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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Brain Responses to Anticipation and Consumption of Beer with and without Alcohol
Smeets, Paul A.M. ; Graaf, Cees de - \ 2019
Chemical Senses 44 (2019)1. - ISSN 0379-864X - p. 51 - 60.

Beer is a popular alcoholic beverage worldwide. Nonalcoholic beer (NA-beer) is increasingly marketed. Brain responses to beer and NA-beer have not been compared. It could be that the flavor of beer constitutes a conditioned stimulus associated with alcohol reward. Therefore, we investigated whether oral exposure to NA-beer with or without alcohol elicits similar brain responses in reward-related areas in a context where regular alcoholic beer is expected. Healthy men (n = 21) who were regular beer drinkers were scanned using functional MRI. Participants were exposed to word cues signaling delivery of a 10-mL sip of chilled beer or carbonated water (control) and subsequent sips of NA-beer with or without alcohol or water (control). Beer alcohol content was not signaled. The beer cue elicited less activation than the control cue in the primary visual cortex, supplementary motor area (reward-related region) and bilateral inferior frontal gyrus/frontal operculum. During tasting, there were no significant differences between the 2 beers. Taste activation after swallowing was significantly greater for alcoholic than for NA-beer in the inferior frontal gyrus/anterior insula and dorsal prefrontal cortex (superior frontal gyrus). This appears to be due to sensory stimulation by ethanol rather than reward processing. In conclusion, we found no differences in acute brain reward upon consumption of NA-beer with and without alcohol, when presented in a context where regular alcoholic beer is expected. This suggests that in regular consumers, beer flavor rather than the presence of alcohol is the main driver of the consumption experience.

Combinations of vegetables can be more accepted than individual vegetables
Stokkom, V.L. van; Graaf, C. de; Wang, S. ; Kooten, O. van; Stieger, M. - \ 2019
Food Quality and Preference 72 (2019). - ISSN 0950-3293 - p. 147 - 158.
Acceptance - Bitterness - Sweetness - Taste - Variety - Vegetables

Enhancing sweetness of vegetables by addition of sucrose or sweeteners can increase acceptance but is not necessarily desirable. An alternative strategy could be to combine vegetables with other vegetables. By offering combinations of vegetables it might be possible to suppress bitterness, enhance sweetness and provide texture variety leading to increased acceptance. The aim of this study was to determine the influence of combining vegetables with other vegetables on sensory properties and acceptance. Carrot (sweet), cucumber (neutral), green bell pepper (bitter) and red bell pepper (sour) were assessed individually and in combination with the other three vegetables in two mixing ratios (1:2 and 2:1). Additionally, four combinations of three vegetables (mixing ratio 1:1:1) were assessed. A trained panel (n = 24) evaluated taste, flavour and texture and a consumer panel (n = 83) evaluated acceptance of all vegetables and combinations. Combining green bell pepper with carrot (1:2 and 2:1) increased sweetness and decreased bitterness. Combining cucumber, carrot or red bell pepper with green bell pepper (1:2) increased bitterness. Mainly sweetness and bitterness were associated with acceptance whereas texture (crunchiness, firmness and juiciness) did not strongly influence acceptance. Cucumber was the most accepted vegetable followed by carrot, red bell pepper and green bell pepper. Acceptance of vegetable combinations can differ from acceptance of individual vegetables depending on vegetable type and mixing ratio. Only 3 of 16 vegetable combinations had higher acceptance compared to the least accepted vegetable in the combination and similar acceptance as the more accepted vegetable in the combination. For 13 of 16 vegetable combinations acceptance did not increase compared to acceptance of individual vegetables. These findings suggest that strategies aimed at increasing vegetable consumption can be devised using specific combinations of vegetables.

Zintuigen nagebootst
Jongsma, Maarten - \ 2018

Wageningse onderzoekers ontwikkelen een techniek om met smaak- en geurreceptoren onze reactie op voedingsstoffen te meten.

