Modelling of dynamic mastication physics of cheese/casein gels as function of milk-fat distribution and intensity of thermo-mechanical treatment

Pasta filata-style cheese products are among the world's most famous cheese varieties. Thermo-mechanical processing of cheese curd results in stringy, fibrous, and anisotropic structures with pleasing texture attributes. A recent area of research focuses on improving yield during the manufacturing of pasta filata-type cheese products by homogenizing the milk. This process reduces the size of fat droplets, leading to better retention of milk fat during curd plasticization. As this sometimes results in texture deficits, this study aims to investigate the impact of thermo-mechanical processing on curd from homogenized and non-homogenized milk. The hypothesis is that increased thermo-mechanical processing, leading to more anisotropic structural elements, may offset texture deficits caused by homogenization. To assess textural and structural changes due to homogenization and thermo-mechanical processing, mechanical tests including rheology and texture analysis were conducted, along with confocal-laser-scanning microscopy. Additionally, sensory evaluation involving panelists consuming the samples and recording mastication properties such as muscle activity and jaw movement was carried out. Dynamic data modeling was used to derive connections between structure and texture. Results showed that homogenization alone did not yield significant differences between the samples, but plasticization and texturization properties differed significantly. Non-homogenized samples developed a distinct fibrous structure, and muscle activities and jaw movements increased significantly (p < 0.01) with longer thermo-mechanical processing.

Creating similar food boluses as that in vivo using a novel in vitro bio-inspired oral mastication simulator (iBOMS-Ⅲ): The cases with cooked rice and roasted peanuts

Food bolus is the major outcome of oral processing of foods. Its structure and properties are crucial for safe swallowing and subsequent gastric digestion. However, collecting the ready-to-swallow bolus for further analysis in either normal or deficient human subjects is difficult, regulatorily or practically. Here, a novel in vitro bio-inspired oral mastication simulator (iBOMS-Ⅲ) was developed to be capable of replicating food boluses comparable to those in vivo. Cooked rice and roasted peanuts were used as the model foods (soft and hard) respectively. Particle size distribution, moisture content and rheology of the food boluses produced in the iBOMS-Ⅲ were assessed. A conventional food blender was also employed as a non-consequential comparation. Eighteen healthy young volunteers of the ages from 20-30 years (10 male and 8 female) were invited to provide the in vivo data. For cooked rice boluses produced by the iBOMS-Ⅲ with 10, 12, 14, and 20 chewing number of cycles, the moisture content exhibited minimal variation (68.3-68.8 wt%), aligning closely with values obtained from the average value of the human subjects (67.5 wt%). Similarly, the boluses from roasted peanut displayed similar moisture contents across masticatory number of cycles (36, 40, and 44 number of cycles), averaging at 35.3 %, mirroring the average in vivo results (33.8 wt%). Furthermore, the shear viscosity of both cooked rice and roasted peanut boluses exhibited minimal variations with iBOMS-Ⅲ chewing number of cycles. The particle size distributions of the boluses produced with 14 and 44 chewing number of cycles matched well with the in vivo data for cooked rice and roasted peanuts, with median particle size (d50) being 1.07 and 0.78 mm, respectively. The physical properties of the food boluses collected from the food blender, with varying grinding times, differed significantly. This study demonstrates the value of the iBOMS-Ⅲ in achieving realistic boluses with two very different food textures.

Anticipating food structure of meat products from mastication physics applying machine learning

