Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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“Everything tastes different” : The impact of changes in chemosensory perception on food preferences, food intake and quality of life during chemotherapy in cancer patients
Vries, Yfke Carlijn de - \ 2017
University. Promotor(en): Kees de Graaf; H.W.M. van Laarhoven, co-promotor(en): R.M. Winkels; Sanne Boesveldt. - Wageningen : Wageningen University - ISBN 9789463436090 - 169
perception - sensory evaluation - food intake - quality of life - food preferences - neoplasms - taste - macronutrients - drug therapy - breast cancer - perceptie - sensorische evaluatie - voedselopname - kwaliteit van het leven - voedselvoorkeuren - neoplasma - smaak - macronutriënten - geneesmiddelenbehandeling - borstkanker

Taste and smell changes are common side effects during chemotherapy in cancer patient and may have an impact on food preferences, food intake and quality of life. However, these relations have hardly been studied systematically in specific cancer populations. The overall aim of this thesis was to assess how the sense of taste and smell change upon treatment with chemotherapy in breast cancer and oesophagogastric cancer patients, and to investigate their consequences in terms of food preferences, food intake and quality of life.

To measure food preferences for both macronutrients and tastes, the Macronutrient and Taste Preference Ranking Task (MTPRT) was developed. in chapter 2, it was shown that by inducing sensory specific satiety for a standardized sweet and savoury meal, it is possible to detect shifts in preferences for both tastes and macronutrients with the MTPRT, and that these results are reproducible.

In Chapter 3 we studied objective and subjective taste and smell perception and food preferences in advanced oesophagogastric cancer patients undergoing palliative chemotherapy. The result showed that only objective taste function decreases during chemotherapy, but other chemosensory measures were unchanged. A lower subjective taste perception was related to a lower preference for high-protein products. Therefore it is important to consider patients’ taste perception, when providing dietary advice to OGC patients

Chapter 4 describes a study with similar outcome measures as chapter 3, but in breast cancer patients at several time points during and after chemotherapy, and compared to a healthy control group. The study showed that breast cancer patients like high-protein, high-fat, sweet and savoury products less during chemotherapy, thus showing altered preferences for macronutrients, but not for tastes. Furthermore, results showed a temporary decrease in taste and smell perception during chemotherapy. These findings show that patients should be informed prior to treatment on chemosensory changes, and that these changes should be monitored during treatment due to the consequences for nutritional intake and quality of life

In chapter 5 we assessed the dietary intake of breast cancer patients before and during chemotherapy compared to a healthy control group, and associations with experienced symptoms during chemotherapy. It was shown that symptoms induced by chemotherapy were associated with lower total energy, protein and fat intake, which was manifested by a lower intake of specific food groups. Therefore, to ensure an optimal dietary intake during chemotherapy, it is important to monitor nutritional status and symptom burden during chemotherapy in breast cancer patients.

To better understand the impact of chemosensory changes during chemotherapy on daily life, 13 advanced oesophagogastric cancer patients were interviewed (see chapter 6). Patients described a substantial impact of chemosensory and food-related changes on daily life (by changing daily routines), social life (eating being less sociable) and roles in the household (changing roles in cooking and grocery shopping).

Finally, in chapter 7, we assessed the association between self-reported taste and smell perception and quality of life in breast cancer patients. A worse taste and smell perception was associated with a worse global quality of life, role, social and emotional functioning shortly after chemotherapy. In patients treated with trastuzumab, a worse taste and smell perception was still associated with quality of life, social and role functioning half a year after chemotherapy had ended.

From the studies in this thesis we can conclude that chemotherapy mainly affects the sense of taste. The subjective perception of taste was associated with a lower preference for food products and lower energy intake. This indicates that it is not necessarily an actual change in the sense of taste or smell that has an impact on patients, but flavour perception as a whole and potentially a lower enjoyment of food. Moreover, these perceived changes in taste and smell can have a substantial impact on cancer patients’ lives, in a practical way by changing daily patterns of eating, but also socially and in roles in the household. A changed chemosensory perception during chemotherapy may lead to a worsened nutritional status, and could thereby negatively impact the response to chemotherapy. Therefore chemosensory perception should be monitored during chemotherapy. Future studies should further investigate the mechanisms behind chemosensory changes, factors that contribute to subjective taste perception and possible interventions to alleviate chemosensory changes during chemotherapy.

Double emulsions as fat replacers : linking emulsion design to stability and sensory perception
Oppermann, Anika - \ 2017
University. Promotor(en): Kees de Graaf, co-promotor(en): Markus Stieger; Elke Scholten. - Wageningen : Wageningen University - ISBN 9789463430722 - 186
fats - fat - sensory sciences - sensory evaluation - emulsions - perception - gelation - vetten - vet - sensorische wetenschappen - sensorische evaluatie - emulsies - perceptie - gelering

The use of double (w1/o/w2) emulsions, in which part of the oil is replaced by small water droplets, is a promising strategy to reduce oil content in food products. For successful applications, (1) significant levels of fat reduction (i.e. significant amounts of water inside the oil droplets) have to be achieved, (2) double emulsions have to be stable against conditions encountered during processing and storage, and (3) the mouthfeel and sensory perception have to be similar to that of full-fat equivalents. With the present work, significant progress was made in understanding the complex relations between double emulsion design, achievable levels of fat reduction, emulsion stability and sensory perception. We show that through careful emulsion design, stable double emulsions with high levels of fat reduction (up to 50%) can be obtained while maintaining fat-related sensory properties, making double emulsions a promising approach for the development of fat-reduced food products.

Lubrication and perception of foods : tribological, rheological and sensory properties of particle-filled food system
Liu, K. - \ 2016
University. Promotor(en): Erik van der Linden, co-promotor(en): Markus Stieger; Fred van de Velde. - Wageningen : Wageningen University - ISBN 9789462576803 - 236 p.
rheological properties - tribology - fat globules - particles - lubrication - sensory evaluation - simulation models - food - gels - rice - reologische eigenschappen - tribologie - vetbolletjes - deeltjes - smering - sensorische evaluatie - simulatiemodellen - voedsel - rijst

Background and aims

Food structure is determined by its composition and the interaction between the compositional or structural elements. Both food structure and the texture perception of foods undergo dynamic changes during different phases of oral processing. During oral processing, both rheological and tribological properties of foods are relevant for sensory perception. The general aim of this thesis was to understand the relationship between the structural properties, rheological and tribological properties during food breakdown, and the sensory perception of foods. More specifically, this thesis aimed to link the properties of food particles in liquid and semi-solid matrices to the tribological and rheological properties, and in this way, understand the sensory perception of these systems.

Methods

Fat droplets and micro-particle fat replacers based on protein and starch were investigated. These particles varied in size, morphology, deformability and stability, as well as their interaction with the surrounding matrix. These particles were dispersed in liquid or semi-solid gel phases, forming the food model systems under consideration. The friction and microstructural evolution of food model systems under shear was determined using a mouth-mimicking tribometer connected to a confocal laser scanning microscopy. The viscosities of liquid systems were analyzed using a rheometer, and the large deformation properties of semi-solid gel systems were determined during uniaxial compression tests. The sensory perception of the food model systems were measured using quantitative descriptive analysis. The release and deposition of fat droplets on the tongue were determined using in vivo fluorescence.

