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

What Is Chalky? Investigating Consumer Language and Perception of Fine Particles in Beverages Containing Pea and Potato Starch

Despite its importance as an undesirable food texture, the phenomenon of chalkiness remains understudied. Chalky sensations presumably arise from fine particulates found in foods, but semantic overlap with other common descriptors of small particles, like gritty or sandy, is unclear. Here, we compare the usage of Chalky with related descriptors, and determine the effect of particle size, concentration, and xanthan content on Chalky ratings in a model beverage. A 23 factorial design with starch particle size (D90 = 33.8 and 64.6 µm), starch concentrations (10 and 20% w/v), and xanthan content (0.075 and 0.15% w/v) was used. Participants' salivary flow rate was also assessed. A multi-sip taste test was performed where naïve consumers (n = 82; 39% men, 60% women; age range = 18-79 years) rated the intensity of Chalky, Powdery, Gritty, Sandy, Mouthdrying, and Residual mouthcoating at 0, 30, and 60 s after each of three consecutive sips. All attribute ratings were highly correlated, with Chalky, Powdery, and Residual Mouthcoating being more closely correlated with each other than Gritty or Sandy. Although Chalky was still reported 60 s after consumption, no evidence of build-up was found with repeated sips. A larger size and higher concentration increased Chalky ratings, with the low-salivary-flow group reporting greater ratings for Chalky relative to the high-flow group. Our results suggest consumer percepts of small particles are overlapping but not entirely redundant. This suggests researchers and product developers should carefully distinguish between these descriptors when trying to understand consumer perception of food products containing fine particles.

Investigating oral somatosensory perception and oral symptoms of head and neck cancer patients: insights on eating behaviour

PURPOSE

Sensory alterations and oral manifestations are prevalent among head and neck cancer (HNC) patients. While taste and smell alterations have been thoroughly investigated, studies on their oral somatosensory perception remain limited. Building upon our previous publication that primarily focused on objective somatosensory measurements, the present work examined self-reported sensory perception, including somatosensation and oral symptoms, in HNC patients and evaluated their link with eating behaviour.

METHODS

A cross-sectional study was conducted using self-reported questionnaires on sensory perception, oral symptoms, sensory-related food preference, and eating behaviour among HNC patients (n = 30). Hierarchical clustering analysis was performed to categorise patients based on their sensory perception. Correlations between oral symptoms score, sensory perception, sensory-related food preference, and eating behaviour were explored.

RESULTS

Two distinct sensory profiles of patients were identified: no alteration (n = 14) and alteration (n = 16) group. The alteration group showed decreased preference towards several sensory modalities, especially the somatosensory. Concerning eating behaviour, more patients in the alteration group agreed to negatively connotated statements (e.g. having food aversion and eating smaller portions), demonstrating greater eating difficulties. In addition, several oral symptoms related to salivary dysfunction were reported. These oral symptoms were correlated with sensory perception, sensory-related food preference, and eating behaviour.

CONCLUSION

This study presented evidence demonstrating that sensory alterations in HNC patients are not limited to taste and smell but cover somatosensory perception and are linked to various aspects of eating. Moreover, patients reported experiencing several oral symptoms. Those with sensory alterations and oral symptoms experienced more eating difficulties.

Artificial saliva induced structural breakdown of surimi gels with starch under continuous compressive motions

Food texture perception is dynamic, influenced by food properties and oral processing. Using the Repeatable Dual Extrusion Cell (RDEC), the oral processing dynamics of surimi gel with different corn starch concentrations (0-15%) in the presence of 1 ml artificial saliva or water were studied. The force-time curve showed increased peak forces with higher corn starch concentrations, peaking significantly at 10%, then decreasing at 15%. Salivary amylase played a crucial role in gel sample degradation, especially in samples with 5% starch, with a work value depletion ratio of 0.535 for sample with 1 ml water (SGW-5) and 0.406 for sample with 1 ml saliva (SGS-5). SEM analysis confirmed the formation of a continuous starch network with reduced intermolecular spaces in SGS-5. The starch-iodine complex showed decreasing order with increasing starch concentration, and SGS-5 exhibited the highest degradation rate (61.61 ± 0.92%). Mathematical modeling revealed that initial decay rates (k1) in gel sample decreased with increasing starch concentration, and samples with starch and artificial saliva had higher initial degradation rates. These findings highlight the intricate interplay between saliva and starch in the surimi gel matrix under continuous compressive motions by RDEC apparatus, providing insights for formulating food products with tailored textures properties.

Effect of simulated saliva on rheological and tribological properties of oleogel-in-water HIPEs during oral processing

HYPOTHESIS

High internal phase emulsions (HIPEs) have great potentials in the food industry to control fat consumption. Textural perception of HIPEs during oral processing is strongly influenced by saliva, which has not been systematically investigated. Therefore, we investigated the roles of saliva in the rheological and tribological properties of HIPEs during oral processing.

EXPERIMENTS

HIPEs (O/W) stabilized by oleogel and a protein were fabricated. Small (SAOS) and large (LAOS) amplitude oscillatory shearing measurements and tribological tests were performed, in combination with structural characterization of the emulsions.

