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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    Clustering of oil droplets in o/w emulsions enhances perception of oil-related sensory attributes
    Fuhrmann, P.L. ; Kalisvaart, Laura ; Sala, G. ; Scholten, E. ; Stieger, M.A. - \ 2019
    Food Hydrocolloids 97 (2019). - ISSN 0268-005X
    o/w emulsions - Sensory perception - Oil droplet clustering - creaminess - Saliva - Lubrication
    The sensory perception of o/w emulsions is determined by their structure and physicochemical properties. The aims of this study were (a) to determine the influence of oil droplet clustering in o/w emulsions on sensory perception and (b) to link their sensory attributes to rheological, tribological and structural properties. Clustered emulsions were prepared by combining o/w emulsions stabilised by different sets of emulsifiers: (a) positively-charged gelatine and negatively-charged whey protein (WPI), and (b) positively-charged gelatine and negatively-charged diacetyl tartaric acid ester of mono- and diglycerides (DATEM). Oil droplet clusters ranging in diameter from 1 to 50 μm were obtained. The difference in charge density between gelatine- and DATEM-stabilised oil droplets was higher than that between gelatine- and WPI-stabilised droplets. This difference allowed to alter the interaction strength within oil droplet clusters. The sensory perception of clustered emulsions was quantified using the Rate-All-That-Apply (RATA) methodology with untrained subjects (n = 83). Participants assessed o/w emulsions varying in cluster size (1 μm–50 μm), cluster strength (tuned by changing the emulsifier-pairs), and single droplet emulsions with and without adjusted viscosity, as well as a reference emulsion with large single droplets (comparable in size to emulsions with large clusters). Creaminess and thickness intensities were significantly higher for clustered o/w emulsions compared to that of single droplet o/w emulsions with the same oil content and similar oil droplet/cluster size. With increasing cluster size, creaminess and thickness intensities increased significantly for hetero-aggregated clusters with weak interactions (gelatine-whey protein). When cluster interactions were stronger (gelatine-DATEM), creaminess intensity increased to a lesser extent and grittiness intensity increased considerably. Thickness and creaminess were strongly correlated to the rheological (e.g. consistency) and tribological properties (e.g. fiction coefficient at 10 mm/s) of o/w emulsions with clustered oil droplets. Grittiness and fattiness were strongly correlated to the tribological properties (slope of mixed regime) of o/w emulsions and their interactions with saliva. We conclude that clustering of oil droplets in o/w emulsions by hetero-aggregation allows to enhance the sensory perception of fat-related attributes by tuning rheological and tribological properties, and provides an effective method to structure liquid foods to obtain specific sensory properties.
    Effect of microparticulated whey protein on sensory properties of liquid and semi-solid model foods
    Liu, K. ; Stieger, M.A. ; Linden, E. van der; Velde, Fred van de - \ 2016
    Food Hydrocolloids 60 (2016). - ISSN 0268-005X - p. 186 - 198.
    MWP - lubrication - Particle size - creaminess - roughness - sensory
    This work describes the sensory properties of microparticulated whey protein (MWP) particles in relation to their rheological and tribological properties. The aim of this work is to obtain a better understanding of the sensory perception of MWP particles compared to oil droplets in liquid and semi-solid matrices. We used liquid MWP-o/w emulsions with controlled viscosities and semi-solid MWP-emulsion-filled gelatin gels as food model systems. Consistent with our previous findings, MWP showed good lubrication properties probably due to ball bearing mechanism in both liquid and semi-solid systems. Sensory results (QDA) revealed that small MWP particles contributed to perception of creaminess due to their lubrication property. Large MWP contributed to the rough and powdery perception, and thus suppressed perception of creaminess. MWP did not contribute to perception of fattiness in contrast to oil droplets. The perception of fattiness was probably related to the film formation properties of oil. As a result, MWP in liquid emulsions were generally perceived as rough but not creamy. In the case of MWP-emulsion-filled gels, although the gel matrix restrained the lubrication function of MWP particles, it also masked the rough perception of big MWP particles. Due to the combined effect of both oil droplets and MWP particles, MWP in gels resulted in an overall positive effect on the creamy perception. We conclude that MWP contributes to fat-related sensations in a different way than oil does. The perception of MWP particles is related to the size of the particle as well as the properties of the surrounding matrix.
