Biomedical subjects

René A de Wijk

Publications and source records attributed to René A de Wijk.

7 recordsLinked to original sources

PubMed2006

The effect of saliva composition on texture perception of semi-solids.

Saliva is expected to be of significance for the perception of food stimuli in the mouth. Mixing the food with saliva, including breakdown and dilution, is considered to be of large importance for semi-solids as these products are masticated without chewing. It is known that there are large variations in composition of saliva originating from different glands and different subjects. In this study we investigated how variations in salivary characteristics affect sensory perception. Eighteen trained subjects participated in the study. Saliva was collected at rest and during three types of stimulation (odour, parafilm chewing and citric acid), and flow rates were determined. The collected saliva was analyzed for protein concentration, buffer capacity, mucin level and alpha-amylase activity. The salivary components measured in this study varied considerably among subjects, but also within subjects as a result of different means of stimulation. Variations in salivary components were correlated with sensory perception of a number of flavour, mouth feel and after feel attributes in the semi-solids mayonnaise and custard dessert. Total protein concentration and alpha-amylase activity were observed to correlate most strongly with texture perception.

Adult↗

PubMed2006

Oral processing assessed by M-mode ultrasound imaging varies with food attribute.

Ultrasonic imaging was used to quantify oral movements made during the oral processing of foods while subjects assessed the intensity of the sensory attributes, thick, creamy, sweet and bitter. A series of four stimuli were prepared with high and low viscosities and high and low sweetness. Over five sessions, subjects (N=8) were asked to consume 5 ml spoonfuls of each of the stimuli while holding an ultrasound probe beneath their chin so as to produce a mid-line sagital image of the floor of the mouth and tongue. In the first session, subjects were asked to swallow the sample. In subsequent sessions, subjects were asked to rate one of the attributes, thickness, sweetness, creaminess or bitterness, in random order. The resulting video recordings were subjected to an image-processing algorithm to quantify the amount of intra-oral manipulation performed. The results demonstrated that oral movements varied with attribute, especially in the period during which the bulk of the food is typically processed and the following swallowing phase. The food's sweetness affected oral movements especially during the bulk phase, whereas the food's viscosity primarily affected movements during the following swallowing and clearance phases.

Adult↗

PubMed2006

Effects of added fluids on the perception of solid food.

The production of sufficient saliva is indispensable for good chewing. Recent research has demonstrated that salivary flow rate has little influence on the swallowing threshold. We examined the hypothesis that adding fluid to a food will influence the chewing process. Twenty healthy subjects chewed on melba toast, breakfast cake, carrot, peanut and Gouda cheese. In addition they chewed on these foods after we added different volumes of tap water or a solution of alpha-amylase. We measured jaw muscle activity and the number of cycles until swallowing. Furthermore, we obtained visual analogue scale (VAS) scores for texture and sound attributes for all foods and fluid conditions. The additional fluids significantly lowered muscle activity and swallowing threshold for melba, cake and peanut. The effect of alpha-amylase in the solutions was rather limited. Doubling the volume of tap water had a larger effect. Several texture and sound attributes of melba, cake and peanut were also significantly affected by the additional fluids. For melba, cake, and peanut we observed significant correlations between the physiology parameters and several attributes for the various fluid conditions. This indicates that the added fluid affects both the physiology (muscle activity and number of cycles) and the sensory perception of a number of texture and sound attributes. Adding fluid facilitates the chewing of dry foods (melba, cake), but does not influence the chewing of fatty (cheese) and wet products (carrot).

Adult↗

PubMed2005

Relating particles and texture perception.

Practically all foods contain particles. It has been suggested that the presence of particles in food may affect the perception of sensory attributes. In the present study we investigated the effect of size and type (hardness and shape) of particles added to a CMC based vanilla custard dessert. The two types of particles included in the study were silica dioxide and polystyrene spheres, varying in size from 2 to 230 microm. Eighteen trained adults participated in the study. They rated the sensation of 17 sensory flavour and texture attributes on a 100-point visual analogue scale (VAS). The results indicate that the addition of particles increased the sensation of roughness attributes and decreased the ratings of a number of presumably favorable texture attributes (smoothness, creamy, fatty and slippery) significantly. These effects increased with increasing particle size up to 80 microm. Roughness ratings deceased for larger particles sizes. Surprisingly, even particles of 2 microm had significant effects: they increased perceived rough lip-tooth feel, and decreased slippery lip-tooth feel and smoothness of the product. The affected attributes had previously been related to lubricative properties of foods. Particles added to semi-solid foods with relatively low levels of fat seem to counteract the lubricating effects of the fat resulting in increased oral friction. In a separate study on size perception the silica dioxide particles were used. By sampling the stimuli between the tongue and palate, subjects rated the size of the particles on a 100-point scale in comparison to anchor stimuli containing no particles and particles of 250 microm. The perceived particle size significantly increased for larger particles. Furthermore, perceived particle size was negatively correlated with roughness ratings. Thus, subjects who were sensitive and perceived the particles as being relatively large reported the same stimuli to have less rough after-feel. In conclusion, particles added to a product induce large effects on texture sensations, and texture sensation is related to individual size perception.