FINDINGS

Particle size and CLSM observation indicated that saliva induced coalescence of droplets by weakening the interface and more EC resulted in faster clustering. SAOS tests revealed that emulsions mixed with saliva had weaker structural strength and lower resistance to deformation. Particularly in large deformation, the HIPEs mixed with saliva presented an acceleration in the droplet-droplet structure breakdown, which led to the pronounced strain-thinning behavior and energy dissipation. Tribological curves further revealed that the corporation of saliva contributed to the release of oil to reduce friction coefficient.

Oral somatosensory alterations and salivary dysfunction in head and neck cancer patients

PURPOSE

Patients with head and neck cancer (HNC) are at high risk of malnutrition due to eating difficulties partly mediated by sensory alterations and salivary dysfunction. Clinical studies have mostly focused on taste and smell alterations, while changes in oral somatosensory perception are largely understudied. The study aimed to investigate oral somatosensory (tactile, texture, chemesthetic, and thermal) responses and salivary functions of HNC patients in comparison to healthy controls.

METHODS

A cross-sectional study was conducted using psychophysical tests in HNC patients (n = 30) and in age- and gender-matched control subjects (n = 30). The tests included measurements of point-pressure tactile sensitivity, whole-mouth chemesthetic stimulation, food texture discrimination, and temperature discrimination. Salivary functions, including hydration, saliva consistency, pH, volume, and buffering capacity, were also evaluated.

RESULTS

HNC patients demonstrated significantly lower chemesthetic sensitivity (for medium and high concentrations, p < 0.05), thermal sensitivity (p = 0.038), and salivary functions (p = 0.001). There were indications of lower tactile sensitivity in the patient group (p = 0.101). Patients were also less sensitive to differences in food roughness (p = 0.003) and firmness (p = 0.025).

CONCLUSION

This study provided evidence that sensory alterations in HNC patients extend beyond their taste and smell. The measurements demonstrated lower somatosensory responses, in part associated with their reduced salivary function. Oral somatosensory alterations and salivary dysfunction may consequently impart the eating experience of HNC patients. Thus, further investigations on food adjustments for this patient group seem warranted.

Differential levels of anti-Mycobacterium tuberculosis-specific IgAs in saliva of household contacts with latent tuberculosis infection

Introduction

Mucosal immunity is strongly elicited in early stages of many respiratory and enteric infections; however, its role in tuberculosis pathogenesis has been scarcely explored. We aimed to investigate Mycobacterium tuberculosis (Mtb) specific IgA levels in saliva in different stages of latent Tuberculosis Infection (TBI).

Methodology

A multiplex bead-based Luminex immunoassay was developed to detect specific IgA against 12 highly immunogenic Mtb antigens. A prospective cohort of household contacts (>14 years) of pulmonary TB cases was established in Santiago, Chile. Contacts were classified as Mtb-infected or not depending on serial interferon-γ release assay results. Saliva samples were collected and tested at baseline and at a 12-week follow-up.

Results

Mtb-specific IgA was detectable at all visits in all participants (n = 168), including the "non-Mtb infected" (n = 64). Significantly higher median levels of IgA were found in the "Mtb infected" compared to the uninfected for anti-lipoarabinomannan (LAM) (110 vs. 84.8 arbitrary units (AU), p < 0.001), anti-PstS1 (117 vs. 83 AU, p < 0.001), anti-Cell Membrane Fraction (CMF) (140 vs. 103 AU, p < 0.001) and anti-Culture Filtrate Proteins (CFP) (median 125 vs. 96 AU, p < 0.001), respectively. Nonetheless, the discriminatory performance of these specific mucosal IgA for TBI diagnosis was low.

Conclusion

Saliva holds Mtb-specific IgA against several antigens with increased levels for anti-LAM, anti-PstS1, anti-CMF and anti-CFP found in household contacts with an established TBI. The role of these mucosal antibodies in TB pathogenesis, and their kinetics in different stages of Mtb infection merits further exploring.

Assessment of masticatory efficiency based on glucose concentration in orthodontic patients - a methodological study

INTRODUCTION

Treatment for malocclusion can cause discomfort and pain in the teeth and periodontium, which may impair masticatory efficiency. The glucose concentration method is widely used to assess masticatory efficiency for its convenience in the clinical situation, although its validity has not been shown.

OBJECTIVE

The aims were to determine the validity of the glucose concentration method and investigate if this method can be applicable to orthodontic patients with braces.

DESIGN

Sixteen healthy individuals (7 men, 9 women, and 26±5 years old) and 16 patients with malocclusions needing orthodontic treatment (5 men, 11 women, and 26±4 years old) participated. Glucose concentration was measured after 5-, 10-, and 15-s mastication of gummy jelly and compared to Hue values obtained from the color-changing gum method (reference method). In addition, all participants were asked to fill out the Oral Health Impact Profile questionnaire (OHIP) to assess differences in perception related to the mouth before and after the placement of braces.