    Textural perception of liquid emulsions: Role of oil content, oil viscosity and emulsion viscosity
    Aken, G.A. van; Vingerhoeds, M.H. ; Wijk, R.A. de - \ 2011
    Food Hydrocolloids 25 (2011)4. - ISSN 0268-005X - p. 789 - 796.
    in-water emulsions - sensory perception - stabilized emulsions - oral conditions - food emulsions - saliva - flocculation - polysaccharide - dispersions - creaminess
    This work describes a study on the in-mouth textural perception of thickened liquid oil-in-water emulsions. The variables studied are oil content, oil viscosity, and the concentration of polysaccharide thickener. Gum arabic was chosen as the thickener because of the nearly Newtonian behavior of its solutions and special care was taken to suppress aroma clues. Based on the experimental results and findings from previous studies, this work shows that the emulsion droplets influence textural sensory perception of liquid emulsions by three main mechanisms, each of which relate to changes in specific sensory attributes, and none of which were found to be significantly dependent on the viscosity of the oil: 1) by increasing the viscosity, 2) by becoming incorporated in the mucous oral coating, and 3) by spreading oil at the oral surfaces. Based on these results, the possibility for replacement of emulsified fat by a polysaccharide thickener is evaluated.
    Relating the effect of saliva-induced emulsion flocculation on rheological properties and retention on the tongue surface with sensory perception
    Vingerhoeds, M.H. ; Silletti, E. ; Groot, J. de; Schipper, R.G. ; Aken, G.A. van - \ 2009
    Food Hydrocolloids 23 (2009)3. - ISSN 0268-005X - p. 773 - 785.
    oil-in-water - custard desserts - alpha-amylase - oral texture - creaminess - protein - tannin - model - viscosity - lysozyme
    Perception of food emulsions can often not be directly related to the structure of the products before consumption. Taking into account the changing product structure upon oral processing might increase understanding of the relation between perception and product properties. This study aims to gain insight in the effect of saliva-induced flocculation on perception of emulsions at neutral pH. Whey protein (WPI)-stabilized emulsions flocculating in a reversible manner with saliva were compared with lysozyme-stabilized emulsions that irreversible flocculate with saliva. The main emulsion variables, besides the emulsifying protein, were oil content (2.5% oil vs 10% oil), and the effect of emulsion thickening with guar gum (at 10% oil). To relate perception to processes occurring in the oral cavity, the emulsions were characterized before and after oral processing with respect to morphology and rheological properties (viscosity, storage and loss moduli). In addition, insight in retention of emulsion droplets on the tongue surface was obtained by measuring emulsifier and oil content in tongue swabs. Saliva-induced emulsion flocculation clearly shows a large effect on perception of the here studied emulsions. WPI-stabilized emulsions showed little retention on the tongue surface and perception was characterized by creaminess, fattiness and thickness. Guar gum thickening further increased perception of these attributes. On the other hand, for lysozyme-stabilized emulsions perception was largely related to attributes like dryness, roughness and astringency. In addition, a large viscosity increase upon oral processing and clear retention of emulsion droplets on the tongue surface was observed. Guar gum thickening decreased the effects of irreversible flocculation, likely because of its lubricating properties and increased viscosity. Although the amount of mucins recovered from the tongue surface was unaffected by orally processing of lysozyme-stabilized emulsions, the sensory characteristics of these emulsions reminds one of astringency perception of e.g. tannins that precipitate salivary proteins.
    Modelling oral conditions and thickness perception of a starch product
    Heinzerling, C.I. ; Smit, G. ; Dransfield, E. - \ 2008
    International Dairy Journal 18 (2008)8. - ISSN 0958-6946 - p. 867 - 873.
    alpha-amylase - flavor perception - custard desserts - saliva flow - texture - viscosity - release - creaminess - behavior - taste
    Food components stimulate salivation, and the flow and composition of the saliva also affect the perception of the food product. In starch-containing foods, salivary ¿-amylase breaks down the starch and this may cause thinning in semi-solid foods. The aims were to determine the importance of salivary composition to perceived thickness. Vanilla custard was assessed for taste intensity, creaminess and thickness. To extend the range of saliva composition and flow, an ¿-amylase inhibitor was added to the samples at different concentrations and the pH of the samples was lowered by adding citric acid. From each collected spat-out bolus, temperature, pH, dilution factor and ¿-amylase activity were measured. Addition of amylase inhibitor reduced saliva ¿-amylase activity and increased perceived thickness and creaminess. Acidification increased mechanical thickness prior to testing and perceived thickness but did not reduce the in situ ¿-amylase activity because the saliva stimulated by acidified custards was also more concentrated in ¿-amylase. Alpha-amylase activity varied widely among subjects and so decreasing oral ¿-amylase activity would not guarantee an increase in perceived thickness and creaminess of starch-based foods.
