Determining chewing efficiency using a solid test food and considering all phases of mastication

Effects of distribution, structure and interactions of starch, protein and cell walls on textural formation of cooked rice: A review

The constitution and forms of rice determine its processing and cooking properties and further control the cooked rice quality. As the two main components, starch and protein content correlations and their characteristics have been extensively explored. However, rice is mainly consumed as polished kernels, components distribution, cytoplasmic matrix, and cell walls work together, and the properties of extracted components or flour are difficult to reflect the quality of cooked rice accurately. Thus, this review summarizes the multi-scale structure changes of main components during real rice cooking conditions. The dynamic thermal changes and leaching behaviors in rice kernels are compared with pure starch or rice flour. The in situ changes and interactions of starch granules, protein bodies, and cell walls during cooking are reviewed. Based on this, different textural evaluation methods are compared, and the advantages and disadvantages are pointed out. The oral chewing perception and bionic chewing simulation for textual evaluation have gradually become hot. Both rice quality controllers and eating quality evaluators attempt to establish an accurate quality evaluation system with the increased demand for high-quality rice.

Effect of chewing ability on in vivo oral digestive characteristics and in vitro gastrointestinal starch hydrolysis of three different types of cooked rice

Chewing ability has a strong effect on food digestion. However, little is known about the relationship between the food mastication degree and the subsequent gastric emptying. This study was to explore the effects of individual chewing ability (strong and weak) on the in vivo oral processing characteristics and in vitro dynamic gastrointestinal starch hydrolysis of three types of rice (japonica rice, indica rice and waxy rice). Results showed that the swallowable bolus in the weak chewing group had larger holes and a looser microstructure with more small rice particles, while the strong chewing ones obtained a bolus with higher saliva content (up to 28%) and starch hydrolysis degree (up to 13.55%). Moreover, the gastric retention and starch hydrolysis of the strong chewing ability group were higher in the artificial gastric dynamic system (AGDS). The indica rice particles with the higher degree of fragmentation contacted enzymes easier and hydrolyzed quicker, thus emptying through the stomach faster (81.76%). However, the oral chewing properties of rice mainly influenced the starch digestion in the stomach and the initial stage of the small intestine (∼5 min). This study suggested that the chewing ability and rice variety can influence the bolus properties, which in turn affected the gastric emptying and the degree of starch hydrolysis during digestion.

The effect of food supplements on completely edentulous women rehabilitated with complete dentures: A randomized controlled trial

Aim

Neglected oral health is a major issue, especially in women of developing countries, leading to early loss of teeth which may further lead to malnutrition, degradation of overall health, and increased chances of osteoporosis. Thus, the aim of this study was to assess the effect of food supplement on masticatory performance, nutritional status, electromyography (EMG) (masseter and temporalis), and bone mineral density (BMD) among women rehabilitated with complete denture.

Settings and Design

Hospital based randomized controlled trial.

Materials and Methods

A randomized controlled trial with 106 women of 45-65 years rehabilitated with complete denture (56 received food supplement and 50 did not receive food supplement) and 52 healthy control was conducted. The outcomes were assessed at baseline and 3 and 6 months of follow up (after complete denture fabrication). Outcomes were measured via masticatory performance, nutritional status (hemoglobin, serum calcium, albumin, and Vitamin D level), EMG of masseter and temporalis muscles, and BMD.

Statistical Analysis Used

Friedman's analysis of variance test was used as a nonparametric test, and the Statistical Package for the Social Sciences version 21.0 at a significance level of 0.05 was used for statistical analysis.

Results

A statistically significant change was observed during follow up for the group with food supplement for BMD, EMG, and masticatory performance. When biochemical parameters were assessed during follow up, no statistically significant change was observed for both groups (with and without food supplement), except for serum calcium level in group which received food supplement.

Conclusion

It was found that the magnitude of effect was remarkably meager in food supplement group which could be perhaps due to less time given for follow up period. Longer duration of trials would yield better results.

