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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Assessing the susceptibility of amylose-lysophosphatidylcholine complexes to amylase by the use of iodine
Ahmadi-Abhari, S. ; Woortman, A.J.J. ; Hamer, R.J. ; Loos, K. - \ 2014
Starch-Stärke 66 (2014)5-6. - ISSN 0038-9056 - p. 576 - 581.
wheat-starch - chain-length - inclusion complexes - fatty-acids - in-vivo - digestion - binding - digestibility - microscopy - property
The formation of amylose-lysophosphatidylcholine (LPC) inclusion complexes renders amylose less susceptible to amylase digestion. In order to better understand this phenomenon on a structural level, the complexation of 9% wheat starch suspensions with 0, 2, 3, and 5% exogenous LPC was developed in RVA. Amylose-LPC inclusion complexes were isolated after 15, 30, 60, 120, and 240min in vitro digestion of the wheat starch suspensions to quantify the amount of non-complexed amylose by spectrophotometry. The samples were dissolved in DMSO containing 0.5% LiBr and exposed to iodine. In addition, parts of the digesta were defatted and subjected to the same procedure to elucidate the total amount of amylose that remained undigested. In this way, more insight was obtained into the protective effect of amylose-LPC complex formation on digestion of starch. This study confirms that the amylose susceptibility to amylolysis decreases in the presence of LPC. Higher LPC concentrations not only induced the formation of more amylose inclusion complexes but also resulted in more stable complexes which remained undigested as well as longer amylose chains after enzyme hydrolysis, due to the presence of LPC inside the amylose helix. In addition, a higher melting enthalpy of the amylose-LPC complexes in the digesta demonstrates the protective effect of LPC during enzyme hydrolysis.
Controlling rheology and structure of sweet potato starch noodles with high broccoli powder content by hydrocolloids
Silva, E. ; Birkenhake, M. ; Scholten, E. ; Sagis, L.M.C. ; Linden, E. van der - \ 2013
Food Hydrocolloids 30 (2013)1. - ISSN 0268-005X - p. 42 - 52.
scanning microscopy clsm - pasta products - wheat-starch - xanthan gum - nonstarch polysaccharides - sensory evaluation - cooking quality - lupin flours - corn starch - food gums
Incorporating high volume fractions of broccoli powder in starch noodle dough has a major effect on its shear modulus, as a result of significant swelling of the broccoli particles. Several hydrocolloids with distinct water binding capacity (locust bean gum (LBG), guar gum, konjac glucomannan (KG), hydroxypropyl methylcellulose (HPMC) and xanthan gum), were added to systems with 4 and 20% (v/v dry based) broccoli particles, and the effect of this addition on dough rheology, mechanical properties and structure of cooked noodles was investigated. Hydrocolloids with low (LBG and guar gum) and intermediate (KG) water binding capacity had no significant effect on shear rheology of the dough. Adding hydrocolloids with high water binding capacity (HPMC and xanthan gum) decreased the shear modulus of dough with 20% broccoli particles significantly. CLSM analysis of cooked noodles showed that in samples containing xanthan gum there was also an inhibition of swelling of starch granules. Strength and stiffness of cooked noodles with 20% broccoli particles were higher for samples containing xanthan gum, than samples without xanthan gum. The cooking loss and swelling index of samples with added hydrocolloids were slightly lower than samples without hydrocolloids. Our results showed that hydrocolloids with high water binding capacity can be used to control the degree of swelling of vegetable particles and starch granules in starch noodle products, and thereby control both dough rheology and textural properties of the cooked noodles
The structural and hydration properties of heat-treated rice studied at multiple lenght scales
Witek, M.M. ; Weglarz, W. ; Jong, L. de; Dalen, G. van; Blonk, J.C.G. ; Heussen, P. ; Velzen, E. van; As, H. van; Duynhoven, J.P.M. van - \ 2010
Food Chemistry 120 (2010)4. - ISSN 0308-8146 - p. 1031 - 1040.
