Search Results (108)

This study investigated the kinetics of chalcopyrite dissolution in an alkaline monosodium glutamate (MSG) solution using H₂O₂ and KMnO₄. The aims were to optimize process conditions for maximum copper dissolution and to study the kinetic mechanism of dissolution under varying conditions, such as particle size, oxidant type and concentration, temperature, and the presence of gangue minerals. Results showed that KMnO₄ exhibited better oxidative efficiency and stability than H₂O₂, yielding copper recoveries above 90% in most conditions while keeping the dissolution of some gangue metals, such as calcium, magnesium, and iron, lower, thereby reducing MSG consumption. Temperature and particle size were the most important factors in the effects on leaching kinetics; smaller particles allow higher initial reaction rates, while larger particles allow prolonged dissolution. The shrinking core model (SCM) was thus used to perform kinetic analysis and determine that diffusion controls the leaching process through the product layer. The calculated activation energies of 18.2 kJ/mol of MSG-H₂O₂ and 17.3 kJ/mol of MSG-KMnO₄ confirm the diffusional mechanism. Full article

This study aimed to identify novel umami peptides from both natural and enzymatically hydrolyzed peptides from Jinhua ham, and to characterize their properties. Following LC–MS identification, known flavor sequences were annotated using a curated flavor-peptide database containing 2617 known flavor peptides, and potential novel umami peptides were screened through an integrated approach combining multiple machine learning models and LibDock molecular docking. From over 2000 identified peptides, this integrated virtual screening pipeline precisely yielded 10 candidate umami peptides, which were confirmed to possess distinct umami characteristics by sensory evaluation and electronic tongue analysis. These peptides had umami intensities ranging from 2.87 ± 1.38 to 3.90 ± 1.56 and significantly lower taste thresholds (0.1109–0.2634 mg/mL) than that of monosodium glutamate (MSG, 0.3 mg/mL). Subsequent CDOCKER analysis demonstrated significantly stronger binding affinity and stability of these peptides to the T1R1/T1R3 receptor compared with MSG, with -CDOCKER ENERGY values of 78.45–94.95 and -CDOCKER INTERACTION ENERGY values of 56.67–86.71, both significantly higher than those of MSG (22.27 and 46.58, respectively). Hydrogen bonds were identified as the dominant binding force, accounting for over 66% of total interactions, and HIS145 and ARG247 were confirmed as the key residues maintaining the stability of the peptide-receptor complex. Overall, these findings provide mechanistic insight into the umami properties of Jinhua ham peptides and support their potential application in food processing. Full article

Introduction: Uterine fibroids are benign tumors arising from uterine smooth muscle and significantly affect women’s health worldwide. While conventional treatments often involve hormonal therapies or invasive surgeries, these approaches are limited by cost, side effects, and fertility concerns. This study aimed to evaluate the in vivo bioactivity of four medicinal plant extracts, Lepidium sativum, Prunus armeniaca, Solenostemma argel, and Stachys palustris, in ameliorating monosodium glutamate (MSG)-induced uterine changes in rats, providing preliminary preclinical evidence. Methods: The extracts were evaluated for their flavonoid and total phenolic contents, antioxidant capacity, and hormonal modulatory effects. Female Wistar rats were treated with monosodium glutamate to induce uterine changes, followed by interventions with herbal extracts. Outcomes were evaluated via biochemical, hormonal, and histological analyses. Results: Among the four extracts, Lepidium sativum and Stachys palustris showed superior antioxidant activity, restoring catalase, glutathione, and superoxide dismutase levels. These extracts also significantly reduced estrogen levels and estrogen receptor expression, correlating with improved histological outcomes, including reduced endometrial hyperplasia and myometrial thickness. Solenostemma argel and Prunus armeniaca exhibited moderate effects. Conclusions: This study underscores the potential of Lepidium sativum and Stachys palustris as natural therapeutic agents for fibroid management through antioxidant activity and hormonal modulation. Future research should focus on clinical validation to translate these findings into effective treatments. Full article