Results

Food structural elements could be manipulated to control the tribological properties of food model systems. Morphology, size, and deformability of food particles determine the lubrication behavior of the food systems. Spherical particles with micrometer size were able to reduce friction through a ball bearing mechanism, while irregularly shaped particles increased friction by increasing apparent surface asperity contacts. Deformable particles could flatten the surface by filling asperities, thus reduced friction. Coalescence of unstable droplets could plate-out on the surface and form film patches, thus reduced friction. Other structural elements, such as emulsifiers and sticky molecules, also influenced tribological properties of the systems. Interactions between the food structural elements could influence the rheological properties of liquid and semi-solid food systems. These properties as well as tribological properties were inter-related and all of them affect sensory perception. The inter-relations between physical and sensory properties of food systems were influenced by oral processing, such as oral processing duration and temperature. Furthermore, several fat reduction and replacement strategies were suggested, including increasing the availability of fat that is in contact with oral surfaces, improving the lubrication by ball bearing of particles, and reducing perception of negative attributes such as roughness.

Conclusions

This thesis showed the importance of food particle properties in both the tribological properties and sensory perception of foods, and emphasized the different lubrication mechanisms of different structure elements and their relation to perception. The differences in behavior of food particles between liquid and semi-solid gel systems were highlighted. These findings would enable a better understanding of relationship between food structure and their physical and sensory properties, and this would allow designing or modifying food products with targeted texture and sensory perception.

Sensory quality of drinking water produced by reverse osmosis membrane filtration followed by remineralisation
Vingerhoeds, M.H. ; Nijenhuis, M.A. ; Ruepert, N. ; Bredie, W.L.P. ; Kremer, S. - \ 2016
Water Research 94 (2016). - ISSN 0043-1354 - p. 42 - 51.
drinking water - water quality - sensory evaluation - taste research - reverse osmosis - membranes - filtration - drinkwater - waterkwaliteit - sensorische evaluatie - smaakonderzoek - omgekeerde osmose - membranen - filtratie
Membrane filtration of ground, surface, or sea water by reverse osmosis results in permeate, which is almost free from minerals. Minerals may be added afterwards, not only to comply with (legal) standards and to enhance chemical stability, but also to improve the taste of drinking water made from permeate. Both the nature and the concentrations of added minerals affect the taste of the water and in turn its acceptance by consumers. The aim of this study was to examine differences in taste between various remineralised drinking waters. Samples selected varied in mineral composition, i.e. tap water, permeate, and permeate with added minerals (40 or 120 mg Ca/L, added as CaCO3, and 4 or 24 mg Mg/L added as MgCl2), as well as commercially available bottled drinking waters, to span a relevant product space in which the remineralised samples could be compared. All samples were analysed with respect to their physical–chemical properties. Sensory profiling was done by descriptive analysis using a trained panel. Significant attributes included taste intensity, the tastes bitter, sweet, salt, metal, fresh and dry mouthfeel, bitter and metal aftertaste, and rough afterfeel. Total dissolved solids (TDS) was a major determinant of the taste perception of water. In general, lowering mineral content in drinking water in the range examined (from <5 to 440 mg/L) shifted the sensory perception of water from fresh towards bitter, dry, and rough sensations. In addition, perceived freshness of the waters correlated positively with calcium concentration. The greatest fresh taste was found for water with a TDS between 190 and 350 mg/L. Remineralisation of water after reverse osmosis can improve drinking quality significantly.
Oral coatings: a study on the formation, clearance and perception
Camacho, S. - \ 2015
University. Promotor(en): Kees de Graaf, co-promotor(en): Markus Stieger; F. van de Velde. - Wageningen : Wageningen University - ISBN 9789462575653 - 223
afdeklagen - eiwitten - orale toediening - tong - mond - smering - emulsies - in vivo experimenten - sensorische evaluatie - perceptie - dynamica - zoetheid - fluorescentie - coatings - proteins - oral administration - tongue - mouth - lubrication - emulsions - in vivo experimentation - sensory evaluation - perception - dynamics - sweetness - fluorescence

Oral coatings are residues of food and beverages that coat the oral mucosa after consumption. Several studies have reported on the lubrication properties in mouth, and the after-feel and after-taste impact of oral coatings. Further, oral coatings have been suggested to influence subsequent taste perception. Although it is well known that oral coatings can influence sensory perception, there was little information available on the chemical composition and physical properties of oral coatings. As such, the aim of this thesis was to understand which factors influence the composition of oral coatings and their sensory perception.

This study started with the development of an appropriate calibration method for an already described methodology to quantify oil oral coatings: in vivo fluorescence. Further, the samples studied were shifted from pure oil (used on previous studies) to a more realistic food beverage: o/w emulsions. Pig´s tongues are known to be a good model of human tongue. As such, Chapter 2 used pig´s tongues on the calibration of the method, to mimic the fluorescence in mouth of oil coatings. On chapter 2, Confocal Scanning Laser Microscopy images showed that stable o/w emulsions (1-20% (w/w)) stabilised by Na-caseinate created individual oil droplets on the surface of the pigs tongue, as such a new descriptor for oil coatings was developed. Oil fraction, i.e. mass of oil per surface area of the tongue, was shown to be higher on the back compared to the front anterior part of the tongue. This is thought to be due to the morphology of the tongue and abrasion of the oil coating owed to the rubbing with the palate. Further, in vivo measurements showed that oil fraction deposited on the tongue increased linearly with oil content of o/w emulsions. Coating clearance from the tongue was a fast process with around 60% of the oil being removed on the first 45s. After-feel perception (Fatty Film and Flavour Intensity) was shown to be semi-logarithmic related to oil fraction on the tongue.

Chapter 3, further investigated different properties of 10% (w/w) o/w emulsions that influence the oil fraction deposited on the tongue, its clearance and after-feel perception. Three different properties were studied: protein type, protein content and viscosity of the o/w emulsions. To study the influence of protein type, two different proteins which behave differently in-mouth were studied: Na-caseinate - creates emulsions which do not flocculate under in mouth conditions, and lysozyme – creates emulsions which flocculate under in mouth conditions. To study the influence of protein content, three concentrations of Na-caseinate and lysozyme were used (0.2, 3, 5.8% (w/w) all in excess to stabilize the water/oil interface). To study the influence of viscosity of o/w emulsions, three o/w emulsions stabilized with 3% (w/w) Na-caseinate were thickened with varying concentrations of xanthan gum (0-0.5%) (w/w).

Generally, the irreversible flocculation of lysozyme stabilized emulsions with saliva did not create a significant difference on oil deposition compared to emulsions stabilized with Na-caseinate, immediately after expectoration of the emulsions. Nevertheless, lysozyme stabilised emulsions caused slower oil clearance from the tongue surface compared to emulsions stabilized with Na-caseinate. Protein content had a negative relation with oil fraction on the tongue for lysozyme stabilized emulsions and no relation for Na-caseinate stabilized emulsions. The presence of thickener decreased deposition of oil on tongue, although viscosity differences (i.e., thickener content) did not affect oil fraction. After-feel perception of creaminess and fatty-film was strongly influenced by the presence of thickener likely due to lubrication in-mouth, i.e., the higher the concentration of thickener in the emulsions the stronger was the perception. Oral coatings perception was further influenced by the protein used in the emulsions, with Na-caseinate stabilised emulsions creating coatings with higher perception on creaminess and fatty-film.

Chapter 2 and chapter 3 provided knowledge on the deposition and clearance of oil coatings, but little was known on the formation of oil coatings. Chapter 4 focused on the formation of oil coatings formed by Na-caseinate stabilised o/w emulsions (1-20% (w/w)). The formation of oil coatings was a rapid process, where the maximum oil deposition was achieved at normal drinking behaviour (~3s). Further, in Chapter 4 we investigated the hypothesis often referred on literature, in which oil coatings form a physical barrier which prevents tastants to reach the taste buds, and thus create a reduction on taste perception. It was concluded that oil coatings formed by emulsions within one sip did not affect subsequent sweetness perception of sucrose solutions. We suggested that the oil droplets deposited on the tongue (as seen on chapter 2) did not form a hydrophobic barrier that is sufficient to reduce the accessibility of sucrose to the taste buds and consequently does not suppress taste perception.

