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.

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Starch meets biotechnology : in planta modification of starch composition and functionalities
Xu, Xuan - \ 2016
University. Promotor(en): Richard Visser, co-promotor(en): Luisa Trindade. - Wageningen : Wageningen University - ISBN 9789462579200 - 169
starch - potato starch - potatoes - solanum tuberosum - plant biotechnology - biotechnology - genetic engineering - transgenic plants - modified starches - phosphate - arabidopsis thaliana - plant breeding - zetmeel - aardappelzetmeel - aardappelen - plantenbiotechnologie - biotechnologie - genetische modificatie - transgene planten - gemodificeerd zetmeel - fosfaat - plantenveredeling

Storage starch is an energy reservoir for plants and the major source of calories in the human diet. Starch is used in a broad range of industrial applications, as a cheap, abundant, renewable and biodegradable biopolymer. However, starch needs to be modified before it can fulfill the required properties for specific industrial applications. Genetic modification of starch, as a green technology with environmental and economic advantages, has attracted increasingly attention. Many achievements obtained from earlier studies have demonstrated the feasibility and potential of using this approach to produce starches with novel properties (Chapter 2).

The main objective of this research was to produce novel starches with enhanced functionalities through genetic modification, while gaining a better understanding of storage starch biosynthesis. A focus on potato was warranted as it represents a superior model system for storage starch biosynthesis studies and for the production of starches with novel properties. To this end, a number of enzymes from various sources have been expressed in potato tubers to modify starch phosphate content and polysaccharide structure, since these two characteristics have long been recognized as key features in starch properties.

To modify starch phosphate content and explore starch (de)phosphorylation, a human phosphatase enzyme named laforin, and modifications of it, were introduced into potato (Chapter 3). Interestingly, modified starches exhibited a significantly higher phosphate content rather than the expected lower phosphate content. Transcriptome analysis showed that the increase in phosphate content was a result of upregulation of starch phosphorylating genes, which revealed a compensatory response to the loss of phosphate content in potato starch. Furthermore, the increase of phosphate content in potato starch was reached to a threshold level. This was in line with the observations in the modified starches from overexpressed- Glucan water dikinase (GWD1) transgenic plants (Chapter 4). Furthermore, overexpression of two starch dikinases from Arabidopsis thaliana, glucan water dikinase 2 and 3 (AtGWD2 and AtGWD3), did not result in a significant increase in phosphate content of potato starch (Chapter 5). Taken together, these results indicated that phosphate content of potato starch is under strict control.

Morphological analysis of starch granules containing different levels of phosphate content confirmed the indispensible role of phosphate content in the normal formation of starch granules, since cracked granules were observed in the starches containing low phosphate content, while irregular bumpy shaped granules were observed in the tubers from plants containing high phosphate content. Interestingly, further analyses on the expression level of genes involved in starch metabolism and sugar-starch conversion suggested that starch phosphorylation might affect starch synthesis by controlling the carbon flux into starch while simultaneously modulating starch-synthesizing genes. Further studies are needed to confirm this finding (Chapter 4).

To produce starches with novel structures, an (engineered) 4, 6-α-glucanotransferase (GTFB) from Lactobacillus reuteri 121 was introduced into potato tubers (Chapter 6). The resulting starches showed severe changes in granule morphology, but not in starch fine structure. Transcriptome analysis revealed the existence of a self-repair mechanism to restore the regular packing of double helices in starch granules, which possibly resulted in the removal of novel glucose chains potentially introduced by the (engineered) GTFB.

This research successfully generated starches with various functionalities, including altered gelatinization characteristics (Chapter 3 and 4), improved freeze-thaw stability (Chapter 4) and higher digestibility (Chapter 6). The exploitation of relationships between starch characteristics and starch properties revealed that starch properties represent the outcome of the combined effect of many factors and are highly dependent on the genetic background in which the modification has been performed.

In conclusion, the research described in this thesis demonstrates the great potential of genetic modification in producing starches with novel properties. Meanwhile, these results revealed the presence of complex and exquisite molecular regulation mechanisms for starch biosynthesis in potato. In future research, these regulations need to be taken into account for the relational design of starch in planta. Certainly, a better understanding of the process of starch metabolism in storage organs would be a great step forward towards tailoring starch in an economically important crop such as potato.