RESULTS

Glucose concentrations were strongly correlated to measures of the two-color chewing gum methods (R² =0.965). Both the glucose extraction and chewing gum hue value were the smallest for 5 s chewing cycles and increased as the number of chewing strokes increased for the 15 s chewing cycles. (Hue: R² = 0.510, P < 0.001; glucose: R² = 0.711, P < 0.001) Masticatory efficiency assessed by both methods was significantly lower in orthodontic patients compared to controls (P<0.05), even though it was not affected by bonding (P>0.09). In addition, OHIP scores in physical pain dimension and psychological disability were higher in orthodontic patients than in the control group (P<0.005).

CONCLUSION

Measurement of glucose concentration was confirmed as a reliable and convenient method for assessing masticatory efficiency. Furthermore, it appears that this method is applicable to patients with braces whose perception in the oral cavity could change.

Ozone for SARS-CoV-2 inactivation on surfaces and in liquid cell culture media

This study evaluated the inactivation of SARS-CoV-2, the virus responsible for COVID-19, by ozone using virus grown in cell culture media either dried on surfaces (plastic, glass, stainless steel, copper, and coupons of ambulance seat and floor) or suspended in liquid. Treatment in liquid reduced SARS-CoV-2 at a rate of 0.92 ± 0.11 log₁₀-reduction per ozone CT dose(mg min/L); where CT is ozone concentration times exposure time. On surface, the synergistic effect of CT and relative humidity (RH) was key to virus inactivation; the rate varied from 0.01 to 0.27 log₁₀-reduction per ozone CT value(g min/m³) as RH varied from 17% to 70%. Depletion of ozone by competitive reactions with the medium constituents, mass transfer limiting the penetration of ozone to the bulk of the medium, and occlusion of the virus in dried matrix were postulated as potential mechanisms that reduce ozone efficacy. RH70% was found plausible since it provided the highest disinfection rate while being below the critical RH that promotes mould growth in buildings. In conclusion, through careful choice of (CT, RH), gaseous ozone is effective against SARS-CoV-2 and our results are of significance to a growing field where ozone is applied to control the spread of COVID-19.

A secret of salivary secretions: Multimodal effect of saliva in sensory perception of food

Saliva plays multifunctional roles in oral cavity. Even though its importance for the maintenance of oral health has long been established, the role of saliva in food perception has attracted increasing attention in recent years. We encourage researchers to discover the peculiarity of this biological fluid and aim to combine the data concerning all aspects of the saliva influence on the sensory perception of food. This review presents saliva as a unique material, which modulates food perception due to constant presence of saliva in the mouth and thanks to its composition. Therefore, we highlight the salivary components that contribute to these effects. Moreover, this review is an attempt to structure the effects of saliva on perception of different food categories, where the mechanisms of salivary impact in perception of liquid, semi-solid, and solid foods are revealed. Finally, we emphasize that the large inter-individual variability in salivary composition and secretion appear to contribute to the fact that everyone experiences food in their own way. Therefore, the design of the sensory studies should consider the properties of volunteers' saliva and also carefully monitor the experimental conditions that affect salivary composition and flow rate.

Understanding relations between rheology, tribology, and sensory perception of modified texture foods

The aim of this work was to examine relations between instrumental and sensory parameters in a texture modified food matrix, with and without saliva. Nine pureed carrot samples (eight thickened and a control) were developed with starch (0.4 and 0.8% wt/wt), xanthan (0.2 and 0.4% wt/wt) or starch-xanthan blends that met International Dysphagia Diet Standardisation Initiative (IDDSI) Level 4 guidelines using fork and spoon tests. Rheological and tribological tests were conducted on the food and simulated bolus prepared by adding fresh stimulated saliva to the food (1:5, saliva:food) to mimic oral processing. Perceived sensory properties were identified using a temporal dominance of sensations (TDS) test (n = 16) where panelists were given a list of nine attributes. The area under the curve was extracted from TDS curves for each attribute/sample and this was correlated with rheological (viscosity at 10 s^-1 , G', G″, and tan δ at 1 Hz) and tribological (friction coefficient in three regimes) data. The viscosity of the control sample decreased after adding hydrocolloids (except Starch_0.8%) and with saliva incorporation. G' and G″ either increased or were similar for xanthan and blends and decreased for starch-thickened samples. Hydrocolloid addition increased friction for all samples and was higher with saliva addition. Sensory results showed that samples with starch were perceived as thick and grainy while xanthan was perceived as smooth and slippery. A greater number of sensory attributes correlated with viscoelastic parameters compared to friction coefficients. Correlations were highest with the saliva added samples, further highlighting the importance of including saliva during instrumental testing.

Oral Sensitivity to Flowability and Food Neophobia Drive Food Preferences and Choice

The study aimed to investigate the role of sensitivity to flowability on food liking and choice, the relationship between sensitivity to flowability and food neophobia, and its role in food liking. Five chocolate creams were prepared with different levels of flowability, and rheological measurements were performed to characterise them. One hundred seventy-six subjects filled in the Food Neophobia Scale and a food choice questionnaire (FCq). The FCq was developed to evaluate preferences within a pair of food items similar in flavour but different in texture. Secondly, the subjects evaluated their liking for creams (labelled affective magnitude (LAM) scale) and the flowability intensity (generalised labelled magnitude (gLM) scale). The subjects were clustered into three groups of sensitivity and two groups of choice preference. The effect of individual flowability sensitivity on food choice was investigated. Finally, the subjects were clustered into two groups according to their food neophobia level. The sensitivity to flowability significantly affected the liking of chocolate creams and the solid food choice. The liking of chocolate creams was also affected by the individual level of neophobia (p = 0.01), which, in turn, was not correlated to flowability sensitivity. These results confirm that texture sensitivity and food neophobia affect what a person likes and drives what a person chooses to eat.