‘Met proteomics en metabolomics kun je in een tomaat wel honderden verbindingen identificeren, maar dat zegt niets over de smaakfunctie. Door de grote hoeveelheid variabelen is het bijna een onoplosbare puzzel.’

Vegetable acceptance: a bittersweet story : Role of taste in acceptance of vegetables
Stokkom, Vera L. van - \ 2018
Wageningen University. Promotor(en): Kees de Graaf; Markus Stieger, co-promotor(en): Olaf van Kooten. - Wageningen : Wageningen University - ISBN 9789463433761 - 183
Genomic characterization of extended-spectrum cephalosporin-resistant Salmonella enterica in the Colombian poultry chain
Castellanos, Luis Ricardo ; Graaf-van Bloois, Linda van der; Donado-Godoy, Pilar ; León, Maribel ; Clavijo, Viviana ; Arévalo, Alejandra ; Bernal, Johan F. ; Mevius, Dik J. ; Wagenaar, Jaap A. ; Zomer, Aldert ; Hordijk, Joost - \ 2018
Frontiers in Microbiology 9 (2018)OCT. - ISSN 1664-302X
Chicken - Latin America - MLST - pMLST - S. Heidelberg - S. Java - S. paratyphi B d-tartrate positive

Salmonella enterica serovars have been isolated from Colombian broilers and broiler meat. The aim of this study was to investigate the diversity of ESBL/pAmpC genes in extended-spectrum cephalosporin resistant Salmonella enterica and the phylogeny of ESBL/pAmpC-carrying Salmonella using Whole Genome Sequencing (WGS). A total of 260 cefotaxime resistant Salmonella isolates, obtained between 2008 and 2013 from broiler farms, slaughterhouses and retail, were included. Isolates were screened by PCR for ESBL/pAmpC genes. Gene and plasmid subtyping and strain Multi Locus Sequence Typing was performed in silico for a selection of fully sequenced isolates. Coregenome-based analyses were performed per ST encountered. blaCMY-2-like was carried in 168 isolates, 52 carried blaCTX-M-2 group, 7 blaSHV, 5 a combination of blaCMY-2-like-blaSHV and 3 a combination of blaCMY-2-likeblaCTX-M-2 group. In 25 isolates no ESBL/pAmpC genes that were screened for were found. WGS characterization of 36 selected strains showed plasmid-encoded blaCMY-2 in 21, blaCTX-M-165 in 11 and blaSHV-12 in 7 strains. These genes were mostly carried on IncI1/ST12, IncQ1, and IncI1/ST231 plasmids, respectively. Finally, 17 strains belonged to S. Heidelberg ST15, 16 to S. Paratyphi B variant Java ST28, 1 to S. Enteritidis ST11, 1 to S. Kentucky ST152 and 1 to S. Albany ST292. Phylogenetic comparisons with publicly available genomes showed separate clustering of Colombian S. Heidelberg and S. Paratyphi B var. Java. In conclusion, resistance to extended-spectrum cephalosporins in Salmonella from Colombian poultry is mainly encoded by blaCMY-2 and blaCTX-M-165 genes. These genes are mostly associated with IncI1/ST12 and IncQ1 plasmids, respectively. Evolutionary divergence is observed between Colombian S. Heidelberg and S. Paratyphi B var. Java and those from other countries..

