Dynamic texture perception and oral processing of semi-solid food gels: Part 1: Comparison between QDA, progressive profiling and TDS
Devezeaux de Lavergne, M.S.M. ; Delft, J.M. van; Velde, F. van de; Boekel, M.A.J.S. van; Stieger, M.A. - \ 2015
Food Hydrocolloids 43 (2015). - ISSN 0268-005X - p. 207 - 217.
emulsion-filled gels - sensory texture - rheological properties - mechanical-properties - temporal dominance - time - microstructure - sensations
Texture perception of food is a dynamic phenomenon depending on food properties and oral processing. Several sensory techniques enable to measure texture perception over time. The aim of this study was to compare quantitative descriptive analysis (QDA), temporal dominance of sensation (TDS) and progressive profiling in the assessment of dynamic texture of emulsion filled gels varying in fracture stress (low/high), fracture strain (low/high) and oil release (oil droplets bound/unbound to the gel matrix). The QDA results revealed that the variation of mechanical properties led to significant differences in texture properties perceived at first bite (firmness and brittleness). Texture attributes perceived at later stages of mastication showed significant differences between gels depending on the first bite properties e.g. soft gels were perceived as more melting. Progressive profiling showed that creaminess increased over eating time while firmness decreased. TDS results were in agreement with the other methods and additionally conveyed information on the succession of perceived attributes over time. The TDS sensory trajectories demonstrated that for all gels dynamic perception evolved in a similar fashion but samples with a high or low fracture strain differed at the end of oral processing. We conclude that texture perception of semi-solid gels is dynamic and can be measured by either of the three sensory methods. The mechanical properties of the gels influence the perception of texture attributes at first bite and at later stages of mastication. QDA, TDS and progressive profiling gave matching and complementary results in the assessment of dynamic sensory texture.
Fat droplet characteristics affect rheological, tribological and sensory properties of food gels
Liu, K. ; Stieger, M.A. ; Linden, E. van der; Velde, F. van de - \ 2015
Food Hydrocolloids 44 (2015). - ISSN 0268-005X - p. 244 - 259.
emulsion-filled gels - oil droplets - lubrication properties - texture-perception - matrix interaction - solid foods - microrheology - coalescence - particles - behavior
This work aims to investigate the effect of fat droplet characteristics in emulsion-filled gels on their dynamic rheological, tribological and microstructure properties during breakdown, and their sensory perceptions. Fat droplet characteristics investigated were the interaction of the fat droplet with the gel matrix (modulated by using different emulsifiers to yield droplets being either bound or unbound to the matrix) and the solid fat content (SFC, varying from 4% to 48%). Fat content was varied from 0% to 20%. Elastic modulus and fracture properties of these gels (determined under uni-axial compression) were affected by droplet–matrix interaction, fat content, and SFC. A mouth-mimicking tribometer connected to a CLSM was used to determine tribological properties (friction) and microstructural evolution (fat coalescence) of gels under shear. Gels with unbound droplets led to more coalescence (than bound) and increased fat content also led to more coalescence. The observed increase in fat coalescence related to a decrease in friction, which was also related to an enhancement of the perception of fat-related sensory attributes (determined by quantitative descriptive sensory analysis). The effects of unbound droplets and higher fat content on increasing coalescence and decreasing friction were further enhanced by increasing SFC. Having found that decrease in friction and increase in coalescence relates to an enhancement of perception of fat-related attributes, one would expect that increasing SFC would further enhance the perception of fat-related attributes. This was not found. We attribute this to the fact that our systems are gels that have complicated breakdown behavior.
