Linking oral processing behavior to bolus properties and dynamic sensory perception of processed cheeses with bell pepper pieces

The addition of food particles to food matrices is a convenient approach that allows to steer oral behavior, sensory perception and satiation. The aim of this study was to determine the influence of physical-chemical properties of heterogenous foods on oral processing behavior, bolus properties and dynamic sensory perception. Bell pepper gel pieces varying in fracture stress and concentration were added to processed cream cheese matrices differing in texture. Addition of bell pepper gel pieces to processed cheeses increased consumption time, decreased eating rate and led to harder and less adhesive bolus with more saliva incorporated. Addition of bell pepper gel pieces to processed cheeses decreased dominance rate and duration of creaminess, smoothness, melting and dairy flavor and increased graininess and bell pepper flavor. Increasing fracture stress of bell pepper gel pieces from 100 to 300 kPa resulted in longer consumption time and lower eating rate. For hard/non-adhesive processed cheese matrices increasing gel pieces fracture stress lead to a boli with larger particles and more saliva. These changes were accompanied by decreased dominance perception of creaminess and bell pepper flavor and increased dominance of graininess. Increasing the concentration of bell pepper gel pieces from 15 to 30% did not affect oral behavior but led to the formation of harder and less adhesive bolus with larger particles and less saliva that were perceived with reduced dominance of creaminess, meltiness and dairy flavor while dominance of graininess and bell pepper flavor increased. Changing the texture of the cheese matrix from soft/adhesive to hard/non-adhesive decreased consumption time, increased eating rate, did not influence bolus properties and decreased dominance rate of creaminess, smoothness and melting sensations. Number of chews and total consumption time were positively correlated with saliva content of the bolus, number of bolus particles, bolus hardness, dominance of firmness, chewiness and graininess. We conclude that the modification of physical-chemical properties of processed cheeses and embedded bell pepper gel pieces can be a strategy to steer oral behavior and bolus properties which consequently determine dynamic sensory perception.     

Oral processing behavior and dynamic sensory perception of composite foods: Toppings assist saliva in bolus formation

Composite foods consist of combinations of single foods, such as bread with toppings. Single foods can differ considerably in their mechanical and sensory properties. This study aimed to investigate the effect of toppings on oral processing behavior and dynamic sensory perception of carrier foods when consumed as composite foods. Two carriers (bread, crackers) and three toppings (firm cheese, cheese spread, mayonnaise) were selected and six carrier-topping combinations were prepared. Mastication behavior, bolus properties (33, 66 and 100% of total mastication time) and dynamic sensory perception were determined for single carriers and all carrier-topping combinations. Both carriers with cheese spread and mayonnaise were chewed shorter and with fewer chews than single bread and crackers, although twice the mass of food was consumed. These toppings contributed to a faster bolus formation by providing moisture, so that less saliva was incorporated into the bolus during mastication. As a result of the moisture incorporation, carrier boli with toppings were softened and perceived less firm and less dry than carrier boli alone. The largest effects of toppings on oral processing behavior and perception were found for liquid-like mayonnaise, and these effects were more pronounced in dry crackers than in moist bread. We conclude that toppings assist saliva in bolus formation of carriers. Carriers drive oral processing behavior and texture perception whereas toppings drive overall flavor perception. This knowledge contributes to food design tailored for specific consumer segments and future personalized nutrition.     

Investigating changes in sensory stickiness perception with age

A recent study had shown that a group of younger subjects (21–29 years) selected the term sticky at a significantly greater rate than a group of older subjects (55–70 years) using the Temporal Dominance of Sensations (TDS) methodology with a range of nuts. It was hypothesised that differences between age groups in bolus properties was causing greater sensory stickiness intensity to be perceived by the younger subjects. The aim of the current study was to assess the physical properties of the bolus, as well as the dynamic perception of stickiness using Time Intensity (TI), of the same subjects from the previous study. Subjects undertook a mastication trial where they chewed cashews and expectorated the bolus for assessment of its physical properties. Subjects also undertook a TI task with two separate products: cashews and blended cashews (blended to a particle size that simulated a ready to swallow food bolus), without training of high and low intensity anchors of each sensation. Results showed the bolus properties and oral processing behaviour was similar between the two age groups. Results also showed the dynamics and magnitude of TI for stickiness was similar between the two age groups. The study suggests variables other than bolus properties and stickiness intensity are responsible for differences in the TDS selection of stickiness between younger and older age groups.     