A breakage index for characterizing in vitro nut fragmentation and predicting human oral fragmentation

Breakage of food influences eating experience and sensory perception. The aims of the study were to identify an appropriate breakage index and to develop an in vitro method for predicting the ease of oral breakage of nuts. Kernels of five types of nuts were fragmented in vitro using a texture analyzer and 12 subjects therefore performed molar bites. In addition, peanuts were differently roasted (over 0, 15, 25, and 35 min) to vary texture within the same nut type. Projected particle areas were determined using imaging. Two Breakage Indices were compared (1) BI-I, the difference, after and before fragmentation, in square root values of ratios between total projected area and volume [Agrawal et al., 1997, Archives of Oral Biology, 42(1), 1-9], and (2) BI-II, the ratio of the total projected area after and before fragmentation. BI-II gives a stronger linear regression than BI-I between in vivo and in vitro index values for different types of nuts; Pearson's r = 0.834 versus 0.499 (12 subjects with all data pooled). Using BI-II, a subject's regression result in fragmentation tests with differently roasted peanuts was as strong as when testing different nut types: Pearson's r = 0.984 versus 0.964. Since the range of the in vitro BI-II values was 5.5 times smaller in the peanut tests, the finding of a similarly strong regression indicates a high sensitivity of BI-II to detect differences in food texture. BI-II is useful for food industry to determine how easily solid foods break down and thereby compare the potential of flavor release between foods during chewing.

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.

Effect of frozen storage on preservation of a silicone-based test food material

Aim: This study aimed to evaluate the effect of frozen storage on the physical properties of a silicone-based test food material, highly used to evaluate the masticatory performance in research settings. Methods: A total of 1,666 silicone cubes of Optosil Comfort® with 5.6-mm edges were shaped and stored at -18°C. The cubes were subsequently tested for flexural strength (maximum force, displacement, stress, and strain) before breaking (n = 136), changes in weight and size (n = 170), and masticatory performance (n = 1360) at eight timepoints: immediately after cube preparation (baseline, no freezing), and 1, 2, 3 and 4 weeks, and 2, 4 and 6 months after frozen storage. The cubes were thawed 8 h before each assessment. Results: The maximum force, stress, maximum displacement, and deformation values for the cubes were not affected by freezing (P > 0.05). At all of the time points, the cubes exhibited similar weight (P = 0.366) and size (identical values). The masticatory performance for the cubes also showed no differences from baseline through 6 months (P = 0.061). Conclusion: Freezing Optosil Comfort® silicone cubes did not alter the physical and mechanical properties of the material, being suitable to optimize the assessment of masticatory parameters for research purposes.

The effect of bolus size on masticatory parameters at swallowing threshold in children using a hard, solid, artificial test food

The effect of different bolus sizes on food breakdown has been studied in adults, but not in children. The objective of this study was to study median particle size (MPS) and other parameters of masticatory function at swallowing threshold (ST) in 8–10‐year‐old‐children with two different bolus sizes. A randomized crossover trial was undertaken in 89 eight to ten‐year‐old children. The study was performed with informed consent and ethical approval. The artificial test food used was made of a condensation silicone (Optosil Comfort) following a standardized protocol. Two bolus sizes (three or four quarters of a 20‐mm diameter, 5‐mm thick tablet) were randomized to avoid an order effect and tested in different sessions. Variables were: MPS (X₅₀) at ST, number of cycles until ST, sequence and cycle duration as well as cycles/g. Comparisons were performed with paired t and Wilcoxon tests, regressions and correlations were run. Cutoff for statistical significance was .05. Statistically significant differences were found for all variables; X₅₀ (2.5 ± 0.8 vs. 2.8 ± 0.7 mm, p < .001), cycles until ST (38 vs. 40, p = .022), sequence (25 vs. 27 s, p = .003), and cycle duration (650 vs. 683 ms, p = .015) and cycles/g (27 vs. 21 cycles/g, p < .001), three or four quarters, respectively. In conclusion, in children, as in adults, chewing on a bigger bolus size leads to a larger MPS (X₅₀) at ST. When chewing on a larger bolus the number of cycles increases, but not enough to swallow the same particle size since the number of cycles/g is less with a bigger bolus size.

Effects of food particle loss on the evaluation of masticatory ability using image analysis

PURPOSE

To examine how particle loss affects the evaluation of masticatory ability using the image analysis method.

METHODS

The subjects were divided into two groups:Y-group (healthy young adults: 10 male, 10 female; mean age 27.6 ± 1.9 years), and D-group (denture wearing older adults: 13 male, 9 female; mean age, 75.1 ± 5.3 years). Raw carrots, peanuts, and a combined test food from 5 daily food materials (mixed foods) were selected as test foods. Images of the boluses were captured and processed after the subjects freely masticated the test foods until the point of swallowing or completed half strokes of total chewing cycles. The median particle size (X₅₀) was calculated from the data for each particle. We compared X₅₀ calculated from all particles obtained from the masticatory bolus (as X_50N) with the X₅₀ of only selectively larger particles (as X_50R).

