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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    Food perception and emotion measured over time in-lab and in-home
    Wijk, R.A. De; Kaneko, D. ; Dijksterhuis, G.B. ; Zoggel, M. van; Schiona, I. ; Visalli, M. ; Zandstra, Liesbeth - \ 2019
    Eating context - Facial expressions - Heart rate - Repeated sensory tests
    Background: Real-life human eating behaviour does not take place in a vacuum, rather it happens in context. The context in which consumers eat their foods influences the acceptance of the consumed foods. Consequently, consumers’ hedonic and sensory ratings elicited in a natural consumption context will differ from those elicited under controlled sensory laboratory conditions. Moreover, foods are rarely consumed on one single occasion but are typically consumed repeatedly and ratings may change over repeated consumptions as well. Often, consumer acceptance is tested explicitly, for example with liking ratings, especially when the testing is done outside the laboratory. Implicit tests such as facial expressions and physiological measurements of the autonomic nervous system can provide additional information on consumer acceptance. As a result of technological advantages, such tests are no longer limited to the laboratory but can also be used in natural consumption contexts. Method: Eighteen healthy Dutch consumers (18–65 years of age) tested four test foods plus a warm-up sample ten times on consecutive weekdays and on similar hours using their own laptop and webcam. Test locations alternated between the sensory laboratory and the participant's own home. Explicit measures included liking scores and scores on ten sensory taste/flavour/texture attributes, and implicit measures included facial expressions, heart rate and consumption duration using Face Reader TM . This study was the first to validate the Face Reader TM for usage at home. Results: The liking scores and sensory profiles varied between test foods (p < 0.05), but not between test locations and only some specific sensory attributes showed systematic variation over repeated consumption. In contrast, implicit measures showed systematic effects of test foods, test locations, and repeated consumptions (p < 0.05). Compared to consumption in the laboratory, consumption at home was faster, triggered higher heart rates, and triggered more intense facial expressions of happiness, contempt, disgust and boredom. Conclusions: Implicit tests were more sensitive to effects of test location and repeated consumption than explicit tests. Additional research is required to investigate the relevance of these measures to long term consumer acceptance of food products.
    Measuring cooking experience implicitly and explicitly : Physiology, facial expression and subjective ratings
    Brouwer, Anne Marie ; Hogervorst, Maarten A. ; Erp, Jan B.F. van; Grootjen, Marc ; Dam, Elsbeth van; Zandstra, Elizabeth H. - \ 2019
    Food Quality and Preference 78 (2019). - ISSN 0950-3293
    Cooking - EEG - Electrodermal - Emotion - Facial expression - Food preparation - Heart rate - Physiology

    Understanding consumers’ emotional experience during the process of cooking is important to enable the development of food products. In addition to verbal (‘explicit’) reports, physiological variables and facial expression may be helpful measures since they do not interfere with the experience itself and are of a continuous nature. This study investigated the potential of a range of implicit and explicit measures (1) to differentiate between subtle differences in pleasantness of ingredients, and (2) to identify emotionally salient phases during the process of cooking. 74 participants cooked and tasted a curry dish following standardized timed auditory instructions, either with ‘basic’ or ‘premium’ versions of ingredients. Heart rate, skin conductance, EEG and facial expression were recorded continuously during cooking and tasting. Subjective ratings of valence and arousal were taken directly after. Before and after cooking, participants performed ‘dry cooking’ sessions without ingredients to acquire changes in the physiological variables caused by physical activity only. We found no differences between the ‘basic’ and ‘premium’ groups, neither in implicit, nor in explicit measures. However, there were several robust physiological effects reflecting different cooking phases. Most notably, heart rate was relatively high for two specific phases: adding curry paste from a sachet during cooking, and tasting the prepared dish. The verbal reports of valence and arousal showed similar patterns over phases. Thus, our method suggests that physiological variables can be used as continuous, implicit measures to identify phases of affective relevance during cooking and may be a valuable addition to explicit measures of emotion.

