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Northern fur seals (Callorhinus ursinus) have a distinct life history pattern comprising annual terrestrial breeding and oceanic migration, and the physiological changes associated with these patterns are of particular interest for understanding their environmental adaptations. However, owing to their oceanic distribution, limited information is available on the reproductive physiology of wild individuals during the immature stage and the winter migration period. This study aimed to determine the relationships among the seasonal hormone profiles, body growth, age, and pregnancy using monthly serum samples collected over 3-5 years from two male and two female captive individuals during pubescence and sexual maturation. Small increases in the serum testosterone signaled puberty in males aged 3 and 4 years. Thereafter, males showed considerable increases in testosterone during breeding seasons, indicating sexual maturity. Immature female serum progesterone was maintained at low levels, but after pubescence, females showed an increase in serum progesterone in August, the month next to the peak of delivery, followed by a decrease. In non-pregnant females, progesterone did not increase significantly until the next breeding season, but in pregnant females, they increased again from February to March and then gradually decreased. Immature males increased body mass constantly and reached puberty when their body mass exceeded 20 kg, and they showed seasonal weight fluctuations after puberty. These results provide fundamental information for determining sexual maturity and pregnancy in this species based on sex steroid hormones and body mass measurements.

International audience; 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.

Although the causes have not been specified yet, wild populations of northern fur seals (Callorhinus ursinus) have been decreasing, which is why conservation techniques such as captive breeding and health maintenance should be established. Hematological parameters can be used to maintain the health status of northern fur seals kept in captivity for artificial reproduction and public education. Year-round fluctuations of blood parameters have not been examined for northern fur seals due to the difficulties in obtaining serial blood samples from wild animals during the oceanic migration period from late autumn to spring. In this study, blood samples were collected from four captive northern fur seals and analyzed monthly for more than three years to clarify the seasonal fluctuation patterns in 14 hematological parameters. Many hematological parameters seemed to be seasonal patterns: summer-autumn and winter-spring; leukocyte-related parameters were higher in summer and autumn than in winter and spring; erythrocyte-related parameters were lower in summer and autumn than in winter and spring. Significant seasonal differences in nine of the 14 parameters were observed using a generalized linear mixed model (GLMM) analysis. These results have improved our understanding of the seasonal patterns of hematological characteristics in the northern fur seal and can contribute to the health care of protected or captive northern fur seals.

A soft machine system (texture analyzer equipped with an artificial tongue) was developed to analyze the occurrence of fractures in soft food gels compressed between the tongue and hard palate. Artificial tongues were newly designed with a modulus similar to that of a somewhat tense human tongue, using transparent urethane gels. A model of soft foods that are easy or difficult to crush with the tongue was prepared using gellan gums at different concentrations. A piece of gellan gum gel was uniaxially compressed on an artificial tongue with the flat probe of a texture analyzer. The food gel and artificial tongue were deformed, leading to the fracturing of food gels alone. During compression-induced fracture, the softer food gels exhibited a lower force, lower displacement, and lower true stress than the harder gels on all artificial tongues. The fracture probability of gellan gels was lower for the combination of harder food gels and softer artificial tongues, as softer materials can deform to a larger extent. Fracture displacement of food gels was increased as the modulus of the artificial tongue decreased; however, the fracture force did not differ significantly. These results suggest that an artificial tongue with elastic modulus values similar to those of the actual human tongue is suitable for determining the fracture behavior of foods during compression between the tongue and hard palate.