Whey Protein Derived Mouthdrying Found to Relate Directly to Retention Post Consumption but Not to Induced Differences in Salivary Flow Rate

Whey protein is fortified into beverages to provide functional benefits, however, these beverages are considered mouthdrying. To date whey protein derived mouthdrying has not been quantified using a 'physical measure' in parallel with rated perception. Saliva flow could also relate to whey protein derived mouthdrying, however this has not been previously tested as an intervention. Accordingly, volunteers (n = 40) tested mouthdrying in different whey beverages and the sensory profile was evaluated by a trained sensory panel (n = 10). Volunteers also rated mouthdrying combined with collection of saliva samples post beverage consumption to measure retention to the oral cavity. To modulate saliva flow rate, volunteers both chewed on parafilm (to increase saliva flow) and used cotton wool (to remove saliva) before tasting beverages and rating mouthdrying. Both the volunteers and sensory panel rated whey protein beverages (WPB) as significantly more mouthdrying than the control beverage (whey permeate). The significantly higher rating of mouthdrying from the volunteers coincided with significantly higher protein concentration in saliva samples post WPB consumption, supporting mucoadhesion as the mechanism. Modulating saliva flow did not lead to any difference in rated mouthdrying and future work would be beneficial to evaluate further the influence of natural variation in salivary flow rate.

Addition of chocolate milk to diet corresponds to protein concentration changes in human saliva

Salivary proteins have the potential to alter oral sensory perception of foods. In rodents, dietary polyphenol exposure increases salivary concentrations of polyphenol-binding proteins and several cystatins, which correlate with less aversion to polyphenol-rich solutions. If similar salivary shifts occur in humans, then increasing dietary polyphenols may improve orosensory experience of polyphenol-rich foods. We hypothesized that small dietary changes, focused on polyphenols, would increase expression of salivary binding proteins for polyphenols and thus suppress unpleasant polyphenol sensations. However, analogs of salivary polyphenol-binding proteins are found in foods. Thus, we also hypothesized that food-sourced analogs of these salivary proteins would mitigate changes in saliva and sensation. Human subjects (N=55) alternated weeks of consuming a low polyphenol diet and then a regular diet plus a polyphenol-rich chocolate milk (almond, containing no polyphenol-binding proteins, or bovine, containing polyphenol-binding proteins). Statistical analyses revealed both chocolate milk interventions corresponded to changes in relative expression of 96 proteins and calculated concentration of 146 proteins (both after correction for false discovery rate), out of 1,176 proteins identified through proteomics. Of the proteins that changed, proline-rich proteins and cystatins were noticeable, which reflects prior work in animal studies. Subjects rated all chocolate milks as less flavorful after the bovine chocolate milk intervention week compared to low polyphenol weeks, but generally sensory changes were minimal. However, the results confirm that dietary changes coincide with salivary changes, and that some of those changes occur in proteins that have potential to influence oral sensations.

A Tutorial on Saliva's Role in Swallowing With a Focus on Sjögren's Syndrome

Purpose Saliva is integral to swallowing and necessary for oral health. Understanding saliva's origin and properties is important for swallowing assessment and management. Diseases such as Sjögren's syndrome (SS) can affect saliva negatively, often contributing to dysphagia. Our objectives are to (a) highlight saliva's fundamental role in swallowing, (b) provide a bibliometric overview of literature pertaining to SS pathophysiology and effects on saliva, (c) explore implications of salivary changes on swallowing and quality of life in SS and other populations, and (d) provide suggestions for systematic saliva assessment in practice. Method This tutorial reviews saliva production, composition, and involvement in swallowing within health and disease. Using rapid review methodology, we outline the effect of SS on saliva and describe SS etiology, diagnosis, and treatment. We discuss formal saliva assessments and a multidisciplinary approach. Results Saliva plays a vital role in swallowing, particularly lubrication, bolus formation, and oral health. SS affects the salivary glands altering salivary flow rate and composition. We identified 55 studies (N) measuring salivary changes, grouping them according to four strata demarcated by SS classification criteria updates. For some, xerostomia, dysphagia, and reduced life quality result. Formal saliva assessments include the Clinical Oral Dryness Score, Xerostomia Inventory, and Secretion Rating Scale. Multidisciplinary care is optimal for patients with salivary changes. Conclusion Understanding salivary changes in disease may enhance understanding of swallowing and inform dysphagia practice. Expanding swallowing assessments with formal saliva evaluations, and patient perspectives thereof, may aid in developing bespoke treatments, ultimately improving outcomes and quality of life. Supplemental Material https://doi.org/10.23641/asha.12456449.

