presence of a relative small amount of oil (50 g/l) decreased absorption substantially. Combined oily model systems, oil/casein and oil/pectin, showed a similar effect. The extent of absorption of flavour compounds by LLDPE was influenced by food components in the order: oil or fat >> polysaccharides and proteins > disaccharides. A model based on the effect of the polarity (log P) of flavour compounds and on their partitioning coefficients between food(matrix) and packaging material was developed. The model is able to predict absorption of flavour compounds from foods into LLDPE when lipids in the food matrix are the determining factor in flavour absorption. Results show that the model fits nicely with experimental data of real foods skim and whole milk.

    LLDPE, polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET film and PET bottle) and polyethylene naphthalate (PEN) were immersed in a model flavour solution at different temperatures up to 14 days. The absorption rate and/or total amount of absorbed compounds increased considerably with increasing temperature. Depending on temperature, the total absorption of flavour compounds by the polyolefins (LLDPE and PP) was up to 2400 times higher than by the polyesters (PC, PET and PEN).

    The effect of absorbed flavour compounds on the oxygen permeability of low-density polyethylene (LDPE), PP, PC and PET was studied. Due to swelling of the polymers as a result of absorption of flavour compounds, LDPE and PP showed a significant increase of oxygen permeability of 21% and 130%. The oxygen permeability of PC showed a significant decrease of 11% due to occupation or blockage of the "micro-cavities" by the absorbed flavour compounds. Flavour absorption by PET did not affect the oxygen permeability significantly.

    The influence of flavour absorption LDPE, PC and PET on the taste perception of a flavour model solution and orange juice stored in glass bottles was studied with and without pieces of the respective plastic films. Although the content of flavour compounds between controls and polymer treated samples decreased substantially due to absorption, no significant effect on the taste perception of the model solution and orange juice were observed by triangular taste panel tests.

    Production of Japanese soy-sauce flavours
    Sluis, C. van der - \ 2001
    Wageningen University. Promotor(en): J. Tramper; R.H. Wijffels. - S.l. : S.n. - ISBN 9789058083814 - 165
    sojasaus - sojaproducten - geurstoffen en smaakstoffen - gisten - soya sauce - soyabean products - flavour compounds - yeasts

    The salt-tolerant yeasts Zygosaccharomyces rouxii and Candida versatilis are important for the formation of flavour in Japanese soy-sauce processes. In these processes Z. rouxii produces the flavour components ethanol, higher alcohols and 4-hydroxyfuranones, while C. versatilis is responsible for the production of phenolic flavour components, such as 4-ethylguaiacol and 4-ethylphenol. These yeast-derived flavour components give, amongst other components, the characteristic flavour to Japanese soy sauce.

    Little is known, however, about the flavour formation by the salt-tolerant yeasts, making the process difficult to control. Therefore, in this study, the metabolism of the salt-tolerant yeasts was investigated. Especially, much attention has been paid to the formation of higher alcohols by Z. rouxii . The higher-alcohols formation in Z. rouxii is strongly related to its amino-acid metabolism, whereinα-keto acids are key intermediates.

    The separate effects of the amino acids threonine, cystathionine, and the branched-chain amino acids (isoleucine, valine and leucine) on the metabolism of Z. rouxii were determined. The exogenous addition of these amino acids appeared to have large effects on the higher-alcohols production by Z. rouxii . For the production of the higher alcohols isobutyl alcohol, active amyl alcohol and isoamyl alcohol the Ehrlich pathway appeared to be very important. In this pathway, uptake and transamination of amino acids results in the higher-alcohols formation. The added amino acids also clearly influenced the formation and conversion rate of theα-keto acidα-ketobutyrate, as appeared from measured enzyme activities. This influence did not result in the accumulation ofα-ketobutyrate, because theα-ketobutyrate pool size in Z. rouxii appeared to be tightly regulated. Furthermore, independent of the amino acids added, Z. rouxii produced ethanol under aerobic conditions (Crabtree effect), which is in contrast to what is described in the literature. In addition, the supply of threonine severely inhibited the growth of Z. rouxii .

    In order to clarify the growth inhibitory effect of threonine, the regulation of the aspartate-derived amino-acid metabolism in Z. rouxii was investigated. It was shown that the poor growth of Z. rouxii in the presence of threonine was due to a lack of methionine, which was caused by a blocked methionine synthesis. Threonine seemed to block this synthesis in Z. rouxii by inhibiting the conversion of aspartate. In addition, it was shown that the growth of Z. rouxii was not inhibited by the herbicide sulfometuron methyl (SMM) that is a well-known growth inhibitor of various plants, bacteria and yeasts like Saccharomyces cerevisiae . The insensitivity of Z. rouxii growth to SMM appeared to be caused by the fact that the activity of the enzyme acetohydroxy acid synthase in Z. rouxii , unlike that in S. cerevisiae , was not affected by SMM. On the other hand, the activity of the enzyme threonine deaminase in Z. rouxii was similarly regulated as that in S. cerevisiae . Based on these observations it was concluded that the aspartate-derived amino-acid metabolism in Z. rouxii is only partly like that in S. cerevisiae .

