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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    The effect of replacing sucrose with L-arabinose in drinks and cereal foods on blood glucose and plasma insulin responses in healthy adults
    Pol, Korrie ; Graaf, Kees de; Diepeveen-de Bruin, Marlies ; Balvers, Michiel ; Mars, Monica - \ 2020
    Journal of Functional Foods 73 (2020). - ISSN 1756-4646
    Food matrix - Functionality - Glycaemic response - Insulin response - L-arabinose - Sucrose

    Glycaemic control is important in metabolic diseases such as diabetes and impaired glucose tolerance. L-arabinose inhibits the hydrolysis of sucrose into glucose and fructose. So far little is known about its functionality in different food matrices. We assessed the effect of replacing sucrose with L-arabinose in drinks and in cereal foods on blood glucose and insulin in healthy adults. Glucose and insulin responses were reduced when sucrose was replaced by L-arabinose in drinks. Replacement of sucrose in cereal foods did not affect glucose responses, however it reduced the insulin peak. L-arabinose without sucrose in a drink did not affect glucose responses. Therefore, replacing sucrose with L-arabinose is potentially a good strategy to lower glycaemic and insulin responses. However, the effects depend on the food matrix and the nutritional composition of the food. More research is warranted on the functionality of L-arabinose in different food matrices and in other populations.

    Effects of distraction on taste-related neural processing : a cross-sectional fMRI study
    Duif, Iris ; Wegman, Joost ; Mars, Monica M. ; Graaf, Cees De; Smeets, Paul A.M. ; Aarts, Esther - \ 2020
    American Journal of Clinical Nutrition 111 (2020)5. - ISSN 0002-9165 - p. 950 - 961.
    attention - consumption - distraction - fMRI - insula - orbitofrontal cortex - taste

    Background: In the current obesogenic environment we often eat while electronic devices, such as smart phones, computers, or the television, distract us. Such "distracted eating"is associated with increased food intake and overweight. However, the underlying neurocognitive mechanisms of this phenomenon are unknown. Objective: Our aim was to elucidate these mechanisms by investigating whether distraction attenuates processing in the primary and secondary taste cortices, located in the insula and orbitofrontal cortex (OFC), respectively. Methods: Forty-one healthy, normal-weight participants received fixed amounts of higher-And lower-sweetness isocaloric chocolate milk while performing a high-or low-distracting detection task during fMRI in 2 test sessions. Subsequently, we measured ad libitum food intake. Results: As expected, a primary taste cortex region in the right insula responded more to the sweeter drink (P < 0.001, uncorrected). Distraction did not affect this insular sweetness response across the group, but did weaken sweetness-related connectivity of this region to a secondary taste region in the right OFC (P-family-wise error, cluster, small-volume corrected = 0.020). Moreover, individual differences in distraction-related attenuation of taste activation in the insula predicted increased subsequent ad libitum food intake after distraction (r = 0.36). Conclusions: These results reveal a mechanism explaining how distraction during consumption attenuates neural taste processing. Moreover, our study shows that such distraction-induced decreases in neural taste processing contribute to individual differences in the susceptibility for overeating. Thus, being mindful about the taste of food during consumption could perhaps be part of successful prevention and treatment of overweight and obesity, which should be further tested in these target groups. This study was preregistered at the Open Science Framework as

    How oro-sensory exposure and eating rate affect satiation and associated endocrine responses-a randomized trial
    Lasschuijt, Marlou ; Mars, Monica ; Graaf, Cees de; Smeets, Paul A.M. - \ 2020
    American Journal of Clinical Nutrition 111 (2020)6. - ISSN 0002-9165 - p. 1137 - 1149.
    cephalic phase - eating behavior - eating rate - ghrelin - human - insulin - oro-sensory exposure - pancreatic polypeptide - satiation