Textural Changes by Mastication and Proper Food Texture for Patients with Oropharyngeal Dysphagia

Bolus texture is a key factor for safe swallowing in patients with dysphagia since an improper texture may result in aspiration and/or pharyngeal residue. This article discusses swallowing bolus texture from two key aspects: the textural change of solid food by mastication and the current standardized definition of food texture in Japan. When swallowing a liquid bolus, the texture is mostly maintained from ingestion to swallow onset. For solid food, however, the food is crushed by chewing and mixed with saliva before swallowing; the texture of the ingested food is modified to an easily swallowable form at swallow onset by mastication. Understanding the mechanism of mastication and its assessment are therefore important in deciding the proper diet for dysphagic patients. As standardized criteria for classifying the texture of food and liquid are essential as well, this report also describes the Japanese Dysphagia Diet 2013 that is commonly used as the standardized index for dysphagic diets in Japan.

Liking of food textures and its relationship with oral physiological parameters and mouth-behavior groups

Researchers have categorized people into four "mouth-behavior" groups based on their oral processing preferences, and claimed that members of those mouth-behavior groups differ in their food texture preferences. If people could be classified into groups based on their liking of different textures, food products could be targeted to specific subgroups, potentially enhancing consumer acceptability. In the first part of our study, we grouped people based on their liking ratings of a wide variety of food textures by asking 288 participants to rate their liking of 106 food texture attributes in an online survey. In the second part of our study, we further examined relationships among individuals' food texture liking ratings, mouth-behavior group membership, and measurements of four oral physiological parameters (saliva flow rate, chewing efficiency, biting force, and particle size sensitivity). One-hundred participants completed the online survey on food texture liking, classified themselves into one of four mouth-behavior groups (Chewers, Crunchers, Smooshers, and Suckers), and were measured for four oral physiological parameters. We refuted the idea that large texture-liking subgroups exist. Although our participants self-categorized themselves into the four mouth-behavior groups similarly to previous researchers, our texture liking measurements did not support the presumed preferences of those mouth-behavior groups. Clustering of participants on their oral physiological measurements produced a "low particle-size sensitivity" cluster, a "high biting force" cluster, a "high saliva flow rate" cluster, and a "low saliva flow and low chewing efficiency" cluster. Neither our texture liking nor our oral physiological measurements predicted membership in the four mouth-behavior groups.

Relating oral physiology and anatomy of consumers varying in age, gender and ethnicity to food oral processing behavior

The aim of this study was to link parameters describing oral physiology and anatomy of consumers varying in age, gender and ethnicity to food oral processing behavior. Three groups of healthy consumers were compared: Dutch, Caucasian adults (18-30 yrs, n =32), Chinese, Asian adults (18-30 yrs, n =32) and Dutch, Caucasian older adults (65-85 yrs, n =32). Mastication performance, salivary flow rate (stimulated and unstimulated) and dental status were quantified to characterize oral physiology. Volume of oral cavity, tongue dimensions, facial anthropometry, height and weight were quantified to characterize anatomy. Oral processing behavior of three solid foods (carrot, cheese and sausage) was quantified by video recordings and eating rate (g/s), average consumption time (s), chews per bite (-) and average bite size (g) were determined. Dutch, Caucasian older adults had smaller volume of oral cavity, lower number of teeth and larger head width compared to Dutch, Caucasian adults. Chinese, Asian adults showed significantly higher mastication performance and larger head width compared to Dutch, Caucasian consumers, while dental status did not significantly differ between groups. Males had significantly larger volumes of oral cavity and larger head height and width compared to females. Dutch, Caucasian adults had a shorter average consumption time (s), less chews per bite and consumed the three foods with higher eating rate (g/s) compared to Dutch, Caucasian older adults. Chinese, Asian adults had a significantly longer average consumption time (s), more chews per bite, smaller average bite size (g) and lower eating rate (g/s) compared to Dutch, Caucasian adults. Twenty-one significant relationships were found between oral physiological and anatomical parameters and oral processing behavior. Body weight resulted in the largest β-values, indicating to be the anatomical parameter of largest influence on oral processing behavior. We conclude that only few oral physiological and anatomical parameters related with food oral processing behavior. We suggest that other factors, including cultural factors contribute to variation in food oral processing behavior between different consumer groups more than saliva flow, volume of oral cavity, mastication performance and dental status.

Morphological and masticatory performance variation of mouth behavior groups

Food texture preference and product acceptance are hypothesized to be influenced by mouth behavior. Recent work identified four mouth behavior (MB) groups that describe most consumers in the United States: Chewers, Crunchers, Smooshers, and Suckers. While these behavioral preferences are thought to play a significant role in food selection and purchasing decisions, it is unknown how closely they relate to body and oral cavity measures as well as masticatory apparatus performance. Our objectives were twofold: to determine whether MB groups are related to (a) morphological variation in body, head, and oral cavity size and (b) masticatory apparatus performance (i.e., maximum jaw gape, maximum bite forces at the incisors and first molar). Measurements were collected following an online MB assessment (JBMB Mouth Behavior Typing Tool) where participants self-identified as one of the four types of consumers. As expected, univariate associations were observed between masticatory performance and overall body as well as oral cavity size. These relationships did not persist when assessed with multivariate methods. MB groups did not differ by body, head, or oral cavity measurements; maximum gape; or maximum bite force. Because of small sample sizes for Smooshers and Suckers-a reflection of their limited prevalence in the U.S. population-we interpret the results for these groups with caution. We can more confidently conclude based on our sample that Chewers and Crunchers do not differ in size, bite force, or maximum gape, suggesting other factors primarily drive food texture choice and preference in these individuals.