Zetmeelkorrels als droogtebuffer
Hoekzema, Gerard ; Kroonen, Marc - \ 2016
starch - maize - zetmeel - maïs
Electrostatic separation for functional food ingredient production
Wang, J. - \ 2016
University. Promotor(en): Maarten Schutyser, co-promotor(en): Remko Boom. - Wageningen : Wageningen University - ISBN 9789462576513 - 176 p.
particles - fractionation - separation - electrostatic separation - sieving - nitrogen - polystyrenes - wheat gluten - arabinoxylans - starch - milling - lupinus - rice bran - food - experiments - deeltjes - fractionering - scheiding - elektrostatische scheiding - zeven (activiteit) - stikstof - polystyrenen - tarwegluten - arabinoxylanen - zetmeel - maling - rijstzemelen - voedsel - experimenten

Summary

Dry fractionation is a promising alternative to wet extraction processes for production of food ingredients, since it uses hardly any water, consumes less energy and retains the native functionality of the ingredients. It combines milling and dry separation to enrich agro-materials in specific components such as protein. Electrostatic separation recently emerged as a novel dry separation process and it relies on electrostatic forces for separation. Though the potential of electrostatic separation to fractionate agro-materials has been demonstrated, the effectiveness in terms of purity and yield and the influence of process parameters on charging and separation of food ingredients have not yet been systematically studied. Therefore, the objective of this thesis was to gain better understanding of the charging and separation behaviour of model and agro-materials, provide insight in the critical factors for successful electrostatic separation and explore the potential of this separation method to different agro-materials.

The charging step is critical to the effectiveness of electrostatic separation and is influenced by many factors. Chapter 2 presents characterization of the charging behaviour of single-component model particles in nitrogen gas flowing through aluminium tubes, using a lab-scale electrostatic separator. Polystyrene particles and wheat gluten were used as model particles. Higher gas velocities led to a higher specific charge by increasing the normal component of impact velocity. Smaller particles gained more specific charge than larger ones because of their higher surface to volume ratio and their sensitivity towards gas flow pattern changes. Longer charging tube lengths allowed more contact between the particles and the wall and therefore resulted in higher specific charge. The relative humidity of the nitrogen gas flow within the range 0 – 60% had no influence on the charging behaviour of both model particles.

Chapter 3 demonstrates the potential of applying electrostatic separation to enrich arabinoxylans from wheat bran with the same lab-scale electrostatic separator. A combination of larger particle size, higher gas velocity and shorter charging tube was preferred for separation, because it sufficiently charged the particles while agglomeration was minimized. Electrostatic separation with the optimum setting achieved a similar enrichment in arabinoxylans (from 23% to 30% dry matter basis) as sieving does. However, the combination of electrostatic separation and sieving further improved the enrichment and resulted in a fraction with an arabinoxylans content of 43% dry matter basis, which is around the maximum achievable purity that can be reached by dry fractionation.

To allow better defined charging and separation experiments, a bench-scale electrostatic separator was designed and constructed. With this custom-built separator, the charging and separation of model mixtures prepared from wheat gluten and starch were studied in chapter 4. The net charge of gluten-starch mixtures was not simply the sum of the charge of the two individual components, indicating that particle-particle interactions play an important role. We hypothesized that the formation of agglomerates between oppositely charged particles negatively influenced separation, which was supported by the fact that the dispersibility for mixtures of the two components was lower compared to that of individual components. We found that during electrostatic separation of mixtures, it is important to find the optimal condition that provides sufficient charge to charges, but avoids agglomeration between oppositely charged particles. This could be achieved by the combination of lower dosing rate and higher gas flow rate.

Chapter 5 reports on dry fractionation by combining milling and electrostatic separation with the custom-built bench-scale separator, providing an alternative to wet extraction of protein from lupine seeds. Relatively coarse milling was preferred because it disclosed sufficient protein bodies from the matrix, while avoiding poor dispersibility of the powder due to its very fine particle size. With the optimal settings of single-step electrostatic separation, a fraction with 57.3 g/100 g dry solids could be obtained. The protein content was further improved to 65.0% dry matter basis after two more separation steps, which is 15% higher than obtained by air classification. The yield of the protein enriched fraction was further increased by recycling the fractions from the filter bags, but this was accompanied by a decrease in protein content and vice versa. A significant shift towards better yield and purities was achieved by re-milling the flour that was not collected on the electrodes. A final fraction with a protein content of 65.1% dry matter basis and a yield of 6% was obtained, which recovered 10% of the protein in the original flour.

Chapter 6 explores the possibility of enriching dietary fibre from defatted rice bran by dry fractionation, where the custom-built bench-scale electrostatic separator was used. All three tested separation routes produced fibre-enriched fractions with similar yield (20 – 21 % of the milled flour) and fibre content (67 – 68 % dry matter basis), which recovered 42 – 48 % of the fibre from the original flour. The enriched fractions obtained by a two-step electrostatic separation process contained more small particles compared to the other two, which resulted in different functional properties. Compared to the total dietary fibre extracted by the enzymatic-gravimetric method, the enriched fractions by dry fractionation had a similar water retention capacity and oil binding capacity. This suggests that the fibre-enriched fractions by dry fractionation can be applied in foods and provide similar technological properties and physiological effects as the wet-extracted dietary fibre does.