    Food perception and emotion measured over time in-lab and in-home
    Wijk, R.A. De; Kaneko, D. ; Dijksterhuis, G.B. ; Zoggel, M. van; Schiona, I. ; Visalli, M. ; Zandstra, E.H. - \ 2019
    Food Quality and Preference 75 (2019). - ISSN 0950-3293 - p. 170 - 178.
    Eating context - Facial expressions - Heart rate - Repeated sensory tests
    Background: Real-life human eating behaviour does not take place in a vacuum, rather it happens in context. The context in which consumers eat their foods influences the acceptance of the consumed foods. Consequently, consumers’ hedonic and sensory ratings elicited in a natural consumption context will differ from those elicited under controlled sensory laboratory conditions. Moreover, foods are rarely consumed on one single occasion but are typically consumed repeatedly and ratings may change over repeated consumptions as well. Often, consumer acceptance is tested explicitly, for example with liking ratings, especially when the testing is done outside the laboratory. Implicit tests such as facial expressions and physiological measurements of the autonomic nervous system can provide additional information on consumer acceptance. As a result of technological advantages, such tests are no longer limited to the laboratory but can also be used in natural consumption contexts. Method: Eighteen healthy Dutch consumers (18–65 years of age) tested four test foods plus a warm-up sample ten times on consecutive weekdays and on similar hours using their own laptop and webcam. Test locations alternated between the sensory laboratory and the participant's own home. Explicit measures included liking scores and scores on ten sensory taste/flavour/texture attributes, and implicit measures included facial expressions, heart rate and consumption duration using Face Reader TM . This study was the first to validate the Face Reader TM for usage at home. Results: The liking scores and sensory profiles varied between test foods (p < 0.05), but not between test locations and only some specific sensory attributes showed systematic variation over repeated consumption. In contrast, implicit measures showed systematic effects of test foods, test locations, and repeated consumptions (p < 0.05). Compared to consumption in the laboratory, consumption at home was faster, triggered higher heart rates, and triggered more intense facial expressions of happiness, contempt, disgust and boredom. Conclusions: Implicit tests were more sensitive to effects of test location and repeated consumption than explicit tests. Additional research is required to investigate the relevance of these measures to long term consumer acceptance of food products.
    Heart rate, skin conductance, and explicit responses to juice samples with varying levels of expectation (dis)confirmation
    Verastegui-Tena, Luz ; Trijp, Hans van; Piqueras-Fiszman, Betina - \ 2019
    Food Quality and Preference 71 (2019). - ISSN 0950-3293 - p. 320 - 331.
    Autonomic nervous system - Expectations - Heart rate - Skin conductance - Taste disconfirmation

    Disconfirmations between consumers’ expectations and a product's actual properties can lead to different responses in consumers. Most researchers study these responses focusing on the final judgement of the product. However, looking at consumers’ physiological responses like those of the autonomic nervous system (ANS) could help complement what is known about consumer reactions and final response to disconfirmed expectations. This study evaluated how ANS responses change when tasting juice samples that were as expected, that differed slightly, or that differed greatly from manipulated expectations and whether these responses vary from those obtained when there is no manipulation of expectations. Eighty-six participants tasted fruit and vegetable juices in two separate sessions. They were divided in two conditions. In Condition A, expectations were manipulated by showing participants the image of an ingredient and then providing them with a juice whose flavour was as expected, differed slightly, or differed greatly from that of the image. In Condition B, each juice was first tasted without explicit information shown beforehand and the image of the ingredient was shown afterwards. The images were the same as in Condition A. Heart rate and skin conductance were measured. To confirm that participants perceived confirmations and large and small disconfirmations when tasting the juices, they rated the samples in different sensory properties before and after tasting them. Results from most of the sensory ratings, except sourness and taste intensity, showed that participants perceived the designed confirmation and disconfirmation of expectations accordingly. Regarding ANS responses, heart rate had a larger increase during the second session than during the first. Skin conductance responses increased in Condition A but decreased in Condition B. In conclusion, our design managed to create confirmations and varying levels of disconfirmations. ANS responses did not capture them but seemed to capture factors like attention and the orientation response.