Previous chapters focused on oral coatings formed by liquid o/w emulsions, however studies describing oral coatings formed by semi-solids and solids are scarce. As such, chapter 5 focused on the formation, clearance and sensory perception of fat coatings from emulsion-filled gels. Four emulsion-filled gelatin gels varying in fat content and type of emulsifier (whey protein isolate - created fat droplets bound to matrix; tween 20 - created fat droplets unbound to matrix) were studied. As in for oil coatings formed by liquid o/w emulsions, fat coatings formed by emulsion-filled gels reach their maximum deposition in the first seconds of mastication. This suggests that the first bites are the most relevant for the formation of fat coatings on the tongue. Further, fat fraction deposited on tongue increased when oral processing time of the gels increased. This trend was clearer for gels with higher fat content (15%) compared to gels with lower fat content (5%). Fatty perception increased with increasing mastication time, and decreased after expectoration with increasing clearance time. Fat fraction deposited on tongue and fatty perception are higher in gels with unbound droplets compared to bound droplets, as well as in gels with 15% fat compared to 5% fat.

To elucidate the role of protein on oral coatings, Chapter 6 focused on the development of a method to quantify protein in the oral coatings. Further, Chapter 6 studied the influence of protein content, in-mouth protein behaviour (lysozyme - protein which creates flocs with saliva vs. Na-Caseinate - protein which does not create flocs with saliva) and presence of thickener on the formation of protein oral coatings and sensory perception of protein coatings. Protein coatings were collected from the front and middle part of the anterior tongue using cotton swabs after subjects orally processed protein solutions for different time periods. Protein concentration of the coating (mass protein/mass coating) was quantified with the Lowry method. Similarly to oil/fat coatings, results show protein coatings are formed rapidly, reaching maximum deposition on the first seconds of the samples´ oral processing. Further, different protein in mouth-behaviour (Na-caseinate vs. lysozyme) did not create differences on protein deposition on the tongue. Presence of xanthan-gum in the processed samples decreased protein deposition on the tongue, compared to when samples without xanthan-gum were processed. The perception of protein coatings was strongly influenced by the viscosity and protein used in the samples. Higher viscosity of the samples lead to higher intensity on creaminess and thickness. Lysozyme samples created coatings with high sweetness and astringent intensity, which is related to the molecular structure of the protein.

Changes in the viscosity of beverages can cause changes in thickness perception. The changes in thickness perception can be accompanied by differences in other sensory properties, such as sweetness and creaminess which might be undesirable when reformulating beverages or developing new products. Knowledge on the differences by which viscosity of beverages can be modified to create a difference in sensory perception is currently lacking. Chapter 7 focus on the determination of the Just Noticeable Difference (the minimal difference that can be detected between two stimuli) for thickness perception of beverages. Oral thickness sensitivity (K=0.26) was found to be comparable to literature values for kinesthetic food firmness and spreadability, creaminess, sourness and bitterness perception.

The aim of this thesis was to determine and characterize factors influencing oral coatings and their sensory perception. For this purpose, reliable methods to quantify oil and protein deposited on the tongue had to be developed to later study the macronutrients deposition. Further, the influence of stimulus properties on the formation and clearance dynamics of oral coatings and their impact on sensory perception were investigated.

Microbubble stability and applications in food
Rovers, T.A.M. - \ 2015
University. Promotor(en): Erik van der Linden, co-promotor(en): Marcel Meinders; Guido Sala. - Wageningen : Wageningen University - ISBN 9789462574755 - 138
microbubbles - eiwit - stabiliteit - karakterisering - voedsel - voedseladditieven - oppervlaktespanningsverlagende stoffen - zuurbehandeling - reologische eigenschappen - sensorische evaluatie - tribologie - druk - verwarming - koelen - protein - stability - characterization - food - food additives - surfactants - acid treatment - rheological properties - sensory evaluation - tribology - pressure - heating - cooling

Aeration of food is considered to be a good method to create a texture and mouthfeel of food products that is liked by the consumer. However, traditional foams are not stable for a prolonged time. Microbubbles are air bubbles covered with a shell that slows down disproportionation significantly and arrests coalescence. Protein stabilized microbubbles are seen as a promising new food ingredient for encapsulation, to replace fat, to create new textures, and to improve sensorial properties of foods. In order to explore the possible functionalities of microbubbles in food systems, a good understanding is required regarding the formation of protein stabilized microbubbles as well as their stability in environments and at conditions encountered in food products. The aim of this research was to investigate the key parameters for applications of microbubbles in food systems. In Chapter 1 an introduction to this topic is given.

In Chapter 2, the effect of the microbubble preparation parameters on the microbubble characteristics, like the microbubble yield, size and stability, was investigated. The protein Bovine Serum Albumin (BSA) and the method sonication was used to manufacture the microbubbles. The manufactured number and stability of microbubbles was highest when they were prepared at a pH around 5 to 6, just above the isoelectric point, and at an ionic strength of 1.0 M. This can be related to the protein coverage at the air/water interface of air bubbles formed during sonication. At a pH close to the isoelectric point the BSA molecules is in its native configuration. Also the repulsion between the proteins is minimized at these pH values and ionic strength. Both the native configuration and the limited repulsion between the proteins result in an optimal protein coverage during the first part of sonication. Also a high protein concentration contributes to a higher surface coverage. The surface coverage is proportional to the protein concentration up to a concentration of 7.5% after which an increase in protein concentration did not lead to a substantial increase in the number of microbubble . In the second part of sonication the protein layer around the air bubble becomes thicker and stronger by heat induced protein-protein interactions. We found that and at a preheating temperature of 55-60°C, about 5 °C below the BSA denaturation temperature, and a final solution temperature of 60-65°C most microbubbles were obtained, while at higher temperatures mainly protein aggregates and (almost) no microbubbles are formed. This suggests that at temperature of around 60°C to 65°C protein aggregated mostly at the air-water interface creating a multi-layered shell, while at higher temperature, they also aggregated in bulk. These aggregates cannot form microbubbles. We found that optimal preparation parameters strongly depend on the protein batch. We hypothesize that the differences in microbubble formation between the protein batches is due to (small) differences in the protein molecular and denaturation properties that determine the temperature at which the molecules start to interact at the air-water interface. Microbubbles made with different protein concentration and preheating temperatures shrunk in time to a radius between 300 nm and 350 nm, after which the size remained constant during further storage. We argue that the driving force for the shrinkage was the Laplace pressure, resulting in an air flux from the bubbles to the solution. We argue that the constant final size can be explained by a thickening of the microbubble shell as a result of the microbubble shrinkage, thereby withstanding the Laplace pressure.

In Chapter 3 and Chapter 4, microbubble stability at environments and conditions representative for food products were studies. In Chapter 3 we investigated the stability upon addition of surfactants and acid, When surfactants or acid were added, the microbubbles disappeared in three subsequent steps. The release of air from the microbubble can be well described with the two-parameter Weibull process. This suggests two processes are responsible for the release of air: 1) a shell-weakening process and 2) a random fracture of the weakened shell. After the air has been released from the microbubble the third process is identified in the microbubble disintegration: 3) the shell disintegrated completely into nanometer-sized particles. The probability of fracture was exponentially proportional to the concentration of acid and surfactant, meaning that a lower average breaking time and a higher decay rate were observed at higher surfactant or acid concentrations. For different surfactants, different decay rates were found. The disintegration of the shell into monomeric proteins upon addition of acid or surfactants shows that the interactions in the shell are non-covalent and most probably hydrophobic. After surfactant addition, there was a significant time gap between complete microbubble decay (release of air) and complete shell disintegration, while after acid addition the time at which the complete disintegration of the shell was observed coincided with the time of complete microbubble decay.