A relationship has recently been suggested to exist between tongue pressure measured using balloon-type sensors and the tongue-crushable food range of individuals. This study was conducted to investigate the applicability of a balloon-type pressure sensor for texture evaluation of tongue-crushable soft foods. Six gellan gum gels were used as a soft food model. The fracture force and strain of gels were controlled at two and three levels by changing the gum concentration and acyl-group content, respectively. The pressure sensor was inserted between a food sample and texture analyzer probe, and pressure values during compression of gels were measured. During the compression test, both the food and tongue-pressure sensor were deformed, eventually leading to fracture of food gels. Using the tongue-pressure sensor, the food gels fractured at lower force because of the shape of the sensor but showed longer displacement as the sensor deformed compared to without the sensor. Gels with low-fracture force in the conventional test without the sensor exhibited lower fracture force, work, gradient, and true stress than those with high-fracture force in the sensor test. Displacement, clearance, or distance from the bottom plate, and true stress at fracture were appropriate parameters for expressing the fracture characteristics. Both the true fracture stress and fracture pressure in the sensor test decreased with the fracture strain of gels in a conventional test. These results suggest that by using a larger balloon and faster sampling, the sensor can be used to determine the fracture behavior of tongue-crushable foods.

Introduction Seal parapoxvirus (SPPV) infection has been reported among pinnipeds in aquaria in Japan; however, its seroprevalence is unknown. Therefore, an enzyme-linked immunosorbent assay (ELISA) was developed for serological diagnosis of SPPV infection. Material and Methods The gene encoding the major envelope protein of SPPV was cloned into the eukaryotic expression vector pAcGFP1-N1, which encodes the green fluorescence protein (GFP), thereby producing a fusion protein (Env-GFP). Parental and cloned vector DNA was independently transfected into cultured seal cells for the expression of GFP and Env-GFP. The wells of an ELISA plate were coated with either GFP- or Env-GFP-transfected cell lysates. The light absorbance of each serum sample was adjusted by subtracting the absorbance of GFP-coated wells from that of Env-GFP-coated wells. Sera from two spotted seals (Phoca largha), six beluga whales (Delphinapterus leucas), three Pacific white-sided dolphins (Lagenorhynchus obliquidens), and ten bottlenose dolphins (Tursiops truncatus) from an aquarium in Japan were examined using the ELISA. Results Positive reactions were not observed, except in one preserved sample collected ten years ago from a naturally SPPV-infected spotted seal. Conclusion The established ELISA could be useful in screening marine mammal sera for anti-SPPV antibodies.

C57BL/6J and DBA/2J mice are often used for hearing research because of their early onset and progression of age-related hearing loss (AHL). Here, we report that the hardness of the diet affects the progression of AHL in these mice. When C57BL/6J mice and DBA/2J mice were fed a pellet-type or powder-type standard AIN93M diet, the pellet diet significantly promoted AHL. AHL promotion was eliminated by crushing the pellet diet to a powder. Subsequently, when C57BL/6J mice were fed the pellet-type AIN93M diet obtained from three different manufacturers, two of them significantly promoted AHL. The hardness of the diets was measured, and it was found that the two diets that promoted AHL were significantly harder than the other diet. Next, we attempted to reduce diet hardness by replacing some nutritional ingredients with dried eggs or phosphatidylcholine (PC), and we succeeded in obtaining brittle diets with lower hardness values. Then, C57BL/6J mice were bred with brittle diets for 6 months and the promotion of AHL was suppressed to the equivalent level as the powder diet. Furthermore, when senescence-accelerated mice, SAMP8, were fed a brittle diet for one year, the progression of AHL was also suppressed; however, it did not affect other aging indexes, such as mental and physical performance. We also confirmed that a high-fat pellet diet, which is soft even in pellet form, did not promote AHL. Time-restricted feeding (tRF), which is a chrono-nutritional method to delay aging, ameliorated the promotion of AHL by the hard AIN93M pellets in C57BL/6J mice. These results indicate that the physical form and hardness of diets affect the progression of AHL in mouse models.