The opportunistic pathogen Pseudomonas aeruginosa poses a serious threat to immunocompromised patients. Monosodium glutamate (MSG), a widely used flavor enhancer, has been reported to possess anti-inflammatory and antioxidant properties. However, its therapeutic potential and mechanism against Pseudomonas aeruginosa (P. aeruginosa) infection have remained unexplored. This study systematically elucidated the protective effects and molecular mechanisms of MSG against P. aeruginosa-induced acute lung injury (ALI). In a murine pneumonia model, MSG administration effectively alleviated lung pathological damage, edema, and inflammatory responses. Mechanistically, MSG exerted protection through a multifaceted strategy, including direct suppression of bacterial virulence via binding to PopB of T3SS inhibition of the TLR4/MyD88/MAPK-driven inflammatory cascade and pro-inflammatory cytokine production, enhancement of endogenous antioxidant defense (SOD, CAT), and reshaping of pulmonary macrophages from the M1 to M2 phenotype. Notably, the anti-virulence effect of MSG, achieved by binding to PopB (K_D = 3.52 × 10⁻⁶ M), presented a distinct advantage over traditional antimicrobials by potentially mitigating resistance development. Collectively, these findings indicated that MSG can alleviate ALI caused by P. aeruginosa infection. Full article

Literature suggests that umami, Maillard reaction, and flavor complexity could contribute to sensorial acceptability of plant-based alternatives, but that was yet to be tested. Two field studies with 612 paying customers evaluating a complete meal were conducted in an operating restaurant in Sweden. In the first study, a gray pea burger (Control) was compared to burgers with added monosodium glutamate (MSG) (Umami), grilled (Maillard), or both grilled and added MSG (Complex). In the second study, a simplified gray pea burger (Control 2) was compared to a grilled burger with MSG and aromatics (Complex 2). Check-all-that-apply (CATA) tests show that participants perceived sensory differences between the samples, but their effects in hedonic ratings were inconclusive; only the Maillard sample was significantly more liked than Control and Complex burgers in Study 1. Although limited to their variables and context, these two experiments indicate that umami, Maillard reaction, and complexity, per se, are not key factors to improve liking and willingness to buy (WTB) of plant-based dishes. These results suggest that rather than trying to emulate sensory characteristics considered associated with meat, future research could prioritize addressing cultural barriers to vegetarian food. Full article

In our previous study, a taste sensor employing a lipid/polymer membrane modified with 2,6-dihydroxyterephthalic acid (2,6-DHTPA) enabled the detection of the umami substances monosodium glutamate (MSG) and inosinate monophosphate (IMP). The taste sensor was also able to evaluate the synergistic effect, an umami enhancement phenomenon that occurs between MSG and IMP. However, the structural requirements for modifiers capable of detecting IMP have not yet been clarified. In the present study, to elucidate these requirements, nine different modifiers were prepared, and taste sensor measurements for IMP were conducted in combination with ¹H-NMR analysis. As a result, three distinct patterns were observed: (1) modifiers that exhibited chemical shift changes and generated a potential response in the positive direction (i.e., a positive potential response); (2) modifiers that showed chemical shift changes but produced either an almost zero or a negative potential response; and (3) modifiers that exhibited neither chemical shift changes nor any potential response. For receptor membranes that did not exhibit a positive response, the corresponding modifiers either lacked two carboxyl groups or did not possess intramolecular hydrogen bonding involving hydroxyl groups. From these results, it was clarified that the essential conditions for obtaining a positive potential response to IMP are that the modifier (1) contains two carboxyl groups and (2) possesses intramolecular hydrogen bonding. Full article

