Custard Desserts Research Articles

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

The role of salivary α-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 α-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.

Sensory sub-attributes of creamy mouthfeel in commercial mayonnaises, custard desserts and sauces

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.

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.

THE INFLUENCE OF BITE SIZE AND MULTIPLE BITES ON ORAL TEXTURE SENSATIONS

ABSTRACTThe influence of bite size on sensory mouthfeel and afterfeel sensations was explored in two studies in which single bites of vanilla custard desserts were varied from itollmL (study 1) and in which series of five bites of two different custard desserts were presented consecutively (study 2). In single bites, sensations of perceived creaminess were enhanced with size whereas sensations of astringency and temperature were suppressed. Bite size also affected perceived thickness, but the direction of the effects varied with custard desserts. With multiple bites, creaminess sensations continued to increase, whereas other sensations were unaffected. Switching to a second series of bites of another vanilla custard dessert showed larger sensory effects, especially on astringency sensations but also to a lesser extent on sensations of thickness and fatty afterfeel. Single and multiple bite results are discussed in terms of possible peripheral mechanisms. Switching results are discussed in terms of possible central sensory contrast mechanisms.

The effect of oral and product temperature on the perception of flavor and texture attributes of semi-solids

This study examined the effect of oral and product temperature on the perception of texture and flavor attributes. A trained panel assessed 21 texture and flavor attributes in one high-fat and one low-fat product of two semi-solids: custard dessert and mayonnaise. The products were evaluated at 10, 22 or 35 °C in combination with oral temperatures of 27, 35 and 43 °C.Results showed that modulation of product and oral temperature had significant effects on a number of attributes. Flavor intensities, melting mouth feel, and fat after feel increased, while subjective thickness decreased with increasing product temperature. Neither product- nor oral temperature had an effect on over-all creaminess. Oral temperature affected a number of mouth feel attributes: melting, heterogeneous and smooth. Furthermore, large differences existed in ratings between the high- and low-fat products of custard and mayonnaise, and they were more prominent in mayonnaise.We conclude that the effect of oral temperature on the perception of sensory attributes in semi-solids was small, but present, while the product temperatures influenced the ratings greatly.

TEXTURE AND MOUTHFEEL OF SEMISOLID FOODS: COMMERCIAL MAYONNAISES, DRESSINGS, CUSTARD DESSERTS AND WARM SAUCES

ABSTRACTTexture and mouthfeel sensations of three groups of semisolid foodstuffs (mayonnaises and dressings, custard desserts and warm sauces) were characterised, measured, evaluated and compared based on quantitative descriptive sensory analysis of commercial products. Six groups of texture attributes were generated and used by the sensory panel. These were related to: viscosity, surface feel, bulk homogeneity, adhesion/cohesion, wetness‐dryness and fat. Two groups of nontextural mouthfeel attributes were found to be relevant, which were related to perceived temperature and oral irritation. The importance of the attributes for each product category is discussed.

TEXTURE OF SEMI‐SOLIDS: SENSORY FLAVOR‐TEXTURE INTERACTIONS FOR CUSTARD DESSERTS

ABSTRACTPossible interactions between flavor and oral texture sensations were investigated for four flavorants, diacetyl, benzaldehyde, vanillin, and caffeine, added in two concentrations to model vanilla custard desserts. The flavorants affected viscosities and resulted in corresponding changes in perceived thickness and melting sensations. In addition, flavorants affected prickling sensations, probably via activation of the trigeminal nerve system, and sensations of roughness, astringency, and dryness/mealiness. Finally, the effects of flavorants on these individual texture attributes also resulted in flavorant effects on creaminess and fattiness, sensations based on combinations of the above attributes.