Northern fur seals (Callorhinus ursinus) are endemic to the North Pacific Ocean. They were hunted for their fur and became endangered in the late 1800s, but their populations recovered following the introduction of protection laws. Recently, populations have been decreasing again, although the reasons are unclear. For individuals that are bred and reared in captivity as part of ex situ conservation projects, details of blood characteristics are essential to ensure good health. However, the normal ranges of hematology and serum chemistry of captive northern fur seals have not been defined. This study determined the normal ranges of hematology and serum chemistry of captive fur seals. Blood samples were collected every month for 2 years from four captive northern fur seals in Japan (three born in an aquarium and one kept in the same aquarium following rescue). Fifteen blood characteristics and 29 serum chemistry properties were compared with those previously reported for wild northern fur seals in the USA. Several parameters were not within the normal ranges reported previously in wild northern fur seals. In particular, levels of alkaline phosphatase was outside of the normal ranges previously reported. The hematological and serum chemistry ranges in this study can help provide a guideline for understanding the health of northern fur seals in captivity.

We evaluated the mechanical properties and electrical impedance data of spinach after short time heating. The mechanical fracture properties of samples heated for 40 s significantly differed from those of the non-treated samples. A circular arc of the Cole-Cole plot obtained from the impedance data shrunk after heating for 10 s. Similarity of the circular arcs, i.e. non-uniformity in the electrical characteristics, changed after heating for 30 s. After heating, extracellular resistance values were decreased from 650 to 16 kΩ, and cell membrane capacitance values were decreased from 13 to 0.28 nF. These changes could be evaluated simply by using the length of the coordinate at the top of the circular arc from the origin, and these occurred earlier and were greater in magnitude than those in the fracture properties were. These electrical properties could be an index for the early detection of changes in the fracture properties of samples.

Two cases of extralobar pulmonary sequestrations from a walrus (Odobenus rosmarus) and a Steller sea lion (Eumetopias jubatus) are described in the present study. Grossly, an independent, soft unilocular cystic mass was found within the abdominal cavities of both animals, adherent to the diaphragm in O. rosmarus and attached to the cardia of the stomach in E. jubatus. Histopathologically, the cysts were lined by pseudostratified ciliated columnar epithelium with abundant goblet cells, while the wall comprised of glands, hyaline cartilage, bronchiole- and alveolus-like structures, smooth muscles, and large, well-developed elastic and muscular arteries. The pinniped cases presented are exceptionally rare and to the best of the authors’ knowledge, marks the first descriptions of this congenital anomaly in wildlife.

This study aimed to investigate the retrogradation rate of heat moisture treated sago and arenga starches using different approaches, including a thermal approach using DSC (differential scanning calorimetry), a rheological approach using dynamic viscoelasticity as rheological and syneresis level. The autoclaving procedures prepared the HMT starches at 20% moisture content and warmed to 120°C for 60 min and 90 min for sago and arenga starches, respectively. The Avrami equation was used to express starch retrogradation kinetics based on gelatinization enthalpy (ΔH). The Avrami exponent (n) of HMT and native starches were close to 1.0 (0.77 – 1.20) indicates rapid nuclei growth of the crystal. HMT has a significant influence on the retrogradation of sago starch, both from the values of n and k of the Avrami equation. On the other hand, it does not have a significant effect on arenga starch. Based on the thermal approach (DSC), HMT significantly affects sago starch’s retrogradation rate, but there was no effect on arenga starch. The influence of HMT on the retrogradation rate of arenga starch was observed on rheology and syneresis approaches, although it was not as high as sago starch.

The objective of this study was to clarify the effects of mechanical properties of soft food gels on breakability with the human tongue. Models of nursing care foods were prepared using mixtures of high- and low-acylated-gellan gums to achieve high or low fracture deformation. Mixtures with different concentrations were set to prepare gels with high or low fracture force. Several model tongues with moduli and relative sizes-to-food similar to those of the human tongue were also prepared using transparent urethane gels. A compression test was conducted using a soft machine equipped with an artificial tongue coupled to a conventional texture analyzer to simulate fracture phenomena of soft food gels between the tongue and hard palate. The food gel and artificial tongue were both deformed, with the former being pushed into the latter. Gellan gels with higher fracture force exhibited greater force and work until the fracture observed was similar to that in a conventional test. Highly deformable gels were resistant to fracture with the softer artificial tongue as greater displacement in the combination of gel and artificial tongue was observed prior to being fractured during compression. The gels were encumbered by the surrounding soft artificial tongue. The food gels having high deformation ratio at fracture in the conventional test were difficult to fracture with the soft machine. The results suggest that fracture deformation of food gels alone is a more important factor for gel fracture during compression between the tongue and hard palate.