Alternatives to animal-based products are becoming more relevant. Most of those products rely at some stage on a structuring process; hence researchers are developing techniques to measure the goodness of the structured material. Conventionally, a typical sensory study or texture analysis by measuring deformation forces would be applied to test the produced material for its texture. However, meat alternatives and meat differ in more points than just the texture, making it hard to extract the isolated texture impression. To objectively obtain qualitative and quantitative differences between different food structures, evaluation of oral processing features is an upcoming technology which qualifies as promising addon to existing technologies. The kinematic data of the jaw and exerted forces regarding muscle activities are recorded during mastication. Resulting datasets are high in dimensionality, covering thousands of individual chews described by often more than ten features. Evaluating such a dataset could benefit from applying computational evaluation strategies designed for large datasets, such as machine learning and neural networks. The aim of this work was to assess the performance of machine learning algorithms such as Support Vector Machines and Artificial Neural Networks or ensemble learning algorithms like Extra Trees Classifier or Extreme Gradient Boosting. We evaluated different pre-processing techniques and various machine algorithms for learning models with regard to their performance measured with established benchmark values (Accuracy, Area under Receiver-Operating Curve score, F1 score, precision-recall Curve, Matthews Correlation Coefficient (MCC)). Results show remarkable performance of classification of each single chew between isotropic and anisotropic material (MCC up to 0.966). According to the feature importance, the lateral jaw movement was the most important feature for classification; however, all features were necessary for an optimal learning process.

Kinematics of lateral tongue-pushing movement in coordination with masticatory jaw movement: An anteroposterior projection videofluorographic study

OBJECTIVE

During the mastication of solid food, the tongue pushes the bolus laterally to place it onto occlusal surfaces as the jaw is opened. This movement is referred to as tongue-pushing (TP). TP has an important role in efficient chewing, but its kinematic mechanisms remain unclear. The present study quantified the kinematics of TP and its coordination with masticatory jaw movements.

METHODS

Videofluorography (VFG) in anteroposterior projection was recorded while 14 healthy young adults ate 6 g each of cookies and meat. Small lead markers were glued to the tongue surface (left, right, and anterior) and buccal tooth surfaces (upper molars and lower canines). The position of the tongue and lower canine markers relative to the upper occlusal plane was quantified with Cartesian coordinates, using the right upper molar as the origin. Jaw motion during chewing was divided into TP and Non-TP cycles, based on the lateral movement of the food and tongue markers. The side of the jaw that compressed food particles was defined as the working side, while the other side was termed the balancing side. Horizontal and vertical displacements of tongue and jaw markers were compared between TP and Non-TP cycles, as well as between food types.

RESULTS

The mediolateral displacement of all tongue markers was significantly larger in TP than in Non-TP cycles. Vertical displacement was also significantly greater in TP than in Non-TP cycles for the anterior and working side tongue markers. TP cycles occurred more frequently with meat-chewing than with cookie-chewing.

CONCLUSION

TP is accomplished by rotation and lateral movements of the tongue surface on the working side and the anterior tongue blade, along with medial movement on the balancing side. These movements produce lateral shift and rotation of the tongue surface toward the working side in concert with jaw opening. Designing exercises to improve the strength of the lateral motion and rotation of the tongue body may be useful for individuals with impaired tongue function for eating and swallowing.

The heat is on: Consumers modify their oral processing behavior when eating spicy foods

Food texture properties and consumer characteristics influence oral processing behaviors. Little is known about oral processing behavior of pungent spicy foods. In two experiments, we investigated how adding ground dried chilies to tomato soup or beef patties and curried rice altered oral processing behaviors. In Experiment One, tomato soups differing in concentration of added ground dried chilies (0.01, 0.03, 0.20 or 0.40% w/w) were consumed (n = 23). In Experiment Two, lunch meals that differed in added ground dried chilies consisting of beef patties (0.0, 0.6 or 1.2% w/w) and curried rice (0.0, 0.4 or 1.0% w/w) were consumed (n = 49). Sip/bite sizes were determined using hidden balances. Oral processing behavior was quantified using video recordings followed by post hoc annotations of specific behaviors. When eating tomato soup, increasing oral burn was associated with increasing number of water sips, water intake and total time between sips. For the solid meals (beef patties and curried rice), increasing oral burn was associated with increased time between bites and total sips of water; conversely, total oral exposure time, total number of chews and number of chews per bite all decreased with greater burn. Saliva content and rate of saliva incorporation into the solid food bolus increased with added ground dried chilies while oral exposure time decreased. We conclude consumers adapt their oral processing behaviors to oral burn of solid foods by reducing oro-sensory exposure time, chewing bites less, increasing time between bites, and consuming more water, potentially to mitigate the discomfort associated with the burn imparted by ground dried chilies.

