Glutamate Solution Research Articles

Taste Testing in a Pediatric Case of Congenital Aglossia

Objective: Congenital aglossia (CA) is a rare inborn condition characterized by absence of the tongue. This study aimed to determine gustatory function in a pediatric female participant with CA. Methods were developed based on previous taste discrimination research of a participant with isolated congenital aglossia (ICA) and anecdotal reports of individuals with CA possessing the ability to discern taste stimuli. Methods: In this randomized, double-blinded trial, 78 samples were presented to an 11-year-old Hispanic female with CA in the presence of her parents. Triplicate samples of sucrose (sweet), citric acid (sour), sodium chloride (salty), caffeine (bitter) and monosodium glutamate (umami) solutions at five concentration levels each were tested, with three water samples. Contingency tables were developed with participant responses. Descriptive statistics were run to determine accuracy of stimuli identifications, with correct identification set at ≥ 66.6% accuracy (2 out of 3). Taste identification accuracy versus stimuli taste, concentration, and presentation order were tested for statistically significant association (p ≤ 0.05) using Chi-square testing. Results: Out of five stimuli, the participant correctly identified sour and umami. Umami was accurately identified 100% of the time, and sour 66.6% of the time. Correct identification threshold criteria were not met for sweet, salty, and bitter samples. There was no statistically significant association between taste identification accuracy and particular taste, concentration levels, or presentation order. Bitter taste was commonly recorded as sour, and bitter as salty. Conclusion: This study supports previous findings indicating that people with CA may accurately identify sour, though at a higher threshold than previously found in the ICA trial or in persons without CA. Compared to the previous trial, the participant in this trial could accurately identify umami. Higher discrimination thresholds of sour and umami, and misidentification of sweet, salty, and bitter stimuli, may indicate gustatory impairment among individuals with CA.

Study on Processing Technology and Quality of Moringa oleifera leaves with y - Aminobutyric Acid

In order to obtain the high level of γ-aminobutyric acid Moringa oleifera leaves, Use 7% sodium glutamate solution to soak the fresh Moringa oleifera leaves, study effect of different treatment times and three different drying methods( hot air drying, vacuum freeze drying, shadow drying) on the formation of y-aminobutyric acid and quality (total flavonoids, soluble sugar, amino acids, polyphenols, color)of dried Moringa oleifera leaves. The results indicated that shadow-dried Moringa oleifera leaves had the hightest retention of γ-aminobutyric acid, but its browning degree were not preferable, soluble sugar was damaged gravely, and its vulnerable to weather conditions. Vacuum freeze dried Moringa oleifera leaves had the hightest retention of flavonoids, polyphenols and amino acids. The y-aminobutyric acid content of Vacuum freeze dried and hot air dried Moringa oleifera leaves had no much difference. Hot air dried Moringa oleifera leaves browning degree were preferable, it’s had an moderate content of soluble sugar and amino acids, the short drying time is characteristics of this drying method.with the treatment time increased, the content of γ-aminobutyric acid and amino acids content first increased and then decreased. Flavonoids and polyphenols content first decreased and then increased. Soluble sugar content decreased. In summary, after soaking with 7% sodium glutamate solution for 10h, then dried by hot air drying(drying temperature of 60°C), was the most suitable way for industrial production of the high level of γ-aminobutyric acid Moringa oleifera leaves.

Experimentally induced masseter-pain changes masseter but not sternocleidomastoid muscle-related activity during mastication

The aim of this study was to verify the effects of induced masseter-muscle pain on the amplitude of muscle activation, symmetry and coactivation of jaw- and neck-muscles during mastication. Twenty-eight male volunteers, mean age±SD 20.6±2.0years, participated in this study. Surface electromyography of the masseter and sternocleidomastoid (SCM) muscles was performed bilaterally during mastication of a gummy candy before and after injections of monosodium glutamate solution and isotonic saline solution. As a result, we observed a decrease in the amplitude of activation of the masseter muscle on the working side (p=0.009; d=0.34) and a reduction in the asymmetry between the working and the balancing side during mastication (p=0.007; d=0.38). No changes were observed either on the craniocervical electromyographic variables. In conclusion, experimentally induced pain reduced the masseter muscle activation on the working side, thereby reducing the physiological masseters’ recruitment asymmetry between the two sides during mastication. No effects on SCM activity were detected. These results may partly explain the initial maladaptative changes underlying TMD conditions.