A Historical Review of Persian Medicine Studies into Saliva Manifestations for Potential Applications for Diagnosis and Management of Metabolic Syndrome

BACKGROUND AND OBJECTIVES

Regarding the development of diagnostic tests based on saliva and the prevalence of metabolic syndrome (MetS), the aim of this study is to review Persian Medicine manuscripts in the field of saliva manifestations, its relation to metabolic syndrome, and treatment recommendations.

METHODS

This study is a mini-review. We investigated the canon of medicine and some important Persian medical or pharmaceutical manuscripts from the 9th to the 19th centuries. PubMed and Google Scholar databases were explored for finding relevant information about the relationship between saliva and metabolic syndrome and its treatment.

RESULTS

Studies have suggested that maldigestion is one of the important causes of MetS. Sialorrhea may be an early symptom of maldigestion. Attention to sialorrhea and its treatment may be useful in the prevention and treatment of metabolic syndrome based on PM sources. In PM, sialorrhea is treated with 3 major approaches: lifestyle modification along with simple or compound medicines.

CONCLUSION

Saliva manifestations could be considered as early symptoms of metabolic syndrome. As mentioned in WHO strategies, traditional medicine can be used along with modern medicine due to its effectiveness in the management of various ailments.

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.

Interactions of salivary mucins and saliva with food proteins: a review

Mucins are long glycoprotein molecules responsible for the gel nature of the mucous layer that covers epithelial surfaces throughout the body. Mucins, as the major salivary proteins, are also important proteins for the food oral processing and digestion. The interactions of salivary mucins and saliva with several food proteins and food protein emulsions, as well as their functional properties related to the food oral processing were reviewed in this paper. The target food proteins of focus were whey proteins (lactoferrin and beta-lactoglobulin) and non-whey proteins (casein, gelatin, galectin/lectin, and proline-rich proteins). Most of the studies suggest that electrostatic attraction (between positively charged food proteins with negatively charged moieties of mucin mainly on glycosylated region of mucin) is the major mode of interaction between them. On the other hand, casein attracts the salivary proteins only via non-covalent interactions due to its naturally self-assembled micellar structure. Moreover, recent studies related to β-lactoglobulin (BLG)-mucin interactions have clarified the importance of hydrophobic as well as hydrophilic interactions, such as hydrogen bonding. Furthermore, in vitro studies between protein emulsions and saliva observed a strong aggregating effect of saliva on caseinate and whey proteins as well as on surfactant-stabilized emulsions. Besides, the sign and the density of the charge on the surface of the protein emulsion droplets contribute significantly to the behavior of the emulsion when mixed with saliva. Other studies also suggested that the interactions between saliva and whey proteins depends on the pH in addition to the flow rate of the saliva. Overall, the role of interactions of food proteins and food protein emulsions with mucin/saliva-proteins in the oral perception, as well as the physicochemical and structural changes of proteins were discussed.

Saliva could act as an emulsifier during oral processing of oil/fat

Human saliva is a fluid naturally secreted in the oral cavity that interacts with food and food components for bolus formation, structure degradation, as well as lubrication. Because of the presence of salivary proteins, we speculate that saliva could also function as an effective emulsifier during oral processing of oil/fat. In this preliminary work, experiments were then designed to test this hypothesis. Whole human saliva from three healthy subjects were collected and analyzed for protein content, surface tension, and molecular weight distribution. Saliva emulsions were obtained both in vitro one and in situ for all three participating subjects. Droplet size distribution, zeta potential, and microstructure of such emulsions were examined immediately after the emulsification. Results show that stable saliva emulsions can be produced during oral processing of either pure oil (rapeseed oil) or fat food (pork belly in this work). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that protein fractions of 27 and 55 kDa molecular weights were favored for emulsion formation. This work suggests that human saliva could function as an effective emulsifier and oral emulsification could be an important mechanism for the oral processing of oil/fat. Despite being preliminary, findings from this work provide a new scientific insight to our understanding of the oral behavior of oil/fat and their sensory perception. PRACTICAL APPLICATIONS: Food industry is currently under a growing pressure to use novel techniques and ingredients to minimize the use of oil/fat in food products but without compromising its sensory quality. However, food industry has limited progresses because of the lack of understanding of the mechanisms of oral sensation and perception of oil/fat. Whereas there have been extensive debates about the sensory mechanisms of oil/fat, this work takes a step back by examining the oral behavior of oil/fat. Findings show that saliva can actually function as emulsifier to oil/fat, which means that ingested oil/fat will be dispersed and converted into an emulsion at the oral stage. The findings from this work offer food industry new insight on the sensory mechanisms of oil/fat.