Chapter 7 concludes the thesis with a general discussion on the main findings, based on which two schemes for protein enrichment and fibre enrichment were proposed. Subsequently the challenges to achieve a successful electrostatic separation for agro-material and up-scaling are discussed. Finally, the chapter ends with an outlook on future research.

This thesis provided insight in the key factors for successful electrostatic separation. It demonstrated the potential of applying this separation method for functional ingredient production from different agro-materials and also gave directions for further improvement and scaling-up.

The effect of replacing lactose by starch on protein and fat digestion in milk-fed veal calves
Pluschke, A.M. ; Gilbert, M.S. ; Williams, B.A. ; Borne, J.J.G.C. van den; Schols, H.A. ; Gerrits, W.J.J. - \ 2016
Animal 10 (2016)8. - ISSN 1751-7311 - p. 1296 - 1302.
lipase - milk-fed calf - starch - trypsin - α-amylase

Replacing dairy components from milk replacer (MR) with vegetable products has been previously associated with decreased protein and fat digestibility in milk-fed calves resulting in lower live weight gain. In this experiment, the major carbohydrate source in MR, lactose, was partly replaced with gelatinized corn starch (GCS) to determine the effect on protein and fat digestibility in milk-fed calves. In total, 16 male Holstein-Friesian calves received either MR with lactose as the carbohydrate source (control) or 18% GCS at the expense of lactose. In the adaptation period, calves were exposed to an increasing dose of GCS for 14 weeks. The indigestible marker cobalt ethylenediaminetetraacetic acid was incorporated into the MR for calculating apparent nutrient digestibility, whereas a pulse dose of chromium (Cr) chloride was fed with the last MR meal 4 h before slaughter as an indicator of passage rates. The calves were anesthetized and exsanguinated at 30 weeks of age. The small intestine was divided in three; small intestine 1 and 2 (SI1 and SI2, respectively) and the terminal ileum (last ~100 cm of small intestine) and samples of digesta were collected. Small intestinal digesta was analysed for α-amylase, lipase and trypsin activity. Digestibility of protein was determined for SI1, SI2, ileum and total tract, whereas digestibility of fat was determined for SI1, SI2 and total tract. Apparent protein digestibility in the small intestine did not differ between treatments but was higher in control calves at total tract level. Apparent crude fat digestibility tended to be increased in SI1 and SI2 for GCS calves, but no difference was found at total tract level. Activity of α-amylase in SI2 and lipase in both SI1 and SI2 was higher in GCS calves. Activity of trypsin tended to be higher in control calves and was higher in SI1 compared with SI2. A lower recovery of Cr in SI2 and a higher recovery of Cr in the large intestine suggest an increased rate of passage for GCS calves. Including 18% of GCS in a milk replacer at the expense of lactose increased passage rate and decreased apparent total tract protein digestibility. In the small intestine, protein digestion did not decrease when feeding GCS and fat digestion even tended to increase. Overall, effects on digestion might be levelled when partially replacing lactose with GCS, because starch digestion is lower than that of lactose but fat digestion may be slightly increased when feeding GCS.

Low emission feed : opportunities to mitigate enteric methane production of dairy cows
Hatew, B. - \ 2015
University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink; Wilbert Pellikaan. - Wageningen : Wageningen University - ISBN 9789462574458 - 228
melkkoeien - rundveevoeding - methaanproductie - milieueffect - pensfermentatie - voer - zetmeel - maïskuilvoer - graskuilvoer - diervoeding - dairy cows - cattle feeding - methane production - environmental impact - rumen fermentation - feeds - starch - maize silage - grass silage - animal nutrition

As global demand for high-quality food originating from animal production is expected to rise due to an increasing human population and consumer income level, the expected role of ruminants in meeting this demand brings multiple challenges. Ruminant production needs to adapt to environmental changes and, at the same time, reduce its impact on the environment. Ruminants production systems have a major impact on the environment through the emission of greenhouse gases such as methane (CH4), nitrous oxide and carbon dioxide. Microbial fermentation of feeds in the gastrointestinal tract, known as enteric fermentation, is the main source of CH4 emissions from dairy production. Enteric CH4 emission is strongly related to the amount of feed fermented in the rumen, which depends on feed intake, feed composition and rumen fermentation conditions associated to the intrinsic characteristics of these feeds and the characteristics of the whole diet. Important gaps in knowledge remain however. The prime aim of this thesis was to investigate the effects of various feeding strategies to mitigate enteric CH4 emissions of dairy cows.