In Chapter 4 the stability of the microbubbles upon pressure treatment, upon fast cooling after heating and at different storage temperatures was studied. The microbubble stability significantly decreased when microbubbles were pressurized above 1 bar overpressure for 15 seconds or heated above 50°C for 2 minutes. Above those pressures the microbubbles became unstable by buckling. Buckling occurred above a critical pressure. This critical pressure is determined by the shell elastic modulus, the thickness of the shell, and the size of the microbubble. Addition of crosslinkers like glutaraldehyde and tannic acid increased the shell elastic modulus. It was shown that microbubbles were stable against all tested temperatures (up to 120°C) and overpressures (4.7 bar) after they were reinforced by crosslinkers. From the average breaking time at different storage temperatures, we deduced that the activation energy to rupture molecular bonds in the microbubbles shell is 27 kT.

In Chapter 5, we investigated the effect of microbubbles on the rheological, tribological sensorial properties of model food systems and we compared this effect to the effect on food systems with emulsion droplets and without an added colloid. We investigated the effect in three model food systems, namely fluids with and without added thickener and a mixed gelatine-agar gel. In a sensory test panellists were asked whether they could discriminate between samples containing microbubbles, emulsion droplets or no added colloid. Emulsions could be sensorially well distinguished from the other two samples, while the microbubble dispersion could not be discriminated from the protein solution. Thus, we concluded that at a volume fraction of 5% of these BSA covered microbubbles were not comparable to oil-in-water emulsions. The good discrimination of emulsion might be ascribed to the fact that emulsion had a lower friction force (measured at shear rates form 10 mm/s to 80 mm/s) than that microbubbles dispersions and protein solutions. Upon mixing emulsions and microbubble dispersions the friction value approximated that of emulsions. This effect was already noticed at only 1.25% (v/v) oil, indicating that microbubbles had not a significant contributions to the friction of these samples. Also microbubble dispersions with and without protein aggregates were compared. The microbubble dispersions with and without thickener containing protein aggregates had a higher viscosity than the those samples without protein aggregates. Protein aggregates in the gelled microbubble sample yielded a higher Young’s modulus and fracture stress. The differences between the gelled samples could be well perceived by the panellists. We attribute this mainly to the fracture properties of the gel. In general we concluded that microbubbles, given their size of ~ 1 mm and volume fraction of 5%, did not contribute to a specific mouthfeel.

Finally in Chapter 6, the results presented in the previous chapters are discussed and put in perspective of the general knowledge on microbubbles production, stability, and applications in food. We described the main mechanisms leading to microbubble formation and stability. We showed that the production parameters significantly influence the interactions in the microbubble shell, and the those interactions highly determine the stability of the microbubbles under several conditions. We reported about limitations of sonication as a method to produce microbubbles suitable for food applications and we provided some ways to overcome these limitations. The use of microbubbles in food systems has been explored and we clearly see possible applications for microbubbles in food. We reported about directions for possible further research.

In this work we made significant progress in understanding the interactions in the microbubble shell and their relation to microbubble stability. We also advanced in comprehension towards possible applications of microbubbles in food.

The Perfect Meal: The Multisensory Science of Food and Dining
Spence, C. ; Piqueras Fiszman, B. - \ 2015
Oxford, UK : John Wiley and Sons - ISBN 9781118490822 - 424
maaltijden - zintuigen - sensorische evaluatie - meals - senses - sensory evaluation
The appetizing and satiating effects of odours
Ramaekers, M.G. - \ 2014
University. Promotor(en): Tiny van Boekel, co-promotor(en): Pieternel Luning; Catriona Lakemond. - Wageningen : Wageningen University - ISBN 9789461739995 - 164
geurstoffen - eetlust - verzadigdheid - sensorische evaluatie - voedingsgewoonten - odours - appetite - satiety - sensory evaluation - feeding habits
Background and aim

Unhealthy eating habits such as unhealthy food choices or overeating increase the prevalence of obesity, diabetes, cancer, cardiovascular and other diseases. Therefore, it is important to understand how separate factors, such as sensory processes, influence our eating behaviour. As one of the sensory modalities, olfaction has a relationship with food intake regulation. Previous research reveals that food odours can induce both appetite and satiation. In this thesis, we split appetite and satiation into a ‘general’ part and a ‘food specific’ part. General appetite and general satiation refer to the desire to eat in general. General satiation measured by subjective ratings (e.g. by using line scales) is also named ‘subjective satiation’. The specific part refers to the desire to eat a specific food: e.g. the appetite for a banana or the appetite for tomato soup.

The main objective of this thesis was to investigate under which circumstances odours are appetizing or satiating in order to identify factors that influence our eating behaviour.Odours arrive at the odour receptors via two routes: the orthonasal route via the nose to perceive the outside world or retronasally via the mouth to ‘taste’ the food. The appetizing and satiating effects of ortho- and retronasally smelled odours were investigated by varying the odour exposure time, the odour concentration(retronasal only), the odour type, passive versus active sniffing (orthonasal only) and by switching between odour types.

Methods

We conducted six within-subject experiments. All participants were healthy normal-weight women (age 18-45 y and BMI 18.5-26 kg/m2). In four experiments (studies 2A, 2B, 3A and 3B), we investigated the appetizing and satiating effects of orthonasal odours, with two experiments addressing odours that were smelled passively in rooms with ambient odours (chapter 2) and two addressing actively smelled odours by sniffing the contents of a cup (chapter 3). In studies 2A (passive, n=21), 2B (passive, n=13) and 3A (active, n=61), we investigated the effects of exposure timeand odour typeon appetite, the appetite for specific foods, food preference and food intake. Differences between passiveand active exposure were investigated by comparing the data from 2A and 3A. In the fourth experiment (n=30) using a similar set-up, sweet and savoury odours were presented directly after each other, to explore the effects of daily encounters with a variety of food odours (i.e. switching). In all orthonasal studies, general appetite and the appetite for specific foods were monitored over time, using visual analogue scales. General appetite comprised hunger and desire-to-eat ratings. The appetite for specific products addressed the appetite for smelled products and the appetites for a set of other products that were congruent and incongruent with the odour (studies 2A, 2B, 3A and 3B). Food preference was assessed using a computerised program offering pairs of food pictures (studies 2A, 2B and 3B).

Furthermore, two experiments addressed the satiating effects of retronasal odours while consuming tomato soup ad libitum (studies 4A and 4B). The retronasal odour exposure was disconnected from the soup base consumptionby use of a retronasal tube that was connected to an olfactometer. The odours were delivered directly into the nasal cavity at the moment a sip of soup base was swallowed. In study 4A (n=38), the satiating effects of odour exposure time(3 and 18 s) and odour concentration(5x difference) were investigated. In study 4B(n=42),we investigated whether addition of cream odourto tomato soup, in combination with a low or high viscosity, affected satiation. Hunger and appetite ratings were monitored over time during odour exposure, by using 100 mm visual analogue scales (VAS).