How are macronutrient intake, BMI, ethnicity, age, and gender related to the composition of unstimulated saliva? A case study

This study investigated how macronutrient intake, BMI, ethnicity, age, and gender are related to the composition of unstimulated saliva. First, two groups of Caucasian, Dutch subjects varying in daily intake of carbohydrate, fat, and protein were selected. The daily intake of macronutrients differed by two- to threefold between the low (n = 14) and high (n = 16) macronutrient intake groups. The same subjects were divided into two groups based on BMI: normal weight (n = 14, 22.5 ± 2.0 kg/m² ) and overweight (n = 16, 28.1 ± 3.4 kg/m² ). Second, one group of Caucasian, Dutch (n = 15) and one group of Asian, Chinese (n = 15) subjects were selected. Unstimulated saliva was collected from all groups. Protein concentration, amylolytic activity, lipolytic activity, and saliva flow rate were determined. None of the salivary parameters varied according to macronutrient intake and BMI. An effect of ethnicity on protein concentration was observed (p < .01; η² = 0.142), with Asians having a 45% higher protein concentration in unstimulated saliva than Caucasians. Age had a significant effect on all salivary parameters. Protein concentration (p < .01; η² = 0.256), amylolytic activity (p < .01; η² = 0.234), and lipolytic activity (p < .05; η² = 0.207) increased with age, while saliva flow rate decreased (p < .01; η² = 0.262). Gender had a significant effect on saliva flow rate (p < .01; η² = 0.130), with male subjects having a 32% higher flow rate than females. Age was the factor that had the greatest impact on the characteristics of unstimulated saliva. As the modulation of saliva composition according to diet has been reported previously, the extent to which macronutrient intake can affect saliva composition needs to be further investigated. PRACTICAL APPLICATIONS: Saliva plays an important role in food oral processing. From the breakdown of food structures to the binding of flavor compounds and the formation of a swallowable bolus, saliva is essential for the perception and appreciation of foods. Identifying the factors that affect saliva composition is, therefore, necessary to understand the differences in eating behavior, food perception, and preference across different consumer groups. This article aims to highlight the importance of considering saliva variability when designing food products that meet the needs of specific consumer groups.

Associations between food consumption patterns and saliva composition: Specificities of eating difficulties children

Identifying objective markers of diet would be beneficial to research fields such as nutritional epidemiology. As a preliminary study on the validity of using saliva for this purpose, and in order to explore the relationship between saliva and diet, we focused on clearly contrasted groups of children: children with eating difficulties (ED) receiving at least 50% of their energy intake through artificial nutrition vs healthy controls (C). Saliva of ED and C children was analyzed by various methods (targeted biochemical analyses, 2-D electrophoresis coupled to MS, ¹H NMR) and their diet was characterized using food frequency questionnaires, considering 148 food items grouped into 13 categories. Complete datasets were obtained for 16 ED and 16 C subjects (median age 4.7y and 5.0y, respectively) and the statistical link between salivary and dietary characteristics was studied by Multiple Factor Analysis (MFA). Overall, ED children showed as expected lower consumption frequency scores and higher food selectivity. The two groups of children differed in "diet/saliva" associations. Some distinctive salivary variables were common to both groups of children. For example, carbonic anhydrase 6 and the consumption frequency of biscuits & sweets and drinks were positively associated with the MFA axis 1 in C children, but oppositely associated in ED children. Specifically for ED children, abundant salivary proteins (cystatins, amylase, amylase fragments) and some metabolites (amino acids, galactose, lactate) correlated with axis 1, together with the consumption frequency of sauces & seasonings, bread & cereal products, ready-to-eat meals, fish, biscuits & sweets, drinks and potatoes. Specifically for C children, several proteins (serum albumin, haptoglobin, Igκ, apolipoprotein A-1, α-1 antitrypsin) correlated with axis 1, together with the consumption frequency of biscuits & sweets, milk & dairy products, drinks, fruit, meat and vegetables. This study demonstrates that the qualitative aspect of diet is linked to saliva composition, and that the associations between dietary consumption and salivary composition differ between groups of subjects with contrasted diets.

Impact of the Breakdown Behavior on Chinese Traditional Stewed Pork with Brown Sauce: Physical Properties Using Microstructural Analysis

The potential physics differences of Chinese traditional stewed pork during mastication were investigated. Ten subjects chewed and expectorated the fat and lean layers of stewed pork with brown sauce at different stages of mastication. The produced boluses were analyzed for their physical properties. The results suggested the subjects’ saliva secretion and moisture content of the boluses during mastication increased significantly depending on subjects and food types studied (P<0.05) and led to increase of bolus apparent particle size because of saliva uptake. Bolus first peak force tended to decrease significantly, whereas bolus flowability increased significantly during mastication (P<0.05). Further, microstructure of boluses revealed series processing was conducted by comminution, aggregation, hydration, and dilution. The boluses ready-to-swallow possessed a higher flowability and a homogenetic matrix. Therefore, the changes in physics and microstructure of bolus contributed to dynamic texture perception of traditional Chinese stewed pork with brown sauce.