First experiment was conducted to investigate the effects of type and level of starch in the concentrate. Inclusion of a high level (53%) of starch in the concentrate that accounted for 40% of the total mixed ration dry matter (DM) produced lower CH4 per unit of estimated rumen fermentable organic matter (eRFOM) than a low level (27% of DM) of starch (43.1 vs. 46.9 g/kg of eRFOM). Methane production per kg of eRFOM also was lower for diets based on rapidly fermentable starch (gelatinized maize grain) compared to diets based on slowly fermentable starch (native maize grain) (42.6 vs. 47.4 g/kg of eRFOM). However, inclusion of 53% of starch in the concentrate from both types of starch did not affect CH4 emission intensity (CH4 Ei) (CH4 emission per kg of fat- and protein-corrected milk; FPCM). In a subsequent experiment, maize silage was prepared from whole-plant maize harvested at a very early (25% DM), early (28% DM), medium (32% DM) and late (40% DM) stage of maturity and fed to dairy cows as an alternative to concentrate as starch source. Diet consisted of (on DM basis) 75% maize silage, 20% concentrate and 5% wheat straw. Increasing harvest maturity of maize silage linearly decreased CH4 yield (21.7, 23.0, 21.0 and 20.1 g/kg of DM intake) and CH4 emission as a fraction of gross energy intake (6.3, 6.7, 6.3 and 6.0%). Methane Ei tended to decrease linearly with maturity (13.0, 13.4, 13.2 and 12.1 g/kg FPCM). In another experiment grass silage as roughage source was tested. This experiment was designed to investigate the effects of N fertilisation of grassland and maturity of grass at cutting on CH4 emission in dairy cows. Two N fertilisation rates (65 vs. 150 kg of N/ha) were examined in combination with three stages of grass maturity (early, 28 days of regrowth; mid, 41 days of regrowth; and late, 62 days of regrowth). Diet contained 80:20 ratio (on DM basis) of grass silage (mainly ryegrass) and concentrate. Dry matter intake decreased with N fertilisation and maturity, and FPCM decreased with maturity but was unaffected by N fertilisation. Methane Ei (mean 15.0 g/kg of FPCM) increased by 31% and CH4 per unit digestible OM intake (mean 33.1 g/kg of DOMI) increased by 15% with increasing maturity. Methane yield (mean 23.5 g/kg of DM intake) and CH4 as a fraction of gross energy intake (mean 7%) increased by 7 and 9% with maturity, respectively, which implies an increased loss of dietary energy with progressing grass maturity. Rate of N fertilisation had no effect on CH4 Ei and CH4 yield.

Despite the importance of in vitro gas production technique for evaluating feeds, in vitro study as a stand-alone approach was considered inadequate to fully evaluate the potential effect of feeds and rumen fermentation modifiers on CH4 production, because in vitro studies are frequently performed separately rather than in parallel with in vivo studies. To test this hypothesis, both in vitro and in vivo CH4 measurements were measured simultaneously using cows in the first experiment that were fed (and adapted to) the same dietary material used as a substrate for in vitro incubation, as donor for microbial inoculum. It was found that 24-h in vitro CH4 (mL/g of incubated organic matter) correlated well with in vivo CH4 when expressed per unit of eRFOM (R2 = 0.54), but not when expressed per unit of organic matter ingested (R2 = 0.04). In the same experiment, results showed that incubation of the same substrate with rumen inocula obtained from donor cows adapted to different diets produced a variable amount of CH4 suggesting that it is important to consider the diet of the donor animal when collecting rumen inocula for in vitro incubation. Even though the in vitro technique has limitations to represent in vivo conditions, it is useful for screening of large sets of animal feeds or feed additives to be used as a CH4 mitigation strategy. In this thesis, two in vitro experiments were conducted to examine the effects of variation in structural composition of condensed tannins (CT) in sainfoin accessions collected from across the world on CH4 production, and CT extracts obtained from a selected sainfoin accessions on CH4 production. Results revealed substantial variation among CT in their effect on in vitro CH4 production and this variation was attributed to differences in chemical structure of CT. Condensed tannins evaluated in this thesis showed to have potential to reduce in vitro CH4 production, but require further investigations to fully evaluate their in vivo effects.

In conclusion, results from the research work conducted in this thesis show that changes in the basal diet of dairy cows and in roughage production management can substantially reduce the amount of enteric CH4 produced and thereby influence the impact of dairy production on the environment.

Pre- and post-treatment enhance the protein enrichment from milling and air classification of legumes
Pelgrom, P.J.M. ; Wang, J. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2015
Journal of Food Engineering 155 (2015). - ISSN 0260-8774 - p. 53 - 61.
seed moisture-content - product characteristics - flour - pea - separation - fractions - starch - extraction - storage - lipids
Air classification is a milder and more sustainable method to obtain protein-enriched fractions than commonly used wet fractionation. The protein content of air-classified fractions is generally lower than obtained with wet methods, therefore we applied pre- and post-treatments to increase the protein purity. A starch-rich legume, pea, and an oil-rich legume, lupine, were pre-treated by varying the moisture content, defatting, soaking or freezing cycles. Higher moisture contents and defatting of lupine increased the protein purity, but lower moisture contents increased the protein yield. Soaking and freezing cycles lowered the particle density, which impaired the separation. Electrostatic separation is based on electrostatic charging behaviour and was successfully applied to enrich air-classified fractions by separating protein and fibre into oppositely charged fractions. The results showed that pre- and post-treatments yielded protein fractions that are significantly purer than those obtained in single-step milling and air classification.
Kinetic modelling of enzymatic starch hydrolysis
Bednarska, K.A. - \ 2015
University. Promotor(en): Tiny van Boekel; Remko Boom, co-promotor(en): Anja Janssen. - Wageningen : Wageningen University - ISBN 9789462573086 - 159
hydrolyse - enzymen - zetmeel - stochastische modellen - verwerking - hydrolysis - enzymes - starch - stochastic models - processing