Results

The results showed that orthonasalexposure to food odours influenced the appetite for specific foods via a typical pattern: the appetite ratings for the smelled foods increased by +6-20 mm(SSA; all P<0.001), the appetite for congruent sweet and savoury foods increased by +5 mmand the appetite for incongruent sweet and savoury foods decreased by -5 mm (all P<0.01), measured by using 100 mm VAS (studies 2A, 2B, 3A and 3B). This typical pattern was found in all studies, independently of passive or active smelling, exposure time or switching between odours (studies 2A, 2B, 3A and 3B). Results in study 3B showed that the appetite for specific products adjusted to the new odour within one minute after a switch between sweet and savoury odours. Similar results were found with a computerised food preference program, in which participants chose repeatedly between pairs of foods (studies 2A, 2B and 3B). Food preference shifted in circa 20% of the choices. Furthermore, passively smelled food odours had a large effect on the appetite for the smelled foods (+15 mm; P<0.001) and a small effect on general appetite (+4 mm; P=0.01; study 2A). Actively smelled food odours had nosignificant effect on general appetite or food intake (studies 3A and 3B). Non-food odours appeared to suppress general appetite slightly (-2 mm, P=0.01). The appetizing effects did not change over timeduring a twenty-minute odour exposure (studies 2A, 2B, 3A and 3B) and the typical pattern of odour effects on the appetite for specific foods was not affected by switching between sweet and savoury odours (study 3B). The pleasantness of the odour decreased by -4 mmduring active smelling (P=0.005), whereas the appetite for the smelled food remained high (P<0.001; study 3B).

Furthermore, the results from the retronasalstudies showed that an increase in both retronasal odour exposure time and concentration reduced ad libitum intake by 9 % (i.e. 3 sips and 22 kJ; P=0.04) and had no effect on subjective satiation (study 4A). Adding cream odour decreased subjective satiation with circa 5 %between 7 and 13 minutes after the start of consumption (P=0.009), but did not affect ad libitumintake (study 4B). Retronasally smelled odour significantly contributed to the development of sensory-specific satiety (study 4A).

Conclusions

Orthonasally smelled odours affect to a larger extend what you eat, than how much you eat. They influence the appetite for specific foods via a typical pattern: the appetite for the smelled foods and for congruent sweet or savoury foods increases, whereas the appetite for incongruent sweet or savoury foods decreases. This typical pattern is independent of exposure time, passive or active smelling and switchingbetween odours. The reason for this pattern is unknown, however, it may be caused by the preparation of the body for the intake of the smelled food, as food odours may provide information about the nutrient composition of their associated foods. Furthermore, passiveodour exposure may enhance general appetite (how much), whereas activesmelling appears to have no effect. Interestingly,the appetite for the smelled foods remained elevated during the 20-minute smelling, althoughthe pleasantness of the smelled odour decreased a little over time. This shows an earlier assumption from literature incorrect: a decrease in pleasantness of the odour does not lead to less appetite for the smelled food. This seeming contradiction may result from different mechanisms, such as a decrease in hedonic value during prolonged sensory stimulation on the one hand and anticipation of food intake on the other hand. Furthermore, food odours were found to change preference in circa 20% of the cases. Probably, food odours shift food preference, but do not overrule strong initial preferences in circa 80% of the cases.

Moreover, retronasally smelled odours probably have a small influence on satiation, though the evidence is not very strong. An increase in both retronasal odour concentrationand odour exposure timemay enhance satiation. Adding cream odourmay temporarily affect subjective satiation but does not affect food intake. However, the satiating effects that were found in these studies with retronasal odour exposure were borderline significant and data on food intake and subjective appetite ratings were not consistent, which probably reflects thesmall effect size.

Orthonasal odours influence food preference and could potentially be used to encourage healthy eating behaviour. The studies in this thesis were conducted under controlled circumstances and the results possibly deviate from behaviour in daily life. Therefore, it is unclear how strong the influence of odours is on our eating behaviour in daily situations. Finally, we advise product developers not to focus on changing retronasal odour characteristics in order to enhance satiation of products, seen the small effects that were found in this thesis.

Consumers and vegetables: effects of domestic processing on sensory and health properties
Bongoni, R. - \ 2014
University. Promotor(en): Tiny van Boekel, co-promotor(en): Bea Steenbekkers; Ruud Verkerk; Matthijs Dekker. - Wageningen : Wageningen University - ISBN 9789461739254 - 151
groenten - consumenten - voedselbereiding thuis - sensorische evaluatie - gezondheid - kookkwaliteit - vegetables - consumers - home food preparation - sensory evaluation - health - cooking quality

The quality of foods e.g. vegetables at the time of consumption depends on the post-purchase handling conditions especially by domestic processing. On the one hand, from the consumer’s perspective, domestic processing i.e. cooking improves the sensory acceptability of vegetables. On the other hand, from the food technologist’s perspective, nutrients like vitamins and phytochemicals are degraded (though bioaccessibility can increase) by various processing conditions.

An approach that integrates consumer and food technologist perspectives is necessary to have processed vegetables that are acceptable by consumers but are higher in nutrients. Therefore, the Consumer Orientated Food Technology (COFT) approach is introduced in this thesis. The COFT approach aims to redefine the ‘current’ vegetable product into a ‘new’ product that aligns with consumer sensory preferences but possesses a higher amount of nutrients.

The first objective of this thesis was to evaluate research methods: in-home observations, observations using cameras in a model-kitchen and self-reporting questionnaire for their reliability, validity and practicality for collection of data on consumer (n = 25) behaviour towards broccoli. All three methods were found to be test-retest, inter-observer, intra-observer and parallel-form reliable and face, concurrent and content valid. However, due to wide inter-individual variability in behaviour towards domestic processing of broccoli, self-reporting questionnaire was established as the most practical among these three research methods.

The second aim was to use this research method – self-reporting questionnaire – to identify consumer common motives and behaviour (domestic processing conditions) towards broccoli (n = 542) and carrots (n = 348) among Dutch study sample; and to identify consumer groups with comparable motives and behaviour. Hierarchical cluster analysis, performed separately for both vegetables, identified three groups of consumers: texture-orientated (56-59 %), health-orientated (20-30 %) and taste-orientated (8-26 %) for both vegetables.

The third aim was to study the influences of the above identified common domestic processing conditions on sensory and health attributes of broccoli and carrots. Firmness, colour and amount of phytochemicals (glucosinolates in broccoli and carotenes in carrots) were analysed instrumentally. Firmness, greenness, juiciness, flavour, sweetness, bitterness were measured on a 9-point hedonic scale and overall liking was measured on a 100 mm Visual Analogue Scale using an untrained consumer panel (n = 100). Steaming compared boiling with a cold (water) start and hot (water) start showed least losses in glucosinolates from broccoli and β-carotenes from carrots at different cooking times. It was found that for optimal liking the texture of the cooked vegetables should be in the range of medium firmness. In addition, consumers did not show any statistically significant differences in liking between steamed and boiled vegetables.

The fourth aim was to optimise the processing conditions that will yield vegetables with equal liking but with higher amount of phytochemicals. Using mathematical modelling, optimised processing conditions are proposed for consumers who cook broccoli till low firmness is achieved (soft texture). These simulations show that adapting temperature, time and amount of water used during boiling will result in at least 18 % higher amount of glucosinolates and will still give soft textured broccoli.