Microstructure, texture and oral processing: New ways to reduce sugar and salt in foods
Stieger, M.A. ; Velde, F. van de - \ 2013
Current Opinion in Colloid and Interface Science 18 (2013)4. - ISSN 1359-0294 - p. 334 - 348.
proteins/polysaccharide mixed gels - viscoelastic model foods - cheddar cheese texture - emulsion-filled gels - sensory perception - flavor release - pulsatile stimulation - complex coacervation - spatial-distribution - temporal perception
Food oral processing as the bridge between food texture, microstructure and sensory perception has gained enormous interest in the last decade. This review provides an overview of the role of the microstructure of soft- and semi-solid foods in food oral processing and sensory perception. Phase separated mixed protein polysaccharide gels and emulsion-filled gels are described as suitable model foods to investigate food oral processing systematically. Special attention is given to the sensory perception of texture, taste and interactions thereof. Several approaches to reduce the salt and sugar content of semi- and soft-solid foods without compromising taste are reviewed. These reduction approaches are based on an understanding of food oral processing in relation to the microstructure of the foods and its breakdown. (c) 2013 Elsevier Ltd. All rights reserved.
Time to first fracture affects sweetness of gels
Sala, G. ; Stieger, M.A. - \ 2013
Food Hydrocolloids 30 (2013)1. - ISSN 0268-005X - p. 73 - 81.
emulsion-filled gels - sugar - perception - fat - deformation - preferences - texture - flavor - impact - foods
The aim of this study was to investigate the influence of the breakdown behaviour on sweetness intensity of gelled model foods. Emulsion-filled gelatine/agar gels varying mainly in fracture strain (eF) were used. The fracture strain was modified by changing either the ratio between gelatine and agar concentration or the size of the oil droplets embedded in the gel matrix. The sugar content of all gels was kept constant at 6 wt%. The fracture strain of the gels varied between eF = 37% and eF = 72%. The number of gel fragments (n) obtained after uniaxial compression of a gel specimen increased with decreasing fracture strain from n = 10 (eF = 72%) to n = 200 (eF = 37%). A quantitative descriptive analysis sensory study revealed that the sweetness intensity perceived after firstfracture of the gel in the mouth was higher for gels with lower fracture strain. The sweetness intensity of the most brittle gel (Isweet = 65; eF = 37%) was almost twice as high as the sweetness intensity of the least brittle gel (Isweet = 36; eF = 72%). In addition, the panelists determined the time after which the maximum sweetness intensity was perceived (tmax). The maximum sweetness intensity of brittle gels was perceived after tmax = 6 s (eF = 37%), whereas for less brittle gels the maximum sweetness intensity was perceived after tmax = 15 s (eF = 72%). The temporal evolution of sweetness intensity after the maximum sweetness intensity was comparable for all gels. The results suggest that the velocity of formation of new surfaces of the food in contact with the taste buds influences sweetness intensity in addition to the total surface which is generated during breakdown of the food.
Inhomogeneous distribution of fat enhances the perception of fat-related sensory attributes in gelled foods
Mosca, A.C. ; Rocha, J.L. ; Sala, G. ; Velde, F. van de; Stieger, M.A. - \ 2012
Food Hydrocolloids 27 (2012)2. - ISSN 0268-005X - p. 448 - 455.
emulsion-filled gels - oil droplet - custard desserts - texture - microstructure - deformation - fracture - cheese
This study investigated the effect of the spatial distribution of fat on the perception of fat-related sensory attributes using a model system that consisted of layered agar/gelatin gels containing oil-in-water (O/W) emulsion droplets dispersed in the gel matrix. Four layers of gel varying in the amount of emulsion droplets were combined to prepare samples with homogeneous and inhomogeneous distributions of fat (emulsion droplets). The composition of the gels was optimized to obtain samples with comparable mechanical properties. A significant enhancement of mouthfeel attributes such as spreadable and melting was observed in samples with inhomogeneous distributions of fat in a Quantitative Descriptive Analysis (QDA) panel. Inhomogeneous samples with large differences in fat content between layers were perceived more spreadable and melting than the sample in which fat was homogeneously distributed. Creaminess ratings tended to increase as the difference in fat content between layers increased in the inhomogeneous samples. Additionally, the position of the high-fat layers in the sample affected the perception of fat-related attributes. The sample with high-fat layers on the outside had the highest ratings for all mouthfeel and afterfeel attributes. The enhancement of fat-related attributes by an inhomogeneous distribution of fat depended on the overall fat content. The enhancement at 15 wt% fat was larger than that at 5 wt% fat. We suggest that the modulation of the spatial distribution of fat can be used to reduce the fat content of food products without causing undesirable changes in the sensory properties