Fibrous food and particle size influence electromyography and the kinematics of oral processing

Structure-sensory relationships are essential for understanding food perception. Food microstructure impacts how a food is comminuted and processed by the human masticatory system. This study investigated the impact of anisotropic structures, explicitly the structure of meat fibers, on the dynamic process of mastication. For a general understanding of texture-structure relationships, the three typically used deformation-tests: Kramer shear cell-, Guillotine cutting- and texture-profile-analyses were conducted. 3D jaw movements and muscle activities of the masseter muscle were additionally tracked and visualized using a mathematical model. Particle size had a significant effect on jaw movements and muscle activities for both the homogeneous (isotropic) and fibrous (anisotropic) meat-based samples with the same composition. Mastication was described using jaw movement and muscle activity parameters determined for each individual chew. The adjusted effect of fiber length was extracted from the data, suggesting that longer fibers induce a more strenuous chewing in which the jaw undergoes faster and wider movements requiring more muscle activity. To the authors' knowledge, this paper presents a novel data analysis approach for identifying oral processing behavior differences. This is an advancement on previous studies because a holistic overview of the entire mastication process can be visualized.

The significance and potential of functional food ingredients for control appetite and food intake

Dramatically rising global levels of obesity have raised consumers’ commercial and public health interest in foods that may help control appetite and weight. The satiety cascade consists of sensory, cognitive, physical, and hormonal events following food intake, preventing overeating, and the desire to eat for a long time. Functional foods can be one of the most influential factors in reducing appetite as long as effective ingredients, such as fiber and protein, are used to design these products. Also, functional foods should be designed to reduce appetite at different levels of oral processing, stomach, small intestine, and large intestine by various mechanisms. Therefore, the satiety power of functional foods depends on the type of ingredients and their amount. Because each compound has a different mechanism of action, it is recommended to use different compounds to influence satiety in functional foods.

Reformulation of Traditional Fermented Tea Sausage Utilizing Novel (Digital) Methods of Analysis

The main objective of this paper was to investigate the effect of fat reduction on different quality traits of tea sausage. This study also aimed to deploy the following digital methods of analysis: three-dimensional (3D) laser imaging, computer vision system and oral processing. Three batches of tea sausage with different amounts of pork back fat were manufactured: control (25%), medium fat (17.5%) and low fat (10%). Samples for the analyses were taken on the production day and after 7, 14, 21, 28 and 35 days of ripening. The fat level significantly influenced shrinkage, texture, pH, a_w, moisture and ash contents, peroxide value, acid number, number of chewing strokes, consumption time, eating rate and fat intake rate. Oxidative stability, colour and microbiological parameters were not affected by fat reduction. The results of the sensory analysis showed that the fat level can be reduced to 17.5% without negatively affecting the quality and sensory properties of the product. The ripening time of the fat-reduced tea sausage should be reduced to 28 days. A strong correlation between shrinkage and weight loss suggests the possibility of using 3D laser imaging in predicting weight loss and moisture content of dry sausages.

Current Perspectives on Food Oral Processing

Food oral processing (FOP) is a fast-emerging research area in the food science discipline. Since its first introduction about a decade ago, a large amount of literature has been published in this area, forming new frontiers and leading to new research opportunities. This review aims to summarize FOP research progress from current perspectives. Food texture, food flavor (aroma and taste), bolus swallowing, and eating behavior are covered in this review. The discussion of each topic is organized into three parts: a short background introduction, reflections on current research findings and achievements, and future directions and implications on food design. Physical, physiological, and psychological principles are the main concerns of discussion for each topic. The last part of the review shares views on the research challenges and outlooks of future FOP research. It is hoped that the review not only helps readers comprehend what has been achieved in the past decade but also, more importantly, identify where the knowledge gaps are and in which direction the FOP research will go.