cp-mas nmr - native starch granules - solid-state nmr - molecular mobility - extrusion-cooking - phase-transitions - wheat-starch - puffed rice - water - organization
The impact of heat-treatment on structure and hydration properties of rice was studied at different length scales (µm–nm). Heat-treatment introduced micro- and macro-pores within rice kernels (µCT) and, within intact cell walls, disintegrated starch granules were observed (SEM, CSLM). In native kernels starch predominantly occurred as crystalline A-type starch and, upon heat treatment, amorphous and V-type starch appeared (XRD, 13C CP MAS NMR). Plasticization of amorphous starch by water was more pronounced for heat-treated than for native kernels (13C SPE MAS NMR). Within native kernels, more effective spin diffusion between water and starch chains was present (WISE-Exchange), confirming the inter-helical nanoscale order of amylose helices. Upon heat-treatment, this inter-helical nanoscale order was lost, as well as microscale granular compartmentalisation (TD NMR). These findings explain why, upon heat-treatment, vapour sorption is lower and starch is more prone to gelatinization (DSC).
Relations between sensorial crispness and molecular mobility of model bread crust and its main components as measured by PTA, DSC and NMR
Nieuwenhuijzen, N.H. van; Tromp, R.H. ; Mitchell, J.R. ; Primo-Martin, C. ; Hamer, R.J. ; Vliet, T. van - \ 2010
Food Research International 43 (2010)1. - ISSN 0963-9969 - p. 342 - 349.
glass-transition temperature - wheat-starch - fracture-behavior - pulsed h-1-nmr - water-content - gluten - foods - state
Consumer appreciation of brittle cellular foods, like bread crusts, depends on textural properties such as crispness. This crispy character is lost above a certain water activity. It is not known what exactly is happening in these crusts when water enters. So is it unclear whether it is the change in the starch or the gluten that initiates the loss of crispness with ageing time. In this paper the effect of water on the glass transition of model bread crusts was studied using two complementary techniques: phase transition analysis (PTA) and temperature modulated differential scanning calorimetry (TMDSC). The mobility of water was studied with nuclear magnetic resonance (NMR). The results were compared with sensory data. Bread crusts prepared with different types of flour were tested to evaluate the effect of flour composition on the crispness of model crusts equilibrated at different relative humidities. In addition the single flour components starch and gluten were studied. Sensory crispness scores decreased with increasing aw from 0.55 upwards. At aw 0.70 sensory crispness was completely lost. Both DSC and PTA showed a transition point at an aw of 0.70-0.75. NMR gave a transition point in the mobility of the protons of water at aw 0.58. This supports the hypothesis that loss of crispness starts as a result of processes at a molecular level, before the macroscopic glass transition. This also suggests that the presence of water that is not directly attached to the solid matrix causes the loss of crispness at low aw. At higher aw increased mobility of the macromolecules will start to play a role. NMR experiments with the separate flour components indicate that the T2 transition point in starch samples occurs at a lower RH than for gluten. This could imply that starch loses crispness at lower aw than gluten. Increased mobility of small components and side chains might induce increased energy dissipation upon deformation of the material resulting in less available energy for fracture propagation and with that in a less crispy product.
On the applicability of Flory-Huggins theory to ternary starch-water-solute systems
Habeych Narvaez, E.A. ; Guo, X. ; Soest, J.J.G. van; Goot, A.J. van der; Boom, R.M. - \ 2009
Carbohydrate Polymers 77 (2009)4. - ISSN 0144-8617 - p. 703 - 712.