Adult↗

PubMed2004

The role of alpha-amylase in the perception of oral texture and flavour in custards.

The role of salivary alpha-amylase in odour, flavour, and oral texture sensations was investigated in two studies in which the activity of salivary amylase present in the mouth of human subjects was either increased by presenting custards with added alpha-amylase or decreased by presenting custards with added acarbose, an amylase inhibitor. For starch-based vanilla custard desserts, amylase resulted in increased melting and decreased thickness sensations, whereas acarbose had the opposite effect, i.e., decreased melting and increased thickness. Other affected attributes included creamy mouth feel, creamy after feel, and fatty after feel. Creaminess, which is considered to be a highly desirable food quality, decreased by as much as 25% with added amylase and increased by as much as 59% with added acarbose. Neither additional amylase nor acarbose affected sensations for a nonstarch-based carboxy methylcellulose (CMC) vanilla custard dessert. This indicates that the effects of amylase on viscosity-related sensations of starch-based custards, such as perceived melting and thickness, are caused by amylase-induced breakdown of starch. Partial Least Square (PLS) analysis indicated that the effects of amylase and acarbose on perceived creaminess are not only driven by their effects on perceived melting and thickness, but also by their effects on perceived flavour.

Acarbose↗

PubMed2004

Amount of ingested custard dessert as affected by its color, odor, and texture.

The effects of nonoral sensations, such as visual texture and odor, on the size of the first bite were investigated in a series of studies using specially constructed food delivery cups with lower, from which custards were ingested ("ingested custard"), and upper, from which a custard was viewed and/or smelled ("upper custard") compartments. Ingested and upper custards were either the same or different. Bite size was defined as the weight of custard sucked out of the lower compartment during a single suck through an 11-mm diameter straw. The results from the first study indicated that the recognition of oral qualities of custards via vision or olfaction determined the size of the first bite. When this recognition was favorable, e.g., when the upper custard was known to be creamy, a relatively large bite was taken, irrespective of the custard that was actually ingested. When this recognition was unfavorable, a relatively small bite was taken. The second study showed that when recognition was prevented by modifications of the upper custard's color, odor, or visual texture, bite size was determined by the oral qualities of the ingested custard. This was confirmed in a third study, where the oral characteristics of the ingested custard were varied by adding a flavorant (benzaldehyde) and/or by using nose clips to eliminate retronasal smelling. Bite sizes decreased significantly when these variations reduced creaminess. Odor and visual texture characteristics of the upper custard significantly affected the perception of creaminess and other attributes related to the food's viscosity, melting, and thickness.

Adult↗

PubMed2003

The role of intra-oral manipulation in the perception of sensory attributes.

To gain insight into the effect of oral processes on perception, we defined a set of five specific oral manipulations and investigated their effects on the perception of low and high fat versions of two semi-solid foodstuffs, vanilla custard desserts and mayonnaises. Behavior modifications ranged from simply placing the stimulus on the tip of the tongue to vigorously moving it around in the mouth. Sensory ratings for mouth-feel and flavor attributes were made 5s after placing the stimulus in the mouth, and after-feel attributes were rated immediately after swallowing. Most attributes showed a similar pattern, with lowest attribute ratings where the tongue's movement was restricted and gradually increasing ratings with increasing complexity of the tongue movements. An individual's normal oral processing behavior typically resulted in the most intense sensations of flavor and mouth-feel. Residence time for all mouth-feel attributes, except prickling, was determined by the time required for tongue movements. The exact tongue movements required for sensations appeared to be related to food groups and individual foods, rather than to specific mouth-feel attributes.

Adult↗