Saba bank fisheries: reasons for cautions optimism
Debrot, A.O. ; Graaf, M. de - \ 2018
Wageningen Marine Research (WMR Policy brief ) - 5 p.
Temporal dominance of sensations, emotions, and temporal liking measured in a bar for two similar wines using a multi-sip approach
Silva, Ana P. ; Voss, Hans Peter ; Zyl, Hannelize van; Hogg, Tim ; Graaf, Cees de; Pintado, Manuela ; Jager, Gerry - \ 2018
Journal of Sensory Studies 33 (2018)5. - ISSN 0887-8250

Eating and drinking are dynamic processes where both sensations and emotions might evolve or change over time during multiple bites/sips. However, most previous studies have measured food-evoked emotions statically, that is, at a fixed time point after consumption and using a single bite/sip approach. This study aimed to explore the sensitivity of temporal dominance of sensations (TDS), of emotions (TDE), and temporal liking (TL), using a multi-sip approach, to differentiate between two comparable tasting wines. A glass of wine, in an appropriate consumption context, a bar, was served to 69 consumers, in two different sessions. It was shown that TDS and TDE captured small differences between equally liked wines. Wines were distinguishable during consumption, based on the dominance of basic sensations such as acid, bitter, and dry, rather than aromatic sensations and based on three emotions pleased, comforted, and relaxed. These emotions were dominant in both wines and in all stages of consumption but differed in the dominance rates. So, the impact of wine consumption on emotions was more uniform during consumption while new sensations became dominant during drinking. Practical implications: The method tested in this study showed a sensitivity level sufficient to capture subtle but significant differences between similar, equally liked wines. Wines tested have a major difference in wine-making process, that is, one of the wines had a particular wood aging processing in new oak barrels conferring specific flavors and associated costs. For the wine industry, the method can be particularly useful to understand to which extent consumers perceive differences in sensations and emotions, in a blind tasting, to investigate if increased costs of production are acceptable and justified. For other food products, the method can be useful to use during product development stage, when the aim is to differentiate prototypes with subtle differences in ingredients composition and associated costs. Knowing when certain sensations and emotions occur during consumption might help to create successful products in the market. Further research using different food or beverages is however necessary to assure its validity.

Evaluation of dietary taste patterns as assessed by FFQ against 24-h recalls and biomarkers of exposure
Langeveld, A.W.B. van; Teo, P.S. ; Mars, M. ; Feskens, E.J.M. ; Graaf, C. de; Vries, J.H.M. de - \ 2018
European Journal of Clinical Nutrition (2018). - ISSN 0954-3007 - 9 p.
Background/objective: Taste is of key importance in food choice and dietary patterns, but studies on taste profiles are limited. We previously assessed dietary taste patterns by 24 h recalls (24hR), but for epidemiological studies food frequency questionnaires (FFQ) may also be suitable. This study compared dietary taste patterns based on FFQ against 24hR and biomarkers of exposure. Subjects/methods: A taste database including 467 foods’ sweet, sour, bitter, salt, umami and fat sensation values was combined with food intake data to assess dietary taste patterns: the contribution to energy intake of 6 taste clusters. The FFQ’s reliability was assessed against 3-d 24hR and urinary biomarkers for sodium (Na) and protein intake (N) in Dutch men (n = 449) and women (n = 397) from the NQplus validation study (mean age 53 ± 11 y, BMI 26 ± 4 kg/m2). Results: Correlations of dietary taste patterns ranged from 0.39–0.68 between FFQ and 24hR (p < 0.05). Urinary Na levels, but not N levels, were positively associated with % energy intake from ‘salt, umami & fat’ tasting foods (Na; FFQ, r = 0.24, 24hR, r = 0.23, p < 0.001, N; FFQ, r = 0.08, p = 0.1394, 24hR, r = 0.05, p = 0.3427). Conclusions: The FFQ’s reliability against 24hR was acceptable to good for ranking of adults’ dietary taste patterns. Associations between dietary taste patterns and urinary Na and N were similar for FFQ and 24hR. These findings suggests that both FFQ and 24hR can be used in combination with our taste database, to investigate potential relationships between dietary taste patterns and subgroups at risk of obesity and chronic diseases such as cardiovascular disease.
Sweetness but not sourness enhancement increases acceptance of cucumber and green capsicum purees in children
Stokkom, V.L. van; Poelman, A.A.M. ; Graaf, C. de; Kooten, O. van; Stieger, M. - \ 2018
Appetite 131 (2018). - ISSN 0195-6663 - p. 100 - 107.
Acceptance - Children - Sourness - Sweetness - Taste - Vegetables

