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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Environmental conditions alter the effect of organic acid salts on digestibility and intestinal morphology in Nile tilapia (Oreochromis niloticus)
Tran-Ngoc, Kim T. ; Huynh, Son T. ; Sendão, João ; Nguyen, Thinh H. ; Roem, Arjen J. ; Verreth, Johan A.J. ; Schrama, Johan W. - \ 2018
Aquaculture Nutrition (2018). - ISSN 1353-5773 - 11 p.
digestibility - hypoxia - intestinal morphology - normoxia - organic acid - soybean meal diet

The impact of two dietary organic acids (OAs) on nutrient digestibility and intestinal morphology was determined in Nile tilapia under conditions of dissolved oxygen in the water: normoxia and hypoxia. Four diets designated as control (0 g/kg organic acid salt), KDF (2 g/kg potassium diformate), CAB (2 g/kg calcium butyrate) and their combination (4 g/kg of a mixture of KDF and CAB, ration 1:1) were formulated with 520 g/kg of soybean meal in order to produce soybean meal enteritis-like symptoms. The four diets were tested first under normoxic conditions (6 mg/L) for a period of 5 weeks, followed by a test period under hypoxic conditions (3 mg/L). The results showed that OAs were unable to significantly improve growth and nutrient digestibility under normoxic conditions but under hypoxic conditions, there was a significant enhancement of the growth and nutrient digestibility. Fish fed OA-supplemented diets showed improvements in the intestinal morphology under the normoxic conditions, and these effects were more pronounced under the hypoxic conditions. Experimental findings suggest that OAs can improve the nutrient digestibility and intestinal morphology under hypoxic conditions. A synergistic effect by the combination of formic and butyric acid on growth, digestibility and intestinal morphology was not found.

Gender action plans in the aquaculture value chain : what's missing?
Bosma, Roel H. ; Nguyen, Thi Dien ; Calumpang, Lorna M. ; Carandang, Sef Alba - \ 2018
Reviews in Aquaculture (2018). - ISSN 1753-5123
farmed seafood - gender mainstreaming - inequality - patriarchy - poverty - women

Gender equality has been a political issue in view of human rights and welfare since several decades. Therefore, many countries have developed Gender Action Plans (GAPs) that support equal access of both sexes to education, employment and finance. Two workshops on GAPs in aquaculture and a literature review brought about the question: what's missing in Asian sectoral GAPs. Not all reviewed Asian countries have GAPs for fishery/ aquaculture, but all encountered constraints to achieve their goals regarding equal access for women. Women's contribution in aquaculture tends to go beyond the traditional gender divide. For example, women may lead in the area of production because they can combine aquaculture with their homebound tasks and own vertically integrated companies. However, skewed perceptions on the role, status and perception of women and men, more so in strong than weak patriarchies (the former accept the subservient role, while the latter exercise the dominant role) limit women's access to training opportunities on new aquaculture technologies. Women are also left out in policy- and decision-making processes; and in the value chain, women receive lower wages than men. Their role is underestimated by lack of disaggregated data, as reflected in post-disaster interventions and industrial development programs. To be effective sectoral GAPs, based on disaggregated data, should have budgets, plans and target indicators for which leaders could be held accountable. These GAPs, however, can't address the required radical change in attitude toward women; unless deliberately planned educational media campaigns are embedded into the national GAPs.

Gas sensors for detection of volatile organic compounds at room temperature : Air qualty control & medical diagnosis
Nguyen, Minh Quyen - \ 2017
University. Promotor(en): Cees van Rijn. - Wageningen : Wageningen University - ISBN 9789463437042 - 178

The need of detecting acetone in ambient environment in laboratories and factories to monitor leakage and prevent accidents for human safety and health protection has involved numerous studies. Also, in human breath, acetone at ppm level is present amongst more than two hundred kinds of other volatile organic compounds. The development of reliable gas sensors for breath analysis is aimed to detect acetone at sub-ppm level in human breath for diabetes diagnosis. Field effect transistor based gas sensors have shown great potentials in detecting analytes at molecular level.

In a first approach fluorinated-terminated monolayers have been formed on silicon nanowires, that can detect an organic gas (2-octanone) at 0.5 ppm level. Surface formation and stability of these fluorinated monolayers on silicon nanowires have been characterized; Preliminary results towards VOCs have shown high-quality monolayers in various extreme conditions with good surface passivation.

As a second approach new nanogap IDEs structures have been developed for acetone detection, and sensing performance could be enhanced by using a nanocomposite (PVPH) sensing layer. Adding functionalized silicon nanoparticles in the PVPH polymer network, a higher sensitivity has been obtained. The IDE-PVPH devices demonstrated good reproducibility after multiple cycles of gas exposure. By reducing the gap-width to the nanoscale, the sensitivity of the device in acetone detection is increased drastically. A detection limit with nanogap IDEs is found to a level of 10 ppm when using PVPH as the sensing layer. Both micro and nano-gap IDEs operate at room temperature and show a good stability even after long-term storage. At room temperature, the detection limit of nanogap capacitive sensors depends heavily on the thermal and mechanical stability of other (parasitic) components that limit the resolution of the measurement. Emphasis is given on the nanostructure of nanogap IDEs; this type of capacitive sensors provide a larger dynamic range of the capacitance as compared to micro IDEs and herewith the signal to noise ratio is considerably improved. The results illustrate an improvement in measurement resolution from pico farads to femto farads. When using nanogap structures, a larger absolute change in capacitance will improve thus the detection limit. Both micro and nano gap sensors showed a relative change of 0.2 % with respect to the bare IDE capacitance and the limit of detection increased by a factor of 12. Further downscaling feature sizes in micro and nano IDE structures are promising for the development of novel portable gas sensors that are applicable in many fields such as industrial and laboratorial security. They promote a new generation of gas sensors for detection of a variety of VOCs at low concentrations in environmental air monitoring as well as disease diagnosis.