Pregestational Obesity-Induced Embryopathy.

Several epidemiologic studies in humans have shown a relationship between pregestational obesity and congenital malformations in offsprings. However, there are no experimental evidence in animal models of obesity and pregnancy that reproduce the teratogenesis induced by this pathological condition. To evaluate the effect of monosodium glutamate-induced obesity on embryonic development. Female rats received subcutaneously (4 mg/g body weight) monosodium glutamate (MSG) solution or saline solution 0.9% (vehicle control) at days 2, 4, 6, 8, and 10 of life. At 90 days of age, all animals were mated, and on day 11 of pregnancy, the animals were killed. Biochemical variables (glucose, triglycerides, total cholesterol, and insulin) were determined in plasma of dams and embryo homogenates (DNA and protein content, advanced oxidation protein products). Embryos were evaluated for malformations, crown-rump length, and somite number. Obese rats presented higher triglyceride levels as compared to nonobese rats. Increased proportion of malformed embryos, decreased crown-rump length, somite number, DNA, and protein content were observed in offspring of obese rats. The model of obesity induced with MSG reproduces the maternal obesity-induced teratogenesis. The hypertriglyceridemia observed in MSG obese pregnant rats could be related to increased birth defect.

Research on the Changes to the Lipid/Polymer Membrane Used in the Acidic Bitterness Sensor Caused by Preconditioning.

A taste sensor that uses lipid/polymer membranes can evaluate aftertastes felt by humans using Change in membrane Potential caused by Adsorption (CPA) measurements. The sensor membrane for evaluating bitterness, which is caused by acidic bitter substances such as iso-alpha acid contained in beer, needs an immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning”. However, what happens to the lipid/polymer membrane during MSG preconditioning is not clear. Therefore, we carried out three experiments to investigate the changes in the lipid/polymer membrane caused by the MSG preconditioning, i.e., measurements of the taste sensor, measurements of the amount of the bitterness substance adsorbed onto the membrane and measurements of the contact angle of the membrane surface. The CPA values increased as the preconditioning process progressed, and became stable after 3 d of preconditioning. The response potentials to the reference solution showed the same tendency of the CPA value change during the preconditioning period. The contact angle of the lipid/polymer membrane surface decreased after 7 d of MSG preconditioning; in short, the surface of the lipid/polymer membrane became hydrophilic during MSG preconditioning. The amount of adsorbed iso-alpha acid was increased until 5 d preconditioning, and then it decreased. In this study, we revealed that the CPA values increased with the progress of MSG preconditioning in spite of the decrease of the amount of iso-alpha acid adsorbed onto the lipid/polymer membrane, and it was indicated that the CPA values increase because the sensor sensitivity was improved by the MSG preconditioning.

Osmotic Coefficients of Two Amino Acid Magnesium Salts at 298.15 and 310.15 K

The concentration dependence of the vapor pressures of magnesium l-glutamate and magnesium l-aspartate solutions has been studied with the help of vapor pressure osmometry measurements, performed as a function of salt concentration in the range mi = 0.01–0.43 and mi = 0.01–0.30 mol·kg−1, respectively, at T = 298.15 and 310.15 K. From these experimental results, the activities of water and the corresponding osmotic coefficients have been calculated for all systems investigated. Mean molal ion activity coefficients were obtained from experimental data fits with the Pitzer equations and the corresponding dual and triple interaction parameters were derived. β(2) Pitzer parameters different from zero are required where the osmotic coefficient decreases strongly with increasing concentration at 298.15 and 310.15 K. β(1) and β(2) analysis shows that the interaction nature is different for magnesium aspartate and magnesium glutamate solutions (the ratio of repulsion/attraction parts is different). The decrease in the chemical potential of the glutamates corresponds to the Hofmeister series: KGlu > NaGlu > Mg(Glu)2 > Ca(Glu)2.

Characterization and kinetics of CO2 absorption into aqueous 1-ethyl-3-methylimidazolium glutamate solution

The kinetic of carbon dioxide (CO2) into aqueous 1-ethyl-3-methylimidazolium glutamate ([Emim]2[Glu]) solution was investigated by a double stirred-cell absorber. The Density and viscosity of [Emim]2[Glu] solution were measured with concentrations ranging from 0.3 to 1.5molL−1 at temperatures from 298.15 to 323.15K. The diffusivity of CO2 in [Emim]2[Glu] solution were estimated at the same temperatures and concentrations. The effects of the [Emim]2[Glu] concentration, absorption temperature and CO2 concentration were studied. The results showed that absorption CO2 into aqueous [Emim]2[Glu] solution was the fast pseudo-first order reaction regime. The enhancement factor E, the overall reaction kinetic constant kOV and the second-order rate constant k2 were calculated by the two-film theory. The result showed that E was linear with CILs1/2, and the second-order rate constant could be expressed as following equation: k2=9.253×107exp(−3665/T).