RESULTS

Significant correlations were observed between X_50N and X_50R (p < 0.01) determined in almost all masticatory conditions. In particular, for particle sizes of 2 mm or more, the correlation coefficient between X_50N and X_50R was notably strong (r > 0.75).

CONCLUSION

The method of analyzing only larger particles makes it possible to evaluate masticatory ability without losing the characteristics of the original particle size distribution of the entire bolus. This finding can be applied for the evaluation of masticatory ability, especially among older adults who have difficulty retrieving the total amount of test food due to decreased activities of daily living.

Reliability and validity of a new colour-changing test food with an acid-base reaction for the clinical assessment of masticatory performance

The aim of this study was to determine the reliability and validity of a new test food for the clinical assessment of masticatory performance. The test food had two overlapping acidic/basic halves. Ten dentate subjects chewed one unit for 10-100 cycles. One subject chewed ten units for the same number of cycles. Differences in the L*, a* and b* colour axes were determined before and after chewing by ANOVA. Colour guides were created based on the values of these axes and matched with the number of cycles. The reliability of the guides was evaluated using 30 images, where three examiners indicated the number of cycles in which the colour closest to that of a chewed material was found. The data were contrasted with the real values of the guides to determine the validity (Kappa coefficients). The equivalence of the guides with the median particle size (X₅₀) was determined using equidimensional curves. The test food progressively changed from green to pink during chewing. As the number of cycles increased, the a* values increased and the b* values decreased (p < 0.05). Overall, the guides showed a Kappa value >0.8 for the intra-examiner and inter-examiner reliability and the validity comparisons. The a* and X₅₀ values were inversely proportional to each other, and the b* values showed a direct relationship with the X₅₀ values. The L* values did not show correspondence. The new test food showed high reliability and validity for the assessment of masticatory performance through clinical colour guides matched with the number of cycles and X₅₀.

Consensus on the terminologies and methodologies for masticatory assessment

A large number of methodological procedures and experimental conditions are reported to describe the masticatory process. However, similar terms are sometimes employed to describe different methodologies. Standardisation of terms is essential to allow comparisons among different studies. This article was aimed to provide a consensus concerning the terms, definitions and technical methods generally reported when evaluating masticatory function objectively and subjectively. The consensus is based on the results from discussions and consultations among world‐leading researchers in the related research areas. Advantages, limitations and relevance of each method are also discussed. The present consensus provides a revised framework of standardised terms to improve the consistent use of masticatory terminology and facilitate further investigations on masticatory function analysis. In addition, this article also outlines various methods used to evaluate the masticatory process and their advantages and disadvantages in order to help researchers to design their experiments.

The Influence of Initial Breakage on Size Reduction during Habitual Chewing of a Solid Test Food

OBJECTIVES

Food comminution during chewing is due to intra-oral particle selection and subsequent breakage. Under conditions of habitual chewing and a nearly complete selection, the influence of initial breakage on particle size reduction was studied in trials with a first chewing cycle (N = 1) from a sequence of randomized trials with various cycle numbers. Furthermore, relationships were examined between degree of fragmentation from breakage (r-fr), molar maximal bite force (MBF) and chewing efficiency (the number of cycles needed to half the initial particle size, N(1/2-Xo)).

DESIGN

Thirty-one subjects with a natural dentition chewed samples of 2 half-cubes (9.6 × 9.6x4.8 mm) of Optosil®, using sequences with 1-7 cycles, in 2-10 randomized trials; 10 trials with one cycle. Particle size distributions by underweight, characterized by median particle size, X₅₀, were obtained using sieving. N(1/2-Xo) was derived from the log(X₅₀)-log(N) relationship. and r-fr from the cumulative distribution of underweight fractions of damaged particles for N = 1. MBF was determined on both sides of the jaw using a force transducer and averaged.