    BACKGROUND: Longer oral processing decreases food intake. This can be attributed to greater oro-sensory exposure (OSE) and a lower eating rate (ER). How these factors contribute to food intake, and the underlying physiological mechanisms, remain unclear. OBJECTIVES: We aimed to determine the independent and simultaneous effects of OSE and ER on satiation and associated endocrine responses. METHODS: Forty participants in study 1 [mean ± SD age: 24 ± 4 y; BMI (in kg/m2): 22 ± 2] and 20 in study 2 (mean ± SD age: 23 ± 3 y; BMI: 23 ± 2) participated in a 2 × 2 randomized trial. In both studies, participants ate chocolate custard with added caramel sauce (low OSE) or caramel fudge (high OSE) and with short (fast ER) or long breaks (slow ER) in between bites, until fullness. In study 2, endocrine responses were measured during the meal. RESULTS: In study 1, participants ate (mean ± SEM) 42 ± 15 g less in the slow- than in the fast-ER condition, only within the high-OSE condition (P = 0.04). In study 2, participants ate 66 ± 21 g less in the high- than in the low-OSE condition and there were no intake differences between slow and fast ER (P = 0.35). Eight minutes after starting to eat, insulin concentrations increased by 42%-65% in all treatments compared with the control. At the end of the meal, insulin concentrations were 81% higher in the high-OSE, slow-ER than in the low-OSE, fast-ER condition (P = 0.049). Pancreatic polypeptide (PP) increased by 62%, 5 min after meal onset in the low-OSE, fast-ER condition (P = 0.005). Ghrelin concentrations did not change. CONCLUSIONS: Greater OSE increases insulin responsiveness. In contrast, PP responses are stronger when OSE is reduced and ER is fast. Insulin and PP responses may mediate the independent effects of OSE and ER on food intake. These may be beneficial eating strategies, particularly for type 2 diabetic patients, to control food intake and maintain glucose homeostasis.This trial was registered at as NL6544.

    The importance of swelling for in vitro gastric digestion of whey protein gels
    Deng, Ruoxuan ; Mars, Monica ; Sman, Ruud G.M. Van Der; Smeets, Paul A.M. ; Janssen, Anja E.M. - \ 2020
    Food Chemistry 330 (2020). - ISSN 0308-8146
    Acid - Green fluorescent protein - In vitro gastric digestion - Pepsin - Swelling - Whey protein gel

    In this paper we report the importance of swelling on gastric digestion of protein gels, which is rarely recognized in literature. Whey protein gels with NaCl concentrations 0–0.1 M were used as model foods. The Young's modulus, swelling ratio, acid uptake and digestion rate of the gels were measured. Pepsin transport was observed by confocal laser scanning microscopy using green fluorescent protein (GFP). With the increase of NaCl in gels, Young's modulus increased, swelling was reduced and digestion was slower, with a reduction of acid transport and less GFP present both at surface and in the gels. This shows that swelling affects digestion rate by enhancing acid diffusion, but also by modulating the partitioning of pepsin at the food-gastric fluid interface and thereby the total amount of pepsin in the food particle. This perspective on swelling will provide new insight for designing food with specific digestion rate for targeted dietary demands.

    Jardins de la galaxie: pouvez-vous cultiver des légumes sur Mars? Espace
    Wamelink, Wieger - \ 2020

    onderzoek van Wieger Wamelink wordt aangehaald

    Can we grow vegetables on Mars?
    Wamelink, Wieger - \ 2020

    onderzoek van Wieger Wamelink wordt aangehaald

    From Eat to trEat : Engineering the mitochondrial Eat1 enzyme for enhanced ethyl acetate production in Escherichia coli
    Kruis, Aleksander J. ; Bohnenkamp, Anna C. ; Nap, Bram ; Nielsen, Jochem ; Mars, Astrid E. ; Wijffels, Rene H. ; Oost, John Van Der; Kengen, Servé W.M. ; Weusthuis, Ruud A. - \ 2020
    Biotechnology for Biofuels 13 (2020)1. - ISSN 1754-6834
    Alcohol acetyl transferase (AAT) - Eat1 - Escherichia coli - Ethyl acetate - Mitochondria

    Background: Genetic engineering of microorganisms has become a common practice to establish microbial cell factories for a wide range of compounds. Ethyl acetate is an industrial solvent that is used in several applications, mainly as a biodegradable organic solvent with low toxicity. While ethyl acetate is produced by several natural yeast species, the main mechanism of production has remained elusive until the discovery of Eat1 in Wickerhamomyces anomalus. Unlike other yeast alcohol acetyl transferases (AATs), Eat1 is located in the yeast mitochondria, suggesting that the coding sequence contains a mitochondrial pre-sequence. For expression in prokaryotic hosts such as E. coli, expression of heterologous proteins with eukaryotic signal sequences may not be optimal. Results: Unprocessed and synthetically truncated eat1 variants of Kluyveromyces marxianus and Wickerhamomyces anomalus have been compared in vitro regarding enzyme activity and stability. While the specific activity remained unaffected, half-life improved for several truncated variants. The same variants showed better performance regarding ethyl acetate production when expressed in E. coli. Conclusion: By analysing and predicting the N-terminal pre-sequences of different Eat1 proteins and systematically trimming them, the stability of the enzymes in vitro could be improved, leading to an overall improvement of in vivo ethyl acetate production in E. coli. Truncated variants of eat1 could therefore benefit future engineering approaches towards efficient ethyl acetate production.

