E621: Monosodium Glutamate (MSG / Umami Flavor Enhancer)
Food Additives & E-Numbers · 7 specs
Direct Answer
Monosodium Glutamate (E621, MSG, C5H8NO4Na) is the sodium salt of L-glutamic acid produced via Corynebacterium glutamicum sugar fermentation, activating human T1R1/T1R3 heterodimer umami taste receptors to enhance savory mouthfeel.
Source: Codex Standard 192-1995 / EFSA ANS Panel (2017) / JECFA (1987) / FDA GRAS 21 CFR 182.1 · Last reviewed Aug 28, 2026
Specs
| INS / E-Number | INS 621 / E621 |
| Chemical Formula | C₅H₈NO₄Na · H₂O (Sodium 2-aminopentanedioate monohydrate) |
| Functional Class | Flavor Enhancer (Umami savory tastant) |
| Acceptable Daily Intake (ADI) | 30 mg/kg body weight per day (EFSA 2017) / Not Specified (JECFA 1987) |
| Taste Receptor Target | T1R1 + T1R3 G-protein coupled receptor (GPCR) heterodimer + mGluR4 |
| Sodium Content | 12.3% Sodium by weight (compared to 39.3% in standard table salt NaCl) |
| Synergistic Umami Multiplication | 1:1 ratio with E627 (Disodium Guanylate) / E631 (Disodium Inosinate) increases umami perception up to 8-fold |
Umami Taste Receptor Transduction & Synergy
Free L-glutamate ions bind to the Venus flytrap domain of human tongue T1R1/T1R3 taste bud receptors, triggering intracellular calcium signaling that the brain perceives as rich, savory brothiness. When combined with purine ribonucleotides (Disodium Inosinate E631 or Disodium Guanylate E627), the nucleotides lock glutamate into the receptor pocket, multiplying umami intensity by 800%.
Dietary Sodium Reduction Strategy
Because MSG contains only 12.3% sodium compared to 39.3% in table salt (NaCl), replacing 30% to 50% of salt with MSG in soups, processed meats, and snacks reduces total recipe sodium by 25% to 40% with zero loss in palatability or consumer flavor acceptance.