Sweetness resulting from sucrose released from agar gels of varying concentrations of agar (0.5, 1.0, and 1.5% w/w) and sucrose (10%–50% w/w) was evaluated. The intensity of sweetness as perceived by subjects was investigated during consumption of the gels. A time–intensity method was applied: the maximum intensity and area under the time–intensity curve were higher in gels with lower concentrations of agar as expected from previous studies. The intensity of sweetness as estimated by the area under the time–intensity curve increased with sucrose concentration, but the maximum intensity tended to reach a plateau above a certain sucrose concentration. The manifestation of the maximum sweetness was delayed with increasing concentrations of sucrose and agar. The total duration of the perception of sweetness was longer in gels with higher sucrose concentrations but did not depend on the concentration of agar in the range examined. Instrumental characterization of these gels was also conducted. Young's modulus, fracture stress, fracture strain, and energy obtained from a conventional uniaxial compression test of sample gels increased with sucrose concentration and the modulus, stress, and energy were higher in gels with higher agar concentration. Although mechanical characteristics such as Young's modulus, fracture stress, strain, and energy, increased with increasing sucrose concentration, the sweetness intensity tended to a plateau; therefore, physiological and psychological factors experienced during oral processing should be taken into account to understand the perceived sweetness intensity.

The structure of soft foods with similar fracture forces may be destroyed by compression between the tongue and palate or mastication during natural oral processing. Our objective was to identify the mechanical properties determining the oral strategy for the initial size reduction of soft gels. Three gellan gels with an equivalent fracture force and different fracture strains were evaluated by instrumental compression testing and sensory evaluation. In addition, a combination of a gellan gel and a sonagel, which has an apparent elastic modulus similar to that of the human tongue, was subjected to a compression test and ultrasound (US) elastography. The fracture profile of the gellan gel on the sonagel in the instrumental compression test corresponded to the oral strategy. The strain ratio of the gellan gel to the sonagel observed in US elastography had a high linear correlation with the reciprocal of the apparent elastic modulus of the gellan gel. The oral strategy of gels changes from tongue–palate compression to mastication with increasing apparent elastic modulus or decreasing the relative strain against the sonagel. The results reveal that the apparent elastic modulus influences the oral strategy for the natural consumption of gels although a threshold value was not clearly determined in conventional compression testing using hard materials. Practical Applications An appropriate care food that can be consumed using compression between the tongue and hard palate without chewing is increasingly required in an aging society. Instrumental methods are often used for texture characterization of such foods. Probes are usually made of metal or materials that are much stiffer than foods and completely dissimilar to the tongue. Ultrasound (US) elastography can detect the strain ratio between food gels and a sonagel, which is used as an artificial tongue in this study. We suggest that the strain ratio obtained from US elastography can be used to evaluate the deformation behavior of soft foods and a soft material whose mechanical characteristics are similar to those of the human tongue. As the strain ratio was highly correlated with the reciprocal of the apparent elastic modulus measured using conventional compression testing, the modulus was an important parameter for selecting the tongue compression.