    Multilevel optimisation of anaerobic ethyl acetate production in engineered Escherichia coli
    Bohnenkamp, Anna C. ; Kruis, Aleksander J. ; Mars, Astrid E. ; Wijffels, Rene H. ; Oost, John Van Der; Kengen, Servé W.M. ; Weusthuis, Ruud A. - \ 2020
    Biotechnology for Biofuels 13 (2020)1. - ISSN 1754-6834
    Alcohol acetyl transferase (AAT) - Anaerobic - Bioreactor - Eat1 - Escherichia coli - Ethyl acetate - Fermentation

    Background: Ethyl acetate is a widely used industrial solvent that is currently produced by chemical conversions from fossil resources. Several yeast species are able to convert sugars to ethyl acetate under aerobic conditions. However, performing ethyl acetate synthesis anaerobically may result in enhanced production efficiency, making the process economically more viable. Results: We engineered an E. coli strain that is able to convert glucose to ethyl acetate as the main fermentation product under anaerobic conditions. The key enzyme of the pathway is an alcohol acetyltransferase (AAT) that catalyses the formation of ethyl acetate from acetyl-CoA and ethanol. To select a suitable AAT, the ethyl acetate-forming capacities of Atf1 from Saccharomyces cerevisiae, Eat1 from Kluyveromyces marxianus and Eat1 from Wickerhamomyces anomalus were compared. Heterologous expression of the AAT-encoding genes under control of the inducible LacI/T7 and XylS/Pm promoters allowed optimisation of their expression levels. Conclusion: Engineering efforts on protein and fermentation level resulted in an E. coli strain that anaerobically produced 42.8 mM (3.8 g/L) ethyl acetate from glucose with an unprecedented efficiency, i.e. 0.48 C-mol/C-mol or 72% of the maximum pathway yield.

    Ultra-Processing or Oral Processing? A Role for Energy Density and Eating Rate in Moderating Energy Intake from Processed Foods
    Forde, Ciarán G. ; Mars, Monica ; Graaf, Kees De - \ 2020
    Current Developments in Nutrition 4 (2020)3. - ISSN 2475-2991
    eating rate - energy density - energy intake rate - food texture - metabolic disease - obesity - ultra-processed foods - unprocessed foods

    Background: Recent observational data and a controlled in-patient crossover feeding trial show that consumption of "ultra-processed foods" (UPFs), as defined by the NOVA classification system, is associated with higher energy intake, adiposity, and at a population level, higher prevalence of obesity. A drawback of the NOVA classification is the lack of evidence supporting a causal mechanism for why UPFs lead to overconsumption of energy. In a recent study by Hall the energy intake rate in the UPF condition (48 kcal/min) was >50% higher than in the unprocessed condition (31 kcal/min). Extensive empirical evidence has shown the impact that higher energy density has on increasing ad libitum energy intake and body weight. A significant body of research has shown that consuming foods at higher eating rates is related to higher energy intake and a higher prevalence of obesity. Energy density can be combined with eating rate to create a measure of energy intake rate (kcal/min), providing an index of a food's potential to promote increased energy intake. Objective: The current paper compared the association between measured energy intake rate and level of processing as defined by the NOVA classification. Methods: Data were pooled from 5 published studies that measured energy intake rates across a total sample of 327 foods. Results: We show that going from unprocessed, to processed, to UPFs that the average energy intake rate increases from 35.5 ± 4.4, to 53.7 ± 4.3, to 69.4 ± 3.1 kcal/min (P < 0.05). However, within each processing category there is wide variability in the energy intake rate. Conclusions: We conclude that reported relations between UPF consumption and obesity should account for differences in energy intake rates when comparing unprocessed and ultra-processed diets. Future research requires well-controlled human feeding trials to establish the causal mechanisms for why certain UPFs can promote higher energy intake.