Monosodium glutamate (MSG), a widely used flavor enhancer, has been implicated in oxidative stress-mediated systemic and reproductive toxicity, particularly affecting the male gonadal system. This study evaluated the ameliorative potential of eugenol, a phenolic compound with potent antioxidant properties, against MSG-induced reproductive toxicity in male Wistar rats. Thirty rats were randomly divided into five groups: group 1 (control), group 2 (MSG 2.5 g/kg), group 3 (eugenol 200 mg/kg), group 4 (MSG + eugenol 100 mg/kg), and group 5 (MSG + eugenol 200 mg/kg). Treatments were administered orally for 28 days. Hematological, biochemical, hormonal, antioxidant, gross, and histopathological assessments were conducted after sacrifice on Day 29. MSG exposure significantly reduced testicular weight, testosterone levels, TEC, Hb, PCV, serum proteins, and testicular GSH and SOD, while markedly elevating TLC, AST, ALT, BUN, creatinine, and TBARS. Severe testicular degeneration, vascular congestion, germ-cell loss, and disrupted seminiferous tubules were observed histologically. Co-administration of eugenol resulted in significant and dose-dependent amelioration of MSG-induced alterations, restoring hematological and biochemical parameters, improving antioxidant status, and elevating testosterone levels. Gross pathology and histopathology demonstrated progressive structural recovery, with the higher eugenol dose showing near-normal testicular architecture and active spermatogenesis. Eugenol alone produced no adverse effects and remained comparable to the control group across all parameters. The findings indicate that eugenol confers strong protective effects against MSG-induced reproductive toxicity, primarily through its antioxidant and cytoprotective actions. Eugenol may serve as a promising natural therapeutic agent for mitigating chemically induced male reproductive impairments. Full article

Flavor quality fundamentally influences the market value of bivalves, yet the molecular basis of interspecific umami variation remains poorly understood, hindering flavor-directed breeding. This study compared umami compounds and related gene expression across six economically important bivalve species from Southeast China: Crassostrea sikamea, Meretrix meretrix, M. mercenaria, Cyclina sinensis, Ruditapes philippinarum, and Sinonovacula constricta. Using quantitative chemical analysis and qPCR, key taste components and gene expression levels were assessed during the peak flavor season. Results identified glutamic acid, aspartic acid, guanosine monophosphate, and adenosine monophosphate as major umami contributors. Crassostrea sikamea showed the highest umami intensity (Equivalent umami concentration = 449.35 g Monosodium Glutamate/100 g dry weight), followed by Meretrix meretrix (EUC = 329.56 g MSG/100 g dry weight). Expression of glutamate dehydrogenase 1 strongly correlated with glutamic acid content (r = 0.90, p < 0.01), indicating its regulatory role. glutamic-oxaloacetic transaminase 1 and adenylosuccinate synthase also associated positively with aspartic and glutamic acids, respectively, while hypoxanthine phosphoribosyltransferase 1 correlated negatively. Bioinformatics revealed species-specific variations in key enzyme active sites. This study integrates flavor phenotyping with genetic analysis, offering novel insights into umami regulation and providing candidate genes for molecular breeding aimed at flavor enhancement, but subject to further functional validation and heritability analysis. Full article

Instant noodles have become a staple convenience food worldwide, with rising consumption particularly among younger, busier populations. This study investigates consumer perceptions, health concerns, consumption habits, and purchasing behaviors related to pre-packaged noodles in Kosovo. A structured questionnaire was administered to 400 participants, exploring attitudes toward health impacts, ingredient awareness, product preferences, and purchasing motivations. Findings revealed mixed perceptions of noodle healthiness, with older and more educated individuals significantly more likely to view them as unhealthy (p < 0.001). Although most respondents expressed concern about ingredients such as fat, calories, and salt, awareness of additives like monosodium glutamate (MSG) remained low (p < 0.001), indicating a gap in consumer knowledge. Consumption patterns varied notably by age, gender, income, and health status. Younger and lower-income groups consumed noodles more frequently (p < 0.001), often driven by time constraints rather than taste or nutritional value. One-third of participants reported a sense of addiction, strongly linked to both frequency and portion size. When purchasing, consumers prioritized label clarity, origin, and natural ingredients over sensory appeal, and advertising exerted only a moderate influence on choices. These results suggest that while practical needs drive consumption, health concerns and demographic factors strongly shape perceptions and behavior. Efforts to reduce unhealthy consumption should focus on clearer labeling, accessible nutrition education, and promoting healthier, convenient alternatives. Full article