Model cheese aroma perception is explained not only by in vivo aroma release but also by salivary composition and oral processing parameters

The aim of the present paper was to determine, from four model cheeses differing in fat content and firmness, the respective impacts ofin vivoaroma release, bolus rheology, chewing activity, mouth coating and salivary composition on dynamic aroma perception.

Influence of hydration and starch digestion on the transient rheology of an aqueous suspension of comminuted potato snack food

Oral processing of most foods is inherently destructive: solids are broken into particles before reassembly into a hydrated bolus while salivary enzymes degrade food components. In order to investigate the underlying physics driving changes during oral processing, we capture the transient rheological behaviour of a simulated potato chip bolus during hydration by a buffer with or without α-amylase. In the absence of amylase and for all oil contents and solids weight fractions tested, we find a collapse of the transient data when graphed according to simple Fickian diffusion. In the presence of amylase, we find effects on the transient and pseudo steady state bolus rheology. Within the first minute of mixing, the amylase degrades only ≈6% of the starch but that leads to an order of magnitude reduction in the bolus elasticity, as compared to the case without amylase. Thus, for an in vitro bolus, only a small amount of starch needs to be digested to have a large impact on the bolus rheology very soon after mixing.

Attenuated acute salivary α-amylase responses to gustatory stimulation with citric acid in thin children

Salivary α-amylase (sAA) is responsible for the ‘pre-digestion’ of starch in the oral cavity and accounts for up to 50 % of salivary protein in human saliva. An accumulating body of literature suggests that sAA is of nutritional importance; however, it is still not clear how sAA is related to individual's nutritional status. Although copy number variations (CNV) of the salivary amylase gene (AMY1) are associated with variation in sAA levels, a significant amount of sAA variation is not explained by AMY1 CNV. To measure sAA responses to gustatory stimulation with citric acid, we used sAA ratio (the ratio of stimulated sAA levels to those of resting sAA) and investigated acute sAA responses to citric acid in children with normal (Normal-BMI, n 22) and low (Low-BMI, n 21) BMI. The AMY1 gene copy number was determined by quantitative PCR. We, for the first time, demonstrated attenuated acute sAA responses (decreased sAA ratio) to gustatory stimulation in Low-BMI (thinness grade 3) children compared with the Normal-BMI children, which suggest that sAA responses to gustatory stimulation may be of nutritional importance. However, child's nutritional status was not directly related to their resting or stimulated sAA levels, and it was not associated with AMY1 gene copy number. Finally, AMY1 CNV might influence, but did not eventually determine, sAA levels in children.

Characteristics of the saliva flow rates of minor salivary glands in healthy people

OBJECTIVES

To investigate the normal range and characteristics of saliva secretion in the minor salivary glands (MSGs).

DESIGN

The flow rates of MSGs were measured in 4 anatomical locations of oral mucosa, and the relationship between MSG flow rates and whole saliva flow rates were assessed in 300 healthy subjects stratified by age and sex. An additional 30 young females were further evaluated for flow symmetry, effects of stimulation, circadian effects in MSGs, and the relationship with the flow rates of major salivary glands.

RESULTS

(1) The mean saliva flow rates were 2.10 ± 0.66 (lower labial glands), 2.14 ± 0.62 (upper labial glands), 2.88 ± 0.72 (buccal glands) and 2.15 ± 0.51 (palatal glands) μl/min/cm(2), respectively. The flow rate of buccal glands was significantly higher than the rates of SMGs in other locations (P < 0.01). (2) 5-year-old children had the lowest MSG flow rates (P < 0.0001) while the 10-14-year-old group had the highest (P < 0.001). (3) MSG flow rates were independent of sex (P > 0.05), right vs. left (P > 0.05), and citric acid (2.5%) stimulation (P > 0.05). (4) Only labial MSG displayed a significant secretory circadian rhythm with the highest rate in the evening (P < 0.05). (5) A weak correlation was found between the flow rate of palatal glands and that of unstimulated whole saliva (r = 0.195, P = 0.007).

CONCLUSIONS

Our findings provide a reference for functional evaluation of MSGs and for donor site selection of MSG transplantation for treatment of severe dry eye syndrome.

Oral and salivary changes among renal patients undergoing hemodialysis: A cross-sectional study

We wanted to assess oral and salivary changes in end stage renal disease (ESRD) patients undergoing hemodialysis (HD) and to understand the correlation of such changes with renal insufficiency. The cross-sectional study was performed among 100 ESRD patients undergoing HD. Among these, 25 patients were randomly selected to assess the salivary changes and compared with 25 apparently healthy individuals who formed the control group. Total duration of the study was 15 months. Oral malodor, dry mouth, taste change, increased caries incidence, calculus formation, and gingival bleeding were the common oral manifestations. The flow rates of both unstimulated as well as stimulated whole saliva were decreased in the study group. The pH and buffer capacity of unstimulated whole saliva was increased in the study group, but stimulated whole saliva did not show any difference. ESRD patients undergoing HD require special considerations during dental treatment because of the various conditions inherent to the disease, their multiple oral manifestations and the treatment side-effects.