The transgenerational study of insulin action in female offspring adult Wistar rats

Materials and methods Twelve newborn female Wistar rats were used, and half of them submitted to saline solution administration (control) and the other half were administrated monosodium glutamate solution, 4.0 mg/Kg body weight (obese) in neonatal period. At adult age (90 days of life) these female rats were mated with health male rats and the female offspring were used, divided into two groups: control (CONT, n=28) and obese (OB, n=15), according to its previous dam group. In all adult age (from 3rd to 7th months) the rats were monthly evaluate the Lee Index, water and food intake, 12h-fasting glycemia, oral glucose tolerance test (OGTT) and insulin test tolerance (ITT). In addition, from OGTT Results it was estimated the area under the glycemic curve (AUC). All data were statistically analyzed with 5% significance.

Effect of maternal obesity on insulin action in male adult offspring rats

Materials and methods twelve newborn female Wistar rats were used, and half of them submitted to saline solution administration (control) and the other half were administrated monosodium glutamate solution, 4.0 mg/Kg body weight (obese) in neonatal period. At adult age (90 days of life) these female rats were mated with health male rats and the male offspring were used, divided into two groups: control (CONT, n=29) and obese (OB, n=19), according to its previous dam group. In all adult age (from 3rd to 7th months) the rats were monthly evaluate the Lee Index, water and food intake, 12h-fasting glycemia, oral glucose tolerance test (OGTT) and insulin test tolerance (ITT). In addition, from OGTT Results it was estimated the area under the glycemic curve (AUC). All data were statistically analyzed with 5% significance.

Optimization of a sensory evaluation protocol for measuring the umami taste

Umami substances linger in mouth for a long time, making it difficult to achieve an accurate sensory measurement. The objective was to establish a reproducible protocol to accurately measure the intensity of umami taste. Two-alternative-forced choice (2-AFC), ranking, and rating methods were compared for discrimination ability of umami taste intensities of monosodium glutamate solutions. Monadic rating and rank-rating methods were compared for accuracy in measurement of umami intensities since neither 2-AFC nor ranking method generates numerical intensity values. Mouth rinsing protocol efficiencies were investigated for 7 palate cleansing methods during umami intensity evaluation. 2-AFC was the most powerful method, followed by ranking and rating methods, for discrimination of different umami samples. Monadic rating and rank-rating methods both showed similar error rates but monadic rating was slightly more accurate than rank-rating. Crackers, a toothbrush, and water at 45oC were more effective palate cleansers than carrots and water at 18oC.

The cleaner production of monosodium l-glutamate by resin-filled electro-membrane reactor

In this study, electro-membrane reactors were developed for the cleaner production and in situ separation of monosodium l-glutamate (NaGA) from ammonium glutamate (NH4GA) solution. The process performances were compared both before and after the addition of resins to the compartments of the reactors. The recovery rate of the resin-filled electro-membrane reactor in which all of the compartments were filled with resins was higher than that of the other reactors, while the reaction time and energy consumption were relatively low. Additionally, the effects of the current density, the initial concentration and the volumetric ratio of product solution and feed solution on the performance of the resin-filled reactor were investigated. Under the optimized conditions, 94.15% of the glutamate was successfully recovered, and the glutamate migration rate and energy consumption were 3.132mol/(m2h) and 0.920kWh/kg NaGA, respectively. The final concentration of NaGA reached 0.603mol/L. The resin-filled electro-membrane reactor provides a novel, environmentally friendly and energy-efficient method for the production of NaGA.