    Application of oral tissue in tribological measurements in an emulsion perception context
    Dresselhuis, D.M. ; Hoog, E.H.A. de; Cohen Stuart, M.A. ; Aken, G.A. van - \ 2008
    Food Hydrocolloids 22 (2008)2. - ISSN 0268-005X - p. 323 - 335.
    in-water emulsions - dairy-products - human tongue - lubrication - creaminess - behavior - chocolate - texture - cavity - saliva
    Tribological measurements are indicated to be a tool in predicting the creamy in-mouth sensation of a food product. Tribological measurements relating lubricational behaviour of a food product to perception are often conducted with artificial surfaces. In this work we used pig's tongue to mimic the human tongue, which has the advantage of having surface characteristics similar to a human tongue. Using biological material has also some drawbacks. The most important drawbacks are the limited availability, the individual differences between the tongues, and the relative fast degradation of the tissue. The aim of this study was to identify the characteristics of the tongue in terms of surface roughness, deformability and wetting properties. The knowledge on these characteristics can serve as reference when using modified poly dimethyl siloxane (PDMS) in tribological experiments relating perception to in-mouth friction. Furthermore, we demonstrated that these characteristics are crucial in tribological studies to draw rightful conclusions. Tribological measurements were performed with an experimental set-up combining friction measurement with confocal scanning laser microscope (CSLM) observations. We identified the importance of these characteristics for tribology measurements performed in relation to sensory perception. It is shown that the tongue surface has some very typical characteristics, including the presence of papillae and a hydrophilic mucus layer, and an elastic modulus that is at least two orders of magnitude smaller than that of smooth PDMS surfaces. The different surface characteristics appear to lead to completely different lubricational behaviour of the food emulsions between these surfaces. Furthermore, for food emulsions differences in the occurrence of coalescence were found between shearing with pig's tongue and PDMS surfaces. Therefore, we conclude that for studies relating sensory properties of food systems to lubricational behaviour, a careful choice of representative surfaces is essential and that modification of smooth PDMS can result in surfaces having characteristics closer to tongue tissue
    Relations between rheological properties, saliva-induced structure breakdown and sensory texture attributes of custards
    Janssen, A.M. ; Terpstra, M.E.J. ; Wijk, R.A. de; Prinz, J.F. - \ 2007
    Journal of Texture Studies 38 (2007)1. - ISSN 0022-4901 - p. 42 - 69.
    perceived oral texture - semisolid foods - flow properties - alpha-amylase - fluid foods - perception - model - viscosity - mayonnaise - creaminess
    The relevance of initial rheological properties and mechanical and enzymatic structure breakdown in determining selected sensory texture attributes of custards was studied. The so-called structure breakdown cell was used to characterize saliva-induced breakdown, i.e., by monitoring digestion of starch by amylase from saliva. Based on rheological parameters, some attributes could be predicted well, while others more poorly or were not predicted. Predictable attributes were primarily determined by bulk properties; poorly and nonpredictable attributes originated from properties of the outer low-viscosity surface layers or were not related to rheological properties. Both mechanical and enzymatic breakdown were important for creaminess, thickness and melting. Enzymatic breakdown was the dominant mechanism involved in the perception of fattiness, roughness and stickiness but not heterogeneity. Creaminess was the only attribute that was also determined by initial rheological properties and mechanical and enzymatic breakdown. Custards displaying high creaminess ratings had high initial stiffness, the structure broke down at low stress and enzymatic breakdown was slow. Microstructural organization of starch plays a dominating role in defining rheological and breakdown behavior of custards and in this way determines creaminess to a high extent.