For children it is important to consume enough vegetables to establish healthy dietary patterns. Taste acceptance is an important factor contributing to food choice and consumption. Sweetness and sourness enhancement can increase acceptance of specific foods in children. The aim of this study was to determine the effect of sweetness and sourness enhancement on acceptance of cucumber and green capsicum purees in 5-6-year-old children. Three concentrations of sucrose (2, 5 and 10%) and citric acid (0.05, 0.08 and 0.15%) were added to cucumber and green capsicum purees. Children (n = 70, 5.7 ± 0.5 yrs) assessed acceptance of the vegetable purees using a 5-point hedonic facial scale. Sweetness enhancement significantly increased acceptance of cucumber purees (5 and 10% sucrose) and green capsicum purees (2 and 10% sucrose) compared to unmodified purees. Sourness enhancement (0.05, 0.08 and 0.15% citric acid) did not significantly influence acceptance of cucumber and green capsicum purees compared to unmodified purees. Children differed in acceptance of vegetable purees with added sucrose and citric acid. Sweetness likers (cucumber 77.1%, green capsicum 58.6%) accepted sucrose concentrations better than sweetness non-likers in both vegetables. Sourness likers (cucumber 50.0%, green capsicum 44.3%) accepted medium and high concentrations of citric acid better than sourness non-likers in cucumber and all citric acid concentrations in green capsicum. We conclude that enhancement of sweetness increases acceptance of cucumber and green capsicum purees in most children whereas enhancement of sourness is better accepted by only a few children. This study highlights the challenge to get children to better accept vegetables, since only sweetness enhancement improved acceptance while addition of sucrose is undesirable. For a small subset of children enhancing sourness might be an alternative strategy to increase acceptance of vegetables.

Effect of Taste Enhancement on Consumer Acceptance of Pureed Cucumber and Green Capsicum
Stokkom, Vera L. van; Graaf, Cees de; Kooten, Olaf van; Stieger, Markus - \ 2018
Journal of Food Science 83 (2018)10. - ISSN 0022-1147 - p. 2578 - 2585.
acceptance - capsicum - cucumber - taste - vegetable

Abstract: Vegetables have low taste intensities, which might contribute to low acceptance. The aim of this study was to investigate the effect of taste (sweetness, sourness, bitterness, umami, and saltiness) and fattiness enhancement on consumer acceptance of cucumber and green capsicum purees. Three concentrations of sugar, citric acid, caffeine, mono-sodium glutamate, NaCl, and sunflower oil were added to pureed cucumber and green capsicum. Subjects (n = 66, 35.6 ± 17.7 y) rated taste and fattiness intensity. Different subjects (n = 100, 33.2 ± 16.5 years) evaluated acceptance of all pureed vegetables. Taste intensities of vegetable purees were significantly different (P < 0.05) between the three tastant concentrations except for umami in both vegetable purees, sourness in green capsicum puree, and fattiness in cucumber puree. Only enhancement of sweetness significantly (P < 0.05) increased acceptance of both vegetable purees compared to unmodified purees. In cucumber purees, relatively small amounts of added sucrose (2%) increased acceptance already significantly, whereas in green capsicum acceptance increased significantly only with addition of 5% sucrose. Enhancement of other taste modalities did not significantly increase acceptance of both vegetable purees. Enhancing saltiness and bitterness significantly decreased acceptance of both vegetable purees. We conclude that the effect of taste enhancement on acceptance of vegetable purees differs between tastants and depends on tastant concentration and vegetable type. With the exception of sweetness, taste enhancement of taste modalities such as sourness, bitterness, umami, and saltiness was insufficient to increase acceptance of vegetable purees. We suggest that more complex taste, flavor, or texture modifications are required to enhance acceptance of vegetables. Practical Application: Results can be used by cultivators to select and grow vegetable varieties with enhanced taste and flavor. Especially for cucumber, relatively small sweetness enhancement is sufficient to increase acceptance.