Brow and Masticatory Muscle Activity Senses Subjective Hedonic Experiences during Food Consumption

Sensing subjective hedonic or emotional experiences during eating using physiological activity is practically and theoretically important. A recent psychophysiological study has reported that facial electromyography (EMG) measured from the corrugator supercilii muscles was negatively associated with hedonic ratings, including liking, wanting, and valence, during the consumption of solid foods. However, the study protocol prevented participants from natural mastication (crushing of food between the teeth) during physiological data acquisition, which could hide associations between hedonic experiences and masticatory muscle activity during natural eating. We investigated this issue by assessing participants’ subjective ratings (liking, wanting, valence, and arousal) and recording physiological measures, including EMG of the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles while they consumed gel-type solid foods (water-based gellan gum jellies) of diverse flavors. Ratings of liking, wanting, and valence were negatively correlated with corrugator supercilii EMG and positively correlated with masseter and suprahyoid EMG. These findings imply that subjective hedonic experiences during food consumption can be sensed using EMG signals from the brow and masticatory muscles.

Understanding the oral processing of solid foods: Insights from food structure

Understanding the relationship between the structure of solid foods and their oral processing is paramount for enhancing features such as texture and taste and for improving health-related factors such as management of body weight or dysphagia. This paper discusses the main aspects of the oral processing of solid foods across different categories: (1) oral physiology related to chewing, (2) in-mouth food transformation, (3) texture perception, and (4) taste perception, and emphasis is placed on unveiling the underlying mechanisms of how food structure influences the oral processing of solid foods; this is exemplified by comparing the chewing behaviors for a number of representative solid foods. It highlights that modification of the texture/taste of food based on food structure design opens up the possibility for the development of food products that can be applied in the management of health.

Food Oral Processing-An Industry Perspective

We illustrate how scientific understanding of Food Oral Processing enables food product development with specific benefits for several target populations. in vivo, in vitro, and in silico approaches are discussed in the context of their ability to quantify oral processing from the molecular to the macroscopic scale. Based on this understanding, food structures with enhanced performance in terms of hedonic and nutritional properties as well as appropriateness for age and certain medical conditions can be developed. We also discuss current gaps and highlight development opportunities from an industry perspective.

How addition of peach gel particles to yogurt affects oral behavior, sensory perception and liking of consumers differing in age

Addition of particles to foods, such as fruit pieces to dairy products or vegetable pieces to soup, is a convenient approach to alter nutritional composition, appearance, perception and acceptance. The aim of this study was to investigate the effect of addition of peach gel particles to yogurt on oral behavior, sensory perception and liking of consumers differing in age. One homogeneous yogurt and seven yogurts with peach gel particles were prepared. The added peach gel particles varied in size, fracture stress, or concentration. Oral behavior of n = 62 healthy Dutch, young adults (21 ± 2 years) and n = 62 healthy Dutch elderly (70 ± 5 years) participants was characterized by video recordings. Yogurts' sensory properties and liking were scored on nine-point scales. Elderly consumed yogurts with higher number of chews and longer consumption time leading to lower eating rate than young adults. Addition of particles, regardless of characteristics, increased number of chews, consumption time, and decreased eating rate up to 60% for both consumer groups, with an average decrement of 110 g/min for young and of 63 g/min for elderly consumers. With increasing peach gel hardness and concentration, the number of chews and consumption time increased while eating rate decreased. Peach gel particle size did not affect oral behavior. Sensory perception of yogurts with added peach gel particles was similar for healthy young adult and healthy elderly. Only small differences in sensory perception were observed between the young adults and elderly for flavor attributes, crumbliness, juiciness, and perceived particle size. Similarly, minor differences in liking of a few yogurts with peach pieces were observed between both consumer groups. Thus, healthy ageing seems to affect sensory perception of semi-solid foods to a limited extent only. We conclude that changes in food texture by addition of particles can be used as a strategy to steer eating rate and potentially impact food intake of young adult and elderly consumers while maintaining or enhancing food palatability. Additionally, particle characteristics can be modified to target specific consumer groups that might differ in eating capabilities.