CONCLUSIONS

A strong, decreasing regression occurred in X₅₀ at N = 1 with r-fr (R² = 0.934, p < 0.001). The decreasing regression of N(1/2-Xo) with r-fr was moderately strong (R² = 0.454; p < 0.001). Thus, initial size reduction is strongly determined by breakage and overall reduction partly, when chewing small amounts of particles. N(1/2-Xo) vs. MBF and r-fr vs. MBF were weakly related (R²≤0.124, p = 0.052-0.127). The lack of a pronounced relationship between r-fr and MBF suggests that either MBF is not relevant but supra-threshold force, or that another factor, occlusion, may influence breakage.

Nutritional status and masticatory function of the indigenous compared with non-indigenous people of Nayarit, Mexico

OBJECTIVE

The objective of this study was to compare the nutritional statuses and masticatory function of the non-indigenous and indigenous adult people of the state of Nayarit, Mexico.

DESIGN

Forty-two indigenous (Cora or Huichol ethnic group) and 100 non-indigenous people, all adults with natural dentition, participated in this cross-sectional study. They performed a free-style masticatory test consisting five trials of chewing silicon pieces for 20 cycles. Masticatory performance was determined by sieving the silicon particles, masticatory laterality was determined by calculating the asymmetry index, and the cycle duration was also recorded. Weight and body fat mass were measured using a portable digital weighing machine and height and body circumferences were recorded to calculate the body mass index (BMI), body fat percentage, and the waist-hip ratio. Each aspect of masticatory function and each nutritional variable were compared using T-test, analysis of variance, and Kruskal-Wallis or Mann-Whitney tests, as appropriate.

RESULTS

Body fat percentage, BMI, and waist-hip ratio were higher (P < 0.0005) in the indigenous group compared to the non-indigenous. The indigenous group had a significantly shorter stature than the non-indigenous group. Cora group had a higher BMI and higher percentage of body fat than the Huichol group (P < 0.05). No significant differences were detected between the groups for any aspect of masticatory function.

CONCLUSIONS

Indigenous people from the Nayarit, especially the Cora ethnic group, are more obese, have more total body fat, and more abdominal fat than non-indigenous people. Indigenous people show similar masticatory function.

Optimizing a determination of chewing efficiency using a solid test food

A test using a solid food is relevant to measure chewing ability (CA) as (a) it includes an integrated functioning of all oral structures involved, (b) an impairment of chewing a solid food causes inevitably diet restrictions, and (c) chewing efficiency (CE) can easily be defined. CE is the number of chewing cycles, N(1/2-Xo), needed to attain a particular chewing outcome (a median particle size, X ₅₀ , which is half the initial particle size Xo) whereas chewing performance (CP) is a state of chewing outcome (X ₅₀ ) at an arbitrary number of chewing cycles. The use of CE is preferable for CA because inter-subject ratios are constant regardless of the initial conditions of the test food. Furthermore, the inter-subject variation is two times larger for CE values than for CP ones, yielding a better inter-subject differentiation of CA. However, a determination of CP needs only one N-value, and that of CE at least two N-values for enabling an interpolation of N(1/2-Xo). Using samples of only two half-cubes (9.6 x 9.6 x 4.8 mm; limiting test load) of Optosil (an artificial test food), and detailed previous information on log(X ₅₀ )-log(N) relationships (Liu et al., Archives of Oral Biology, 2018, 91, 63-77) as a "gold standard," a short procedure has been developed for a priori choosing two appropriate N-numbers, and the subsequent determination of a subject's CE. This procedure has been developed using results from 20 young adults (23.7 years, SD 1.1) and was validated in 10 middle-aged and older adults (52.3 years, SD 10.1), where impairments in the dentition were reflected in the CE-values. Our short procedure to determine CE will improve studies on relationships between CA and food preference, or between CA and dental factors and/or physiological factors. The first type of relationship may be of interest for food industry whereas the second type may be of interest for population studies in rapidly aging societies and for clinical studies in dentistry. Results can be compared between subjects and studies without bias by using CE rather than CP as a measure of CA.

Locking up of food between posterior teeth and its influence on chewing efficiency

OBJECTIVES

Food particles are intra-orally locked up between antagonistic posterior teeth, during each chewing cycle. Food locking up (FL) may enhance selection of particles for subsequent breakage, hence chewing efficiency (CE). The two aims were to determine FL, and to examine the relationship between FL and CE.