Modulation of event-related potentials to food cues upon sensory-specific satiety
Zoon, Harriët F.A. ; Ohla, Kathrin ; Graaf, Cees de; Boesveldt, Sanne - \ 2018
Physiology and Behavior 196 (2018). - ISSN 0031-9384 - p. 126 - 134.
Electro-encephalography - Food anticipation - Food consumption - Neural response - Olfactory - Visual

Tempting environmental food cues and metabolic signals are important factors in appetite regulation. Food intake reduces liking of food cues that are congruent to the food eaten (sensory-specific satiety). With this study we aimed to assess effects of sensory-specific satiety on neural processing (perceptual and evaluative) of visual and olfactory food cues. Twenty healthy female subjects (age: 20 ± 2 years; BMI: 22 ± 2 kg/m2) participated in two separate test sessions during which they consumed an ad libitum amount of a sweet or savoury meal. Before and after consumption, event-related potentials were recorded in response to visual and olfactory cues signalling high-energy sweet, high-energy savoury, low-energy sweet and low-energy savoury food and non-food items. In general, we observed that food intake led to event-related potentials with an increased negative and decreased positive amplitudes for food, but also non-food cues. Changes were most pronounced in response to high-energy sweet food pictures after a sweet meal, and occurred in early processes of perception (~80–150 ms) and later processes of cognitive evaluation (~300–700 ms). Food intake appears to lead to general changes in neural processing that are related to motivated attention, and sensory-specific changes that reflect decreased positive valence of the stimuli and/or modulation of top-down cognitive control over processing of cues congruent to the food eaten to satiety.

Colouring perception : emphasising attractiveness through packaging
Tijssen, Irene Odilia Jelly Marcelle - \ 2018
Wageningen University. Promotor(en): Kees de Graaf, co-promotor(en): Gerry Jager; Liesbeth Zandstra. - Wageningen : Wageningen University - ISBN 9789463434836 - 148
An approach to assessing the quality of birth centres results of the Dutch birth centre study
Boesveld, Inge C. ; Hermus, Marieke A.A. ; Velden-Bollemaat, Eline C. van der; Hitzert, Marit ; Graaf, Hanneke J. de; Franx, Arie ; Wiegers, Therese A. - \ 2018
Midwifery 66 (2018). - ISSN 0266-6138 - p. 36 - 48.
Birth centres - Quality - Quality indicators - Structure and process assessment

Objective: to determine the usability of a recently developed set of 30 structure and process birth centre quality indicators. Design: an explorative study using mixed-methods including literature, a survey, interviews and observations. The study is part of the Dutch Birth Centre Study. We first determined the measurability of birth centre quality indicators by describing them in detail. Next, we assessed the birth centres in the Netherlands according to these indicators using data derived from the Dutch Birth Centre General Questionnaire, the Dutch Birth Centre Integration Questionnaire, interviews, and policy documents. Setting and participants: representatives of 23 birth centres in the Netherlands. Measurements and findings: 28 of the 30 quality indicators could be used to assess birth centres in the Netherlands, one had no optimal value defined, another could not be scored because the information was not available. Each quality indicator could be scored 0 or 1. Differences between birth centres were shown: the scores ranged from 7 to 22. Some of the quality indicators can be combined or made more specific so that they are easier to assess. Some quality indicators need adaptation because they are only applicable for some birth centres (e.g. only for freestanding or alongside birth centres). Key conclusions and implications for practice: 28 of the 30 quality indicators are usable to assess structure and process quality of birth centres. With the findings of this study the set of structure and process quality indicators for birth centres in the Netherlands can be reduced to 22 indicators. This set of quality indicators can contribute to the development of a quality system for birth centres. Further research is necessary to formulate standards or minimum quality requirements for birth centres and to improve the set of birth centre quality indicators.

