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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Working up a lactofermented vegetable product
Nagy-Gasztonyi, M. ; Biekman, E.S.A. ; Krebbers, B. - \ 2002
Acta Alimentaria 31 (2002)4. - ISSN 0139-3006 - p. 407 - 412.
The combination of lactofermentation and enzyme-treatment (Rohament-PL as endo-polygalacturonase and the mixture of Rohament-PL and Rohalase 7069 as cellulase) of sliced carrot and orange juice resulted in a homogeneous product, with pleasant organoleptic features, after 18 h fermentation period. Two ways of inoculation were applied with Lactobacillus plantarum. The addition of Rohament-PL, even at 150 mg kg-1 concentration, simultaneous inoculation with Lactobacillus plantarum (circumstances: 28 °C, 80 r.p.m. shaking) promoted the growth of lactobacilli. By 42 h fermentation time LAB count increased up to 3.2-4.8×109 cm-3. Furthermore the surface colour of the samples was more intensive (higher L-, a- and b-values) than without Lactobacillus plantarum inoculation. The application of Rohament-PL (50-100 mg kg-1) resulted in a homogeneous carrot puree, the combination of Rohament-PL (150 mg kg-1) and Rohalase 7069 (150 mg kg-1) in the process gave a more fluid product, as proved by the lower specific viscosity values.
Modelling the change in colour in broccoli and green beans during blanching
Tijskens, L.M.M. ; Schijvens, E.P.H.M. ; Biekman, E.S.A. - \ 2001
Innovative Food Science and Emerging Technologies 2 (2001)4. - ISSN 1466-8564 - p. 303 - 313.
The green colour of vegetables changes considerably during heat treatments like blanching. Green beans from two different countries and growing seasons, and the stems and florets of broccoli were heat-treated from 40 up to 96 °C. The colour was monitored with the CIE-Lab system. Expressing the green colour as -a*/b* proved to considerably reduce the observed variance within measuring samples. It can be considered as a kind of internal standardisation. The colour was modelled by a simplified kinetic mechanism of two consecutive reactions: one that increases colour, one that degrades colour. First, all data sets were analysed separately using non-linear regression. The obtained percentage variance accounted for (R2adj) ranged from 75.7 to 90.8ÐAllowing separate initial conditions but with the kinetic parameters in common, the data of the same vegetable type (green beans and broccoli separately) could be pooled and analysed together (R2adj = 87.4 and 77.2°respectively). The kinetic parameters obtained were so similar that a complete pooled and generic analysis was possible even for green beans and broccoli together. These findings greatly validate the developed model and indicate that the formation and degradation of visible colour in vegetables is governed by processes related to the colouring compounds (like chlorophyll and chlorophilides), irrespective of the vegetables under study.
Modelling the effect of pH on the colour degradation of blanched broccoli
Tijskens, L.M.M. ; Barringer, S.A. ; Biekman, E.S.A. - \ 2001
Innovative Food Science and Emerging Technologies 2 (2001)4. - ISSN 1466-8564 - p. 315 - 322.
In ready-to-eat salads, a low pH is often applied in the salad dressing. The effect of pH on the colour change of blanched-frozen-and-thawed broccoli was studied. Different acids were used to achieve the pH values in buffer solutions. A model on chlorophyll degradation in fruits and vegetables was developed based on a simplification of existing knowledge. From integral non-linear regression analysis, it was concluded that the pH gradient at the boundary between product and buffer solution had a marked effect at low pH values. Furthermore, based on the analyses and the obtained residuals, another colour degrading process was revealed that gradually increases in relative importance at higher pH values. The effect of the five acids applied could be attributed to a single proportionality factor, probably related to the hydrophilic nature of the acid applied. The statistical analysis showed a percentage variance accounted for (R2adj) of more than 99.6ÐThe apparent rate of colour degradation was found to be linearly related to the concentration of hydrogen ions. ? 2001 Elsevier Science Ltd. All rights reserved.
Modeling the effect of temperature and pH on activity of enzymes: The case of phytases
Tijskens, L.M.M. ; Greiner, R. ; Biekman, E.S.A. ; Konietzny, U. - \ 2001
Biotechnology and Bioengineering 72 (2001)3. - ISSN 0006-3592 - p. 323 - 330.
pH Effects in Foods: Development, Validation and Calibration of a Fundamental Model
Tijskens, L.M.M. ; Biekman, E.S.A. ; Greiner, R. ; Seyhan, F. ; Barringer, S.A. - \ 2001
Acta Horticulturae 566 (2001). - ISSN 0567-7572 - p. 309 - 315.
The effects of pH observed in the activity of a number of enzymes from different origins and the degradation of green colour in blanched vegetables, was modelled based on fundamental kinetic principles by considering hydrogen ions as an integral part of the reaction mechanism. Parameters were estimated by non-linear regression analysis with explained parts (R2adj) was in all cases except for the enzyme lipase, well over 95°and frequently well over 98&Eth;Applying fundamental models in integral data analysis made it possible to pinpoint aberrations at high and low pH ranges in the discoloration of vegetables, which remained unnoticed using classical analysis procedures. The model on enzyme activity was successfully applied to analyse and to describe a double optimal pH region when iso-enzymes are present in the total pool of active enzymes.
pH in Action
Tijskens, L.M.M. ; Biekman, E.S.A. - \ 2001
Acta Horticulturae 566 (2001). - ISSN 0567-7572 - p. 301 - 306.