Inconvenientes y beneficios del comportamiento higiénico de la abeja de la miel (Apis mellifera L.) : una revisión
Leclercq, Gil ; Pannebakker, Bart ; Gengler, Nicolas ; Nguyen, Bach Kim ; Francis, Frédéric - \ 2017
Journal of Apicultural Research 56 (2017)4. - ISSN 0021-8839 - p. 366 - 375.
American foulbrood - Apis mellifera - chalkbrood - efficiency - hygienic behavior - Varroa destructor

The hygienic behavior of honey bee workers contributes to the social immunity of colonies. The ability of workers to detect and remove unhealthy or dead brood prevents the transmission of brood diseases inside the colony. Over the last five decades, this trait has been extensively studied and improved in several research and breeding programs. Given the strong interest for hygienic behavior, we here review the costs and benefits associated with this trait, extending preceding reviews on this subject from the late 1990s. Since the 1990s, there have been no major new insights on the efficiency of this behavior against American foulbrood and chalkbrood. However, the number of publications on hygienic behavior against the mite Varroa destructor has considerably increased, fueling the debate regarding the efficiency of hygienic behavior against this parasite. Breeding programs have shown that selection for a specific trait might also impact other traits. Thus, we also review the cost of trade-offs between hygienic behavior and other economically important traits for bee breeders. Overall, the benefits of hygienic behavior seem to largely outweigh its costs for both colonies and bee breeders.

Flowering locus C (FLC) is a potential major regulator of glucosinolate content across developmental stages of Aethionema arabicum (brassicaceae)
Mohammadin, Setareh ; Nguyen, Phuong ; Weij, Marco S. van; Reichelt, Michael ; Schranz, Eric - \ 2017
Frontiers in Plant Science 8 (2017). - ISSN 1664-462X
Aethionema - Brassicaceae - Development - Glucosinolates - Multi-trait analyses - QTL

The biochemical defense of plants can change during their life-cycle and impact herbivore feeding and plant fitness. The annual species Aethionema arabicum is part of the sister clade to all other Brassicaceae. Hence, it holds a phylogenetically important position for studying crucifer trait evolution. Glucosinolates (GS) are essentially Brassicales-specific metabolites involved in plant defense. Using two Ae. arabicum accessions (TUR and CYP) we identify substantial differences in glucosinolate profiles and quantities between lines, tissues and developmental stages. We find tissue specific side-chain modifications in aliphatic GS: methylthioalkyl in leaves, methylsulfinylalkyl in fruits, and methylsulfonylalkyl in seeds. We also find large differences in absolute glucosinolate content between the two accessions (up to 10-fold in fruits) that suggest a regulatory factor is involved that is not part of the quintessential glucosinolate biosynthetic pathway. Consistent with this hypothesis, we identified a single major multi-trait quantitative trait locus controlling total GS concentration across tissues in a recombinant inbred line population derived from TUR and CYP. With fine-mapping, we narrowed the interval to a 58 kb region containing 15 genes, but lacking any known GS biosynthetic genes. The interval contains homologs of both the sulfate transporter SULTR2;1 and FLOWERING LOCUS C. Both loci have diverse functions controlling plant physiological and developmental processes and thus are potential candidates regulating glucosinolate variation across the life-cycle of Aethionema. Future work will investigate changes in gene expression of the candidates genes, the effects of GS variation on insect herbivores and the trade-offs between defense and reproduction.

Administrative co-management in special use forests of Vietnam
Dung, Nguyen Kim - \ 2017
University. Promotor(en): Arthur Mol, co-promotor(en): Simon Bush. - Wageningen : Wageningen University - ISBN 9789462579866 - 183
forests - forest administration - forest management - nature conservation - environmental protection - vietnam - bossen - bosbeheer - bosbedrijfsvoering - natuurbescherming - milieubescherming

To protect its natural heritage and biodiversity, Vietnam has established a system of ‘special use forest’ (SUFs) which is “the backbone of the national protected areas”. The ineffective management of SUFs based solely on the state leads to a decline in biodiversity and density of the forests. Recognizing this, collaborative or ‘co’-management for SUFs is advocated to get more participation and shared responsibilities and rights between government and non-state actors. However, it is widely noted that co-management is a particularly great challenge in Vietnam because of the nature of strong state control, decades of SUF conflicts, and the lack of capacity and initiatives of communities to negotiate with the government in co-management arrangements. This PhD thesis questions the degree to which co-management can be put in Vietnamese SUFs and the degree of ‘adaptiveness’ it can engender. Conditions of the economic, political and social context surrounding SUFs becomes key to any understanding of how co-management can be implemented, including insights into how co-management may need to be amended to adjust to ‘fit’ the context of mono-organisational states.