Matters of taste : Dietary taste patterns in the Netherlands
Langeveld, Astrid W.B. van - \ 2018
Wageningen University. Promotor(en): Kees de Graaf, co-promotor(en): Monica Mars; Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789463432979 - 230
Altered neural responsivity to food cues in relation to food preferences, but not appetite-related hormone concentrations after RYGB-surgery
Zoon, Harriët F.A. ; Bruijn, Suzanne E.M. de; Smeets, Paul A.M. ; Graaf, Cees de; Janssen, Ignace M.C. ; Schijns, Wendy ; Aarts, Edo O. ; Jager, Gerry ; Boesveldt, Sanne - \ 2018
Behavioural Brain Research 353 (2018). - ISSN 0166-4328 - p. 194 - 202.
Endocannabinoid - Energy-density - fMRI - Food cues - Ghrelin - Obesity - Olfactory - Reward - Roux-en-Y gastric bypass surgery - Visual

Background: After Roux-en-Y gastric bypass (RYGB) surgery, patients report a shift in food preferences away from high-energy foods. Objective: We aimed to elucidate the potential mechanisms underlying this shift in food preferences by assessing changes in neural responses to food pictures and odors before and after RYGB. Additionally, we investigated whether altered neural responsivity was associated with changes in plasma endocannabinoid and ghrelin concentrations. Design: 19 RYGB patients (4 men; age 41 ± 10 years; BMI 41 ± 1 kg/m2 before; BMI 36 ± 1 kg/m2 after) participated in this study. Before and two months after RYGB surgery, they rated their food preferences using the Macronutrient and Taste Preference Ranking Task and BOLD fMRI responses towards pictures and odors of high-, and low-energy foods and non-food items were measured. Blood samples were taken to determine plasma endocannabinoid and ghrelin concentrations pre- and post-surgery. Results: Patients demonstrated a shift in food preferences away from high-fat/sweet and towards low-energy/savory food products, which correlated with decreased superior parietal lobule responsivity to high-energy food odor and a reduced difference in precuneus responsivity to high-energy versus low-energy food pictures. In the anteroventral prefrontal cortex (superior frontal gyrus) the difference in deactivation towards high-energy versus non-food odors reduced. The precuneus was less deactivated in response to all cues. Plasma concentrations of anandamide were higher after surgery, while plasma concentrations of other endocannabinoids and ghrelin did not change. Alterations in appetite-related hormone concentrations did not correlate with changes in neural responsivity. Conclusions: RYGB leads to changed responsivity of the frontoparietal control network that orchestrates top-down control to high-energy food compared to low-energy food and non-food cues, rather than in reward related brain regions, in a satiated state. Together with correlations with the shift in food preference from high- to low-energy foods this indicates a possible role in new food preference formation.

Ons dagelijks (afval)water
Temmink, B.G. - \ 2018
In: Afvalwater / van Loosdrecht, Mark, Stams, Alfons, Hoekstra, Wiel, van de Graaf, Astrid, Den Haag : Stichting BWM - ISBN 9789073196902 - p. 23 - 28.
Altered neural inhibition responses to food cues after Roux-en-Y Gastric Bypass
Zoon, H.F.A. ; Bruijn, S.E.M. de; Jager, G. ; Smeets, P.A.M. ; Graaf, C. de; Janssen, I.M.C. ; Schijns, W. ; Deden, L. ; Boesveldt, S. - \ 2018
Biological Psychology 137 (2018). - ISSN 0301-0511 - p. 34 - 41.
Bariatric surgery - fMRI - Food preferences - go/no-go - Impulsivity - Inhibitory control - Weight-Loss