Smaaksegmentatie geeft richting aan productontwikkeling en marketing (interview met Wouter Verkerke, Caroline Labrie en Siet Sijtsema)
Staalduinen, J. van; Verkerke, W. ; Labrie, C.W. ; Sijtsema, S.J. - \ 2013
Onder Glas 10 (2013)12. - p. 52 - 53.
groenten - fruit - smaakonderzoek - consumentenvoorkeuren - smaakpanels - sensorische evaluatie - productontwikkeling - marketing van voedingsmiddelen - kwekers - glastuinbouw - vegetables - taste research - consumer preferences - taste panels - sensory evaluation - product development - food marketing - growers - greenhouse horticulture
De belangstelling voor gezonde en lekkere voeding groeit. Dat maakt het interessant om meer inzicht te krijgen in de smaakvoorkeuren van specifieke doelgroepen. Het Smaakteam van Wageningen UR Gastuinbouw en de afdeling Consument en Ketenonderzoek van het LEI brengen deze de komende jaren in kaart. Het project ‘Smakelijke vermarkting van gezonde groenten en fruit’ moet de opmaat worden voor consumentgerichte productontwikkeling en effectievere marketing.
Een model met een smaakje (Interview met Caroline Labrie)
Langen, E. ; Labrie, C.W. - \ 2013
Kas Magazine / TuinbouwCommunicatie 2013 (2013)4. - ISSN 1878-8408 - p. 14 - 17.
paprika - vruchtgroenten - smaak - smaakonderzoek - sensorische evaluatie - capsicum - cultivars - modellen - onderzoek - sweet peppers - fruit vegetables - taste - taste research - sensory evaluation - models - research
Over smaak valt niet te twisten. En toch gebeurt dat maar al te vaak. "Er kan oeverloos over de smaak van paprika's worden gepraat en gediscussieerd. Daarom is het belangrijk dat de smaak van paprika's geobjectiveerd wordt", vertelt Caroline Labrie van Wageningen UR Glastuinbouw. Dat kan met een smaakmodel voor paprika. De ontwikkeling hiervan is drie jaar geleden gestart. Het model moet uitkomst gaan bieden voor veredelaars, maar ook telers kunnen er hun voordeel mee doen.
Pasta highly enriched with vegetables: from microstructure to sensory and nutritional aspects
Vicente Da Silva, E.M. - \ 2013
University. Promotor(en): Erik van der Linden, co-promotor(en): Leonard Sagis; Elke Scholten; Matthijs Dekker. - S.l. : s.n. - ISBN 9789461736864 - 167
deegwaren - broccoli - voedselverrijking - reologische eigenschappen - sensorische evaluatie - voedingswaarde - pasta - food enrichment - rheological properties - sensory evaluation - nutritive value

A lifestyle that combines poor food choices with very low or no physical activity can result in the development of diseases such as obesity, and this is affecting a growing number of children. One of the most effective strategies to fight obesity combines physical activity and the consumption of low energy-dense foods, such as vegetables. Vegetables are known to have health benefits but are often non-appealing to children/adolescents due to their bitterness, undesired texture, and their low satiating capacity. One of the possible solutions to increase vegetable intake by children is to incorporate vegetables in a food matrix they like. Several studies have shown that pasta is very much appreciated by children, making it an ideal candidate for the development of vegetable-enriched foods. In this work, dried broccoli powder (BP) was used to enrich pasta-like products. We have investigated aspects that are important to sensorial properties and aspects related to possible health benefits. One aspect relevant to sensorial properties is rheology. The rheology of sweet potato starch (SPS) dough was drastically affected by high volume fractions of BP. This was caused by the swelling of the broccoli powder, up to a maximum of 7.6 times their original volume. In order to control this high swelling capacity of the particles two approaches were followed and both resulted in the prevention of particle swelling. The first was the use of hydrocolloids with high water binding capacity (e.g. xanthan gum) and the second was the use of a different matrix (durum wheat semolina (DWS)). DWS pasta did not show to be greatly affected by the incorporation of high amounts of broccoli powder. The acceptability of pasta products was assessed using a test panel. The results showed that all samples tested (0 – 30%BP) were acceptable, where 30% BP turned out to be on the limit of acceptability. Glucosinolates (GLs) are phytochemicals that are associated with the health benefits of broccoli. An increasing volume fraction of broccoli powder resulted in an increasing content of glucosinolates in dried cooked pasta. At volume fractions higher than 20% BP this effect levels off. From this work, we can conclude that as much as 20% BP can be added to DWS pasta to improve nutritional properties (in terms of GLs) while maintaining acceptable sensorial properties.

Saliva and sensory perception : interplay between the person and the food stimuli
Heinzerling, C.I. - \ 2013
University. Promotor(en): Gerrit Smit, co-promotor(en): J.H.F. Bult. - S.l. : s.n. - ISBN 9789461736505 - 132
speeksel - sensorische evaluatie - perceptie - smaak - textuur - saliva - sensory evaluation - perception - taste - texture

The perception of food is influenced by various parameters, many of them being different from individual to individual. What we perceive is not the same because each individual is different. Saliva volume and composition vary widely among people and will influence the chemical and structural composition of the food. Thus, the dilution and mixing of the food with saliva determines the extent of food-saliva interactions and connected to that also how the food item is perceived. It is clear from literature that saliva affects our perception and it is also clear that the rate and composition of salivation is dependent on what we perceive. However, it has not been clear to what extent. Since saliva can be measured objectively for each individual and it can be manipulated in a controlled fashion, more can be learned from the relationship between oral processing and perception. And with that various questions can be addressed, such as: Can the individual differences in sensory assessment be accounted for by their individual salivary composition? Is it possible to affect the sensory perception of an individual by modifying their salivary flow and composition? Different tastes stimulate different amounts of saliva but do they also affect the saliva composition? Or are the differences in saliva composition caused by the differences in salivary flow rate? Can different amounts of saliva, and thus also different dilution factors, affect the taste perception? Furthermore, can taste-taste interactions be explained by an increase in salivary flow rate? Is it possible that the increased salivation, induced by the increased thickness, will dilute the tastant and hence decrease the perceived intensity? Or are taste-texture interactions caused by cross-modal interactions? Or is the increased viscosity of the texture decreasing the concentration of taste molecules? The aim of this thesis is to show how and to what extent saliva influences, and is influenced by, taste and texture.

The addition of amylase inhibitor reduces saliva α-amylase activity and increases perceived thickness and creaminess. However, alpha-amylase activity varies widely among subjects and therefore a decreased oral α-amylase activity will not guarantee an increase in perceived thickness and creaminess of starch-based foods. Comparisons of the different tastants show that the pH of stimulated parotid saliva increases linearly, irrespective of the nature of the tastant. Protein concentration decrease and protein amount increase with increase in flow rate for all tastants. After correcting for the effect of flow rate, the protein amount is affected by the nature of the tastant with the greatest secretion after stimulation by citric acid. Flow rate is largely responsible for pH but tastant appears to play an additional role in affecting protein secretion. Significant decreases in perception with increasing salivary flow rates are observed for citric acid and sodium chloride. This can partially be explained by a dilution effect which is in line with previous studies on detectable concentration differences. However, since the bitterness and sweetness remain unaffected by the salivary flow conditions and the dilution effect is comparable to that of saltiness, further explanations are still needed.

Suppression of taste intensity in binary mixtures is not affected by the rate of salivation. This is more likely explained by psychophysics. When the taste is separated from the texture, no texture-taste effects are observed. Dilution with saliva did occur and the tastant availability was unaffected in this set-up. The conclusion is therefore that texture-taste interactions are not caused by dilution effects or cross-modal interactions but can best be explained by the release of tastants.

The work described in this thesis shows how the individual perception can be affected by the salivary flow and composition and how the individual salivary flow and composition can be affected by the sensory stimuli taste and texture.