Exploring how age,medication usage,and dentures effect the sensory perception and liking of oral nutritional supplements in older adults

Sensory perception of Oral Nutritional Supplements (ONS) by older and younger adults has been investigated, but few studies have examined the sensory perception of ONS within different older adult cohorts. This study sought to investigate effects of older age, dentures, and medications on sensory perception, liking, and intake of a high- and low-viscosity ONS (0.009 and 0.177 Pa.s respectively at 50.1 s⁻¹) and assess effects of ONS on appetite.Eighty older adults (51 aged 65–74 years, 29 aged 75 + years, mean age 74 ± 8 years, age range 65–97 years, 35 men, 45 women) evaluated two ONS over two different days. Each ONS (200 mL) was consumed over five sips (40 mL each). The panellists evaluated each sip using a check-all-that-apply questionnaire (CATA) comprising taste and texture attributes. After each CATA evaluation panellists recorded their liking using a 9-point hedonic scale followed by their hunger, fullness, desire to consume more ONS, and thirst using 100 mm visual analogue scales.The over 75 year olds had significantly lower appetite than the 65–74 year olds on tasting both ONS. Denture wearing influenced the mouthfeel while medication status effected the flavour perception of the high viscosity ONS. Liking did not change across the five sips for any study cohort, however, sensory perception changed with increasing sips. This study provides insight on factors affecting ONS adherence in older adults. Avoiding perceptions of watery/runny mouthfeel while maintaining creaminess may improve acceptability and adherence. The study justifies the CATA methodology for use in different older adult cohorts.     

The role of oral processing in dynamic sensory perception

Food oral processing is not only important for the ingestion and digestion of food, but also plays an important role in the perception of texture and flavor. This overall sensory perception is dynamic and occurs during all stages of oral processing. However, the relationships between oral operations and sensory perception are not yet fully understood. This article reviews recent progress and research findings on oral food processing, with a focus on the dynamic character of sensory perception of solid foods. The reviewed studies are discussed in terms of both physiology and food properties, and cover first bite, mastication, and swallowing. Little is known about the dynamics of texture and flavor perception during mastication and the importance on overall perception. Novel approaches use time intensity and temporal dominance techniques, and these will be valuable tools for future research on the dynamics of texture and flavor perception.     

Tribology and its growing use toward the study of food oral processing and sensory perception

Here we provide a comprehensive review of the knowledge base of soft tribology, the study of friction, lubrication, and wear on deformable surfaces, with consideration for its application toward oral tribology and food lubrication. Studies on “soft-tribology” have emerged to provide knowledge and tools to predict oral behavior and assess the performance of foods and beverages. We have shown that there is a comprehensive set of fundamental literature, mainly based on soft contacts in the Mini-traction machine with rolling ball on disk configuration, which provides a baseline for interpreting tribological data from complex food systems. Tribology-sensory relationships do currently exist. However, they are restricted to the specific formulations and tribological configuration utilized, and cannot usually be applied more broadly. With a careful and rigorous formulation/experimental design, we envisage tribological tools to provide insights into the sensory perception of foods in combination with other in vitro technique such as rheology, particle sizing or characterization of surface interactions. This can only occur with the use of well characterized tribopairs and equipment; a careful characterization of simpler model foods before considering complex food products; the incorporation of saliva in tribological studies; the removal of confounding factors from the sensory study and a global approach that considers all regimes of lubrication.     