Assessment of the Miniature Kramer Shear Cell to Measure Both Solid Food and Bolus Mechanical Properties and Their Interplay with Oral Processing Behavior

This study assessed the usefulness of the miniature Kramer shear cell to determine relevant instrumental parameters of solid foods and bolus counterparts, examining their relationships with oral processing behaviors to obtain greater knowledge about the texture perception process. Six solid foods with different textural properties were tested. Bolus mechanical properties were also determined by means of cone penetration tests and rheological measurements, and their particle size distributions by sieving. Oral processing behavior (chewing time, number of chews, chewing rate, eating rate) and food saliva uptake (SU) of a young volunteer and a panel of 39 untrained participants were analyzed. The Kramer mechanical properties were very suitable for detecting different levels of food and bolus textural hardness and fracturability and the associated degrees of fragmentation achieved during mastication. Chewing time and number of chews were highly correlated with Kramer food and bolus mechanical properties for the single subject and for the panel's oral processing behaviors. For the single subject, SU and eating rate also showed strong correlations with food and bolus mechanical properties, unlike chewing rate and food moisture content (FMC). In contrast, eating rate, FMC, and SU did not vary with the oral activities of the panel.

Effects of food properties on chewing in pigs: Flexibility and stereotypy of jaw movements in a mammalian omnivore

Chewing is a rhythmic oral behavior that requires constant modifications of jaw movements in response to changes in food properties. The food-specific kinematic response is dependent on the potential for kinematic flexibility allowed by morphology and modulation of motor control. This study investigates the effects of food toughness and stiffness on the amplitude and variability of jaw movements during chewing in a typical omnivorous mammalian model (pigs). Jaw movements were reconstructed using X-ray Reconstruction Of Moving Morphology (XROMM) and kinematic data associated with the amplitude of jaw pitch (opening-closing) and jaw yaw (mediolateral rotation) were extracted for each cycle. Between-food differences were tested for the amplitude of jaw movements during each phase of the gape cycle, as well as in their respective within-food variability, or stereotypy, as indicated by coefficients of variation. With increasing toughness, jaw pitch amplitude is decreased during fast close, larger and more stereotyped during slow close, smaller but more variable during slow open, and more variable during fast open. In addition, when chewing on tougher foods, the amplitude of jaw yaw during slow close only increases in a subset of individuals, but all become less variable (i.e., more stereotyped). In contrast, increasing food stiffness has no effect on the amplitude or the variability of jaw pitch, whereas jaw yaw increases significantly in the majority of individuals studied. Our data demonstrate that food stiffness and toughness both play a role in modulating gape cycle dynamics by altering the trajectory of jaw movements, especially during the slow-close phase and tooth-food-tooth contact, albeit differently. This highlights how a generalist oral morphology such as that of pigs (e.g., bunodont teeth lacking precise occlusion, permissive temporomandibular joint allowing extensive condylar displacements in 3 dimensions) enables organisms to not only adjust chewing movements in their amplitude, but also in their variability.

Dynamic Oral Texture Properties of Selected Indigenous Complementary Porridges Used in African Communities