The objective of this study was to quantify natural eating behavior of soft solid foods and identify a mechanical property of food that has the strongest influence on mastication in humans. Electromyography (EMG) of both masseter and suprahyoid muscles was performed to quantify the muscle effort required to naturally masticate five gellan gels. The gels were categorized into two groups; those with (1) similar fracture strain and three different fracture loads (F1

The objectives of this study are to identify mechanical properties that dictate natural oral processing of soft solid foods and to quantify the effects of mouthful sizes. Two types of hydrocolloid gels with similar fracture loads but different elastic moduli and fracture strains were prepared using agar (A) or a mixture of konjac mannan, κ-carrageenan, and locust bean gum (K). Subsequently, 3, 6, 12, and 24 g mouthfuls of A and K gels were randomly served to subjects and the effects of mechanical properties and mouthful sizes were quantitatively analyzed within an individual. Electromyographic (EMG) activities of both masseter muscles and the suprahyoid muscle were recorded as jaw-closing and jaw-opening muscles, respectively. Total 33 EMG variables relating mastication and swallowing difficulties were classified into six groups by influences of gel types and mouthful sizes. Despite similar fracture loads, K gels with greater fracture strain and work required more mastication effort and less swallowing effort than A gels, which had higher elastic modulus. Doubling of mouthful sizes between 3 g and 24 g increased oral processing times and the numbers of chewing actions and swallows by 1.4 fold. These variables were approximately proportional to 0.7 of the power of the mouthful mass, and they can be predicted using this relation. Mastication effort exhibited lower dependence on sample mass than the three variables and durations and muscle activities per masseter muscle action did not vary significantly with mouthful sizes and gel types.

Eating difficulty of solid foods was analyzed using electromyography (EMG) of five hydrocolloid gels with varying textures. Eleven subjects ate gel samples under normal conditions and EMG activities of both sides of masseter (jaw-closing) and suprahyoid (jaw-opening) muscles were recorded during eating. Differences in EMG variables among samples were analyzed separately before and after the first swallow using repeated-measure statistics. The time before the first swallow was related to chewing effort and was estimated according to numbers of chewing actions, masseter muscle activities per chew and the sum of masseter muscle activities during chewing. EMG variables were also correlated with resistance to fracture, which was extracted as the first principal component from sensory evaluations of gel texture, but did not directly relate to any single parameter from mechanical tests or sensory evaluations. The time after the first swallow to the end of eating corresponded with the number of swallows, the EMG amplitude of suprahyoid muscles during chewing, the sum of masseter activity and suprahyoid muscle activity during the period after the first swallow. These EMG variables corresponded with sensory evaluations of adhesiveness but not with other single mechanical and sensory parameters or principal components. The present data suggest that at least two independent factors affect eating difficulty. Although differences among the five gels were predominantly reflected by chewing difficulty, these remained significant after the first swallow.

The objective of this study was to study and compare the impact of HMT on rheology and textural properties observed between sago and arenga starces, and then related to structural change of amylopectin. The HMT were conducted using the autoclaving method at 20% moisture content and heated to 120 C for 60 min for sago and 90 min for arenga starch as optimum condition. The HMT shifted gelatinization temperature higher and reduced the enthalpy of both starches. The HMT sago starch paste exhibited an exceptionally strong shear thinning behavior as shown by a rapid decrease of viscosity and an increase of shear rate. The HMT clearly made the texture of starch gels more fragile compared to their native form and reduced their breaking point to a lower strain. The HMT effect on the rheological properties and texture of the sago starch was greater than the changes observed with the arenga starch. Major changes in rheological properties after HMT was not followed by changes in amylopectin structure. The HMT process did not significantly affect the amylopectin chain-length distribution in Arenga starch. In the sago starch, HMT affect to long chain amylopectin with DP ≥ 37. The HMT effect on rheology and textural properties was higher in sago starch than arenga starch. This study demonstrated that long chain amylopectin with DP ≥ 37 plays an important role in contributing to the rheological change caused by the HMT.