This study optimized γ-aminobutyric acid (GABA) formation in Vietnamese fermented pork (nem chua) using a central composite design to tune salt, sugar, and monosodium glutamate (MSG) under co-inoculation with Lactiplantibacillus plantarum CP1.2 and Pediococcus acidilactici CP1.4. Fermentations proceeded at room temperature; pH, titratable acidity, GABA (colorimetry), formal nitrogen, ammoniacal nitrogen (indophenol blue), and microbial counts were measured, with a packaging comparison between polypropylene (PP) and polyethylene (PE). Response surface analysis (R² = 0.8897) predicted an optimum at 2.0% salt, ~15.9–16.0% sugar, and ~2.9–3.0% MSG, yielding 7.44 mg/g GABA. Validation at these conditions achieved higher GABA (8.32 ± 0.24 mg/g), with pH near 4.70 and lactic acid ~18.5 g/kg. Across seven storage days, GABA peaked at day 1 (8.72–8.84 mg/g) and declined to 4.74–5.07 mg/g (day 7) as acidity increased. PE tended to preserve GABA better and reduced aerobic counts relative to PP, whereas PP limited ammoniacal nitrogen later in storage; lactic acid bacteria remained abundant (≥9.4 log CFU/g). Sensory attributes (color, aroma, taste, firmness) decreased over time but were higher in PE. The results show that balanced seasoning ratios, starter cultures, and packaging can maximize GABA enrichment while maintaining safety and quality in nem chua, providing a practical basis for scale-up of GABA-enhanced fermented meat products and tailoring shelf-life with packaging. Full article

A taste sensor composed of a lipid/polymer membrane using tetradodecylammonium bromide (TDAB) as the lipid and modified with 2,6-dihydroxyterephthalic acid (2,6-DHTPA) has recently been reported to exhibit high sensitivity and selectivity toward the umami substance monosodium L-glutamate (MSG). In this study, we aimed to investigate whether this sensor can also detect another umami substance, inosine monophosphate (IMP), and whether it can evaluate the umami synergistic effect—an enhancement of umami intensity—observed when IMP is mixed with MSG. Furthermore, ¹H-NMR analysis was conducted to examine the nature of interactions between the membrane modifier and umami substances. The results demonstrated that IMP can be successfully detected using the sensor, and that, as previously reported for MSG, sensor sensitivity is influenced by the presence or absence of intramolecular hydrogen bonding within the modifier and intermolecular hydrogen bonding between the modifier and the umami substance. In addition, the response to mixed solutions of MSG and IMP was greater than the sum of individual responses, indicating that the umami synergistic effect can be evaluated using the taste sensor. NMR measurements also revealed that the presence of the membrane modifier enhances the interaction between IMP and MSG, supporting the observed synergistic effect. Full article

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the vertebrate central nervous system, known for its role in promoting sleep, reducing anxiety, regulating blood pressure, and modulating stress, cognition, and behavior. Microbial fermentation offers an effective method for GABA production, with certain lactic acid bacteria (LAB) strains recognized as efficient producers. This study assessed the GABA-producing potential of 31 LAB strains, including isolates from traditional Bulgarian foods and plants. The strains were cultivated in an MRS medium supplemented with 1% monosodium glutamate (MSG), and GABA production was quantified using HPLC after derivatization with dansyl chloride. Most strains produced between 200 and 300 mg/L of GABA. However, Levilactobacillus brevis NCTC 13768 showed much higher productivity, reaching 3830.7 mg/L. To further evaluate its capacity, L. brevis NCTC 13768 was cultivated for 168 h in MRS medium with and without MSG. Without MSG, GABA production peaked at 371.0 mg/L during the late exponential phase. In contrast with MSG, GABA levels steadily increased, reaching 3333.6 mg/L after 168 h. RT-qPCR analyses of the glutamic acid decarboxylase (GAD) system showed that the genes of glutamate decarboxylase (gadB), glutamate-GABA antiporter (gadC), and transcriptional regulator (gadR) are significantly overexpressed when the culture reaches the late stationary phase of growth (96 h after the beginning of cultivation). These results identify L. brevis NCTC 13768 as a high-yield GABA producer, with potential applications in the production of fermented functional foods and beverages. Full article