Child malnutrition remains a major public health problem in low-income African communities, caused by factors including the low nutritional value of indigenous/local complementary porridges (CP) fed to infants and young children. Most African children subsist on locally available starchy foods, whose oral texture is not well-characterized in relation to their sensorimotor readiness. The sensory quality of CP affects oral processing (OP) abilities in infants and young children. Unsuitable oral texture limits nutrient intake, leading to protein-energy malnutrition. The perception of the oral texture of selected African CPs (n = 13, Maize, Sorghum, Cassava, Orange-fleshed sweet potato (OFSP), Cowpea, and Bambara) was investigated by a trained temporal-check-all-that-apply (TCATA) panel (n = 10), alongside selected commercial porridges (n = 19). A simulated OP method (Up-Down mouth movements- munching) and a control method (lateral mouth movements- normal adult-like chewing) were used. TCATA results showed that Maize, Cassava, and Sorghum porridges were initially too thick, sticky, slimy, and pasty, and also at the end not easy to swallow even at low solids content—especially by the Up-Down method. These attributes make CPs difficult to ingest for infants given their limited OP abilities, thus, leading to limited nutrient intake, and this can contribute to malnutrition. Methods to improve the texture properties of indigenous CPs are needed to optimize infant nutrient intake.

Impact of composition and texture of protein-added yogurts on oral activity

Understanding how oral processing is altered in response to changes in the composition and mechanical properties of food provides useful information to design food with improved satiating capacity which is largely influenced by oral exposure. In turn, this information deepens the knowledge about the physiology of texture perception. Six yogurts were formulated with different amounts of protein and protein sources and addition of apple cubes: control (C), extra skimmed milk powder-added (MP), whey protein isolate-added (WPI), and whey protein microgels-added (WPM). In addition, MP was also added with maltodextrin (MPMD) and with fresh apple cubes (MPF). Activities of masseter, anterior temporalis and anterior digastric muscles during oral processing of each sample were recorded (electromyography), and jaw movement amplitudes in three dimensions were determined (jaw tracking system). The jaw muscle activities were highly dependent on the type of yogurt. Addition of apple cubes (MPF) almost doubled the oral processing time, number of chews, and muscle activity of all samples. MP and MPMD required similar but lower values of oral processing than MPF attributed to their reinforced network of milk protein. The lowest values were found for WPI, C and WPM, indicating a weaker, more fluid material. These behavioral results, which clearly differentiate the samples, are discussed in connection to the rheological and sensory properties of the yogurts. This study suggests that adding apple cubes significantly alters the oral processing pattern, such that they may be a more effective way of increasing the oral processing time (time exposure) compared to more subtle changes in the protein amount or source. Nevertheless, changes in the protein amount and source also affected, although to a lesser extent, the behavioral, rheological, and sensory properties of yogurt.

Perception and measurement of food texture: Solid foods

There is still a gap between instrumental measurement and sensory evaluation because of the complexity of food texture in spite of many efforts. In sensory evaluation, the terms describing the texture should be well understood by panelists, which poses a problem of establishing lexicons and training panelists. In the instrumental measurement, more efforts are required to understand the large deformation and fracture behavior of foods. The texture profile analysis (TPA) proposed by Alina Szczesniak, Malcolm Bourne, and Sherman has been applied to many foods, and was useful to develop the understanding of textures. But sometimes confusion of the interpretation of TPA parameters appeared. Many new techniques have been introduced to quantify TPA parameters. Recent efforts to fill the gap between sensory evaluation and instrumental measurements, human measurements, or physiological measurements have been introduced. This endeavor is an effort of synthesizing the dentistry and biomedical approach, sensory and psychological approach, and material science approach, and therefore, the collaboration among these disciplines is necessary. This manuscript mainly discusses texture studies for solid foods.

PRACTICAL APPLICATIONS

To fill the gap between the sensory evaluation and the instrumental measurement of texture, it is necessary to examine the physical change of foods during the oral processing. This will give us the designing principle of palatable and safe foods.