I learned about food texture by reading many articles in the Journal of Texture Studies (JTS) and Prof. Bourne's textbook Food Texture and Viscosity, Concept and Measurement. I present here his great contributions as both the Editor-in-Chief of JTS and as the author of a superior textbook in the cultivation of future food texture researchers. Prof. Bourne has provided significant guidance to those in the industry using his textbook to suggest appropriate approaches to measure, evaluate, and alter the textures of agro-products and processed foods. I began my career in food rheology, learned the physiological techniques necessary for measuring mastication, and developed relationships with good sensory scientists along the way. I am happy to offer advice to agriculture and food scientists, researchers, and engineers in the food industry regarding food texture. I would like to be a follower of Prof. Bourne and support young food texture scientists in the 21st century. PRACTICAL APPLICATIONS Food texture studies conducted during the last century are beginning to evolve. Based on previous publications in the Journal of Texture Studies, I believe that several areas can be further examined in this century. First, methods to evaluate the textures of heterogeneous materials, such as fruits and vegetables, require improvements. Second, the monitoring of rapid changes in food texture during oral processing should be considered during the design of food products. Third, a new instrumental method that mimics the movement and breakdown of soft foods by the tongue is being developed. The optimization of food processing to reduce the loss of agro-products and production of high-quality foods both require more attention according to the Sustainable Development Goals adopted by the United Nations in 2015.

The strength of taste is thought to be affected not only by content of food, but also by the texture. The previous study on the relationship between the saltiness and texture of heat-induced surimi gels prepared with different setting conditions revealed that the difference of physical properties did not affect the perceived saltiness of surimi gels, notwithstanding the breaking strength was very different according to the setting time. This result was seemed to contradict to the findings obtained with other food material so far. Therefore, this study was aimed to clarify the relationship between the intensity of saltiness and texture of heat-induced surimi-based products focusing on the fragmentation of the gel. To prepare various types of surimi gels having different physical properties from the same material, surimi gels were prepared by 2-steps heating with different level of pre-heating at 60oC (modori). The physical properties of surimi gels were evaluated by puncture test, two-bite texture profile analysis and measurement of expressible water. The particle size of surimi gels after chewing in mouth by every panelist was also evaluated. The physical properties of heat-induced surimi gels became softer and more fragile according to the preheating time at 60oC. Maximum saltiness intensity in the gel was evaluated comparing with different reference solutions. The result of the sensory evaluation suggested that the difference in physical properties derived by heat induced degradation during pre-heating at 60oC affected the perceived saltiness during consumption of surimi gels, and that the fragmentation of the gel will strongly correlate to the perceived saltiness of surimi gels.

Salt intake is an important concern for health reasons and saltiness is affected not only by content of food, but also by the texture. Surimi-based products, such as kamaboko, are elastic gels with approximately 2% NaCl; despite recent concerns among Japanese consumers regarding high-salt foods, little is known about the relationship between saltiness and texture in these products. This study was aimed to clarify the relationship between saltiness and texture using heat-induced surimi gels as a model of surimi-based product. Various types of heat-induced gels with different physical properties were prepared from surimi and washed surimi by two-step heating with different setting (preheating) times at 30°C. Washed surimi was prepared to remove the additives, because the additives were thought to affect the taste of surimi gel. The physical properties of heat-induced gels were characterized by puncture breaking strength and expressible water. The perceived saltiness of the heat-induced surimi gels was evaluated with fixed number of chewing. Next, to improve the demerit of this method, the perceived saltiness of the washed surimi gels was evaluated by free chewing conditions. The perceived saltiness after fixed number of chewing and the maximum saltiness intensity during free chewing was evaluated using sensory tests by comparisons with salt solutions of known concentrations. The physical properties of heat-induced gels differed considerably depending on the salt content and heating conditions. A longer setting time was associated with a higher breaking force and lower expressible water, regardless of salt content. On the other hand, perceived saltiness depended on the NaCl concentration, but not greatly influenced by the physical properties of the gels prepared from both surimi and washed surimi. The perceived saltiness of all gels tested was less than 1/3 of solution with the same NaCl concentration. The maximum saltiness intensity did not correlate with breaking force, breaking strain and expressible water of heat-induced gels. From these results, it was suggested that the difference in physical properties derived by setting did not affect the relative saltiness intensity of gels to NaCl solution during consumption of surimi gels.