    Buitenaardse groenten: “We kunnen al pizza maken op Mars”
    Wamelink, Wieger - \ 2020

    onderzoek van Wieger Wamelink wordt aangehaald

    Boeren op Mars
    Wamelink, Wieger - \ 2020

    onderzoek van Wieger Wamelink wordt aangehaald

    Van wie is Mars?
    Wamelink, Wieger - \ 2020

    onderzoek van Wieger Wamelink wordt aangehaald

    Kunnen astronauten op Mars straks voedsel kweken dankzij eigen urine?
    Wamelink, Wieger - \ 2020

    onderzoek van Wieger Wamelink wordt aangehaald

    A feeling of full-filment : Sensory and physiological processes involved in satiation
    Lasschuijt, Marlou - \ 2020
    Wageningen University. Promotor(en): K. de Graaf, co-promotor(en): P.A.M. Smeets; M. Mars. - Wageningen : Wageningen University - ISBN 9789463952484 - 251

    Satiation is a process that occurs during eating and involves inhibitory signals at a sensory, hormonal, digestive and cognitive level. The taste and texture of food influence this process. Harder foods with an intense taste are more satiating, i.e. we need to eat less of these foods to feel full, compared to softer foods with lower taste intensity. Oro-sensory exposure (OSE), the in-mouth taste perception of food, thus plays an important role in satiation and influences meal size. However, how oro-sensory signals affect satiation is not fully understood. Therefore, the main aim of this thesis was to better understand the role of sensory signals in the physiological processes underlying satiation. To study this we investigated the effect of OSE (duration and intensity) and eating rate on food intake, associated (cephalic) endocrine responses and brain reactivity. 

    We started by investigating the independent contributions of oral processing duration and taste intensity and their combined effect on satiation (chapter 2). This was done by manipulating texture and sweet taste intensity of model foods (2x2 study design, soft and hard vs. sweet and high sweet). Hard textured model foods decreased food intake through increased OSE duration, whereas sweetness intensity did not affect intake.

    To better understand the physiology underlying the effects of oro-sensory exposure on satiation we studied the effect of texture and sweetness intensity on endocrine cephalic phase responses (chapter 3). Cephalic phase responses are neurally mediated anticipatory and conditioned responses to food cues and are considered the first phase of digestion. Insulin, pancreatic polypeptide and ghrelin responses were measured while participants modified sham fed (chew and spit) the same model foods as used in chapter 2. We expected a cephalic peak increase in these hormones 5-15 min after food exposure. However, we did not find a typical cephalic phase peak response for any of the hormones. Insulin levels tended to be higher 5 min after starting to chew but this increase could not be not be attributed to the texture or taste manipulations. In addition, we found that pancreatic polypeptide was more responsive to sweetness. Ghrelin concentrations were higher when chewing the hard texture compared to the soft texture model foods.

    Based on the results from chapter 2 and 3 we hypothesized that part of the mechanism behind the oro-sensory exposure duration effect on satiation might be eating rate. When the duration of oro-sensory exposure is increased, eating rate is slowed down. Previous studies have shown that a reduced eating rate also leads to a decrease in food intake. Additionally, we hypothesized that part of the reason why we did not find typical cephalic responses in chapter 2 was because the model foods scored ‘neutral’ on liking, whereas palatability may be important to trigger a cephalic response. We therefore investigated the effect of OSE duration and eating rate on food intake (palatable chocolate custard) and associated endocrine responses (chapter 4). Two studies were set up. In both studies subjects ate until fullness of chocolate custard with and without fudge pieces (low or high oro-sensory exposure) at two different eating rates (slow or fast eating rate). In study 1 participants received a small portion and in study 2 a larger portion. Additionally, blood samples were collected during the meal in study 2. We found that a reduced eating rate (ER) (only in the high oro-sensory exposure condition) (study 1) and increased oro-sensory exposure (study 2) decreased food intake but that this was dependent on the portion size. Eight minutes after starting to eat, insulin concentrations increased for all treatments compared to control. At the end of the meal insulin concentrations were higher in the high OSE, slow ER compared to the low OSE, fast ER condition. Pancreatic polypeptide increased at 5 min after meal onset in the low OSE, fast ER condition. There were no changes in ghrelin concentration. Greater OSE thus increases insulin responsiveness. In contrast, PP responses are stronger when OSE is reduced and ER is fast. Prandial Insulin and PP responses may mediate the independent effects of OSE and ER on food intake.