Comparison of physical chewing measures to consumer typed Mouth Behavior

The purpose of this study was to investigate the hypotheses that when presented with foods that could be chewed in different ways, (1) are participants jaw movements and chewing sequence measures correlated with Mouth Behavior (MB) group, as measured by the JBMB typing tool? (2) can MB group membership can be predicted from jaw movement and chewing sequence measures? One hundred subjects (69 female and 31 male, mean age 27 ± 7.7 years) were given four different foods (Mentos, Walkers, Cheetos Puffs, Twix) and video recordings of their jaw movements made. Twenty-nine parameters were calculated on each chewing sequence with 27 also calculated for the first half and second half of chewing sequence. Subjects were assigned to a MB group using the JBMB typing tool which gives four MB groups ("Chewers," "Crunchers," "Smooshers," and "Suckers"). The differences between individual chewing parameters and MB group were assessed with analysis of variance which showed only small differences in average chewing parameters between the MB groups. By using discriminant analysis, it was possible to partially discriminate between MB groups based on changes in their chewing parameters between foods with different material properties and stages of the chewing. A 19-variable model correctly predicted 68% of the subjects' membership of a MB group. This partially confirms our first hypothesis that when presented with foods that could be chewed in different ways participants will use a chewing sequence and jaw movements that correlate with their MB as measured by the JBMB typing tool.

PRACTICAL APPLICATIONS

The way consumers chew their food has an impact on their texture perception of that food. While there is a wide range of chewing behaviors between consumers, they can be grouped into broad categories to better target both product design and product testing by sensory panel. In this study, consumers who were grouped on their texture preference (MB group) had jaw movements, when chewing a range of foods, which partially reflected group membership. Therefore, while MB group membership could not be predicted from jaw movement measurements, there were similarities in jaw movements within the members of the groups. A better understanding of how jaw movement during chewing relates to consumer sensory perception would aid in new solid product design with controlled textural attributes.

Bolus matters: the influence of food oral breakdown on dynamic texture perception

This review article focuses on design of food structure, characterisation of oral processing by boli characterisation and dynamic texture perception. Knowledge of the food properties governing bolus formation and bolus properties determining temporal changes in texture perception is of major importance. Such knowledge allows academia to better understand the mechanisms underlying texture perception and food industry to improve product texture. For instance, such knowledge can be used for developing foods with desired texture perception that fit in a healthy diet or that are customized to specific consumer groups. The end point of oral processing is the formation of a safe-to-swallow bolus. The transitions of solid and soft solid foods into bolus are accompanied by tremendous modifications of food properties. The review discusses dynamic changes in bolus properties resulting in dynamic changes of texture perception during oral processing. Studies monitoring chewing behaviour are discussed to complement the relationships between bolus properties and dynamic texture perception. We conclude that texture perception evolves over mastication time and depends on food properties, such as mechanical properties, mainly in the beginning of oral processing. Towards the middle and end of oral processing, bolus properties depend on food properties and explain texture perception better than food properties.

Caramel as a Model System for Evaluating the Roles of Mechanical Properties and Oral Processing on Sensory Perception of Texture

Food formulation can have a significant impact on texture perception during oral processing. We hypothesized that slight modifications to caramel formulations would significantly alter mechanical and masticatory parameters, which can be used to explain differences in texture perception. A multidisciplinary approach was applied by evaluating relationships among mechanical properties, sensory texture, and oral processing. Caramels were utilized as a highly adhesive and cohesive model system and the formulation was adjusted to generate distinct differences in sensory hardness and adhesiveness. Descriptive analysis was used to determine sensory texture, and mechanical properties were evaluated by oscillatory rheology, creep recovery, and pressure sensitive tack measurements. Oral processing was measured by determining activity of anterior temporalis and masseter muscles via electromyography and tracking jaw movement during chewing. The substitution of agar or gelatin for corn syrup at 0.6% w/w of the total formulation resulted in increased sensory hardness and decreased adhesiveness. Creep recovery and pressure sensitive tack testing were more effective at differentiating among treatments than oscillatory rheology. Hardness correlated inversely with creep compliance, and both stickiness and tooth adhesiveness correlated with pressure sensitive adhesive force. Harder samples, despite being less adhesive, were associated with increased muscle activity and jaw movement during mastication. Tooth packing, not linked with any mechanical property, correlated with altered jaw movement. The combination of material properties and oral processing parameters were able to explain all sensory texture differences in a highly adhesive food.