Effects of different food hardness on cognitive inhibitory control function.

Mastication leads to an immediate enhancement in cognitive functions, including inhibitory control. Furthermore, the hardness of the food increases sympathetic nerve activity during and immediately after mastication. Hence, the cognitive function could be enhanced by increased sympathetic nerve activity. The present study aimed to investigate the effects of food hardness on cognitive inhibitory control function in humans. The participants were 23 healthy adults (19-22 years old). Experiments were conducted with two types of gummies (soft and hard). The participants ingested 13 g of gummies and performed a stop-signal task to measure cognitive inhibitory control function after they rested for 5 min. The reaction time for the stop-signal task after gummy consumption was significantly shorter in the hard gummy condition compared to the soft gummy condition (p < .05). Furthermore, the accuracy rate of the responses was also significantly higher in the hard gummy condition compared to the soft gummy condition (p < .05). The results of the present study suggest that food hardness enhances cognitive inhibitory control function in humans.

Improvement of chewing and swallowing risks in community-dwelling older adults using texture-modified food.

BACKGROUND/OBJECTIVES: Understanding the mechanism of chewing and swallowing food is important when creating a proper diet for older adults. This study investigated whether texture-modified model foods can reduce the difference in chewing and swallowing parameters between healthy community-living young and older adults. SUBJECTS/METHODS: In total, 35 older and 20 young adults (mean age: 75 and 25 years, respectively), matched for sex and number of teeth, were recruited and their unstimulated salivation and tongue pressure were measured. Simultaneous assessment of chewing and swallowing characteristics was conducted using surface electromyography and a videofluoroscopic swallowing study while the participants ingested 8 g of model food with one to four levels of hardness. RESULTS: The average tongue pressure and salivation among older adults were 61% and 49.7%, respectively, of the corresponding values observed in young adults. The older adult group used significantly (P < 0.05) increased muscle force with more chewing cycles (P < 0.05) than the young adult group, which was maintained even when consuming foods with the lowest hardness, although without chewing. However, the age effect on oral processing time existed only for the hardest foods. Swallowing difficulties among older adults were demonstrated by the significant increase in vallecula aggregation time. The total food intake duration was significantly (P < 0.05) longer in older adults than in young adults, regardless of food hardness. CONCLUSIONS: There were measurable differences in the process of chewing and swallowing food between young and older adults, which can be improved with food hardness control. Adjusting food hardness may help food intake in healthy older adults.

[Identification of factors influencing the texture sensitivity of young healthy volunteers based on a model for distinguishing the hardness of an agar-gelatin gel].

Elucidating the causes of variability in food texture sensitivity is important for understanding the mechanisms underlying food choice and portion size, eating rates, and enjoyment of food. Since texture perception significantly affects eating behavior, it is assumed that ability to recognize food texture, in turn, may depend on eating behavior. The aim of the study was to elucidate the relationship between the ability to recognize the hardness of an agar-gelatin gel, on the one hand, and the nutritional value of the diet, the type of eating behavior and the level of hunger and satiety feelings, on the other hand. Material and methods. In 38 healthy residents of Syktyvkar (15 men, 23 women aged 21 to 31 years) food textural sensitivity was determined by pairwise comparison of the hardness of model agar-gelatin gels and the level of the feeling of stomach fullness at the time of testing. All participants completed a food diary, the Dutch Eating Behavior Questionnaire, the Yale Food Addiction Scale, and assessed the standard organoleptic and hedonic properties of commercial fruit jelly. Statistical processing of the data was performed using non-parametric statistics: the Mann-Whitney U-test, Fisher's exact test, and calculating the Spearman's correlation coefficient. Results. The ability to recognize the hardness of food gel was found to vary significantly among the participants. The percentage of correct answers given by participants with high food textural sensitivity (n=20) was equal to 92 and 82% when comparing agargelatin gels with hardness in the range of 40-300 and 800-1000 kPa, respectively. Participants with low food texture sensitivity (n=18) gave the correct answer in 74 and 31% of cases when tasting soft and hard gels, respectively. Participants with high and low sensitivity to food gel texture did not differ in the type of eating behavior, as well as in the average daily intake of energy, macronutrients and dietary fiber. Correlation analysis revealed a negative relationship (rs=-0.37, p=0.020) between the percentage of correct answers when determining the hardness of the agar-gelatin gel and the level of the stomach fullness among all participants (n=38). In the sensory evaluation of fruit jelly, it was found that the descriptor «hard¼ was chosen by 60 and 22% (p=0.025) of the participants from the groups with high and low textural sensitivity, respectively. Conclusion. The ability to discriminate the hardness of an agar-gelatin gel is higher in people with a low level of stomach fullness feeling. Sensitivity to the texture of food gel is not related to energy value and macronutrient content in the daily diet and does not depend on the type of eating behavior. Participants with high food textural sensitivity are more likely to use the characteristic "hard" when evaluating fruit jelly.