Kinetic modelling of enzymatic starch hydrolysis – a summary

K.A. Bednarska

The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch. After the background information about the enzymes, the substrate and the basics of the model in the first chapter, we describe a model predicting the outcome of wheat starch liquefaction by α-amylase from Bacillus licheniformis at 50°C in chapter 2. We demonstrate the ability of the model to predict starch hydrolysis products larger than the oligosaccharides considered in the existing models. The model in its extended version follows all the products of wheat starch hydrolysis separately, and despite the quantitative differences, the qualitative predictions are satisfactory. We also show that the difference between the experimental and computed data might stem from the inaccuracy of the subsite map.

In the following chapters the model is used to find a better description of the hydrolysis data at two temperatures (50°C and 80°C), by varying the energy values of the subsite map and evaluating the inhibition. We hypothesize that a subsite map that is based on the cleavage patterns of linear, short molecules does not account for the complexity of hydrolysis of amylopectin. The branched structure of amylopectin molecules influences the composition of the hydrolysis products by restricting the access to some of the bonds. The presence of branches creates steric obstacles for the enzyme. The used α-amylase has difficulties hydrolysing and accommodating α-(1,6)-glycosidic bonds, which imposes on the hydrolysis of the α-(1,4)-glycosidic bonds located in its proximity. On this basis, we analyse the subsite maps in detail and suggest which of the subsites are crucial when making predictions about the product composition of starch hydrolysates. On top of that we propose new subsite maps that allow a quantitative description of the experimental data.

After the model was shown to work at different experimental conditions, we also test it at increased the dry matter content during wheat starch hydrolysis. We follow both the liquefaction by BLA and the saccharification process by glucoamylase from Aspergillus niger at low moisture content. The liquefaction model, is used to predict all of the products of wheat starch hydrolysis at higher dry matter contents (30-60 w/w%). The liquefaction model also creates the substrate matrices representing maltodextrins to be used in the saccharification model. The saccharification of liquefacts to glucose is followed with a new mechanistic model, also using the assumptions of the subsite theory. The saccharification model predicts all of the reaction products using the subsite maps of glucoamylase available in literature.

The findings described in the thesis are summarized and put in context in the general discussion. We demonstrate how the parameters of the liquefaction model at low moisture contents were chosen. The outcomes of the model are also compared with the experimental data at 30-60 w/w%. Next, we test our liquefaction model with starch hydrolysis data at 5 and 60 w/w% taken from literature, to verify both the approach we used and the validity of the parameters we obtained in previous chapters. The method used to improve the subsite maps is also tested on another enzyme, Bacillus amyloliquefaciens α-amylase. After discussing the factors that influence saccharification at high dry matter contents, we conclude the chapter with describing the potential of stochastic modelling and its practical use.