    To determine whether typical cephalic phase responses were specific to certain food cues or  sub-populations we quantified outcomes of existing literature on cephalic insulin and pancreatic polypeptide responses in a systematic review (chapter 5). In addition, we aimed to quantify the hypotheses made by previous qualitative cephalic phase reviews that cephalic responses allow for larger meal sizes, induce satiation earlier on in the meal and improve postprandial glucose homeostasis. A cephalic phase insulin and pancreatic polypeptide increase was observed in about half of all included treatments. About one fifth of the treatments induced a significant increase from baseline. The size of the cephalic insulin increase relative to spontaneous fluctuations was small and there was substantial variation in magnitude and onset time of cephalic insulin and pancreatic polypeptide responses between food cues and individuals. Based on this we concluded that cephalic phase insulin responses are small compared to spontaneous fluctuations. Although cephalic pancreatic polypeptide responses are of a larger magnitude, both show substantial variation in magnitude and onset time. Based on the current evidence, we refute the hypotheses that CPRs improve satiation and glucose homeostasis in daily life

    Finally, to determine how OSE or taste signals are processed in the brain to affect satiation we performed an fMRI study in which we measured neural reactivity to chocolate milk in the brain(stem) over the course of satiation (chapter 6). Additionally we measured gastric volume such that we could identify regions that respond solely to taste, independent of gastric distention. We found that taste activation in the parabrachial nuclei (PBN) in the brain stem, and bilateral (anterior) insula, amygdala and putamen gradually decreased as satiation increased, in line with the decrease in affective value of the chocolate milk stimuli. When subjects were hungry and completely satiated this effect could completely be explained by gastric filling, whereas this was not the case when subjects felt half full.  Responses of these brain regions are thus modulated by gastric volume and sensory satiation seems especially important early in the meal when not completely satiated.

    To conclude, we confirmed that increased OSE can decrease food intake. Insulin, PP and ghrelin cephalic phase responses do not mediate the oro-sensory exposure effect on satiation. Instead, we hypothesize that the underlying mechanisms are 1) a direct effect of oro-sensory exposure on satiation through sensory satiation and 2) an indirect effect of increased oro-sensory exposure duration which also slows down ingestion rate. This allows more time for stomach distention signals, hormone secretion, and early uptake of nutrients which are processed by the brain and induce satiation.

    Bean experiment result indicated crops could be grown on the moon or Mars
    Wamelink, Wieger - \ 2020
    Q&A | Mars and moon soil researcher
    Wamelink, Wieger - \ 2020
    'Wij delen onze passie voor de planeet Mars'
    Wamelink, Wieger - \ 2020

    interview met Wieger Wamelink n.a.v. zijn lezing bij Maatschappij tot Nut van 't Algemeen in Winterswijk samen met Bertina Mulder

    Gemüse für Mars und Mond
    Wamelink, Wieger - \ 2020

    interview met Wieger Wamelink in Terra-Mater

    Exploring in vitro gastric digestion of whey protein by time-domain nuclear magnetic resonance and magnetic resonance imaging
    Deng, Ruoxuan ; Janssen, Anja E.M. ; Vergeldt, Frank J. ; As, Henk Van; Graaf, Cees de; Mars, Monica ; Smeets, Paul A.M. - \ 2020
    Food Hydrocolloids 99 (2020). - ISSN 0268-005X
    Gastric digestion - Gel - In vitro - MRI - Time-domain NMR - Whey protein

    Gastric digestion is crucial for protein breakdown. Although it has been widely studied with in vitro models, verification in vivo remains a big challenge. Magnetic resonance imaging (MRI) has the potential to bridge this gap. Our objective was to use the transverse relaxation time (T2) and rate (R2 = T2 −1) to monitor hydrolysis of protein-rich food during in vitro gastric digestion. Whey protein solution and heat-induced hydrogels were digested by means of simulated gastric fluid (SGF). Free amino groups (–NH2 groups) and protein concentration in the supernatant were measured. T2 and R2 of the digestion mixture were determined by time-domain nuclear magnetic resonance (TD-NMR) and MRI. Subsequently, relative amplitudes (TD-NMR) for different T2 values and T2 distribution (MRI) were determined. For the solution, protein concentration and T2 did not change during digestion. For the gels, water in supernatant and gel phase could be discriminated on the basis of their T2 values. During digestion, R2 of supernatant correlated positively with protein (–NH2 groups) concentration in SGF. Also, the decrease in relative amplitude of gel fraction correlated linearly with the increase of supernatant protein concentration. MRI T2-mapping showed similar associations between R2 of supernatant and protein (–NH2 groups) concentration. In conclusion, T2-measurements by TD-NMR and MRI can be used to monitor in vitro gastric digestion of whey protein gels; TD-NMR measurements contributed to interpreting the MRI data. Thus, MRI has high potential for monitoring in vivo gastric digestion and this should be further pursued.

    Een heerlijk vers tomaatje gekweekt op Mars
    Wamelink, Wieger - \ 2019

    interview met Wieger Wamelink

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