Análisis cinemático de la masticación de alimentos duros y blandos en participantes dentados utilizando articulografía electromagnética 3D / Kinematic analysis of hard and soft food mastication in dentate participants using 3D electromagnetic articulography

RESUMEN: Diversos estudios reportan que el tipo de alimento influye directamente en los patrones cinemáticos de la masticación. El objetivo de este estudio fue analizar y comparar los ciclos masticatorios de participantes adultos y completamente dentados durante la masticación de alimentos de diferente textura y dureza (maní y zanahoria) utilizando articulografía electromagnética 3D. Se evaluaron 11 participantes sanos (5 hombres; 6 mujeres), de 31,9 ± 5,2 años de edad. Mediante articulografía electromagnética 3D, se registró la masticación de dos alimentos de prueba (maní y zanahoria). Los datos de movimiento mandibular fueron procesados con MATLAB® y obteniendo diferentes parámetros-frecuencia masticatoria en ciclos por segundo, velocidad de descenso y ascenso mandibular, área de las proyecciones de cada ciclo masticatorio en los tres planos del espacio-que fueron comparados según tipo de alimento y género de los participantes. Se encontraron diferencias estadísticamente significativas entre las áreas de los ciclos masticatorios en el plano horizontal según tipo de alimento, siendo mayor para la masticación de zanahoria (P=,003). Así mismo, se detectaron diferencias estadísticamente significativas entre las áreas sagitales de los ciclos entre hombres y mujeres, siendo mayor en mujeres (P=,042). Nuestros resultados concuerdan con otros estudios que afirman que la textura del alimento influye en las características cinemáticas de los ciclos masticatorios.

SUMMARY: Several studies report that the type of food directly influences the kinematic patterns of mastication. The aim of this study was to analyze and compare the chewing cycles of adult and fully dentate participants during the mastication of foods of different texture and hardness (peanuts and carrots) using 3D electromagnetic articulography. Eleven healthy participants (5 men; 6 women), 31.9 ± 5.2 years old, were evaluated. By means of 3D electromagnetic articulography, the mastication of two test foods (peanuts and carrots) was recorded. The data associated to mandibular movement were processed with MATLAB® obtaining different parameters-masticatory frequency in cycles per second, mandibular descent and ascent rate, area of the projections of each masticatory cycle in the three planes of space-which were compared according to type of food and sex of the participants. Statistically significant differences were found between the areas of the masticatory cycles in the horizontal plane according to type of food, being greater for carrots (P=.003). Likewise, statistically significant differences were detected between the sagittal areas of the cycles between men and women, being greater in women (P=.042). Our results agree with other studies that affirm that the texture of the food influences the kinematic characteristics of the masticatory cycles.

The influence of food hardness on the physiological parameters of mastication: A systematic review.