Rheological,textural, micro-structural and sensory properties of mango jam

Mango jam behaved as pseudoplastic fluid exhibiting yield stress. The Herschel–Bulkley (HB) model described adequately the steady-state rheological behavior of jam. Temperature dependence of the consistency index followed Arrhenius relationship. Time dependent structural breakdown characteristics of mango jam followed Hahn model. Hardness of mango jam increased with pectin concentration and acidity. Hardness increased up to 60% sugar concentration but decreased with further increase in sugar concentration at all pH and pectin levels. Stickiness, work of shear, and adhesion did not show any systematic trend with pH, pectin, and sugar concentration. The overall acceptability was rated highest for mango jam prepared with 65% sugar, 1% pectin at pH 3.4. Principal component analysis (PCA) revealed that hardness and work of shear are the most relevant among all the characteristics (physicochemical, sensory, textural, rheological, and compositional) studied for mango jam. Microstructure of mango jam was found to be composed of network regions with large pores as well as dense, compact regions with small pores.     

Toasting of corn flakes: Product characteristics as a function of processing conditions

Toasting of corn flake is an important processing step that dictates the attributes of the finished product with particular reference to consumer acceptability. The effect of important toasting variables such as moisture content, temperature and time of toasting of corn flakes on quality attributes has been investigated employing response surface methodology (RSM). A central composite experimental design consisting of five coded levels (−1.682, −1, 0, 1 and 1.682) of each independent variables has been employed. The response functions are thickness of flake, bulk density, puncture force, colour parameters and the sensory overall acceptability. Further, the changes in the microstructure of the flakes have been monitored. The energy expenditure during the toasting process was also determined, and 721–746 J g⁻¹ of energy was required to have properly toasted flakes. These response functions can be correlated (r  0.82, p  0.01) with the independent variables by second order polynomials consisting of linear, quadratic and interaction terms. The effect of temperature and time usually dominates over the moisture content for toasting of corn flakes. Optimum conditions for achieving best puffing and overall acceptability have been obtained.     

Enhancing expected food intake behaviour,hedonics and sensory characteristics of oil-in-water emulsion systems through microstructural properties,oil droplet size and flavour

Food reformulation, either to reduce nutrient content or to enhance satiety, can negatively impact upon sensory characteristics and hedonic appeal, whilst altering satiety expectations. Within numerous food systems, perception of certain sensory attributes, known as satiety-relevant sensory cues, have been shown to play a role in food intake behaviour. Emulsions are a common food structure; their very nature encourages reformulation through structural design approaches. Manipulation of emulsion design has been shown to change perceptions of certain sensory attributes and hedonic appeal, but the role of emulsions in food intake behaviour is less clear. With previous research yet to identify emulsion designs which promote attributes that act as satiety-relevant sensory cues within emulsion based foods, this paper investigates the effect of oil droplet size (d_4,3: 0.2–50 μm) and flavour type (Vanilla, Cream and No flavour) on sensory perception, hedonics and expected food intake behaviour. By identifying these attributes, this approach will allow the use of emulsion design approaches to promote the sensory characteristics that act as satiety-relevant sensory cues and/or are related to hedonic appeal. Male participants (n = 24) assessed the emulsions. Oil droplet size resulted in significant differences (P < 0.05) in ratings of Vanilla and Cream flavour intensity, Thickness, Smoothness, Creamy Mouthfeel, Creaminess, Liking, Expected Filling and Expected Hunger in 1 h’s time. Flavour type resulted in significant differences (P < 0.05) in ratings of Vanilla and Cream flavour intensity, Sweetness and Liking. The most substantial finding was that by decreasing oil droplet size, Creaminess perception significantly increased. This significantly increases hedonic appeal, in addition to increasing ratings of Expected Filling and decreased Expected Hunger in 1 h’s time, independently of energy content. If this finding is related to actual eating behaviour, a key target attribute will have been identified which can be manipulated through an emulsions droplet size, allowing the design of hedonically appropriate satiating foods.     