Intramuscular Temperature Modulates Glutamate-Evoked Masseter Muscle Pain Intensity in Humans

To determine whether glutamate-evoked jaw muscle pain is altered by the temperature of the solution injected. Sixteen healthy volunteers participated and received injections of hot (48°C), neutral (36°C), or cold (3°C) solutions (0.5 mL) of glutamate or isotonic saline into the masseter muscle. Pain intensity was assessed with an electronic visual analog scale (eVAS). Numeric rating scale (NRS) scores of unpleasantness and temperature perception, pain-drawing areas, and pressure pain thresholds (PPTs) were also measured. Participants filled out the McGill Pain Questionnaire (MPQ). Two-way or three-way repeated measures ANOVA were used for data analyses. Injection of hot glutamate and cold glutamate solutions significantly increased and decreased, respectively, the peak pain intensity compared with injection of neutral glutamate solution. The duration of glutamate-evoked pain was significantly longer when hot glutamate was injected than when cold glutamate was injected. No significant effect of temperature on pain intensity was observed when isotonic saline was injected. No effect of solution temperature was detected on unpleasantness, heat perception, cold perception, area of pain drawings, or PPTs. There was a significantly greater use of the "numb" term in the MPQ to describe the injection of cold solutions compared to the injection of both neutral and hot solutions. Glutamate-evoked jaw muscle pain was significantly altered by the temperature of the injection solution. Although temperature perception in the jaw muscle is poor, pain intensity is increased when the muscle tissue temperature is elevated.

Intramuscular pH modulates glutamate-evoked masseter muscle pain magnitude in humans.

This study was conducted to determine whether glutamate-evoked jaw muscle pain is modulated by the acidity and temperature of the solution injected. Thirty two participants participated and received injections of high-temperature acidic (HT-A) glutamate (pH 4.8, 48 °C), high-temperature neutral (HT-N) glutamate (pH 7.0, 48 °C) and neutral temperature neutral (NT-N) glutamate (pH 7.0, 38 °C) solutions (0.5 mL) into the masseter muscle. Pain intensity was assessed with an electronic visual analogue scale (eVAS). Numerical rating scale (NRS) scores of unpleasantness and temperature perception, pain-drawing areas, mechanical sensitivity and pressure pain thresholds (PPT) were also measured. Participants filled out the McGill Pain Questionnaire (MPQ). One or two way ANOVAs were used for data analyses. Injection of HT-A glutamate solutions significantly increased the area under the VAS-time curve compared with injection of HT-N glutamate and NT-N glutamate solution (p < 0.040). The duration of glutamate-evoked pain was significantly longer when HT-A glutamate was injected than when NT-N glutamate was injected (p < 0.017). No significant effects of acidity were detected on pain drawings, NRS unpleasantness and heat perception, but there was a significant effect of acidity on MPQ scores and mechanical sensitivity. Acidity and temperature modulate glutamate-evoked jaw muscle pain suggesting an interaction between acid sensing and glutamate receptors which could be of importance for understanding clinical muscle pain conditions.

Anion effect on glutamate solutions at 298.15 and 310.15 K as deduced from vapor pressure measurements

Osmotic coefficients are inferred from vapor pressure osmometry measurements that were performed for the ternary systems sodium glutamate–sodium thiocyanate–water varying the concentration of NaGlu and NaSCN (mNaGlu=0.09, 0.33, 0.57mol/kg and mNaSCN=0.1–1mol/kg) at T=298.15K and 310.15K. No strong interaction between glutamate and thiocyanate as suggested by theoretical MD and half-empirical quantum-chemical calculations (ab initio methods) can be concluded based on the experimental data. Absolute values of osmotic coefficients show mostly negative deviations from ideal state at both temperatures and for all sodium glutamate background concentrations. This is typical of a simple salt solution and a hint at only minor interactions between amino acid and salt.

DNA nanopore translocation in glutamate solutions.

Nanopore experiments have traditionally been carried out with chloride-based solutions. Here we introduce silver/silver-glutamate-based electrochemistry as an alternative, and study the viscosity, conductivity, and nanopore translocation characteristics of potassium-, sodium-, and lithium-glutamate solutions. We show that it has a linear response at typical voltages and can be used to detect DNA translocations through a nanopore. The glutamate anion also acts as a redox-capable thickening agent, with high-viscosity solutions capable of slowing down the DNA translocation process by up to 11 times, with a corresponding 7 time reduction in signal. These results demonstrate that glutamate can replace chloride as the primary anion in nanopore resistive pulse sensing.