Improving sustainability of striped catfish (Pangasianodon hypophthalmus) farming in the Mekong Delta, Vietnam through recirculation technology
Nguyen, Nhut - \ 2016
University. Promotor(en): Johan Verreth, co-promotor(en): Marc Verdegem. - Wageningen : Wageningen University - ISBN 9789462579194 - 180
fish culture - recirculating aquaculture systems - aquaculture - fishes - nutrients - vietnam - visteelt - recirculatie aquacultuur systemen - aquacultuur - vissen - voedingsstoffen

The aim of this thesis was to document improvements in sustainability indicators of striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878) production through the application of recirculation and waste treatment techniques. To be able to document improvements in sustainability, in each system studied the same set of twenty sustainability indicators were measured. Indicators related to the use of fingerlings, water, diesel oil, electricity, labor, chemicals and antibiotics.

Also, indicators related to nutrient utilization efficiencies and waste discharge were monitored. In addition, a sampling scheme, allowing to calculate organic matter, nitrogen, phosphorous and chemical oxygen demand mass balances covering a full production cycle and applicable in different production systems, was developed. Overall, from a sustainability point of view, striped catfish culture in ponds compared well to other important aquaculture species.

Although favorable, it was concluded that water, chemicals and antibiotics use, survival, and the amounts of waste discharged could be further reduced through recirculation and treatment of solid wastes. The realized improvements through RAS technology and waste treatment technology were quantified in lab or pilot scale experiments. Large improvements were realized for water, antibiotic and chemical use, survival, waste discharge and color grade of striped catfish fillets at harvest. In addition, in RAS, utilization efficiencies of nutrients supplied through feeding were improved.

Solid wastes removed from ponds or RAS could be partially re-used by making compost or producing methane for generating electricity. Another approach tested was the integration of a denitrification reactor in the recirculation system, which allowed to decompose solid waste and reduce nitrogen discharge. Denitrification in RAS did not affect fish growth, nutrient retention efficiencies and the quality of the fish fillets produced, and thus also improved sustainability of striped catfish farming.

In conclusion, application of recirculation and waste treatment techniques tested in this thesis improved the sustainability for striped catfish culture. The challenge remains to scale up RAS and waste treatment technology for striped catfish to the production volumes handled in outdoor ponds without raising production costs.

Feasibility of a simple microsieve-based immunoassay platform
Zweitzig, Daniel R. ; Tibbe, Arjan G. ; Nguyen, Ai T. ; Rijn, Cees J.M. van; Kopnitsky, Mark J. ; Cichonski, Kathleen ; Terstappen, Leon W.M.M. - \ 2016
Journal of Immunological Methods 437 (2016). - ISSN 0022-1759 - p. 21 - 27.
Diagnosis - Disease - Immunoassay - Infectious - Microsieve - Serology

The intrinsic properties of silicon microsieves, such as an optically flat surface, high overall porosity, and low flow resistance have led to an increasing number of biotechnology applications. In this report, the feasibility of creating a microsieve-based immunoassay platform was explored. Microsieves containing 5μm pores were coupled with poly-acrylic acid chains, and then mounted into a plastic holder to enable rapid reagent exchanges via a wicking mechanism. The mounted microsieves were coated with infectious disease-related antigens at [2.5 and 25μg/mL], [20 and 50μg/mL], and [20 and 100μg/mL] to facilitate detection of serum-derived human antibodies against Rubella (3-day measles), B. burgdorferi (Lyme disease), or T. pallidum (syphilis), respectively. The prototype microsieve-based immunoassay platform was able to distinguish positive control sera containing antibodies against Rubella, T. pallidum, and B. burgdorferi from negative control sera with similar qualitative results as FDA-approved ELISA tests. Testing of a WHO IgG syphilitic standard at 0.3, 0.15, 0.075, 0.0375, and 0.01875IU/mL demonstrated that the T. pallidum microsieve assay is able to distinguish disease-specific IgG signal from background signal at similar, and possibly lower, levels than the corresponding ELISA. The T. pallidum microsieve assay prototype also differentiated positive clinical serum samples from negative donor samples, and the results were in good agreement with ELISA (R2 =0.9046). These feasibility studies demonstrate the potential for utilizing microsieves, along with a reagent wicking device, as a simple diagnostic immunoassay platform.

Capture of Tumor Cells on Anti-EpCAM-Functionalized Poly(acrylic acid)-Coated Surfaces
Andree, Kiki C. ; Barradas, Ana M.C. ; Nguyen, Ai T. ; Mentink, Anouk ; Stojanovic, Ivan ; Baggerman, Jacob ; Dalum, Joost van; Rijn, Cees J.M. van; Terstappen, Leon W.M.M. - \ 2016
ACS Applied Materials and Interfaces 8 (2016)23. - ISSN 1944-8244 - p. 14349 - 14356.
antibodies - circulating tumor cells - epithelial cell adhesion molecule (EpCAM) - flow model - polycarboxylate coating - surface plasmon resonance

The presence of tumor cells in blood is predictive of short survival in several cancers and their isolation and characterization can guide toward the use of more effective treatments. These circulating tumor cells (CTC) are, however, extremely rare and require a technology that is sufficiently sensitive and specific to identify CTC against a background of billions of blood cells. Immuno-capture of cells expressing the epithelial cell adhesion molecule (EpCAM) are frequently used to enrich CTC from blood. The choice of bio conjugation strategy and antibody clone is crucial for adequate cell capture but is poorly understood. In this study, we determined the binding affinity constants and epitope binding of the EpCAM antibodies VU1D-9, HO-3, EpAb3-5, and MJ-37 by surface plasmon resonance imaging (SPRi). Glass surfaces were coated using a poly(acrylic acid) based coating and functionalized with anti-EpCAM antibodies. Binding of cells from the breast carcinoma cell line (SKBR-3) to the functionalized surfaces were compared. Although EpAb3-5 displayed the highest binding affinity HO-3 captured the highest amount of cells. Hence we report differences in the performance of the different antibodies and more importantly that the choice of antibody to capture CTC should be based on multiple assays.