differential scanning calorimetry - crystalline polymorph - thermoplastic starch - solvent interactions - phase-transitions - potato starch - wheat-starch - dry starch - gelatinization - glycerol
The effects of glucose and glycerol on gelatinization of highly concentrated starch mixtures were investigated with wide-angle X-ray scattering and differential scanning calorimetry. The gelatinization/melting of starch was found to be a two step process. In the first step the granule swells at low temperatures (i.e., 30¿50 °C), which is followed by a solvent¿temperature cooperative step that induces loss of crystallinity. The results were interpreted with an extended form of the adapted Flory equation. The values of the model parameters (, ¿Hu, ¿12, ¿13, and ¿23) obtained were similar to the values reported in the literature. Ternary phase diagrams were constructed with melting lines representing fully gelatinized starch. The crystalline region of starch with glucose was larger than with glycerol. This could be understood from the differences in ¿13 (solute¿solvent interaction). The extended form of Flory¿Huggins model somewhat under predicts the experimental values of the gelatinization process. Comparing the Flory¿Huggins model with experiments led to the conclusion that Flory equation is a useful tool to interpret and predict the gelatinization and melting behaviour of ternary starch-based systems. But the experiments are complex, the systems are often not in true equilibrium and other disturbing effects are easily encountered. Therefore one should be cautious in the translation of experimental results to the thermodynamics of gelatinization in multicomponent systems
Water Content or Water Activity: What Rules Crispy Behavior in Bread Crust?
Nieuwenhuijzen, N.H. van; Primo-Martin, C. ; Meinders, M.B.J. ; Tromp, R.H. ; Hamer, R.J. ; Vliet, T. van - \ 2008
Journal of Agricultural and Food Chemistry 56 (2008)15. - ISSN 0021-8561 - p. 6432 - 6438.
food-products - wheat-starch - gluten - temperature - mobility - h-1-nmr
A dry crust loses its crispness when water migrates into the crust. It is not clear if it is the amount of water absorbed or the water activity (aw) that leads to a loss of crispness. The hysteresis effect observed when recording a water sorption isotherm allowed us to study the effects of aw and moisture content separately. All experiments were carried out on model bread crusts made from Soissons bread flour. The effect of water content and water activity on the glass transition of model bread crusts was studied in detail using two complimentary techniques: phase transition analysis (PTA) and nuclear magnetic resonance (NMR). The results were compared with sensory data and results from a puncture test, which provided data on acoustic emission and fracture mechanics during breaking of the crusts. The water content of the crust was found to be decisive for the transition point as measured by PTA and NMR. However, both water content and water activity had an effect on perceived crispness and number of force and sound peaks. From this may be concluded that the distribution of the water in the samples with a history of high water content is more inhomogeneous, which results in crispy and less crispy regions, thus making them overall more crispy than samples with the same water content but higher aw.
The effect of pressure and temperature on the gelatinisation of starch at various starch concentrations
Baks, T. ; Bruins, M.E. ; Janssen, A.E.M. ; Boom, R.M. - \ 2008
Biomacromolecules 9 (2008)1. - ISSN 1525-7797 - p. 296 - 304.
differential scanning calorimetry - high hydrostatic-pressure - wheat-starch - phase-transformations - water mixtures - crystalline - diagram - transitions - moisture - system
The effects of pressure, temperature, and treatment time on the degree of gelatinization were determined with differential scanning calorimetry measurements for wheat starch¿water mixtures with starch concentrations varying between 5 and 80 w/w %. Although simple models could be used to describe the degree of starch gelatinization as a function of pressure or temperature, a more complex model based on the Gibbs energy difference had to be used to describe the degree of gelatinization as a function of both pressure and temperature. The experimental and model data were used to construct a phase diagram for 5, 30, and 60 w/w % wheat starch¿water mixtures. Data obtained from literature were in accordance with our phase diagrams. These phase diagrams can be used to estimate the degree of gelatinisation after applying a certain pressure and temperature on a starch¿water mixture with starch concentrations in the range of 5 and 60 w/w %.
Effect of gelatinization and hydrolysis conditions on the selectivity of starch hydrolysis with alpha-amylase from Bacillus licheniformis
Baks, T. ; Bruins, M.E. ; Matser, A.M. ; Janssen, A.E.M. ; Boom, R.M. - \ 2008
Journal of Agricultural and Food Chemistry 56 (2008)2. - ISSN 0021-8561 - p. 488 - 495.