Based on fundamental chemical relations, well-established in chemical engineering and chemical technology over almost a century, the effects of pH in food and agricultural products will be deduced for different situations and processes. Based on simple equilibria and dissociation of water, salts, acids and bases, and considering the reaction of hydrogen ions in these food-related systems, simple and reliable formulations are developed capable of describing surprisingly well the discoloration of blanched vegetables and the activity of enzymes in different buffered and unbuffered systems. The line of reasoning is generic and can be applied repeatedly to different problems, situations and processes.
Modelling the quality behaviour induced by processing
Tijskens, L.M.M. ; Biekman, E.S.A. - \ 1999
Food technology journal 2-3 (1999). - p. 86 - 91.
Ontwikkeling en selectie van een meetmethode waarmee de grauwverkleuring van voorgebakken frites kan worden voorspeld
Otten, J. ; Gooijer, H. de; Slotboom, E. ; Eijck, P.C.M. van; Meinders, M.B.J. ; Golbach, F.B.T.F. ; Schipper, C.M.A. ; Biekman, E.S.A. ; Braaksma, A. - \ 1998
Wageningen : ATO-DLO (Rapport / ATO-DLO B329) - 49
Effect of Shrinkage on the Temperature Increase in Evacuated Mushrooms - (Agaricus bisporus) During Blanching
Biekman, E.S.A. ; Remmen, H.J. van; Kroese-Hoedeman, H.I. ; Ogink, J.J.M. ; Schijvens, E.P.H.M. - \ 1997
Journal of Food Engineering 33 (1997). - ISSN 0260-8774 - p. 87 - 99.
Optimally canning of mushrooms
Schijvens, E.P.H.M. ; Biekman, E.S.A. ; Deelen, W. van; Kroese-Hoedeman, H.I. ; Ruisch, J. - \ 1997
Food Management 15 (1997)11. - ISSN 0168-325X - p. 41 - 43.
Mealiness in fruits : consumer perception and means for detection : FAIT CT 95-032 : 1st annual progress report
Dijk, C. van; Biekman, E.S.A. ; Leguijt, C. ; Yuksel, D. ; Vuurst - de Vries, R.G. van; Termeer, J. ; Smits, A.A.M. ; Gerritsen, Y.A.M. ; Boeriu, C. ; Tijskens, L.M.M. ; Schaik, A. van - \ 1996
Wageningen : Agrotechnological Research Institute (ATO-DLO) - 18
Grondstofkwaliteit van Nederlandse aardappelen in relatie tot hun verwerkingskwaliteit : jaarlijkse rapportage onderzoeksprogramma Friteskwaliteit ten behoeve van het Produktschap voor Aardappelen
Biekman, E. ; Braaksma, A. ; Eijck, P.C.M. van; Oosterhaven, J. ; Wilkinson, E.C. - \ 1996
Wageningen : ATO-DLO (Rapport / ATO-DLO B189) - 15
The texture of processed potatoes: from genes to texture
Marle, J.T. van; Biekman, E. ; Ebbelaar, M. ; Recourt, K. ; Yuksel, D. ; Dijk, C. van - \ 1996
In: Agri-Food Quality, an interdisciplinary approach / Fenwick, R.G., Hedley, C., Richards, R.L., Khokar, S., - p. 181 - 184.
Loss of Solutes during Blanching of Mushrooms (Agaricus bisporus) as a Result of Shrinkage and Extraction
Biekman, E.S.A. ; Schijvens, E.P.H.M. ; Kroese-Hoedeman, H.I. - \ 1996
Journal of Food Engineering 28 (1996). - ISSN 0260-8774 - p. 139 - 152.
The density of common mushroom (Agaricus bisporus) tissue related to the shrinkage at heating
Schijvens, E.P.H.M. ; Ruisch, H. ; Deelen, W. van; Biekman, E.S.A. ; Wichers, H.J. - \ 1996
Mushroom News 44 (1996)9. - p. 14 - 19.
Comparison of the cooking behaviour of the potato cultivars Nicola and Irene with respect to pectin breakdown and the transfer of ions.
Trinette van Marle, J. ; Dijk, C. van; Voragen, A.G.J. ; Biekman, E.S.A. - \ 1994
Potato Research 37 (1994). - ISSN 0014-3065 - p. 183 - 195.
Enzymatic modification of plant cell walls: Enzymatic modification of potato and plant tissue.
Biekman, E.S.A. ; Deelen, W. van; Voragen, A.G.J. - \ 1990
In: Agricultural biotechnology in focus in The Netherlands / Dekkers, J.J., van der Plas, H.C., Vuijk, D.H., Wageningen : Pudoc - p. 183 - 187.
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