OBJECTIVE: This systematic review had the purpose to collect existing data concerning the influence of food hardness on mastication in adults. DESIGN: The review was listed with PROSPERO (CRD42017069760) and was directed following with PRISMA and CRD (Centre for Reviews and Dissemination, University of York) statement. A database search of articles issued from 1998 up to December 2018 was carried-out using four databases: Pubmed, Cochrane Library, Web of Science and Scopus. The lists of references of the articles selected for the review were read to identify any other relevant studies. The included publications were analysed for level of evidence, study design, sample characteristics, test of mastication, primary outcomes and key results. A quality assessment of the articles included in the review was performed. RESULTS: 1686 articles were found through database searching. The studies that complied with all the inclusion criteria and were considered for the conclusive analysis were 38 and their methodological quality was scored as moderate/low. The findings of the analysed articles were consistent, despite the presence of different methodologies and the lack of a complete control of the bias. They revealed that the majority of the chewing parameters, which were gathered in four groups: 1) number of cycles, 2) sequence duration, 3) muscle activity and 4) coordination and amplitudes and shape of mandibular displacements, increased in the transition from soft to hard food. CONCLUSIONS: Hard-diet in adults has an impact on the masticatory function increasing almost all the physiological masticatory parameters, muscle coordination and changes of masticatory side.

Comparison of wearable sensors for estimation of chewing strength.

This paper presents wearable sensors for detecting differences in chewing strength while eating foods with different hardness (carrot as a hard, apple as moderate and banana as soft food). Four wearable sensor systems were evaluated. They were: (1) a gas pressure sensor measuring changes in ear pressure proportional to ear canal deformation during chewing, (2) a flexible, curved bend sensor attached to right temple of eyeglass measuring the contraction of the temporalis muscle, (3) a piezoelectric strain sensor placed on the temporalis muscle, and (4) an electromyography sensor with electrodes placed on the temporalis muscle. Data from 15 participants, wearing all four sensors at once were collected. Each participant took and consumed 10 bites of carrot, apple, and banana. The hardness of foods were measured by a food penetrometer. Single-factor ANOVA found a significant effect of food hardness on the standard deviation of signals for all four sensors (P-value < .001). Tukey's multiple comparison test with 5% significance level confirmed that the mean of the standard deviations were significantly different for the provided test foods for all four sensors. Results of this study indicate that the wearable sensors may potentially be used for measuring chewing strength and assessing the food hardness.

The effect of aging on mastication and swallowing parameters according to the hardness change of solid food.

As part of the aging process, multiple oral physiologic changes occur and these changes may cause individuals to reduce food intake or switch the types of food texture. Thus, the need to develop food products for the elderly has increased. To evaluate the suitability of the food products for the elderly, the evaluation method should be verified and it is important to identify the parameters of mastication and swallowing. Therefore, the purpose of this study was to compare the differences of mastication and swallowing parameters between the young adults and the elderly depending on the varying hardness of rice food product. Subjects included 20 young adults and 40 elderly and bolus transit times of video-fluoroscopic swallowing study (VFSS) were used. Four types of rice products with different hardness were provided including cooked rice, soft-boiled rice, rice gruel and thin rice gruel. In the elderly group, the chewing number, oral processing time, post-faucial aggregation time, valleculae aggregation time (VAT), first subsequence duration and total duration were significantly different according to the changes in food hardness. Of the bolus transit times, the VAT and the second subsequence duration (S-S2) were significantly different between the two groups. These results suggest that VAT and S-S2, key VFSS parameters, as well as the chewing number and total duration are useful tools for evaluating the effect of aging on mastication and swallowing of solid foods. PRACTICAL APPLICATIONS: In Korea, the aging population is rapidly increasing. According to recent surveys, a large number of elderly Koreans have reported chewing difficulties and many of them are in the state of under-nutrition. As aging progresses, multiple physiologic changes occur in mastication and swallowing functions. These changes may cause individuals to reduce their food intake or switch to soft food products. Therefore, the development of texture-modified food products for the elderly is needed and they should be developed based on the understandings of the physiology of mastication and swallowing according to different rheological properties of food products consumed in Korea, which are quite different from those of the western countries. In this study, we compared the differences of mastication and swallowing parameters between the young adults and the elderly depending on the varying hardness of rice food product.

Changes in mandibular movement during chewing of different hardness foods.