Sainfoin (Onobrychis viciifolia) : a forgotten crop for dairy cows with future potential
Huyen, Nguyen Thi - \ 2016
University. Promotor(en): Wouter Hendriks, co-promotor(en): Wilbert Pellikaan; Martin Verstegen. - Wageningen : Wageningen University - ISBN 9789462577268 - 160 p.
onobrychis viciifolia - dairy cows - fodder legumes - fodder crops - legume silage - rumen digestion - nutrition physiology - methane production - milk yield - dairy performance - animal nutrition - melkkoeien - voederpeulvruchten - voedergewassen - peulvruchtenkuilvoer - pensvertering - voedingsfysiologie - methaanproductie - melkopbrengst - melkresultaten - diervoeding

Sainfoin (Onobrychis viciifolia): a forgotten crop for dairy cows with future potential


The world population growth and rising incomes are expected to increase the consumption of animal-derived foods such as meat, eggs and milk. However, livestock production should not only be directed towards increasing productivity but should also incorporate environmental, food safety and animal welfare aspects. Therefore, farm businesses have to respond to the high environment impact of their activities, by using low-input systems including the use of forage legumes. Recent studies have demonstrated that forage legumes with moderate levels of condensed tannins (CT) are beneficial for animal nutrition and animal health. Sainfoin (Onobrychis viciifolia Scop.) is a tanniniferous forage legume containing CT that has potential nutritional and health benefits, i.e. preventing bloating, reducing nematode larval establishment, improving nitrogen (N) utilization and reducing greenhouse gas and N emissions (Chapter 1). However, the use of sainfoin as a fodder crop in dairy cow rations in northwestern Europe is still rather unknown. This thesis investigated the potential of sainfoin in the dairy cow diets and the effect of CT structural properties on rumen fermentation and biohydrogenation (BH).

Chapter 2 reports a study where the effect of sainfoin silage on nutrient digestibility, animal performance, energy and N utilization and methane (CH4) production in dairy cows was investigated. Six rumen cannulated, lactating dairy cows were randomly assigned to either a control (CON) or sainfoin based (SAIN) diet. The CON diet was a mixture of grass silage, corn silage, concentrate and linseed. In the SAIN diet, 50% of the grass silage DM in the CON diet was exchanged by sainfoin silage. Total daily dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) intake did not differ between the two diets. The apparent digestibility of DM, OM, NDF and acid detergent fiber (ADF) were respectively, 5.7, 4.0, 15.7 and 14.8% lower for the SAIN diet. Methane production per kg DM intake was lowest for the SAIN diet and CH4 production as a percentage of gross energy intakes tended to be lower while milk yield was greater for the SAIN diet. Nitrogen intake, N retention and energy retained in body protein were greater for the SAIN than the CON diet. Nitrogen retention as a percentage of N intake tended to be greater for the SAIN diet. These results showed that inclusion of sainfoin silage at the expense of grass silage in dairy cow rations reduced CH4 per kg DM intake. Although nutrient digestibility was decreased, sainfoin silage improved milk production and redirected metabolism towards body protein accretion at the expense of body fat.

In Chapter 3, reticular fatty acid (FA) flow and ruminal BH of C18:3n-3 is reported using the reticular sampling technique (Cr-EDTA and Yb-acetate as digesta flow markers) in the lactating cows fed the SAIN and CON diet in Chapter 2. The reticular flows of DM, OM and N were not affected by dietary treatment. However, NDF flow was higher (1.87 vs. 1.40 kg/d) where the cows were fed the SAIN diet. A higher mono-unsaturated FA flow was caused by the higher trans-9-C18:1 and cis-9-C18:1 flow for the SAIN compared to the CON fed cows. The flows of trans-9,trans-12-C18:2 and cis-12,trans-10 C18:2 were higher in the SAIN diet fed cows, but total poly-unsaturated FA flow was not affected by the different diet treatments. The SAIN diet fed cows had a significant lower ruminal BH of cis-9-C18:1 and C18:3n-3, compared to the CON fed cows and tended to a lower ruminal BH in case of cis-9,cis-12-C18:2. These results show that inclusion of sainfoin silage at the expense of grass silage in dairy cow rations reduces ruminal BH of dietary cis-9-C18:1 and C18:3n-3.

The effects of replacing grass silage by sainfoin silage in a TMR on milk production and FA in milk fat of the dairy cows in Chapter 2 is reported in Chapter 4. Milk yield reported in Chapter 4 was highest for the SAIN diet with every kg of OM digested of the SAIN diet resulting, on average, in 0.2 kg more milk production. The SAIN diet fed cows had a higher C18:3n-3 and cis-9,cis-12-C18:2 proportion in milk fat compared to the CON diet fed cows. A higher proportion of total trans-C18:1 was found in the cows fed the SAIN diet. There were no differences in proportion of total saturated and unsaturated FA in milk fat between the two diets. Our results showed that replacing grass silage by sainfoin silage improved milk yield and milk FA profile of dairy cows.