Towards global experimental design using Bayesian networks : case studies on modeling sensory satiation
Phan, V.A. - \ 2013
University. Promotor(en): Tiny van Boekel; U. Garczarek, co-promotor(en): Matthijs Dekker. - [S.l.] : s.n. - ISBN 9789461735379 - 156
sensorische evaluatie - verzadigdheid - bayesiaanse theorie - proefopzet - wiskundige modellen - modelleren - sensory evaluation - satiety - bayesian theory - experimental design - mathematical models - modeling

Food science problems are complex. Scientists may be able to capture more of the complexity of an investigated theme if they were able to integrate related studies. Unfortunately, individual studies are usually not designed to allow such integration, and the common statistical methods cannot be used for analyzing integrated data. The modeling technique of Bayesian networks has gained popularity in many fields of application due to its ability to deal with complexity, but has emerged only recently in food science. This thesis used data from experiments on sensory satiation as case studies. The objective was to explore the use of Bayesian networks to combine raw data of independently performed but related experiments to build a quantitative model of sensory satiation.
Methods
This thesis started with introducing the theoretical background of Bayesian networks to food science. The available data from various independent experiments on sensory satiation were then examined for their potential to be combined. Finally, the outcomes obtained using Bayesian networks on a single dataset were compared with the published outcomes of the respective study, in which classical statistical procedures were used to analyze the data.
Results
Two hurdles were identified when combining the data of related studies that were performed independently and without the intention of combining their data. The first hurdle was a lack of essential information for reliable estimations of parameters of the combined model network. This information could be obtained by deriving it from existing information in the individual studies or by performing extra experiments; these practices are, however, not always possible. The second hurdle was a possible conflict in causal relationships underlying the individual experimental designs, which can cause misleading analyses of the combined dataset. This was the case for some experiments that involved the control of secondary explanatory variables. As such, an approach termed as Global Experimental Design was proposed in this thesis as a solution to overcome these hurdles. This approach emphasizes the building of an overall network prior to designing individual studies.
In comparison to using the classical statistical procedures, more information can be extracted using Bayesian networks. This technique could make use of the domain knowledge in a transparent manner as well as empirical data with missing values.
Conclusions
It is possible to combine raw data from related studies for a meaningful analysis if effort is made in the phase of experimental design. The approach of Global Experimental Design outlines this phase with the building of an overall network. By using Bayesian networks as a tool for exploratory analysis, scientists are able to gain more insights into a research domain.

Minder zout in brood goed mogelijk (interview met Anke Janssen)
Rees, B. van; Janssen, A.M. - \ 2012
Voedingsmiddelentechnologie 2012 (2012)14/15. - ISSN 0042-7934 - p. 24 - 25.
brood- en bakkerijproductenindustrie - zout - natriumchloride - zoutgehalte - inname - voeding en gezondheid - sensorische evaluatie - bakery industry - salt - sodium chloride - salinity - ingestion - nutrition and health - sensory evaluation
Terwijl minister Schippers de industrie het vuur aan de schenen legt om tot een stevige zoutreductie te komen, wisten de bakkers de afgelopen jaren het zoutgebruik al flink te beperken. Tijdens een workshop van Food & Nutrition Delta, RIVM, TNO en Wageningen UR bleek dat het zoutgebruik in brood nog verder is te verlagen. De meeste deelnemende bakkers zagen een verdere zoutreductie op termijn als een reële optie
Extending crispness : a systematic approach to controlling water migration in bread
Hirte, A. - \ 2012
University. Promotor(en): Rob Hamer, co-promotor(en): C. Primo-Martin. - S.l. : s.n. - ISBN 9789461733139 - 142
brood - water - migratie - sensorische evaluatie - organoleptische kenmerken - bread - migration - sensory evaluation - organoleptic traits

Crispness is one of the most important sensory characteristics of crispy bread, because consumers associate crispness with freshness, wholesomeness, and quality. This sensory sensation, however, is lost within a few hours after baking, because of a fast water uptake of the crust. Therefore, the aim of this thesis was to systematically determine the mechanisms that lead to the fast loss of crispness and to reveal the parameters that are key for crispness retention. We showed that the crust acts as a barrier for water migration, causing water accumulation in the crust. Reducing this barrier property by increasing the water vapor permeability of the crust to an optimal value of 8 × 10–9 g/(m s Pa) resulted in breads with crispness retention that was more than eight times longer. These breads had either channels or cracks in their crust. Despite the changes of the crust properties, these breads had similar crumb softness retention compared to standard breads. The properties of the crumb also affected the water uptake of the crust, but less so than the properties of the crust. Bread containing a crumb with a lower water vapor permeability had a significantly longer crispness retention. Based on these findings, we propose a model that provides a comprehensive view of crispness loss and concluded that the increase in crust permeability is the best way to create breads with a noticeably longer crispness retention.

Cross-modal interactions in complex food matrices
Knoop, J.E. - \ 2011
University. Promotor(en): Gerrit Smit, co-promotor(en): Markus Stieger; J.H.F. Bult. - [S.l.] : S.n. - ISBN 9789461730367 - 218
sensorische evaluatie - perceptie - zintuigen - smaak - aroma - appelsap - kazen - zout - caloriearm voedsel - sensory evaluation - perception - senses - taste - apple juice - cheeses - salt - low calorie foods

In the light of increasing rates of nutrition related diseases, such as obesity, diabetes, high blood pressure and stroke it is necessary to reduce sugar, salt and fat contents of industrial produced food. Reduction of those components generally leads to changes of the sensory properties of the products and rejection by the consumer. Traditional compensation strategies like the use of taste enhancers, artificial sweeteners or fat replacers often lead to off-flavours and consequently to consumer rejection. This thesis describes cross-modal interactions as an alternative strategy to reduce sugar, salt and fat. In the past cross-modal interactions have been describe to influence taste and texture perception, however up to now research focused on simple model systems lacking in perceptual, as well as chemical complexity. This thesis aimed on the application of cross modal interactions involving aroma modification to complex food systems, such as apple juice and cheese. It was investigated whether aromas are able to modify taste perception in complex food matrices and what the driving factors are to which extend aromas can enhance taste perception. Furthermore different cross modal approaches were combined in order to investigate possible additive or synergistic effects on taste enhancement.

At first, the question whether individual aroma components can be identified that have the capacity to enhance taste perception in a complex beverage was addressed [chapter 2]. Apple juice was choosen to represent a complex matrix where interactions between taste and aroma are a natural product characteristic. Ethylhexanoate was identified to significantly enhance sweetness in apple juice, while three other esters selected on the same basis did not show sweetness enhancement. Ethylhexanoate induced sweetness enhancement appeared to be concentration dependent. Concentrations of 5 ppm were found to be most effective to enhance sweetness in this specific system. However, next to sweetness undesired attributes such as flowery and synthetic were also increased significantly. As a conclusion it has to be noticed that flavour balance in complex food is fragile and has to be carefully altered in order to use odour induced taste enhancement as a tool in sugar, salt and fat reduction. Chapter 3 describes the masking of off-flavours induced by ethylhexanoate as described in chapter 2. It was hypothesised that ethylhexanoate induced off-flavours can be masked by restoring flavour balance by equally adding combinations of all four esters. A combination of ethylhexanoate, ethylbutanoate and ethyl-2-methylbutanoate was found to be most effective to restore flavour quality while maintaining ethylhexanoate induced sweetness enhancement. It was concluded that all components that are naturally part of an aroma are needed to achieve a balanced product.

Optimisation of odour presentation time in order to achieve maximum taste enhancement was subject to the study described in chapter 4. Swallowing is the key to aroma release during food consumption. It was demonstrated that aroma is most presented most effectively either 1.7 – 2.5 seconds before or 2.6 – 3.6 seconds after the moment of swallow. Aroma presented directly at the moment of swallow was found to be least effective to enhance taste. It is assumed that olfactory receptor neurons (ORN) do not transmit the activation signal to the brain at the exact moment of swallow in order to spare energy and function most effective, as during normal food consumption the aroma is released shortly after swallowing. This hypothesis was further tested in an fMRI study. Preliminary results support this theory, however at the moment of completion of this thesis data evaluation was still in progress.