    Heart rate and skin conductance responses to taste, taste novelty, and the (dis)confirmation of expectations
    Verastegui-Tena, Luz ; Trijp, Hans van; Piqueras-Fiszman, Betina - \ 2018
    Food Quality and Preference 65 (2018). - ISSN 0950-3293 - p. 1 - 9.
    Autonomic nervous system - Expectations - Heart rate - Novelty - Skin conductance - Taste
    It is unclear whether the responses of the autonomic nervous system (ANS) can measure how people respond to food. Results focused on emotional responses are contradictory; therefore, the focus has shifted to other components of emotion, such as appraisals. The aim of this study was, therefore, to evaluate the differences in ANS responses related to appraisals; particularly taste novelty, valence, and the disconfirmation of expectations.A hundred and fifty-five participants joined this study. They tasted samples of different valence (sweet and bitter) twice: the first time without knowing the taste and the second while being informed of the taste. After this first block, participants tasted two additional samples: one that confirmed expectations and one that disconfirmed them. Heart rate and skin conductance were measured. Results show that the second experience with a taste led to cardiac deceleration. Heart rate changes were only related to valence when participants' expectations were (dis)confirmed. Heart rate decreased for those tastes that disconfirmed expectations and increased for those that confirmed them and the sweet sample had larger increases in heart rate than the bitter. Skin conductance changed in regards to novelty and valence but not to the disconfirmation of expectations. It increased for the bitter sample, decreased for the sweet, and was always higher during the first experience than during the second. In conclusion, the results suggest that cardiac responses are more sensitive to novelty and the disconfirmation of expectations while skin conductance responses capture novelty and valence.
    Beyond expectations : The responses of the autonomic nervous system to visual food cues
    Verastegui-Tena, Luz ; Schulte-Holierhoek, Aurelia ; Trijp, Hans van; Piqueras-Fiszman, Betina - \ 2017
    Physiology and Behavior 179 (2017). - ISSN 0031-9384 - p. 478 - 486.
    ANS - Expectations - Heart rate - Image perception - Skin conductance - Tasting
    Self-report measures rely on cognitive and rational processes and may not, therefore, be the most suitable tools to investigate implicit or unconscious factors within a sensory experience. The responses from the autonomic nervous system (ANS), which are not susceptible to bias due to their involuntary nature, may provide a better insight. Expectations are important for the consumer-product interaction and should be considered. However, research using ANS responses has not focused thoroughly on expectations. Our aim was to investigate the mechanisms underlying ANS responses by evaluating the reactions to different images when expectations about a product are created (before tasting the product) and when they are confirmed and disconfirmed (after tasting the product). In a first study, seventy-five participants tasted four drinks (three identical soy-based drinks and one rice-based drink) and were told that they would be shown their main ingredient either before or after tasting. For the three identical drinks, the images shown were: worms, chocolate, and soy. Heart rate and skin conductance were measured during the procedure. The results showed that ANS responses followed similar patterns when images were presented before or after tasting. Heart rate decreased for all images, with the largest decrease found for chocolate and worms. Skin conductance increased, with the largest increase found for worms. To test whether the effects were solely caused by image perception, a second study was done in which forty participants only saw the images. The responses obtained were smaller and did not completely match those of the first study. In conclusion, it could be said that the ANS responses of the first study were a result of the sensory processing and defense mechanisms happening during the creation and (dis)confirmation of expectations. The second study confirmed that visual perception alone could not account for these effects and that it led to smaller changes. Hence, it seems that the context of use influences the patterns and magnitude of ANS responses to food cues.
    Sensory expectation, perception, and autonomic nervous system responses to package colours and product popularity
    Schulte-Holierhoek, Aurelia ; Verastegui-Tena, Luz ; Goedegebure, Robert P.G. ; Piqueras Fiszman, Betina ; Smeets, Paul A.M. - \ 2017
    Food Quality and Preference 62 (2017). - ISSN 0950-3293 - p. 60 - 70.
    Autonomic nervous system - Descriptive social norm - Heart rate - Packaging - Skin conductance - Taste