Food properties are perceived through oral receptors during eating. In this review, various oral receptors involved in food oral processing of food are briefly described. Touch and taste are the most important senses in oral perception. Different tactile receptors are used to determine the mechanical properties, size, shape and their temporal/spatial changes of food materials in the oral cavity. Instrumental test results are often inconsistent with sensory-perceived food properties. A multiple-point pressure sensor inserted into the mouth with food can be used to mimic the human tactile systems and to relate instrumental and sensory results. Three evaluation systems of food properties with artificial tongues which were designed in different concepts are presented. Physiological research results are useful to simulate oral processing to design texture, flavor and appearance of diets for people with different eating functions. Practical Applications Food oral processing is a dynamic process in which a mouthful of food is reduced in heterogeneity and converted into a more homogenized swallowable bolus. Human-mimetic sensing technologies have been recently developed to analyze the physical and chemical properties, these complex interactions and drastic changes of foodstuffs during oral processing. As practical applications, two current social topics are discussed in terms of homogenization of foods during oral processing. First, with the increase of elderly population, a need for texture-modified foods has emerged: hard food must be converted into paste-like, where the function of oral processing is partly done by pre-oral processing. Second, WASHOKU, the traditional dietary cultures of the Japanese, was added to UNESCO's Intangible Cultural Heritage list in 2013. Seasoning in the mouth, one of the features of oral processing of WASHOKU, is addressed. To improve food texture and flavor is needed for people with various ages and regions.

The objective of this study was to quantify the mastication effort for cooked rice with varying texture. We conducted electromyography (EMG) from both masseter muscles while normal subjects ate 6 g of cooked rice. Rice samples were prepared using different milling ratios and cooked with different amounts in weight of water. The texture of cooked rice samples was instrumentally analyzed. Hardness was similar between 2% milled and 1.80 times weight of water, 6% and 1.65, and 10% and 1.50; however, adhesiveness was lower in lesser milled samples. EMG results showed that the number of chews, mastication time and muscle activities per chew were higher in the harder rice samples that were milled less and cooked with less water. When the hardness of cooked rice was adjusted, EMG variables were not significantly different. The mastication effort per gram of solid content significantly differed with milling ratios. Practical Application Cooked rice is a staple food for many people. The texture of cooked rice can be easily modified by changing milling ratios and water-to-rice grain ratios. As mastication is the first process of digestion, understanding how milling and cooking conditions influence the texture of cooked rice and mastication behavior is important for palatability and nutrition. EMG variables can provide details on mastication effort, proving to be useful for preparing the best texture of cooked rice. As less milled rice requires more mastication per solid content, it is effective to increase number of chews and to decrease eating rate.

The firmness of whole beans and of separated embryos and testas from 20 soybean cultivars grown in the same field conditions was estimated after 40 min cooking with AACC International Approved Method 56-36.01. There were considerable variations in the firmness of whole beans, embryos, and testas among cultivars. Testas were much firmer than embryos because of their leathery texture and resistance at slots in the shear cell during compression. For soft cultivars, the firmness after 10 min cooking was also measured, and an apparent first-order reaction kinetics model was applied to estimate the initial firmness at 0 min cooking and the softening rate constant from firmness data after 10 and 40 min cooking. The estimated initial firmness at 0 min cooking and softening rate constant of embryos and testas varied widely among seven cultivars, and these two parameters were considered to be controlled by different genetic mechanisms, because no correlation was found between the parameters. The softening ...

This study aimed to elucidate the effects of water volume on flow properties of bolus (passage time and velocities) at the esophagus orifice using ultrasonic pulsed wave Doppler method. Five healthy males and five females were asked to consume 3, 6, 9 and 12 mL water in a single swallow. An ultrasound probe was placed against each subject's neck to observe the flow properties of bolus. The velocity spectra of the bolus at the esophagus orifice were analyzed. Our results revealed that velocity of bolus was easily affected by volume of water, and the passage time and velocities increased as the increase in volume. Practical Applications Ultrasonography, using a medical ultrasound instrument, is an effective method for observing bolus kinematics during swallowing. The velocity spectra of bolus can be visualized for different volume of water using the pulsed wave Doppler method. When a bolus of food is swallowed, aspiration that the bolus partly enters the trachea instead of the esophagus may occur. Water is known to show a high possibility of aspiration. This study revealed that reducing volume of water decreases the passage time and velocities of bolus at the esophageal entrance. Therefore, this technique can be used for designing the texture of food materials for people who experience aspiration or suffocation by food.