Phloem flow and sugar transport in Ricinus communis L. is inhibited under anoxic conditions of shoot or roots
Peuke, A.D. ; Gessler, A. ; Trumbore, S. ; Windt, C.W. ; Homan, N. ; Gerkema, E. ; As, H. van - \ 2015
Plant, Cell & Environment 38 (2015)3. - ISSN 0140-7791 - p. 433 - 447.
carbon-isotope composition - mushrooms agaricus-bisporus - distance water transport - organic-matter - membrane-permeability - assimilate transport - plants - leaves - starch - stress
Anoxic conditions should hamper the transport of sugar in the phloem, as this is an active process. The canopy is a carbohydrate source and the roots are carbohydrate sinks.By fumigating the shoot with N2 or flooding the rhizosphere, anoxic conditions in the source or sink, respectively, were induced. Volume flow, velocity, conducting area and stationary water of the phloem were assessed by non-invasive magnetic resonance imaging (MRI) flowmetry. Carbohydrates and d13C in leaves, roots and phloem saps were determined. Following flooding, volume flow and conducting area of the phloem declined and sugar concentrations in leaves and in phloem saps slightly increased. Oligosaccharides appeared in phloem saps and after 3 d, carbon transport was reduced to 77%. Additionally, the xylem flow declined and showed finally no daily rhythm. Anoxia of the shoot resulted within minutes in a reduction of volume flow, conductive area and sucrose in the phloem sap decreased. Sugar transport dropped to below 40% by the end of the N2 treatment. However, volume flow and phloem sap sugar tended to recover during the N2 treatment. Both anoxia treatments hampered sugar transport. The flow velocity remained about constant, although phloem sap sugar concentration changed during treatments. Apparently, stored starch was remobilized under anoxia.
To pool or not to pool? Impact of the use of individual and pooled fecal samples for in vitro fermentation studies
Aguirre, M. ; Ramiro Garcia, J. ; Koenen, M.E. ; Venema, K. - \ 2014
Journal of Microbiological Methods 107 (2014). - ISSN 0167-7012 - p. 1 - 7.
human large-intestine - gut microbiota - model - bacteria - oligosaccharides - metabolism - products - patterns - starch - core
This study investigated the stability and the activity of the microbiota from a single and a pool of donors in the TNO in vitro model of the colon (TIM-2 system). Our findings demonstrate the suitability of the preparation of a pool of fecal sample to be used for fermentation experiments.
Wheat dough rheology at low water contents and the influence of xylanases
Hardt, N.A. ; Boom, R.M. ; Goot, A.J. van der - \ 2014
Food Research International 66 (2014)2014. - ISSN 0963-9969 - p. 478 - 484.
nonlinear viscoelastic behavior - creep-recovery measurements - nuclear-magnetic-resonance - high solid concentrations - flour dough - gluten protein - unextractable solids - dynamic rheology - bread-making - starch
The effect of low water contents and xylanases on wheat dough rheology is reported. Farinograph, dynamic oscillation, and creep-recovery measurements were performed using water concentrations from 34 to 44.8% (total basis). A water reduction from 43.5–44.8% to 34% increased resistance upon mixing as evidenced by higher Farinograph Brabender Unit values, increased G' and G¿-values, and decreased the maximum creep compliance by 1–2 orders of magnitude. Addition of an endoxylanase with a higher selectivity for water-unextractable arabinoxylans and an endoxylanase with a higher selectivity for water-extractable arabinoxylans both resulted in lower G' and Farinograph dough consistencies and an increase in maximum creep compliance. The major influence of both xylanases was the release of water with possible water reductions of 2–5% (on water basis), though no distinct differences between the two xylanases were observed.
Lupine and rapeseed protein concentrate in fish feed: a comparative assessment of the techno-functional properties using a shear cell device and an extruder
Draganovic, V. ; Boom, R.M. ; Jonkers, J. ; Goot, A.J. van der - \ 2014
Journal of Food Engineering 126 (2014). - ISSN 0260-8774 - p. 178 - 189.
trout oncorhynchus-mykiss - rainbow-trout - wheat gluten - glass-transition - kernel meal - starch - extrusion - products - moisture - quality
The techno-functional properties of soy, lupine and rapeseed protein concentrates (SPC, LPC and RPC, respectively) in fish feed were evaluated relative to fish meal (FM). The effects were studied using a shear cell device and an extruder with emphasis on the added moisture content. Six diets were formulated: an SPC-based diet with 300 g SPC kg-1, diets containing 100 and 200 g LPC kg-1 or 100 and 200 g RPC kg-1 and an FM-based diet with 450 g FM kg-1. Each diet was extruded with an added moisture content of 29%, 25% and 22% of the mash feed rate. It was found that the technological properties of LPC closely resemble FM, being high solubility, low water-holding capacity (WHC) and low paste viscosity. The LPC 100 and 200 g kg-1 diets could be extruded at 22% moisture, which gives an extrudate with reduced drying requirements. In addition, less specific mechanical energy was needed for extrusion. In contrast, both SPC and RPC have high WHC and paste viscosity. This explains the higher feed moisture required during extrusion. The properties of the feeds containing RPC could be well within the ranges acceptable for commercial fish feed use at even higher moisture content compared with SPC. The results of the extrusion trials confirmed the observations made from the shear cell device. Thus, the shear cell device can be used to study processing conditions that are close to extrusion conditions.
Autogenerative high pressure digestion : biogass production and upgrading in a single step
Lindeboom, R.E.F. - \ 2014
University. Promotor(en): Jules van Lier, co-promotor(en): Jan Weijma; Caroline Plugge. - Wageningen : Wageningen University - ISBN 9789461738608 - 208