Food oral processing: Mechanisms and implications of food oral destruction

BackgroundFood oral processing is a simultaneous process of food destruction and sensory perception. How a food breaks down its structure inside the mouth and what mechanisms control this process are hugely important to our eating experience and sensory perception. A proper understanding of this process is urgently needed by the food industry for better design and manufacturing of quality tasty food.Scope and approachThis review article analyses research findings from literature and from author's own laboratory in order to identify main controlling mechanisms of food oral destruction. Appropriate experimental evidences are given wherever available to demonstrate the important implications of different destruction mechanisms to sensory perception.Key findings and conclusionsThree major controlling mechanisms of food oral destruction are identified: the mechanical size reduction, the colloidal destabilisation, and the enzymatic interactions. These mechanisms may be applicable to different food materials either independently or collectively. They could also be applicable through the whole eating process or just at a certain stage of an eating process.     

Effect of vacuum application on the physical,rheological and sensory characteristics of an artisanal ice cream

Four milk-based ice cream samples were produced by heating (65°C) the ingredients at different pressures (0.5, 1.0 bar) and times (5, 30 min). Overrun, melting behaviour, particle size, viscosity and sensory analysis were conducted for each time/temperature combination. The 5-min vacuum application resulted in a reduction of overrun and air bubbles size, whereas ice cream viscosity increased. Opposite outcomes were found for the sample treated with vacuum for 30 min, which also showed a significant fat globule size reduction (<3.0 μm). Sensory analysis revealed that the use of vacuum improved sweetness, milky and creamy sensations regardless the treatment times.     

Physical, textural and sensory characteristics of 7-day frozen part-baked French bread

Bread partially baked for 7 min at 250 °C, after cooling, was frozen until core temperature reached −18 °C and stored at this same temperature up to 7 days. Samples were removed daily from the freezer, thawed and baked at 250 °C for 6 min. Analyses were performed 1 h after final baking, and were also conducted on fresh French bread daily produced (control). Weight and specific volume of frozen part-baked bread presented significant difference (P<0.05) compared with fresh one. Sensory analysis was carried out by a trained panel using the Difference from Control test to evaluate the difference and the degree of difference between frozen part-baked French bread (FPBFB) and fresh bread regarding appearance, tactile by direct touch and mouthfeel. All scores obtained indicated that the panelists, during the studied period, considered FPBFB to be slightly different compared with fresh one. Consumer Acceptance test was applied to compare appearance (gloss, roughness and cut on bread surface), oral texture (crust crispness and crumb firmness) and overall flavor between frozen part-baked bread and a commercial brand. All sensory scores obtained from Consumer test indicated that the 4-day frozen part-baked presented a superior acceptance to the commercial brand.     

Effect of using transglutaminase on physical,chemical and sensory properties of set-type yoghurt

This study was conducted in order to evaluate the effects of transglutaminase (TGase) addition on some properties of set-type yoghurts such as titratable acidity, lactic acid, tyrosine, viscosity, gel firmness, syneresis, aroma compounds, sensory analysis, and micro-structural properties. The enzyme was added to yoghurt-milk at different production steps (after homogenization, after pasteurization and together with starter culture addition) and two different incubation times (10 min and 1 h) were used. Five TGase treated yoghurt samples and control sample were analyzed on 1st, 10th, and 20th days of storage. TGase addition did not cause significant changes on chemical properties of yoghurts. However, enzyme addition after pasteurization increased the gel strength and decreased the syneresis. Results of electron microscope showed that enzyme addition led proteins to be distributed more evenly in gel network due to the formation of cross-links between proteins.     