In chapter 5 further optimisation of odour/taste interactions was studied, by investigating the influence of temperature on odour induced taste enhancement. Consumption temperatures differ strongly among products. As aroma release strongly depends on the temperature of the food, it was hypothesised that the magnitude of aroma effects on taste perception changes over consumption temperature. Subjects consumed a sweet and a savoury system at four different temperatures (7, 25, 37 and 50°C). Stimuli temperature and odour presentation were fully controlled by temperature optimised gustometry and olfactometry. Both aroma/taste systems were known to have induced taste enhancement in the past (sweet: apple flavoured tea/ethylhexanoate; savoury: broth/sotolon). No significant effect of temperature was found for either of the stimulus pairs. Results indicate that the complexity of the experiment led to confusion by the panelists under fully randomised stimuli delivery conditions. It was therefore concluded, that temperature effects on the magnitude of odour induced taste enhancement need to be studied in a reduced experimental design.

Temporal contrast as a strategy to enhance salty taste was studied in the experiments described in chapter 6. Salty solutions of different NaCl concentrations were presented in alternating sequence by a gustometer, creating a sensory contrast of low-in salt and high-in salt pulses. It was demonstrated that the sensory contrast induced by the pulsed delivery led to significant taste enhancement. It was shown that high concentrations of NaCl delivered in short pulses were most effective to enhance salty taste. It was concluded that pulsed stimulus delivery can be an additional tool to reduce salt and sugar concentrations in industrial produced food. Chapter 7 combines both cross-modal strategies to enhance taste in this thesis so far, odour induced taste enhancement and temporal contrast of stimulus delivery. Subjects were presented with taste and aroma pulses timed via a gustometer. The aroma was either presented in-phase or out-of-phase with the taste stimulus. A cumulative effect of aroma/taste interactions and temporal contrast of tastant delivery was found, resulting in higher taste enhancement than each of the strategies alone. Overall highest sweetness enhancement was observed when aroma and taste pulses were presented out-of-phase.

Texture modification is a third cross-modal strategy to enhance taste perception. Combinatory effects of texture modification and odour induced taste enhancement are subject to the study reported in chapter 8. Apple juice containing gels were engineered differing in textural properties, aroma and sugar concentration. In contrast to the results presented in chapter 7, only an additive but no synergistic effect was found for those strategies. Texture modification was found to be more effective than aroma modification.

Chapter 9 studies effects of aroma on the taste and the texture of cheese and dairy model gels. In the first study subjects consumed different types of cheese with and without a nose-clip. This way the contribution of the aroma phase on the flavour and texture perception of cheese was studied. Saltiness was influenced significantly by the aroma. It was concluded that the aroma of cheese strongly contributes to a cheeses salty taste. Furthermore it was observed that a decrease in cheese firmness strongly correlated with an increase in buttery aroma notes. This was further studied in fully controlled dairy model gels. For gels tasting of cream cheese a significant decrease in firmness was found upon increasing aroma concentration. No effect of butter aroma on firmness was found for yoghurt-like gels. This once more demonstrates the importance of congruency between stimuli. Only congruent sensory impressions can influence each other. In addition, an increase in creaminess was observed with increasing aroma concentration. The results described in chapter 9 clearly show that aromas cannot only modify taste perception, but also are a valid tool for texture modification.

This thesis demonstrates for the first time, that flavour and texture modification and subsequently the reduction of sugar, salt and (possibly also) fat can be achieved by using cross modal interactions in complex food matrices. New methods have been developed and existing methods have been combined to study aroma/taste interactions in fully controlled settings. Its multidisciplinary approach combines chemical, physical and psychological knowledge in order to discuss and explain results. It furthermore shows that combinations of different strategies are most effective in order to achieve healthier products reduced in sugar, salt and fat.

Routinematige meting smaak tomaat
Verkerke, W. - \ 2011
sensorische wetenschappen - sensorische evaluatie - smaak - tomaten - kennismodellering - meetinstrumenten - sensory sciences - sensory evaluation - taste - tomatoes - knowledge modeling - indicating instruments
Informatieposter over routinematige meting van de smaak van tomaat
Groot onderzoek naar herformulering : nieuwe receptuur : nu nog gezonder
Raaij, J.M.A. van; Hendriksen, M. ; Janssen, A.M. ; Noort, M. ; Temme, E.H.M. - \ 2010
Voedingsmiddelentechnologie 43 (2010)24. - ISSN 0042-7934 - p. 10 - 11.
voedingsmiddelen - zout - vetconsumptie - reductie - smaak - sensorische evaluatie - volksgezondheid - bescherming van de consument - houding van consumenten - voeding en gezondheid - foods - salt - fat consumption - reduction - taste - sensory evaluation - public health - consumer protection - consumer attitudes - nutrition and health
Hoe maak je een voedingsmiddel dan minder zout, suiker of vet bevat, maar nog net zo lekker smaakt als het origineel? Wageningen UR, het RIVM en TNO zoeken gezamenlijk naar mogelijkheden om bestaande voedselproducten te herformuleren. Voor de industrie een uitdaging, voor de consument een goede keuze en voor de volksgezondheid winst.
Food texture and food intake : the role of oral sensory exposure
Zijlstra, N. - \ 2010
University. Promotor(en): Kees de Graaf, co-promotor(en): Monica Mars; Rene de Wijk. - [S.l. : S.n. - ISBN 9789085856665 - 168
voedselopname - eetlustcontrole - textuur - viscositeit - sensorische evaluatie - voedingsfysiologie - eetsnelheden - food intake - appetite control - texture - viscosity - sensory evaluation - nutrition physiology - eating rates
Background and objective: In view of the growing epidemic of obesity, it is important to investigate factors which influence food intake. Food texture has been shown to play a role in food intake regulation but underlying explaining mechanisms are unknown. The aim of this thesis was to determine the effect of food texture on satiation (assessed as ad libitum food intake) and to investigate the mediating role of oral sensory exposure and gastro-intestinal physiology in this effect.
Methods: We started by investigating the effect of food viscosity on ad libitum food intake (n=108). Next, we investigated whether the effect of viscosity could be related to eating effort and/or eating rate (n=49) or to the release of the gastro-intestinal hormones ghrelin, CCK and GLP-1 (n=33). To further explore the role of oral sensory exposure, we investigated the effect of changing bite size and oral processing time of a semi-solid food on satiation (n=22), and the effect of changing food texture of three pairs of solid foods on satiation (n=106). Finally, we observed eating behavior and retro-nasal aroma release in normal weight and overweight subjects (n=54).
Results: Viscosity of food had a clear effect on food intake; increasing viscosity significantly decreased ad libitum food intake and the difference in intake between the liquid and semi-solid product ranged from 29% to 34% in different settings. Eating rate played an important role; the liquid product was consumed significantly faster than the semi-solid product and a standardized eating rate led to similar intakes of these products. The selected gastro-intestinal hormones could not explain the effect of viscosity on food intake; a fixed amount of the liquid and semi-solid test product resulted in a similar response of the hormones. Food intake of a semi-solid food was significantly less when oral processing time was fixed to 9 s compared to 3 s (on average a difference of 42 g) and when consumed with fixed small bite sizes (≈ 5 g) compared to large bite sizes (≈ 15 g) (on average a difference of 106 g). Differences in food texture of solid foods, aimed to change oral processing time, did not affect food intake. Texture differences were probably too subtle to lead to differences in eating rate and subsequently to differences in food intake. Significant positive associations between food intake and eating behaviors such as eating rate and bite size were observed. Small to no differences in eating behavior and retro-nasal aroma release were found between normal weight and overweight subjects.
Conclusion: The results of this thesis show that food viscosity has a direct effect on food intake. Oral sensory exposure plays a major role in this since changing eating rate, oral processing time and bite size affected food intake. These factors contribute to the effect of food texture on food intake. In addition, eating rate and bite size were characteristics of the eating style of an individual.
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