biogas - spijsvertering - druk - methaanproductie - kooldioxide - zetmeel - hydrolyse - digestion - pressure - methane production - carbon dioxide - starch - hydrolysis
Influence of high solid concentrations on enzymatic wheat gluten hydrolysis and resulting functional properties
Hardt, N.A. ; Goot, A.J. van der; Boom, R.M. - \ 2013
Journal of Cereal Science 57 (2013)3. - ISSN 0733-5210 - p. 531 - 536.
ultrafiltration - protein - starch - improvement - fractions - peptides - systems - flour
Enzymatic hydrolysis at increased solid concentrations is beneficial with regard to energy and water consumption. This study examines the influence of the solid concentration on the enzymatic hydrolysis of wheat gluten and the resulting functional properties of the hydrolysate. Wheat gluten was mildly hydrolyzed at a solid concentration varying from 10% to 60% to degrees of hydrolysis (DH%) ranging from 3.2% to 10.2%. The gluten was susceptible to hydrolysis at all solid concentrations but the hydrolysis rate was influenced by increasing solid concentrations. Size-exclusion high-performance liquid chromatography revealed an increase in the ratio of peptides with a molecular mass >25 kDa for solid concentrations of 40% and 60%. The water solubility increased on hydrolysis and was independent of the solid concentration during proteolysis. The foam stability was not influenced by the solid concentration at low DH%. At DH% higher than 8%, high solid concentrations increased the foam stability, which might be related to the presence of more peptides with a molecular mass >25 kDa. In addition, we found increased reactor productivity. The results show the potential of hydrolyzing wheat gluten at high solid concentrations, which could lead to large savings for water and energy when applied industrially.
BOGO van groene grondstoffen naar biobased materialen. Van zetmeel naar plastic.
Broek, L.A.M. van den - \ 2013
Wageningen : FBR Wageningen
lesmaterialen - zetmeel - biopolymeren - bioplastics - handleidingen - chemie op basis van biologische grondstoffen - biobased economy - beroepsopleiding (hoger) - teaching materials - starch - biopolymers - guide books - biobased chemistry - professional education
Practicumhandleiding voor hbo. Met behulp van commercieel zetmeel is het mogelijk om gelen te maken. Door het toevoegen van glycerol tijdens het proces kan men de gel flexibeler maken.
Cracks in bread crust cause longer crispness retention
Hirte, A. ; Hamer, R.J. ; Hoffmann, L. ; Primo Martin, C. - \ 2013
Journal of Cereal Science 57 (2013)2. - ISSN 0733-5210 - p. 215 - 221.
making process - behavior - quality - starch - gluten - baking - crumb - state
Crispness is among the most important factors that the consumer uses to assess the quality of crispy bread. However, this quality attribute is rapidly lost after baking. It is known that crispness retention can be increased more than eight times by enhancing the water vapor permeability of the crust. Current methods to achieve this, i.e., puncturing the bread before baking, require an extra process step. We hypothesize that cracks that appear spontaneously on the crust surface after baking can also enhance water vapor permeability and therefore improve crispness retention. We were able to confirm this hypothesis by preparing composite breads containing the same crumb but different crusts, with crust recipes of varying starch/protein ratios. Crusts systems that were generally high in gelatinized starch content and poor in evenly distributed gluten were more prone to crack after the whole process of part-baking, freezing, and baking off. These cracks led to an increased water vapor permeability of the crust and an eight times longer instrumental crispness retention compared to standard bread. In this paper we also discuss possible causes for crack formation in the crust. We hypothesize that effective cracks are caused by thermal shock in materials with a low ability to dissipate energy.
Thermomechanical Morphology of Peas and Its Relation to Fracture Behaviour
Pelgrom, P.J.M. ; Schutyser, M.A.I. ; Boom, R.M. - \ 2013
Food Bioprocess Technology 6 (2013)12. - ISSN 1935-5130 - p. 3317 - 3325.
mechanical compression test - glass-transition behavior - scanning calorimetry dsc - pisum-sativum - moisture-content - test tmct - starch - legumes - protein - water
Milling and subsequent air classification can be exploited for production of functional protein-enriched fractions from legumes and grains. Fracture behaviour is of large relevance to optimal disentanglement of protein and starch and is determined by the thermomechanical morphology of the seeds. Thermomechanical properties of peas were explored as a function of temperature and moisture content. Differential scanning calorimetry and thermal mechanical compression tests were carried out on pea protein and starch isolates yielding similar glass transition temperatures. Glass transition lines were successfully constructed using the Gordon–Taylor equation. Subsequently, three regions were identified in the state diagram; starch in the glassy and protein in the rubbery state, both components in the glassy state, and both components in the rubbery state. From single pea fracture experiments, it was found that the completely glassy peas fractured at a smaller critical compression distance compared to the peas in the other two regions. This can be explained by the elastic behaviour of the rubbery protein network, having a detrimental effect on the energy efficiency of milling processes. However, from scanning electron microscopy, it appeared that in rough fracture planes, visible when the protein was in the rubbery state, starch granules were present as more separate identities, suggesting increased disentanglement. Disentanglement of protein and starch by milling would then be optimal when protein is in the rubbery state. The latter can be achieved by milling at increased temperature and/or moisture content, which would be an attractive alternative.