Effects of the structural properties of CT, i.e. average polymer size (or mean degree of polymerization, mDP); percentage of cis flavan-3-ols (%cis) and percentage of prodelphinidins (%PD) in CT extracts on CH4 production and fermentation characteristics of rumen fluid using an in vitro gas production technique was investigated in Chapter 5. Extracts of CT from eight plants; black currant leaves, goat willow leaves, goat willow twigs, pine bark, red currant leaves, sainfoin plants, weeping willow catkins and white clover flowers were extracted, in order to obtain CT with a wide range in mDP, %PD and %cis. All CT extracts reduced CH4 concentration, decreased the maximum rate of fermentation for CH4 production and rate of substrate degradation. The correlation between CT structure on the one hand and CH4 production and fermentation characteristics on the other hand showed that the %PD within CT had the largest effect on fermentation characteristics, followed by mDP and %cis.

Chapter 6 reports results of an in vitro study to investigate the effects of the structural properties CT (mDP, %cis and %PD) on rumen fermentation and BH end-products. The total volatile FA (VFA), ammonia concentration and the proportion of branched chain VFA was reduced in all CT extracts, compared to the control. The proportion of cis-9-C18:1; cis-9,cis-12-C18:2; cis-9,cis-12,cis-15-C18:3 were numerically higher in all CT sources, while the proportion of C18:0 and fractional rate of BH of C18:3n-3 were numerically lower in all CT sources, compared to the control. The correlation between CT structural properties on the one hand and fermentation and BH end-products on the other hand showed that the CT with a high %PD and smaller mDP had the largest effect on fermentation end-products. However, mDP was found to be the most important factor affecting rumen BH.

Chapter 7 provides a general synthesis on the major findings of the studies presented in the preceding chapters. In addition, results are reported of a further in vitro as well as an in situ study in which I investigated the mechanisms of CT action in the rumen, in the post-rumen compartments and digestive tract. In the in situ study, fresh sainfoin (Esparcette) was incubated in the rumen and in the abomasum before digested during passage through the digestive tract. For the in vitro study, sainfoin (Ambra) was incubated with rumen fluid buffer for 1, 2, 4, 8, 12, 24 hours. After incubation in situ and in vitro, the incubated material was analyzed for tannin content by butanol-HCl assay. The results showed that the soluble CT dramatically reduced upon introduction in the digestive tract. Additional analyses showed that CT had bound to the fiber and protein (diet and microbes) fractions in the digestive tract.

The present work showed that sainfoin silage can be used in dairy cow rations to improve milk production and N utilization and reduce CH4 emissions per kg DM intake. Moreover, sainfoin silage, when replacing part of the grass silage in a TMR of dairy cows, increases ruminal unsaturated FA flow into the reticulum and reduces ruminal BH of dietary cis-9-C18:1 and C18:3n-3. Cows fed sainfoin silage at the expense of grass silage in a TMR increase the proportion of unsaturated FA in milk fat. In terms of condensed tannin structure, mDP and %PD appear to be the most important properties of CT that affect fermentation and BH end-products. Condensed tannins with a mDP ranging from 5 to 10 monomeric units and a %PD > 70.0% seem to have the highest biological activity in the rumen.

Regulation of a two-component system involved in Bacillus cereus cold adaptation
Diomandé, S.E. ; Nguyen-the, C. ; Abee, T. ; Tempelaars, M.H. ; Doublet, B. ; Brousolle, V. ; Brillard, J. - \ 2015
Involvement of the CasK/R two-component system in optimal unsaturation of the Bacillus cereus fatty acids during low-temperature growth
Diomandé, Sara Esther ; Nguyen-the, Christophe ; Abee, Tjakko ; Tempelaars, M.H. ; Broussolle, Véronique ; Brillard, Julien - \ 2015
International Journal of Food Microbiology 213 (2015). - ISSN 0168-1605 - p. 110 - 117.
B. cereus - Cold adaptation - Desaturase - TCS - Unsaturated FA

Bacillus cereus sensu lato is composed of a set of ubiquitous strains including human pathogens that can survive a range of food processing conditions, grow in refrigerated food, and sometimes cause food poisoning. We previously identified the two-component system CasK/R that plays a key role in cold adaptation. To better understand the CasK/R-controlled mechanisms that support low-temperature adaptation, we performed a transcriptomic analysis on the ATCC 14579 strain and its isogenic ΔcasK/R mutant grown at 12. °C. Several genes involved in fatty acid (FA) metabolism were downregulated in the mutant, including desA and desB encoding FA acyl-lipid desaturases that catalyze the formation of a double-bond on the FA chain in positions Δ 5 and Δ 10, respectively. A lower proportion of FAs presumably unsaturated by DesA was observed in the δcasK/R strain compared to the parental strain while no difference was found for FAs presumably unsaturated by DesB. Addition of phospholipids from egg yolk lecithin rich in unsaturated FAs, to growth medium, abolished the cold-growth impairment of δcasK/R suggesting that exogenous unsaturated FAs can support membrane-level modifications and thus compensate for the decreased production of these FAs in the B. cereus Δ casK/R mutant during growth at low temperature. Our findings indicate that CasK/R is involved in the regulation of FA metabolism, and is necessary for cold adaptation of B. cereus unless an exogenous source of unsaturated FAs is available.