high hydrostatic-pressure - wheat-starch - enzymatic-hydrolysis - phase-transformations - temperature - mechanism - enzymes - stability - complexes - products
Enzymatic hydrolysis of starch can be used to obtain various valuable hydrolyzates with different compositions. The effects of starch pretreatment, enzyme addition point, and hydrolysis conditions on the hydrolyzate composition and reaction rate during wheat starch hydrolysis with ¿-amylase from Bacillus licheniformis were compared. Suspensions of native starch or starch gelatinized at different conditions either with or without enzyme were hydrolyzed. During hydrolysis, the oligosaccharide concentration, the dextrose equivalent, and the enzyme activity were determined. We found that the hydrolyzate composition was affected by the type of starch pretreatment and the enzyme addition point but that it was just minimally affected by the pressure applied during hydrolysis, as long as gelatinization was complete. The differences between hydrolysis of thermally gelatinized, high-pressure gelatinized, and native starch were explained by considering the granule structure and the specific surface area of the granules. These results show that the hydrolyzate composition can be influenced by choosing different process sequences and conditions.
Towards an optimal process for gelatinisation and hydrolysis of highly concentrated starch-water mixtures with alpha-amylase from B. licheniformis
Baks, T. ; Kappen, F.H.J. ; Janssen, A.E.M. ; Boom, R.M. - \ 2008
Journal of Cereal Science 47 (2008)2. - ISSN 0733-5210 - p. 214 - 225.
twin-screw extruder - wheat-starch - enzymatic-hydrolysis - extrusion-cooking - corn starch - sago starch - model - liquefaction - degradation - kinetics
The enzymatic hydrolysis of starch is usually carried out with 30¿35 w/w% starch in water. Higher substrate concentrations (50¿70 w/w%) were reached by using a twin-screw extruder for gelatinisation and for mixing enzyme with gelatinised starch prior to enzymatic hydrolysis in a batch reactor. The aim of this study was to determine which parameters are important for gelatinisation of wheat starch and to investigate the effects of different extrusion conditions on the enzymatic hydrolysis. After extrusion, the degree of gelatinisation was measured. During hydrolysis, the carbohydrate composition, the dextrose equivalent (DE) and the alpha-amylase activity were measured. Gelatinisation measurements showed that mechanical forces lowered the temperature required for complete gelatinisation. During hydrolysis experiments, high DEs were observed even if starch was not completely gelatinised during extrusion. Due to high substrate concentrations, the residual alpha-amylase activity remained high throughout enzymatic hydrolysis, although high temperatures were used. Increased substrate concentrations did not affect the carbohydrate composition of the product. Furthermore, the time required for the batch hydrolysis step could be varied by choosing a different enzyme-to-substrate ratio. This article provides a basis for detailed optimisation of this process to develop an industrial-scale process at high substrate concentrations.
Comparison of methods to determine the degree of gelatinisation for both high and low starch concentrations
Baks, T. ; Ngene, I.S. ; Soest, J.J.G. van; Janssen, A.E.M. ; Boom, R.M. - \ 2007
Carbohydrate Polymers 67 (2007)4. - ISSN 0144-8617 - p. 481 - 490.
differential scanning calorimetry - high hydrostatic-pressure - partial molar volumes - potato starches - water-content - wheat-starch - birefringence measurements - crystalline polymorph - phase-transformations - enzymatic-hydrolysis
A general procedure was developed to measure the degree of gelatinisation in samples over a broad concentration range. Measurements based on birefringence, DSC (Differential scanning calorimetry), X-ray and amylose-iodine complex formation were used. If a 10 w/w % wheat starch-water mixture was used, each method resulted in approximately the same degree of gelatinisation vs. temperature curve. In case the gelatinisation of a 60 w/w % wheat starch-water mixture was followed as a function of the temperature, each method resulted in a different degree of gelatinisation vs. temperature curve. DSC and X-ray measurements are preferred, because they can be used to determine when the final stage of the gelatinisation process has been completed. Birefringence and amylose-iodine complex formation measurements are suitable alternatives if DSC and X-ray equipment is not available, but will lead to different results. The differences between the methods can be explained by considering the phenomena that take place during the gelatinisation at limiting water conditions. Based on the experimental data obtained with DSC and X-ray measurements, the gelatinisation of 10 w/w % and 60 w/w % wheat starch-water mixtures started at the same temperature (approximately 50 °C). However, complete gelatinisation was reached at different temperatures (approximately 75 °C and 115 °C for, respectively, 10 w/w % and 60 w/w % wheat starch-water mixtures) according to the experimental DSC and X-ray data. These results are in accordance with independent DSC measurements that were carried out. The Flory equation was adapted to provide a quantitative explanation for the curves describing the degree of starch gelatinisation as a function of the starch-water ratio and the temperature. The gelatinisation curves that were obtained with the model are in good agreement with the experimentally determined curves. The parameters Tm0, ¿Hu and ¿12 that resulted in the lowest sum of the squared residuals are 291 ± 63 °C, 29.2 ± 3.9 kJ/mol and 0.53 ± 0.05 (95% confidence interval). These values agree with other values reported in literature
Production of glucose syrups in highly concentrated systems
Veen, M.E. van der; Goot, A.J. van der; Boom, R.M. - \ 2005
Biotechnology Progress 21 (2005)2. - ISSN 8756-7938 - p. 598 - 602.