Gamma-aminobutyric acid (GABA) is a bioactive amino acid with anti-inflammatory and neurotransmitter properties, yet limited information exists regarding its production by Lactiplantibacillus paraplantarum. We evaluated factors that influence GABA synthesis by L. paraplantarum HK-1 and assessed its production in vitro and under simulated gastrointestinal conditions. GABA production was analyzed using HPLC with pre-column derivatization, gene expression was assessed through RT-qPCR, and probiotic characteristics were evaluated using standard microbiological methods. L. paraplantarum HK-1 demonstrated dose-dependent GABA production with monosodium glutamate (MSG) supplementation, achieving maximum levels at 500 mM MSG (161.1 µg/mL), which was significantly higher than those in other treatments (p < 0.01). A strong positive correlation was observed between MSG concentration and GABA production (r = 0.908, p = 0.002). Gene expression analysis revealed a 61.6-fold higher gadB expression at 500 mM MSG compared to 250 mM, though statistical significance with GABA production was not achieved (r = 0.741, p = 0.259). The strain exhibited appropriate probiotic characteristics including γ-hemolytic activity, bile salt tolerance, and acid resistance. Under simulated gastrointestinal conditions, maximum GABA production occurred in the distal colon (148.3 ± 19.0 µg/mL with probiotic vs. 7.2 ± 6.2 µg/mL control), with overall production significantly higher in probiotic-treated groups (p < 0.001). Overall, L. paraplantarum HK-1 produced GABA throughout gastrointestinal phases and showed traits consistent with probiotic use. These results position HK-1 as a promising GABA-producing candidate for functional food applications, pending in vivo validation. Full article

Background: Understanding how aroma compounds enhance monosodium glutamate (MSG) umami perception remains a critical challenge in flavor science. Methods: The umami-enhancing effects of meaty flavorings were investigated using nasal clip sensory evaluation (orthonasal blockage). Active aroma compounds were subsequently identified using gas chromatography-mass spectrometry (GC-MS). The three-dimensional structure of the umami receptor T1R1/T1R3 was constructed by homology modeling. The interaction mechanism was deciphered using molecular dynamics (MD) simulations. Results: Seafood essence S demonstrated the most potent umami enhancement. Five key compounds significantly intensified the MSG umami intensity: methional, dimethyl sulfide (DMS), D-limonene (DLE), 2,3-dimethylpyrazine, and dimethyl trisulfide. Notably, this enhancement persisted even under nasal clip conditions, revealing a novel mechanism independent of cross-modal interactions. Sulfur-containing compounds consistently demonstrated umami-enhancing effects across the evaluation conditions. MD simulations showed that aroma compounds induced allosteric remodeling of T1R1/T1R3, strengthening MSG-receptor hydrogen bonding (1.8–2.6-fold increase), reducing receptor flexibility, and stabilizing the ternary complex. Binding affinity was highest for DMS, followed by DLE and methional. Conclusion: This study provides the first receptor-level evidence that aroma compounds directly modulate MSG-taste receptor interactions through allosteric regulation, offering a novel theoretical framework for odor–taste interactions with significant implications for umami enhancer design and flavor research. Full article

This study aims to develop an environmentally friendly hydrometallurgical process for the recovery of zinc from zinc oxide ores. The process includes monosodium glutamate (MSG) leaching, followed by zinc recovery from the pregnant leach solution via electrowinning, and the recirculation of the spent solution to the leaching stage. The study investigated the effects of key leaching parameters and identified the optimal conditions as a pH of 9.5, temperature of 70 °C, 5 h leaching time, solid-to-liquid ratio of 50 g/L, particle size of d₈₀ = 115 µm, and initial MSG concentration of 1.0 M. Under these conditions, 82.3 ± 0.05% of the zinc was extracted with minimal co-dissolution of impurities. Subsequent electrowinning at 100 A/m² for 150 min yielded 74.97 ± 2.43% zinc recovery with 96.4 ± 0.76% purity. The process achieved a current efficiency of 87.08%, while the specific energy consumption was calculated to be 3.98 kWh per kilogram of zinc recovered. The reusability of MSG was examined by recirculating spent electrowinning solution back to the leaching stage. Zinc extraction decreased from 82.2% to 28.5% over three electrowinning–leaching cycles, due to MSG degradation during electrowinning. The results of this study demonstrated that MSG is a selective and effective lixiviant for zinc recovery, while underlining the limitations of its reuse. Full article