Bioactive tannins in forage legumes: Myths, Ignorance and Aspirations
Mueller-Harvey, I. ; Ramsey, Aina ; Fryganas, Christos ; Ropiak, Honorate ; Drake, Chris ; Ortiz, Marina Mora ; Smith, Lydia M.J. ; Skot, L. ; Malisch, Carsten ; Luescher, Andreas ; Kempf, Katharina ; Kolliker, R. ; Desrues, Olivier ; Williams, Andrew R. ; Thamsborg, S.M. ; Azuhnwi, Blasius N. ; Quijada, J.N. ; Hoste, H. ; Girard, M. ; Grosse Brinkhaus, A. ; Dohme-Meier, F. ; Bee, G. ; Nguyen, T.H. ; Pellikaan, W.F. ; Copani, Giuseppe ; Niderkorn, Vincent ; Engstrom, Marica ; Salminen, J.P. ; Wilkinson, Ian ; Totterdell, Paul ; Waghorn, G.C. - \ 2015
Tannin-containing legumes have attracted much interest due to their animal health and nutritional benefits. Although several tannins are anti-nutritional, a few can generate valuable benefits for controlling parasitic nematodes that are resistant to anthelmintic drugs, for improving protein utilization by ruminants and fatty acid profiles in meat and milk products and for reducing greenhouse gases. A 5% dietary maximum limit of tannins has been suggested, but information on structure-activity relationships are essential in order to fully exploit the potential of these natural plant compounds. Breeders also require guidelines and screening tools for optimal tannin compositions, and farmers require tannin-containing forages that provide consistent results.

Plants vary in tannin contents and composition depending on species, variety and growing conditions. Recent research in Europe (‘LegumePlus' and other projects) has focused on new tools for analyzing soluble and insoluble tannins in plants, silages and digesta. This involved isolating different types of tannin standards from a wide range of different plants and thiolysis to assess their purity and composition. We also developed new UPLC-MS/MS, NIR- and NMR-analysis methods and tested tannin-protein interactions. Agronomists and plant breeders assembled germplasm collections, identified sainfoin-specific markers, and strategies for weed control. Ruminant nutritionists studied in vitro and in vivo fermentations, N-balances and the quality of meat and milk products. Parasitologists explored the anti-parasitic properties using a wide range of different tannin types.

The presentation will summarize current knowledge and conclude with a wishlist for ‘ideal' tannin-containing forages. It will emphasize that robust and stable tannin concentrations and compositions are required in addition to high yield, good weed suppression and resistance to climatic stress.
Modelling the formation of heat-induced contaminants during thermal processing of food
Nguyen, H.T. - \ 2015
University. Promotor(en): Tiny van Boekel, co-promotor(en): Ine van der Fels. - Wageningen : Wageningen University - ISBN 9789462574588 - 172
voedsel - maillard-reactie - voedselbereiding - acrylamiden - voedselbesmetting - gezondheidsgevaren - modellen - food - maillard reaction - food preparation - acrylamides - food contamination - health hazards - models

Many of our food products have undergone a heat-treatment before consumption, either at home or at the food industry. Heat treatments not only bring out desired characteristics of the food products such as flavour, texture, taste and safety aspects but also leads to the formation of undesired compounds that may have negative impacts for human health. Such undesired compounds that are generated from the Maillard reaction are neo-formed food contaminants (NFC). NFC are present in many common heat-processed foods, such as potatoes-based products, cereal-based products, baby foods, and dairy products. Therefore, effective mitigation measures are being developed to minimize the generation of such undesired compounds while maintaining the organoleptic attributes of the food products as consumer’s demands. This thesis aimed at understanding the mechanistic pathways for the formation of three neo-formed food contaminants: acrylamide, 5-hydroxymethylfurfural (HMF), and -(carboxymethyl)lysine (CML), using multireponse kinetic modelling.

First, the topic of the Maillard reaction, occurrence and human exposure to the three NFC in heated foods, and multiresponse kinetic modelling is introduced. Then, scientific literature on analytical methods, formation pathways, occurrence in processed foods, and health impacts of CML was reviewed. Based on the literature, an experiment was set up to understand the formation pathway for CML in caseinate-lactose/glucose solutions, each heated at 120oC and 130oC. According to the best fitting mechanistic model, the formation of CML in the two model solutions originated from the reaction between lactose/glucose and lysine residues via the Amadori rearrangement product formation. Moreover, glucose and lactose were degraded via Lobry de Bruyn-Alberda van Ekenstein (LA) arrangement. CML seems to be not thermally stable, and may thus not be an optimal indicator for heat damage of foods.

Another experiment was done for gaining insights into the formation of acrylamide and HMF in biscuits during baking at 200oC. Four biscuit recipes were prepared with three sugar types: (1) sucrose (35 g), (2) glucose (17.5 g) and fructose (17.5 g), (3) fructose (17.5 g), and (4) glucose. The molar ratio of total glucose and fructose to asparagine in each type of biscuit was higher than 1. The concentrations of acrylamide and HMF were lowest in the sucrose-prepared biscuits. Kinetic modelling results suggested that during baking of these four kinds of biscuits, acrylamide was formed via the specific amino acid route, i.e., a reducing sugar reacts with asparagine to form the Schiff base without the Amadori product formation (not via Strecker degradation), and that HMF was formed via caramelisation. Fructose played a key role in the formation of both acrylamide and HMF.