Background: Roux-en-Y gastric bypass (RYGB) surgery is a highly effective weight-loss intervention that often reduces preference and intake of high-energy foods. Research into the neural mechanisms behind this shift has mainly focused on reward processing of food cues. However, the ability to successfully control food intake and thereby weight-loss also depends on inhibitory control capacity. We investigated whether RYGB leads to alterations in neural inhibitory control in response to food cues. Methods: A food-specific go/no-go task with pictures of high-energy (desserts) and low-energy foods (vegetables), was used to assess neural inhibition responses before and after RYGB with functional magnetic resonance imaging. Data from 18 morbidly obese patients (15 females; age 41 ± 11 years; BMI 42 ± 4 kg/m2 before; BMI 36 ± 4 kg/m2 after) were analysed. Pre- and post-RYGB BOLD fMRI responses were compared for response inhibition towards high- and low-energy foods. Participants were tested in a satiated state. Results: Response inhibition to high-energy foods was associated with increased activation of the right lateral prefrontal cortex (PFC), right medial PFC, dorsolateral PFC, right middle cingulate cortex and the right inferior frontal operculum (involved in inhibitory control), after compared to before surgery. Response inhibition to low-energy foods elicited diminished post- compared to pre-surgery responses in the left superior temporal pole, right parahippocampal gyrus and right hypothalamus (involved in metabolic control). Conclusion: Neural changes indicate improved response inhibition towards high-energy food cues, altered influence of metabolic control during response inhibition towards low-energy food cues and a more positive attitude to both high-energy and low-energy food after RYGB. Alterations in neural circuits involved in inhibitory control, satiety signalling and reward processing may contribute to effective weight-loss after RYGB.