A comparison of the effects of added saliva, α-amylase and water on texture perception in semisolids

The effect of adding saliva or a saliva-related fluid (α-amylase solution and water) to custard prior to ingestion on the sensory ratings of odour, flavour and lip–tooth-, mouth- and after-feel sensations was investigated. Saliva had previously been collected from the subjects and each subject received his/her own saliva. Sixteen subjects from a trained panel assessed 17 flavour and texture attributes of soy- and milk-based custard desserts. Immediately prior to administration, two different volumes (0.25 and 0.5 ml) of three different saliva-related fluids (saliva, α-amylase solution and water) were added to the product. The added volumes represented an approximately 33% and 66% increase of the volume of saliva present in the mouth during ingestion. The results show that addition of a fluid affected the mouth-feel attributes of melting, thickness and creamy. Melting was the only attribute on which the type of fluid had an effect, where saliva elicited a stronger melting effect than the α-amylase solution and water. The volume of the added fluid affected a number of attributes (thick and creamy mouth-feel and fatty after-feel). It can be concluded that in general the sensory attributes of semisolids were relatively stable. Mouth- and after-feel sensations were partly affected, while odour, flavour and lip–tooth-feel sensations were not affected by an increase in volume of saliva or other saliva-related fluid during ingestion.

Texture of semi-solids; sensory and instrumental measurements on vanilla custard desserts

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.

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 5 s 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.

The effect of oral temperature on the temperature perception of liquids and semisolids in the mouth

This work examined the influence of oral temperature on oral perception of temperature in liquids and semisolids. A panel of 20 adults assessed the temperature of water, custard dessert and mayonnaise. Oral temperatures were manipulated by 5-s mouth rinses of 10, 35 and 55 degrees C performed prior to assessments, which resulted in oral temperatures of 27, 35 and 43 degrees C, respectively. The products were evaluated at 10, 22 and 35 degrees C. Results show that subjects were able to differentiate between the product temperatures. A large effect of type of product was seen on perceived temperature, where water was, overall, perceived as significantly colder than custard dessert and mayonnaise. The range of perceived thermal ratings was widest for custard dessert, followed by water and mayonnaise. This might be due to differences in composition and structure of the products. Even though oral temperature was varied considerably in the present study, this did not exert large effects on perceived temperature.

The relation between saliva flow after different stimulations and the perception of flavor and texture attributes in custard desserts

Salivary flow rates were measured at rest and after three types of stimulation; odor, Parafilm chewing, and citric acid. The highest flow rate was elicited by citric acid followed by Parafilm and odor, while the lowest flow rate was unstimulated. In order to investigate whether and how the amount of saliva a subject produces influences the sensory ratings, the four types of salivary flow rates were correlated with sensory ratings of three different types of vanilla custard dessert. No significant correlation could be found between any of the salivary flow rates and the sensory ratings. A subject with a larger saliva flow rate during eating did not rate the foods differently from a subject with less saliva flow. The same pattern was seen for all types of stimulation. This finding could indicate that subjects are used to their respective amounts of saliva to such a degree that the differences in sensory ratings between subjects cannot be explained by the interindividual difference in saliva flow rate.

Transit of a meal through the stomach, small intestine, and colon in normal subjects and its role in the pathogenesis of diarrhea

A method for measuring the transit time of a meal, containing sausages, mashed potato, baked beans, and a pineapple custard dessert, through the gastrointestinal tract was evaluated in 14 healthy volunteers. Gastric emptying was determined by incorporating a radioactive marker in the meal and counting over the surface of the stomach using a crystal scintillation detector. Small intestinal transit time was determined by measuring breath hydrogen excretion and by estimating the radioactivity over the cecum. Finally, whole gut transit time was measured by incorporating radiopaque plastic markers or carmine red in the meal and estimating the appearance of these markers in the stool. Our results showed that measurements of small intestinal transit time were reproducible and in the majority of subjects the increase in hydrogen excretion occurred at the same time as the increase in radioactive counts over the surface of the cecum. The passage of the first marker in the stool coincided with the appearance of carmine red. There were no significant correlations between small intestinal transit time and whole gut transit time or the half time for gastric emptying. Incorporation of 10, 25, and 40 g lactulose into our standard meal in place of sucrose increased the rate of transit through the small intestine but did not significantly alter the rate of gastric emptying or the whole gut transit time. Total stool weight for 48 hr after ingestion of the meal was inversely related to whole gut transit time but not to small intestinal transit time suggesting that the tendency to develop diarrhea in response to a meal containing unabsorbable carbohydrate depends more on the lack of colonic accommodation than on the rate of small intestinal transit. Finally, there was no significant correlation between the measurements of small intestinal transit time after a drink of lactulose and the transit time of a meal in the same subjects.