    Consumers’ perception of, and behaviour towards, products are influenced by extrinsic cues, including packaging and social norms. However, the understanding of this process is unsatisfactorily captured by questionnaires. Autonomic nervous system (ANS) responses can be used to measure implicit consumer responses. The aim of this work was to assess how packaging cues and social norms influence product expectation, product perception, and ANS responses. Ninety-eight adults (age: 23.3 ± 3.2 years; BMI: 21.3 ± 2.2 kg/m2) first viewed four images of a yogurt package modified in hue (blue/red), brightness (high/low), and saturation (high/low) and two dummies alongside a fictitious product popularity score. After each image presentation, participants rated their expectations of the yogurt, tasted, and rated their perception of it. Expectations and the perception of liking, healthiness, sweetness, and flavour intensity were rated on 100-unit VAS scales. Heart rate (HR) and skin conductance response (SCR) to the image and tasting were measured. The darker, saturated red package elicited the lowest expectation of healthiness and the highest expectation of flavour intensity and sweetness. Red packages increased SCR while blue packages decreased them. During yogurt tasting, low product popularity was associated with a stronger decrease in SCR than a high popularity. Overall, the measured ANS responses were small. In conclusion, this study was the first to look at the effect of expectations elicited by a product's packaging colour and popularity on explicit ratings and ANS responses. We found differences in SCR to package colour and product popularity, suggesting their importance in affecting consumer responses.

    Monitoring training response in young Friesian dressage horses using two different standardised exercise tests (SETs)
    Bruijn, Cornelis Marinus de; Houterman, Willem ; Ploeg, Margreet ; Ducro, Bart ; Boshuizen, Berit ; Goethals, Klaartje ; Verdegaal, Elisabeth Lidwien ; Delesalle, Catherine - \ 2017
    BMC Veterinary Research 13 (2017). - ISSN 1746-6148
    Friesian - Heart rate - Lactic acid - Longitudinal - Standardized exercise test - Trot

    Background: Most Friesian horses reach their anaerobic threshold during a standardized exercise test (SET) which requires lower intensity exercise than daily routine training. Aim: to study strengths and weaknesses of an alternative SET-protocol. Two different SETs (SETA and SETB) were applied during a 2 month training period of 9 young Friesian dressage horses. SETB alternated short episodes of canter with trot and walk, lacking long episodes of cantering, as applied in SETA. Following parameters were monitored: blood lactic acid (BLA) after cantering, average heart rate (HR) in trot and maximum HR in canter. HR and BLA of SETA and SETB were analyzed using a paired two-sided T-test and Spearman Correlation-coefficient (p* <0.05). Results: BLA after cantering was significantly higher in SETA compared to SETB and maximum HR in canter was significantly higher in SETA compared to SETB. The majority of horses showed a significant training response based upon longitudinal follow-up of BLA. Horses with the lowest fitness at start, displayed the largest training response. BLA was significantly lower in week 8 compared to week 0, in both SETA and SETB. A significantly decreased BLA level after cantering was noticeable in week 6 in SETA, whereas in SETB only as of week 8. In SETA a very strong correlation for BLA and average HR at trot was found throughout the entire training period, not for canter. Conclusions: Young Friesian horses do reach their anaerobic threshold during a SET which requires lower intensity than daily routine training. Therefore close monitoring throughout training is warranted. Longitudinal follow up of BLA and not of HR is suitable to assess training response. In the current study, horses that started with the lowest fitness level, showed the largest training response. During training monitoring HR in trot rather than in canter is advised. SETB is best suited as a template for daily training in the aerobic window.

    Monty Roberts’ public demonstrations : Preliminary report on the heart rate and heart rate variability of horses undergoing training during live audience events
    Loftus, Loni ; Marks, Kelly ; Jones-McVey, Rosie ; Gonzales, Jose L. ; Fowler, Veronica L. - \ 2016
    Animals 6 (2016)9. - ISSN 2076-2615
    Heart rate - Heart rate variability - Horse training - Live demonstration - Monty roberts