    Lubrication of oral surfaces by food emulsions: the importance of surface characteristics
    Hoog, E.H.A. de; Prinz, J.F. ; Huntjens, L. ; Dresselhuis, D.M. ; Aken, G.A. van - \ 2006
    Journal of Food Science 71 (2006)7. - ISSN 0022-1147 - p. E337 - E341.
    perception - creaminess - viscosity - shear - model
    The friction between surfaces in relative motion lubricated by food emulsions has been measured. Different types of surfaces were tested, including metal, glass, rubber, and mucosal surfaces (pig tongue and pig esophagus). We demonstrate that the load-dependent behavior of the coefficient of kinetic friction was different for various types of surfaces used; it decreased with increasing load for the mucosal surfaces, but that was constant for glass metal surfaces. We show that this difference is an effect of the roughness and the deformability of the surfaces. For mucosal surfaces, the friction force did not depend on the oil fraction in the measured range of 10% to 40% (w/w). Further more, 3 commercial dairy products were tested between these surfaces. The lubrication properties of low fat (1.5% fat content) and high-fat (3.5% fat content) milk were comparable to those of the model emulsions. However, the friction force of the commercial cream (3.5% fat content) was found to be much lower.
    Sensory sub-attributes of creamy mouthfeel in commercial mayonnaises, custard desserts and sauces
    Weenen, H. ; Jellema, R.H. ; Wijk, R.A. de - \ 2005
    Food Quality and Preference 16 (2005)2. - ISSN 0950-3293 - p. 163 - 170.
    least-squares regression - semi-solids - texture - creaminess - liquid - perception - acceptance - foods
    The sensory components of creamy mouthfeel in commercial mayonnaises, custard desserts and sauces were determined, using multi-variate analysis of the mean sensory ratings obtained from a quantitative descriptive analysis (QDA) panel. Creamy is a particularly interesting attribute, as it is generally well correlated with consumer preference. Texture attributes which were found to contribute positively to creamy mouthfeel included thick, airy, smooth and fatty mouth- or afterfeel, negative contributions were found for rough, heterogeneous, grainy and melting mouth- or afterfeel. Odour (assessed before ingestion) and non-texture trigeminal attributes had little or no effect on creamy mouthfeel, taste/flavour attributes (assessed while the product is in the mouth) did affect creamy mouthfeel, in some cases positively (caramel flavour) and in some cases negatively (broth and cheese flavour). The use of noseclips or the addition of a flavouring substance, confirmed that olfactory cues and/or intranasal sensations have an effect on creamy mouthfeel
    Texture of semi-solids: sensory and instrumental measurements on vanilla custard desserts
    Wijk, R.A. de; Gemert, L.J. van; Terpstra, M.E.J. ; Wilkinson, C.L. - \ 2003
    Food Quality and Preference 14 (2003)4. - ISSN 0950-3293 - p. 305 - 317.
    influence food flavor - perception - emulsions - creaminess
    A trained panel developed a set of sensory attributes describing flavor, odor, mouth feel and after feel sensations elicited by commercially available vanilla custard desserts. Two main sensory dimensions, one running from "melting" to "thick" and another one running from "rough" to "creamy-soft" could be recognized in the resulting sensory space. The commercial custard desserts were well distributed along the rough-creamy dimension but not along the melting-thick dimension. In a second study, model custards were used that varied in levels and type of thickener (carrageenan and starch) and fat content. This resulted in a better distribution of the custard desserts across the sensory space, and in a confirmation of the two main sensory dimensions. The melting-thick dimension was primarily related to thickener content and to the viscosity measured instrumentally. The rough-creamy/soft dimension was primarily related to fat content. High fat custards produced less sensations of dryness and roughness, more sensations of flavor, and more sensations of creamy and fatty mouth and after feel than their zero-fat containing counterparts. This was confirmed by PLS modeling that showed a good prediction of creamy/soft mouth feel sensations from a combination of flavor/taste sensations (creamy and fatty flavors and absence of bitter/chemical and sickly flavors), mouth feel sensations (thickness and fattiness) and after feel sensations (fatty coating and absence of roughness). It is argued that possible mechanisms by which fat affects the attributes that are part of this dimension include lubrication (friction) and flavor release. (C) 2003 Elsevier Science Ltd. All rights reserved.
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