In a similar experiment, the effects of different types of wheat flour on acrylamide and HMF formation in sucrose-prepared biscuits during baking at 200oC were investigated. Four types of wheat flour, which had the most different concentrations of asparagine, and total glucose and fructose (the reducing sugar), were selected for the preparation of four kinds of biscuits. Out of four wheat flour types, two had the molar ratio of reducing sugars to asparagine lower than 1, and the other two had a ratio higher than 1. Results showed that those different molar ratios in wheat flour did not have effects on the pathways leading to the formation of acrylamide and HMF in all four types of biscuits. Acrylamide was formed via the specific amino acid route, and HMF was formed via caramelisation. No clear correlation was found between the concentration of either acrylamide or HMF in biscuits and the concentration of asparagine or the reducing sugars in wheat flour. Asparagine was not a limiting factor for acrylamide generation in biscuits.

The outcomes of this thesis give insights into the actual reaction pathways for the formation of acrylamide and HMF in biscuits during baking at 200oC and for the formation of CML in the model solutions. These modelling results may help to control the formation of these NFCs in a quantitative way.

Ranking risks posed by composite food products
Stella, P. ; Cerf, O. ; Koutsoumanis, K.P. ; Nguyen-The, C. ; Sofos, J.N. ; Valero, A. ; Zwietering, M.H. ; Hugas, M. - \ 2013
In: Conference proceedings 8th International Conference on Predictive Modelling in Food, Paris, France, 16 - 20 September, 2013. - Paris : CNIEL, IFIP - ISBN 9782356700254 - p. 191 - 192.
Ranking the microbiological safety of foods: A new tool and its application to composite products
Stella, P. ; Cerf, O. ; Hugas, M. ; Koutsoumanis, K.P. ; Nguyen-The, C. ; Sofos, J.N. ; Valero, A. ; Zwietering, M.H. - \ 2013
Trends in Food Science and Technology 33 (2013)2. - ISSN 0924-2244 - p. 124 - 138.
quantitative risk-assessment - yersinia-enterocolitica - escherichia-coli - moisture transfer - water - infection - outbreak - storage - virus
A methodology based on the combination of two complementary approaches to rank microbiological risks in foods is presented. In the forward approach data on the pathogenicity of hazards and their behaviour in food during processing and following steps, up to consumption, are used in decision trees to qualitatively estimate the risk associated with foods. In the backward approach risks are evaluated based on the analysis of data available on the past occurrence of hazards and foodborne outbreaks. The categorisation of foods using the forward approach should prevail, and whenever it leads to a likely risk for a given food, the risk can be further qualified with the results from the backward approach. The methodology developed was applied to rank the public health risk posed by certain composite products, which contain both processed products of animal origin and products of plant origin (e.g., bread, cakes, chocolate). Despite limitations in the data available for these foods, valuable results were obtained. The method is therefore considered suitable for application with success to other types of food, and is proposed as a tool for risk managers to rank foods based on their potential food safety risks
Scientific opinion on public health risks represented by certain composite products containing food of animal origin
Cerf, O. ; Koutsoumanis, K. ; Nguyen-The, C. ; Sofos, J. ; Valero, A. ; Zwietering, M.H. - \ 2012
EFSA Journal 10 (2012)5. - 132 p.
This Opinion reviews the factors that affect microbial survival and growth in composite products, and in foods in general. It concludes that the main factors to be considered are: water activity, pH, temperature and duration of storage, processing, and intensity and duration of other non-thermal physical processes applied. Prevalence and concentration of the pathogens in food are important to determine the risk for consumers. The opinion presents a review of the quantitative microbiology models and databases that can be used to provide quantitative estimations of the impact of the above factors on the survival and growth of the main bacterial pathogens. In composite products, migration and diffusion of moisture and substances among the ingredients may change their physico-chemical parameters, particularly at the interfaces. Therefore, the assessment of the risk posed by composite products needs to consider the combinations of parameters most permissive to survival and growth of pathogens. Two complementary approaches are proposed for the identification and profiling of microbiological hazards in different specific composite products. The first one is based on past outbreaks and prevalence of hazards in the products and leads to the conclusion that the most frequent hazard-composite product combinations are Salmonella in cakes and bakery products. The second one consists in decision tools based on the impact on the pathogens of food composition and food processing. Categorisation of the risk for composite products requires information on their composition, processing and further handling, which can largely differ for foods belonging to the same category. Further conditions may influence the risk and should be verified, i.e. hygienic conditions during preparation of the composite products and their ingredients, shelf-life conditions, and reliability of cooking by consumers to inactivate pathogens. The decision tools developed apply to all composite products considered by the mandate, as well as to all other foods. © European Food Safety Authority, 2012
Greening textile industry in Vietnam
Nguyen Thi Phuong, L. - \ 2011
University. Promotor(en): Arthur Mol, co-promotor(en): Harry Bruning. - [S.l.] : S.n. - ISBN 9789085858782 - 314
milieubeleid - textielindustrie - verontreiniging - milieuafbraak - afvalwater - waterverontreiniging - duurzame ontwikkeling - industrie - ecologie - vietnam - zuidoost-azië - environmental policy - textile industry - pollution - environmental degradation - waste water - water pollution - sustainable development - industry - ecology - south east asia

The textile and garment industry has made a remarkable contribution to the economic development of Vietnam and employs currently a large labor force of 2.5 million people.However, the textile industry is also seen as a most polluting and unsustainable industry due to the use of excessive amounts of materials and the release of large amounts of pollutants into the environment. In order to improve the environmental sustainability and effectiveness of the textile industry in Vietnam this study has looked into preventive measure, reuse/recycling options and improved end-of-pipe technologies, separately and in combination.