    The steady-state culture characteristics of Z. rouxii were investigated in this study as well. It was confirmed that Z. rouxii , like S. cerevisiae , showed the Crabtree effect. It appeared that Z. rouxii started to produce ethanol at a lower dilution rate than S. cerevisiae (0.1 versus 0.3 h -1), while also the maximum specific growth rate of Z. rouxii was lower than that of S. cerevisiae (0.17 versus 0.45 h -1). For this investigation, the acceleration-stat (A-stat) cultivation method in which the dilution rate is continuously changed with a constant acceleration rate was used. The A-stat cultivation can be much less time-consuming than the widely used chemostat cultivation, especially at high acceleration rates. However, at very high acceleration rates the A-stat does not provide steady-state culture characteristics. The highest acceleration rate for estimating the steady-state culture characteristics of Z. rouxii was determined to be 0.001 h -2. For higher acceleration rates, an increased difference between A-stat and chemostat culture at a given dilution rate was observed. This observation for Z. rouxii was confirmed with simulations for S. cerevisiae . Moreover these simulations showed that, for estimating the steady-state culture characteristics with the A-stat, both the metabolic adaptation rate of the yeast and the rate at which the environmental substrate concentrations change should be taken into consideration. At an acceleration rate of 0.001 h -2, the A-stat proved to be advantageous to the chemostat, because the A-stat provided much more data in the same time than the chemostat.

    The A-stat cultivation was also used to study the concomitant extracellular accumulation ofα-keto acids and higher alcohols by Z. rouxii . Allα-keto acids from the aspartate-derived amino-acid metabolism, exceptα-ketobutyrate, could be extracellularly accumulated by exogenous supplying the amino acids valine, leucine, threonine and methionine. From this study it was concluded that in Z. rouxii valine, leucine and methionine were converted via similar Ehrlich pathways as in S. cerevisiae , while for the conversion of threonine both the Ehrlich and amino-acid biosynthetic pathways in Z. rouxii were used. Additionally the Ehrlich pathway appeared to be the only pathway for the formation of the higher alcohol methionol in Z. rouxii .

    Another problem associated with the yeast flavour formation in Japanese soy-sauce processes is that the flavour formation is normally very slow. For this reason the conventional batch process takes about 6 months. In literature the development of a new continuous process using immobilized salt-tolerant yeasts resulted in a 90% reduction of the process time. However, the new immobilized-cell process seemed not very suitable for long-term operation, because alginate was used as immobilization material. The reason for this is that alginate is sensitive to abrasion and chemically unstable towards the high salt concentration in the soy-sauce medium (about 17% (w/v)). To replace alginate, a chemically crosslinked polyethylene-oxide gel was investigated in this study.

    The problem of the chemically crosslinked polyethylene-oxide gel was that Z. rouxii cells did not survive the immobilization procedure. The absence of survival appeared to be caused by the toxic effect of the crosslinker used for making this gel. Therefore, a new immobilization procedure, in which direct contact between the crosslinker and yeast was circumvented, was developed. For both Z. rouxii and C. versatilis the survival percentages in the newly developed polyethylene-oxide gel were high and comparable to those in alginate. Unlike alginate gel, the new polyethylene-oxide gel showed, during rheological studies, to be insensitive to abrasion, even in the presence of high salt concentrations.

    The insensitivity to abrasion of the new polyethylene-oxide gel was confirmed during cultivations in a stirred-tank reactor with varying high salt concentrations (12.5-17% (w/v)). In this reactor no abrasion of polyethylene-oxide gel particles was observed for several days, while alginate gel beads were completely destroyed within one day. However, the polyethylene-oxide particles appeared to stick together, making long-term processing difficult. It also appeared during these cultivations that Z. rouxii and C. versatilis immobilized in the polyethylene-oxide particles were capable of producing characteristic soy-sauce flavours. Therefore, it was concluded that the application of polyethylene-oxide gel in long-term soy-sauce processes is attractive provided that the stickiness of the particles can be controlled.

    However, from a comparison of literature data it was also concluded that the application of immobilized salt-tolerant yeasts instead of free yeasts cells in the continuous process hardly accelerates the flavour formation. For accelerating the flavour formation the continuous microfiltration membrane reactor seems to be more promising. Finally, it was concluded that this study and other recent research has enhanced the understanding of the yeast flavour formation during Japanese soy-sauce processes, which facilitates process control.

    Aromaonderzoek in de lift
    Kan, E.J.M. van; Boelrijk, A. - \ 2000
    Voedingsmiddelentechnologie 33 (2000)14/15. - ISSN 0042-7934 - p. 28 - 29.
    sensorische evaluatie - organoleptische kenmerken - geur en smaak - geurstoffen en smaakstoffen - aromatische stoffen - reuk - smaak - voedselindustrie - voedseltechnologie - productontwikkeling - consumenten - consumentenvoorkeuren - aroma - chemotaxis - sensory evaluation - organoleptic traits - flavour - flavour compounds - flavourings - smell - taste - food industry - food technology - product development - consumers - consumer preferences
    Verslag van het in mei gehouden minisymposium te Wageningen. Het werd georganiseerd door de Vereniging voor Voedingsleer en Levensmiddelentechnologie
    Bepaling van het gehalte aan diacetyl in boter (Methode Prill and Hammer) NEN 3715
    Mazijk-Bokslag, D.M. van; Oortwijn, H. - \ 1981
    Wageningen : RIKILT (Verslag / RIKILT 81.35) - 8
    boter - diacetyl - geurstoffen en smaakstoffen - verwerking - voedselverwerking - voedselbewaring - butter - diacetyl - flavour compounds - processing - food processing - food preservation
    Doel van dit onderzoek is: Verbetering van het NEN 3715 voorschrift: 1. Het maken van een reproduceerbare ijklijn 2. Verbetering van de duplospreiding van het diacetylgehalte. Het verloop van het diacetylgehalte bij verschillende bewaartemperaturen.
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