Double freezing of cod fillets: Influence on sensory,physical and chemical attributes of battered and breaded fillet portions

Fillet samples were processed on board a research vessel from cod (Gadus morhua) in different states of rigor mortis. In addition, headed and gutted fish in different states of rigor were frozen and, after ten days of frozen storage, the fish were thawed, processed into fillets and refrozen. During subsequent frozen storage at –24°C of breaded and battered portions processed from the different fillet batches several quality attributes were tested using sensory, physical, and chemical methods. The measurements indicated differences in the quality attributes depending on refreezing and rigor states. Especially the sensory texture attributes gumminess and, with some restrictions, firmness were found to be suitable for distinguishing single frozen (SF) from double frozen (DF) samples. This finding was supported by the outcome of the measurement of penetration force where generally a significantly (p < 0.05) higher force was necessary to penetrate the DF compared to SF samples. DF samples were generally lighter (higher L*) than SF samples. The colour difference δE between both sample types was at least very clear and therefore visible. However, no clear differences between SF and DF samples were found when evaluating the flavour attributes and using instrumental texture profile analysis for texture characterisation. Also, all chemical parameters measured did not allow to clearly distinguish between single and double frozen samples. Therefore, it can be stated that, at least when using cod as raw material for processing battered and breaded portions, the different methods for preparing the fillet blocks will, if at all, only affect the textural quality of the final products.     

Contribution of temporal dominance of sensations performed by modality (M-TDS) to the sensory perception of texture and flavor in semi-solid products: A case study on fat-free strawberry yogurts

This study aimed to perform Temporal Dominance of Sensations by modality (M-TDS) combined with a multi-intake approach to investigate texture and flavor perception in semi-solid products. Trained panelists (n = 15) evaluated fat-free strawberry yogurts enriched with functional proteins involving texture modifications. As yogurt is a semi-solid product, its in-mouth residence time is short. A multi-intake approach was therefore expected to give more reliable information about the sensory properties perceived by panelists. The two modalities of texture and flavor were analyzed separately to characterize the effect of added proteins. Trials were made according to an experimental design with two factors (protein type and concentration) and three levels each. Different statistical treatments, taking or not the temporality of attributes into account, were performed on standardized and non-standardized data. The implementation of M-TDS was essential to highlight differences of flavor perception in addition to the more evident texture modifications. The study of sensory trajectories evidenced that texture modifications, induced by the use of different whey proteins, slightly modified the perception of flavor and sweetness. The global flavor perception of the samples varied with the number of spoons, which particularly impacted the taste attributes. This study highlighted the importance of using M-TDS when studying texture and flavor in semi-solid products, and the relevance of the multi-intake approach to characterize flavor perception. This methodology enabled panelists to evidence both marked texture differences and subtler flavor modifications, and these useful data were emphasized by combining different statistical treatments.     

Acoustic emission measurement of rubbing and tapping contacts of skin and tongue surfaces in relation to tactile perception

The application of acoustic emission measurement (“acoustic tribology”) is explored for in vivo characterization of rubbing and tapping contacts of the biological tissues of skin and tongue. This acoustic signal originates from physical processes that are closely related to the rapid force fluctuations that are sensed by the rapidly-adapting mechanoreceptors involved in the sensation of touch. Demonstrated is the recording and analysis of sound produced by rubbing and tapping the skin against various surface textures of common materials and by rubbing the tongue against the palate or against food material in the mouth for 1 individual. The technique is shown to be sensitive to skin pre-treatment and pre-meals, and is also shown to discriminate between various surface textures and food materials in a way that relates to perception. The main advantages of the technique are its time-resolution, ease of operation and the fact that it is a direct in vivo measurement of processes that are closely related to texture perception.     

Texture concepts for consumers: a better understanding of crispy–crunchy sensory perception

Differences in the definitions and terms used by consumers to describe their sensory sensations of crispness/crunchiness were studied, highlighting the relevance of using well-defined terms in consumer studies. A questionnaire was presented to consumers from two different Spanish-speaking countries (Spain and Uruguay, n = 200). The answers showed that the terms crispy and crunchy had different meanings or evoked different perceptions depending on the country. The crispy/crunchy food items most frequently mentioned by consumers were dry-crisp, processed products; vegetables or other wet-crisp products were not often mentioned by the consumers interviewed. The main difference between the two countries was that 38% of Spanish consumers did not know the Spanish term for “crunchy” and 17% thought that “crispy” and “crunchy” had the same meaning. The results contribute to a greater knowledge of the terminology used by the consumers to describe oral sensations related to crispness and crunchiness.