The end-of-pipe treatment is the last step in the greening production model. Textile wastewater is very difficult to treat, especially regarding the high color intensity. Removal of color from textile wastewater was studied by varying the pH, the application of a biological treatment step, the application of coagulation/flocculation and of Advanced Oxidation Processes (O3, O3/H2O2, Fenton’s reagent). The coagulation process was very effective in color removal of insoluble dyestuffs (98%), but this process is not so suitable for wastewater containing only soluble dyestuffs (12-55%). Of the Advanced Oxidation Processes, the Fenton’s reagent process was the most effective method for color removal (81-98%)for the four types of wastewater tested. The decolorization with the ozone process at low pH (pH 5)showed that direct oxidation by molecular ozone is much more selective in color removal than the oxidation by hydroxyl radicals. The presence of colloidal particles caused a 12-fold increase for ozone needed to obtain the same color removal efficiency as for a wastewater without colloidal particles.Each of the investigated processes could only remove one or a few types of pollutants from the wastewater, with the consequence that effluents could not meet all the discharge regulations. The combination of an activated sludge process, and a coagulation and ozone process yielded the best color (45 Pt-Co) and COD (30 mg O2/L) removal at the lowest costs (0.3 €/m3), compared with all other tested combinations.

Separate collection of wastewater streams in a factory can also strongly contribute to the efficiency and sustainability of wastewater treatment. In the wet processes of the textile industry 75% of the total water consumption is for rinsing purposes. Wastewater from most rinsing steps contains low amounts of pollutants and can be reused in other process stages or can be discharged without treatment.

An industrial ecology zone model, integrating preventive cleaner production approaches, a waste exchange network for reuse and recycling, and new end-of-pipe technologies, has been developed and assessed in two case studies: the Thanh Cong Company and the Nhon Trach 2 Industrial Zone. The greening production model developed for the Thanh Cong Company, a large-scale textile company in Hochiminh city, included the combination of cleaner production, external waste exchange and end-of-pipe technology. The dyestuffs, auxiliary chemicals, water and energy consumption can be reduced significantly when the proposed cleaner production, the external waste exchange options and the improved end-of-pipe technologies are implemented. Total benefits in savings per day can be more than 1,000 US$.

The industrial ecology zone model was designed in three steps. Firstly the greening production model developed for the Thanh Cong Company was applied to all textile enterprises in the industrial ecology zone that was considered. Secondly an outside waste exchange network was designed. The outside network includes reuse of waste plastics, waste paper and waste oil at recycling companies in the neighborhood. The last step is to treat solid waste and polluted air and to treat and reuse wastewater for irrigation (cotton cultivation), for use in sanitary systems and to water plants in the industrial zone.

The case studies of the greening production model and of the industrial ecology zone model demonstrated that a successful industrial ecology practice not only depends on the interaction between enterprises inside but also on the interaction with the actor networks outside the industrial system:the economic networks, the social networks and the policy networks. These networks can contribute in different ways to the implementation of the models. In the case study of a large textile company the economic network is very important in the implementation of the greening production model and in the case study of an industrial ecology zone the policy network play the most important role in the implementation of the industrial ecology model.

Corrigendum to "Qualified presumption of safety (QPS): a generic risk assessment approach for biological agents notified to the European Food Safety Authority (EFSA)"
Leuschner, R.G.K. ; Robinson, T.P. ; Hugas, M. ; Cocconcelli, P.S. ; Richard-Forget, F. ; Klein, G. ; Licht, T.R. ; Nguyen-The, C. ; Querol, A. ; Richardson, M. ; Suarez, J.E. ; Thrane, U. ; Vlak, J.M. ; Wright, A. - \ 2011
Trends in Food Science and Technology 22 (2011)1. - ISSN 0924-2244 - p. 51 - 52.
Qualified presumption of safety (QPS): a generic risk assessment approach for biological agents notified to the European Food Safety Authority (EFSA)
Leuschner, H.H. ; Robinson, T.P. ; Hugas, M. ; Cocconcelli, P.S. ; Richard-Forget, F. ; Klein, G. ; Licht, T.R. ; Nguyen-The, C. ; Querol, A. ; Richardson, M. ; Suarez, J.E. ; Thrane, U. ; Vlak, J.M. ; Wright, A. - \ 2010
Trends in Food Science and Technology 21 (2010)9. - ISSN 0924-2244 - p. 425 - 435.
yellow mosaic-virus - dairy microorganisms - pediococcus-acidilactici - antibiotic-resistance - escherichia-coli - cross protection - bacillus-cereus - lactobacillus - susceptibility - strains
Qualified Presumption of Safety (QPS) is a generic risk assessment approach applied by the European Food Safety Authority (EFSA) to notified biological agents aiming at simplifying risk assessments across different scientific Panels and Units. The aim of this review is to outline the implementation and value of the QPS assessment for EFSA and to explain its principles such as the unambiguous identity of a taxonomic unit, the body of knowledge including potential safety concerns and how these considerations lead to a list of biological agents recommended for QPS which EFSA keeps updated through an annual scientific review and assessment
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