DESIGN

A spherical gum bolus (volume: 1.3 cm³) that undergoes plastic deformation rather than breakage, was used to determine FL in 20 young adults. Chewing such a bolus with initially a width-length ratio of 1, decreases this ratio, the more locking up elongates the bolus to a greater extent by pressing from the tongue, teeth, and a cheek. Before and after chewing randomly for 2-6 cycles (3 trials each), the bolus was scanned and its width-length ratio was determined using imaging. The number of chewing cycles needed to attain a width-length ratio of 0.5, N(0.5 W-L ratio) was a measure of FL. CE corresponded with the number of cycles needed to halve the initial particle size, N(1/2-Xo), when chewing samples of 2 half cubes (9.6 × 9.6 × 4.8 mm; sample volume: 0.88 cm³) of a solid artificial model food.

CONCLUSIONS

N(0.5 W-L ratio) and N(1/2-Xo) were on average 3.21 cycles (SD 1.14) and 4.04 cycles (SD 1.87) respectively. Whereas a relationship between CE and FL was lacking for subjects whose CE was worse than the median, a pronounced quadratic U-shaped relationship (R² = 0.75; p < 0.01) occurred for subjects whose CE was better. This relationship might reflect an interaction between two tongue functions: transport and subsequently FL of particles.

Influence of lower complete denture use on masseter muscles and masticatory function: A longitudinal study

BACKGROUND

Edentulism can reduce mastication, leading to changes in food pattern, with possible consequences to masticatory muscle thickness.

OBJECTIVES

This study verified masticatory function and oral perception in subjects who did not use lower CDs, and whether the insertion of new upper and lower CDs would improve such variables.

METHODS

Fifteen edentulous elderly who wore only the upper CD were selected and received new upper and lower CD. Volunteers were evaluated at baseline and after 1, 3 and 6 months of new prosthesis use. Masticatory performance (MP) was assessed by the sieving method (X₅₀ values). Masseter thickness (MT) was evaluated by ultrasonography. Oral sensorial ability (OSA) was assessed by oral stereognosis test and maximum tongue pressure (MTP) was verified by pressure sensors. Data were submitted to repeated measures ANOVA and Tukey-Kramer posthoc tests (α = 0.05). Correlation between OSA and MTP was verified by Person's correlation.

RESULTS

X₅₀ and MTP decreased (P < 0.05) after 1 month and remained stable (P > 0.05) for next assessments. After 3 months, MT in rest position was increased (P < 0.05), while during maximum voluntary contraction 1 month was enough to increase MT (P < 0.05). There were no differences for OSA (P > 0.05) and no correlation between OSA and MTP.

CONCLUSION

Masticatory performance and masseter thickness of elderly who did not use the lower dentures were improved after 2 months using new upper and lower CDs. However, new CDs in both dental arch decreased MTP. Brazilian Registry of Clinical Trials (ReBEC #RBR-37gdst).

Characterization of oral tactile sensitivity and masticatory performance across adulthood

Texture perception is one of the most important factors in food acceptance, yet population-wide differences in texture sensations are not well understood. The variation in texture perception across populations is thought to depend on oral tactile sensitivity and masticatory performance. To address this hypothesis, we aimed to measure tactile acuity with a battery of tests and quantitate the relationship to masticatory performance. The study was performed on 98 participants, in three age groups (20-25, 35-45, or over 62). Two main measures of oral sensitivity were performed: to assess bite force, subjects were asked to discriminate between foam samples of varying hardness. Second, to assess lingual sensitivity the subjects were asked to identify 3D printed shapes using their tongue, as well as identify confectionary letters. Additionally, masticatory performance was measured through assessing each participants ability to mix two-colored chewing gum. In general, we found that sensitivity and masticatory performance in the younger age groups was superior to that of older adults. We also found a positive linear trend between bite force sensitivity and masticatory performance with younger participants, a trend not found in older participants. We found no significant relationship between age groups for bite force sensitivity and masticatory performance, suggesting that age-related declines in bite force sensitivity are not a significant cause of altered masticatory performance. This study represents a valuable first step in showing that bite force sensitivity does not depend on age, and the minimal influence of factors such as oral sensitivity on masticatory performance. PRACTICAL APPLICATIONS: In a society that is rapidly aging, it is important to understand the subtle changes in physiology and eating behavior that are associated with aging. This study used a variety of tests oral sensitivity to better understand which aspects of oral physiology are integral for effective chewing. The information gained helps shed light on to the factors that create an effective chewing cycle. Besides moving knowledge forward, this study may help in designing food and rehabilitation programs for those with trouble chewing and swallowing, increasing their overall quality of life.