enzymatic-hydrolysis - alpha-glucosidase - kinetic-model - wheat-starch - glucoamylase - optimization - mechanism - extruder - reactor
We have investigated the hydrolysis of maltodextrins in a high concentration (up to 70%), by means of enzymatic and acid catalysis. The study revealed that the equilibrium compositions of the catalyzed reactions were kinetically determined by the selectivity of the catalyst, the substrate concentration and the reaction time. A model comprising a set of two kinetic equations was used to describe the hydrolysis and condensation reactions of glucoamylase-catalyzed reactions, even to highly concentrated systems. Increased substrate concentration resulted in the formation of more condensation products. The enzyme inhibition was low and was found to be independent of the substrate concentration.
Modeling macromolecular degradation of corn starch in a twin screw extruder
Einde, R.M. van den; Veen, M.E. van der; Bosman, H. ; Goot, A.J. van der; Boom, R.M. - \ 2005
Journal of Food Engineering 66 (2005)2. - ISSN 0260-8774 - p. 147 - 154.
waxy-maize starch - wheat-starch - thermomechanical treatment - extensional viscosity - extrusion-cooking - shear - breakdown - rheometer - flour
Macromolecular degradation of starch in a twin screw extruder was modeled. A shear cell having well-defined flow conditions described earlier was used to measure peak viscosity of corn starch melts at various moisture contents and temperatures. Shear rate and elongation rate distributions in the extruder were estimated from numerical calculations from literature and elongational viscosity was estimated using the Trouton ratio. In this way, stresses in the extruder were calculated and, using relations on maximum stress vs. intrinsic viscosity obtained in earlier work, the expected relative intrinsic viscosity was calculated. The model gave a good prediction of relative intrinsic viscosity after extrusion at various temperatures (97-130 °C), moisture contents (23-45%) and screw speeds (90 or 140 rpm). This suggests that the use of pilot scale equipment having a well-defined flow pattern can be useful for understanding complex processes such as extrusion.
The effect of thermomechanical treatment on starch breakdown and the consequences for process design
Einde, R.M. van den; Bolsius, A. ; Soest, J.J.G. van; Janssen, L.P.B.M. ; Goot, A.J. van der; Boom, R.M. - \ 2004
Carbohydrate Polymers 55 (2004)1. - ISSN 0144-8617 - p. 57 - 63.
single-screw extruder - maize starch - extrusion-cooking - covalent bond - wheat-starch - degradation - depolymerization - time
Macromolecular degradation of starch by heating and shear forces was investigated using a newly developed shear cell. With this equipment, waxy corn starch was subjected to a variety of heat and shear treatments in order to find the key parameter determining the degree of macromolecular degradation. A model based on the maximal shear stress during the treatment gave an improved prediction compared to existing models in literature based on specific mechanical energy input (SME) or shear stress multiplied by time (tau(.)t). It was concluded that molecular weight reduction of starch at the temperatures investigated (85-110degreesC) is a time-independent process, during which the starch molecules are broken down virtually instantaneously by high shear force within time scales investigated. Consequences for design of shear based processes (especially extrusion) are shortly discussed. (C) 2003 Elsevier Ltd. All rights reserved.
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