In order to clarify the change in mandibular movement during chewing of foods with different hardness, 20 healthy subjects were asked to chew 3 types of gummy jellies (containing 6, 8, and 10% gelatin), and the masseter muscular activity and the mandibular movement were recorded. The indicators representing the muscular activity (integral value of masseter muscular activity), the mandibular movement (opening distance, masticatory width, cycle time, opening maximum velocity and closing maximum velocity), and the stability of masticatory movement were calculated, respectively, and compared among the three foods. The integral value of masseter muscular activity was smallest for the 6% gelatin and significantly increased in order as the content of gelatin increased to 8, 10%. The value of each indicator for the mandibular movement increased gradually as the food got harder. The value for all indicators was significantly larger for the 10 than the 6%. However, between the two foods, no significant change was observed for the several indicators. The mean ratio of the 10% gelatin to the 8% gelatin for the cycle time was extremely small, being 1.01, but was between the range of 0.89-1.07 showing aspects of changes within each individual. The other indicators showing small ratio were similar in this aspect. The parameters representing stability of movement showed the lowest values for the 8% gelatin. It was suggested that the hardness of food affected mandibular movement during mastication, but the movement changed variously according to the hardness and exerted muscular activities.

EMG Activity of Masseter Muscles in the Elderly According to Rheological Properties of Solid Food.

OBJECTIVE: To assess the impact of aging on masticatory muscle function according to changes in hardness of solid food. METHODS: Each of fifteen healthy elderly and young people were selected. Subjects were asked to consume cooked rice, which was processed using the guidelines of the Universal Design Foods concept for elderly people (Japan Care Food Conference 2012). The properties of each cooked rice were categorized as grade 1, 2, 3 and 4 (5×10(3), 2×10(4), 5×10(4), and 5×10(5) N/m(2)) respectively. Surface electromyography (sEMG) was used to measure masseter activity from food ingestion to swallowing of test foods. The raw data was normalized by the ratio of sEMG activity to maximal voluntary contraction and compared among subjects. The data was divided according to each sequence of mastication and then calculated within the parameters of EMG activities. RESULTS: Intraoral tongue pressure was significantly higher in the young than in the elderly (p<0.05). Maximal value of average amplitude of the sequence in whole mastication showed significant positive correlation with hardness of food in both young and elderly groups (p<0.05). In a comparisons between groups, the maximal value of average amplitude of the sequence in whole mastication and peak amplitude in whole mastication showed that mastication in the elderly requires a higher percentage of maximal muscle activity than in the young, even with soft foods (p<0.05). CONCLUSION: sEMG data of the masseter can provide valuable information to aid in the selection of foods according to hardness for the elderly. The results also support the necessity of specialized food preparation or products for the elderly.

EMG Activity of Masseter Muscles in the Elderly According to Rheological Properties of Solid Food

OBJECTIVE: To assess the impact of aging on masticatory muscle function according to changes in hardness of solid food. METHODS: Each of fifteen healthy elderly and young people were selected. Subjects were asked to consume cooked rice, which was processed using the guidelines of the Universal Design Foods concept for elderly people (Japan Care Food Conference 2012). The properties of each cooked rice were categorized as grade 1, 2, 3 and 4 (5×10³, 2×10⁴, 5×10⁴, and 5×10⁵ N/m²) respectively. Surface electromyography (sEMG) was used to measure masseter activity from food ingestion to swallowing of test foods. The raw data was normalized by the ratio of sEMG activity to maximal voluntary contraction and compared among subjects. The data was divided according to each sequence of mastication and then calculated within the parameters of EMG activities. RESULTS: Intraoral tongue pressure was significantly higher in the young than in the elderly (p<0.05). Maximal value of average amplitude of the sequence in whole mastication showed significant positive correlation with hardness of food in both young and elderly groups (p<0.05). In a comparisons between groups, the maximal value of average amplitude of the sequence in whole mastication and peak amplitude in whole mastication showed that mastication in the elderly requires a higher percentage of maximal muscle activity than in the young, even with soft foods (p<0.05). CONCLUSION: sEMG data of the masseter can provide valuable information to aid in the selection of foods according to hardness for the elderly. The results also support the necessity of specialized food preparation or products for the elderly.