Exacting responses: lack of endocrine cephalic phase responses upon oro-sensory exposure
Lasschuijt, Marlou P. ; Mars, Monica ; Graaf, Cees de; Smeets, Paul A.M. - \ 2018
Frontiers in Endocrinology 9 (2018). - ISSN 1664-2392
Ghrelin - Insulin - Pancreatic polypeptide - Taste - Texture
Oro-sensory exposure (OSE) to food plays an important role in the regulation of food intake. One proposed underlying mechanism is the occurrence of cephalic phase responses (CPRs). CPRs include the pre-digestive endocrine responses induced by food-related sensory input. Yet, whether OSE duration or sweetness intensity affects CPRs is unknown. The objective of this study was to determine the independent and interactive effects of oro-sensory duration (chewing) and stimulation intensity (sweetness) on endocrine CPRs and satiation. Eighteen males (22 ± 2 years, BMI 22 ± 2 kg/m2) participated in a 2 × 2 randomized study with a control condition. Each session participants performed modified sham feeding (MSF) with one of the four gel-based model foods. During the control session no MSF was performed. Model foods differed in chewing duration (hard or soft texture) and sweetness (low or high intensity). During each session, eight blood samples were collected up till 25 min after MSF onset. Subsequently, food intake from an ad libitum lunch was measured. No typical CPR was found for insulin, pancreatic polypeptide (PP), and ghrelin. However, the overall PP response was 1.1 times greater for the hard sweet MSF condition compared to control (p = 0.02). Overall ghrelin responses were 1.1 times greater for the hard model food compared to the soft model food conditions (p = 0.003). These differences in endocrine response were not associated with differences in food intake at the subsequent meal. Exploratory sub-analysis of the responsive insulin curves showed that after 2.5 min of MSF the hard texture model foods insulin concentrations were 1.2 greater compared to the soft texture. These findings indicate that texture hardness and sweetness increase the overall PP response and that MSF on hard texture increases the overall ghrelin response compared to soft texture model foods. However, MSF on model foods does not lead to a typical CPR. This study, among others, shows that there are major dissimilarities in the endocrine responses to food stimulation between individuals. This emphasizes the importance of considering cephalic responders and non-responders. More research is needed to understand CPRs in relation to food texture and taste properties.
A workshop on 'Dietary Sweetness-Is It an Issue?'
Wittekind, Anna ; Higgins, Kelly ; McGale, Lauren ; Schwartz, Camille ; Stamataki, Nikoleta S. ; Beauchamp, Gary K. ; Bonnema, Angela ; Dussort, Pierre ; Gibson, Sigrid ; Graaf, Cees de; Halford, Jason C.G. ; Marsaux, Cyril F.M. ; Mattes, Richard D. ; McLaughlin, John ; Mela, David J. ; Nicklaus, Sophie ; Rogers, Peter J. ; Macdonald, Ian A. - \ 2018
International Journal of Obesity 42 (2018)4. - ISSN 0307-0565 - p. 934 - 938.
This report summarises a workshop convened by ILSI Europe on 3 and 4 April 2017 to discuss the issue of dietary sweetness. The objectives were to understand the roles of sweetness in the diet, establish whether exposure to sweetness affects diet quality and energy intake, and consider whether sweetness per se affects health. Although there may be evidence for tracking of intake of some sweet components of the diet through childhood, evidence for tracking of whole diet sweetness, or through other stages of maturity are lacking. The evidence to date does not support adverse effects of sweetness on diet quality or energy intake, except where sweet food choices increase intake of free sugars. There is some evidence for improvements in diet quality and reduced energy intake where sweetness without calories replaces sweetness with calories. There is a need to understand the physiological and metabolic relevance of sweet taste receptors on the tongue, in the gut and elsewhere in the body, as well as possible differentiation in the effects of sustained consumption of individual sweeteners. Despite a plethora of studies, there is no consistent evidence for an association of sweetness sensitivity/preference with obesity or type 2 diabetes. A multifaceted integrated approach, characterising nutritive and sensory aspects of the whole diet or dietary patterns, may be more valuable in providing contextual insight. The outcomes of the workshop could be used as a scientific basis to inform the expert community and create more useful dialogue among health care professionals.
Homologous recombination between genetically divergent campylobacter fetus lineages supports host-associated speciation
Gilbert, Maarten J. ; Duim, Birgitta ; Graaf-van Bloois, Linda van der; Wagenaar, Jaap A. ; Zomer, Aldert L. - \ 2018
Genome Biology and Evolution 10 (2018)3. - ISSN 1759-6653 - p. 716 - 722.
Campylobacter fetus - Homologous recombination - Host association - Reptile - Speciation - Whole genome sequencing

Homologous recombination is a major driver of bacterial speciation. Genetic divergence and host association are important factors influencing homologous recombination. Here, we study these factors for Campylobacter fetus, which shows a distinct intraspecific host dichotomy. Campylobacter fetus subspecies fetus (Cff) and venerealis are associated with mammals, whereas C. fetus subsp. testudinum (Cft) is associated with reptiles. Recombination between these genetically divergent C. fetus lineages is extremely rare. Previously it was impossible to show whether this barrier to recombination was determined by the differential host preferences, by the genetic divergence between both lineages or by other factors influencing recombination, such as restriction-modification, CRISPR/Cas, and transformation systems. Fortuitously, a distinct C. fetus lineage (ST69) was found, which was highly related to mammal-associated C. fetus, yet isolated from a chelonian. The whole genome sequences of two C. fetus ST69 isolates were compared with those of mammal- and reptile-associated C. fetus strains for phylogenetic and recombination analysis. In total, 5.1-5.5% of the core genome of both ST69 isolates showed signs of recombination. Of the predicted recombination regions, 80.4% were most closely related to Cft, 14.3% to Cff, and 5.6% to C. iguaniorum. Recombination from C. fetus ST69 to Cft was also detected, but to a lesser extent and only in chelonian-associated Cft strains. This study shows that despite substantial genetic divergence no absolute barrier to homologous recombination exists between two distinct C. fetus lineages when occurring in the same host type, which provides valuable insights in bacterial speciation and evolution.

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