大豆たん白質・デンプン混合ゲルの調味素材としての利用に関する基礎的研究

An 22.5% SPI gel, a 22.5% starch gel, and SPI-starch complexes, that is, 15% SPI-7.5% starch gel and 7.5% SPI-15% starch gel, fabricated by partial substitution of SPI with starch were prepared for use as new ingredients in cooking. The SPI gels were hard and elastic and the SPI-starch mixture gels became softer and more fragile on decreasing the amount of SPI and increasing the amount of starch. When these gels were cooked with water and 10% sucrose solution, their hardness and cohesiveness decreased. In contrast, the SPI gels and the mixture gels prepared by heating in 1% NaCl showed no appreciable physical changes. Furthermore, the weight and physical properties of the mixture gels heated in an "umami" stock (glutamate solution), with higher NaCl concentration and lower pH value, remained constant. The 15% SPI-7.5% starch gels heated in the umami stock were found to be positive for taste. Thus, our results suggest the 15% SPI-7.5% starch gels cooked in the umami stock will have practical use in food processing and cooking in homes.

Flavor Preferences in Animals: Role of Mouth and Gut Nutrient Sensors

Flavor Preferences in Animals: Role of Mouth and Gut Nutrient Sensors

Brain amino acid sensing.

The 20 different amino acids, in blood as well as in the brain, are strictly maintained at the same levels throughout the day, regardless of food intake. Gastric vagal afferents only respond to free glutamate and sugars, providing recognition of food intake and initiating digestion. Metabolic control of amino acid homeostasis and diet-induced thermogenesis is triggered by this glutamate signalling in the stomach through the gut-brain axis. Rats chronically fed high-sugar and high-fat diets do not develop obesity when a 1% (w/v) monosodium glutamate (MSG) solution is available in a choice paradigm. Deficiency of the essential amino acid lysine (Lys) induced a plasticity in rats in response to Lys. This result shows how the body is able to identify deficient nutrients to maintain homeostasis. This plastic effect is induced by activin A activity in the brain, particularly in certain neurons in the lateral hypothalamic area (LHA) which is the centre for amino acid homeostasis and appetite. These neurons respond to glutamate signalling in the oral cavity by which umami taste is perceived. They play a quantitative role in regulating ingestion of deficient nutrients, thereby leading to a healthier life. After recovery from malnutrition, rats prefer MSG solutions, which serve as biomarkers for protein nutrition.

Flavor Preferences Conditioned by Intragastric Monosodium Glutamate in Mice

The consumption of monosodium glutamate (MSG) solutions has been shown to reinforce preferences for MSG and for MSG-paired flavors in mice. These effects appear to have a strong postoral component, such that MSG detected in the gut is associated with concurrently consumed flavors. Two experiments investigated postoral MSG reward by infusing 400mM MSG intragastrically (IG) to C57BL/6 mice as they consumed a conditioned stimulus (CS+) flavor. An alternate CS- flavor was paired with IG water. In Experiment 1, the grape and cherry CS flavors were unsweetened, and intakes and preferences for the CS+ flavor were modest. Experiment 2 attempted to generate stronger preferences by adding 0.05% saccharin to the CS flavors. Sweet taste did enhance intakes during training and testing but did not significantly increase percent CS+ intake or persistence of the preference. However, only conditioning with the sweet CS+ resulted in the mice expressing a preference for oral MSG in an initial choice test with water. These findings extend recent studies demonstrating postoral MSG conditioning in rats.

Arginine glutamate improves healing of radiation-induced skin ulcers in guinea pigs

Purpose: The increase in the incidence of the radiation-induced skin injury cases and the absence of standard treatments escalate the interest in finding new and effective drugs for these lesions. We studied the effect of a 40% solution of arginine glutamate on the healing of radiation-induced skin ulcers in guinea pigs.Materials and methods: Radiation skin injury was produced on the thigh of guinea pigs by 60 Gy local X-ray irradiation. Treatment was started 6 weeks after the irradiation when ulcers had been formed. Arginine glutamate was administered by subcutaneous injections around the wound edge. Methyluracil was chosen as the comparison drug. The animals were sacrificed on day 21 after the start of treatment and the irradiated skin tissues were subjected to histological evaluation, cytokines analysis, lipid peroxidation and antioxidant enzymes analysis.Results: We have shown that arginine glutamate significantly (p < 0.05) decreased levels of pro-inflammatory cytokines in the wound, restored the balance between lipid peroxidation formation and antioxidant enzymes activity and promoted cell proliferation as well as collagen synthesis.Conclusions: These results demonstrate that arginine glutamate successfully improves the healing of radiation-induced skin ulcers. In all probability, the curative effect is associated with the interaction of arginine with nitric oxide synthase II and arginase I, but further investigations are needed to validate this.