    Effective training of horses relies on the trainer’s awareness of learning theory and equine ethology, and should be undertaken with skill and time. Some trainers, such as Monty Roberts, share their methods through the medium of public demonstrations. This paper describes the opportunistic analysis of beat-to-beat (RR) intervals and heart rate variability (HRV) of ten horses being used in Monty Roberts’ public demonstrations within the United Kingdom. RR and HRV was measured in the stable before training and during training. The HRV variables standard deviation of the RR interval (SDRR), root mean square of successive RR differences (RMSSD), geometric means standard deviation 1 (SD1) and 2 (SD2), along with the low and high frequency ratio (LF/HF ratio) were calculated. The minimum, average and maximum RR intervals were significantly lower in training (indicative of an increase in heart rate as measured in beats-per-minute) than in the stable (p = 0.0006; p = 0.01; p = 0.03). SDRR, RMSSD, SD1, SD2 and the LF/HF ratio were all significantly lower in training than in the stable (p = 0.001; p = 0.049; p = 0.049; p = 0.001; p = 0.01). When comparing the HR and HRV of horses during Join-up® to overall training, there were no significant differences in any variable with the exception of maximum RR which was significantly lower (p = 0.007) during Join-up®, indicative of short increases in physical exertion (canter) associated with this training exercise. In conclusion, training of horses during public demonstrations is a low-moderate physiological, rather than psychological stressor for horses. The physiological stress responses observed within this study were comparable or less to those previously reported in the literature for horses being trained outside of public audience events. Furthermore, there is no evidence that the use of Join-up® alters HR and HRV in a way to suggest that this training method negatively affects the psychological welfare of horses.

    Responses of the Autonomic Nervous System to Flavors
    Wijk, René A. de; Boesveldt, Sanne - \ 2016
    In: Multisensory Flavor Perception: From Fundamental Neuroscience Through to the Marketplace / Piqueras-Fiszman, Betina, Spence, Charles, Amsterdam : Elsevier Inc. Academic Press (Woodhead Publishing Series in Food Science, Technology and Nutrition 298) - ISBN 9780081003503 - p. 249 - 268.
    Autonomic nervous system - Flavors - Foods - Heart rate - Product emotions - Skin conductance

    Multisensory flavor perception plays an important role in decision-making, for instance for food products. Autonomic nervous system (ANS) responses, such as heart rate and skin conductance responses, towards such flavor stimuli may provide insights into processes related to consumer acceptance that are poorly accessible with traditional sensory and consumer tests because they are largely subconscious and/or relatively fast and short-lasting. This chapter reviews the origin of ANS responses, their temporal dynamics, as well as their specificity with regard to product emotions and valence. Practical implications-and limitations-of ANS measurements will be discussed, as well as a view on how they could be integrated into consumer research.

    Potassium supplementation and heart rate : A meta-analysis of randomized controlled trials
    Gijsbers, L. ; Molenberg, Famke ; Bakker, S.J.L. ; Geleijnse, J.M. - \ 2016
    Nutrition, Metabolism & Cardiovascular Diseases 26 (2016)8. - ISSN 0939-4753 - p. 674 - 682.
    Blood pressure - BP - Heart rate - HR - Meta-analysis - Potassium - Randomized controlled trial - Randomized controlled trials - RCT

    Background and aims: Increasing the intake of potassium has been shown to lower blood pressure, but whether it also affects heart rate (HR) is largely unknown. We therefore assessed the effect of potassium supplementation on HR in a meta-analysis of randomized controlled trials. Methods and results: We searched PubMed (1966-October 2014) for randomized, placebo-controlled trials in healthy adults with a minimum duration of two weeks in which the effect of increased potassium intake on HR was assessed. In addition, reference lists from meta-analysis papers on potassium and blood pressure were hand-searched for publications. Two investigators independently extracted the data. We performed random effects meta-analyses, subgroup and meta-regression analyses for characteristics of the study (e.g. design, intervention duration, potassium dose and salt type, change in potassium excretion, sodium excretion during intervention) and study population (e.g. gender, age, hypertensive status, pre-study HR, pre-study potassium excretion). A total of 22 trials (1086 subjects), with a median potassium dose of 2.5 g/day (range: 0.9-4.7 g/day), and median intervention duration of 4 weeks (range: 2-24 weeks) were included. The meta-analysis showed no overall effect of increased potassium intake on HR (0.19 bpm, 95% CI: -0.44, 0.82). Stratified analyses yielded no significant effects of potassium intake on HR in subgroups, and there was no evidence for a dose-response relationship in meta-regression analyses. Conclusion: A chronic increase in potassium intake with supplemental doses of 2-3 g/day is unlikely to affect HR in apparently healthy adults.

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