Reducing the stiffness of concentrated whey protein isolate (WPI) gels by using WPI microparticles
Purwanti, N. ; Moerkens, A. ; Goot, A.J. van der; Boom, R.M. - \ 2012
Food Hydrocolloids 26 (2012)1. - ISSN 0268-005X - p. 240 - 248.
rheological properties - water-absorption - powders - aggregation - composites - starch - shear - flow
Concentrated protein gels were prepared using native whey protein isolate (WPI) and WPI based microparticles. WPI microparticles were produced by making gel pieces from a concentrated WPI suspension (40% w/w), which were dried and milled. The protein within the microparticles was denatured and the protein concentration after drying was similar to the native WPI powder. WPI microparticles had irregular shape with an average size of about 70 mm. They absorbed water when dispersed in water, but the dispersion did not gel upon heating. Replacing part of the native WPI powder with WPI microparticles in the protein gel resulted in lower gel stiffness compared with a gel with the same overall protein concentration but without microparticles. However, microparticles also strengthened the continuous phase because they take up water from this phase. This might increase gel stiffness more than would be expected from an inert particle/filler. There was also good bonding between the microparticles and the WPI continuous phase in the gel, which contributed to gel stiffness.
Op weg naar 15 ton zetmeel
PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2012
starch potatoes - cultural methods - crop yield - starch crops - starch - projects - arable farming - working groups
Association of total-mixed-ration chemical composition with milk, fat, and protein yield lactation curves at the individual level
Caccamo, M. ; Veerkamp, R.F. ; Licitra, G. ; Petriglieri, R. ; Terra, F. La; Pozzebon, A. ; Ferguson, J.D. - \ 2012
Journal of Dairy Science 95 (2012)10. - ISSN 0022-0302 - p. 6171 - 6183.
test-day model - dairy-cows - dietary-protein - starch - management
The objective of this study was to examine the effect of the chemical composition of a total mixed ration (TMR) tested quarterly from March 2006 through December 2008 for milk, fat, and protein yield curves for 27 herds in Ragusa, Sicily. Before this study, standard yield curves were generated on data from 241,153 test-day records of 9,809 animals from 42 herds in Ragusa province collected from 1995 to 2008. A random regression sire-maternal grandsire model was used to develop variance components for yields. The model included parity, age at calving, year at calving, and stage of pregnancy as fixed effects. Random effects were herd × test date, sire and maternal grandsire additive genetic effect, and permanent environmental effect modeled using third-order Legendre polynomials. Model fitting was carried out using ASReml. Subsequently, the model with estimated variance components was used to examine the influence of TMR crude protein, soluble N, acid detergent lignin, neutral detergent fiber, acid detergent fiber, starch, and ash on milk, fat, and protein yield curves. The data set contained 46,531 test-day milk yield records from 3,554 cows in the 27 herds recorded during the study period. Initially, an analysis was performed using one dietary component (one-component analysis) within each model as a fixed effect associated with the test-day record closest to the months the TMR was sampled within each herd. An interaction was included with the nutrient component and days in milk. The effect of the TMR chemical component(s) was modeled using a ninth-order Legendre polynomial. The conditional Wald F-statistic for the fixed effects revealed significant effects for acid detergent fiber, neutral detergent fiber, crude protein, starch, and their interactions with days in milk on milk, fat, and protein yield. On the basis of these results, a multicomponent analysis was performed in which crude protein, neutral detergent fiber, and starch were simultaneously included in the model with days in milk interactions. Although both analyses revealed that diet composition influenced production responses depending on lactation stage, the multiple-component analysis showed more pronounced effects of starch and neutral detergent fiber relative to crude protein for all traits throughout lactation.
Carrageenan drying with dehumidified air: drying characteristics and product quality
Djaeni, M. ; Sasongko, S.B. ; Prasetyaningrum, Aji A, A.A. ; Jin, X. ; Boxtel, A.J.B. van - \ 2012
International Journal of Food Engineering 8 (2012)3. - ISSN 1556-3758
kappa-carrageenan - temperature - zeolites - starch - gel
Applying dehumidified air is considered as an option to retain quality in carrageenan drying. This work concerns the effects of operational temperature, air velocity, and carrageenan thickness on the progress of drying and product quality when using dehumidified air. Final product quality and progress of drying were measured by experiments, and a two dimensional model was developed to analyze progress of drying for the different operational conditions. The experimental and modeling results showed that air dehumidification with zeolite reduces the drying time the most at low temperatures. Under these conditions the carrageenan qualities whiteness and gel strength are the least affected by the exposure to the drying temperature. The drying time is the shortest at 120°C, but at this temperature the carrageenan quality degrades the most and is not be improved by air dehumidification. Moreover, the quality is improved by increasing the air velocity and by drying thin carrageenan sheets.
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