Eating difficulty was evaluated by sensory analyses of hydrocolloid gels as a food model. Twenty sample gels were created with a wide range of textures. Twelve panelists rated the eating difficulty for each gel on an unstructured line scale. Subsequently, they also evaluated six texture attributes including firmness, cutting effort, elasticity, extensibility, adhesiveness, and melting rate in the mouth. A principal component analysis characterized the texture attributes of the sample gels on axes of resistance to fracture (principal component 1) and stickiness and flexibility (principal component 2). The contour of the resulting eating difficulty scatter diagram revealed that resistance to fracture and stickiness and flexibility were critical determinants of eating difficulty.

The effects of blending rice flour with wheat flour on bread texture and staling were investigated with three rice varieties with different amylose contents. For the texture analysis of bread crumb, the compression test, puncture test, and tensile test were performed. A flour blend containing rice flour suppressed the recovery of the crumb after compression. For the puncture test, blends with rice flour increased the distance to penetrate the crumb. The rupture strain measured with the puncture test decreased with staling of the bread crumb for all samples tested. The fresh bread crumb sample containing waxy rice flour had much greater extensibility in the tensile test than the other samples tested, but it was dramatically decreased after one day of storage. Endothermic enthalpies corresponding to retrograded amylopectin, which is part of the staling process, were also measured. The enthalpy of bread crumb from the blended flour was lower than that of wheat flour bread up to three days but was hi...

Using electromyography (EMG), we studied the changing texture of softened foodstuffs, prepared using a freeze-thaw impregnation of macerating enzymes, by observing eating behavior. EMG recordings were taken from the masseter muscles and suprahyoid musculature of 6 subjects. All five samples (bamboo shoot, burdock root, lotus rhizome, Pacific cod, shiitake mushroom) were softened sufficiently to be broken up with a spoon. The duration of whole oral processing and three variables of interest extracted from the masseter EMGs (total muscle activity, total duration, and cycle time) were significantly different among the samples. Different oral behaviors were observed especially at later processing times. The bamboo shoot and shiitake mushroom required less effort for oral processing compared with the other three samples. The duration of whole oral processing significantly correlated with two instrumental parameters (dried fibrous residue and cohesiveness). Dried fibrous residue was a good indicator for evaluating the ease of bolus formation. Industrial relevance An enzymatic application using the freeze-thaw impregnation technique has been established for developing softened foods. The food products have a softness that allows crushing with the tongue and upper jaw while retaining the original characteristics of shape and flavor. Such food products have not been previously manufactured; the evaluation of texture properties by a human is indispensable information. The information can be used in controlling the quality of the softened products by manufacturers and in choosing the preferred products by consumers.

Care food is increasingly required in the advanced-aged society. Mechanical properties of such foods must be modified such that the foods are easily broken by the tongue without chewing. When foods are compressed between the tongue and the hard palate, the tongue deforms considerably, and only soft foods are broken. To simulate tongue compression of soft foods, artificial tongues with stiffness similar to that of the human tongue were created using clear soft materials. Model soft gels were prepared using gellan gums. A piece of gel on an artificial tongue was compressed using a texture analyzer. The deformation profile during the compression test was obtained using a video capture system. The soft machine equipped a soft artificial tongue sometimes fractured food gels unlike hard machine, which always fracture gels. The fracture properties measured using the soft machine were better than those obtained from a conventional test between hard plates to mimic natural oral processing in humans. The fracture force on foods measured using this soft machine may prove useful for the evaluation of food texture that can be mashed using the tongue.