What is E624?
Complete guide to understanding E624 (Monoammonium Glutamate) in your food
The Quick Answer
E624 is monoammonium glutamate (MAG), the ammonium salt of glutamic acid, used as a flavor enhancer to provide the “umami” (savory) taste—functioning as a non-sodium alternative to MSG (E621) that delivers identical flavor-enhancing function while reducing sodium intake.
It’s an ammonium salt version of glutamate, providing the characteristic savory “fifth taste” (umami) by enhancing natural food flavors, used in low-sodium products, soups, sauces, and snacks where flavor enhancement without sodium is desired.
E624 is among the RAREST of the glutamate flavor enhancers, minimally used in commercial products—functioning as a flavor enhancer with official regulatory approval but facing IDENTICAL cumulative exposure concerns as other glutamates (E620-E625), where 2017 EFSA found exposure EXCEEDS safe levels in vulnerable populations, particularly infants and children.
📌 Quick Facts
- Category: Synthetic Flavor Enhancer, Glutamate Salt, Taste Modulator
- Source: Produced through bacterial fermentation (non-GMO standard; genetically modified strains used for some production)
- Found in: Soups (rare), low-sodium products, snacks, processed foods (minimal use compared to E621, E622)
- Safety: FDA GRAS approved; EFSA approved; JECFA approved; ADI 30 mg/kg bw (as glutamic acid)
- Natural or Synthetic: Fermentation-derived from bacteria (Corynebacterium glutamicum) with salt formation
- Vegan/Vegetarian: Yes
- Key Concern: IDENTICAL to other glutamates—neurotoxic potential at high exposure; 2017 EFSA found exposure EXCEEDS safe levels in vulnerable populations; RAREST glutamate salt (minimal commercial use)
- Chemical Formula: NH₄C₅H₈NO₄; ammonium salt of L-glutamic acid
The Critical Context—E624 Shares All Glutamate Safety Concerns But Is Rarely Used
E624 monoammonium glutamate is the ammonium salt version of glutamic acid, sharing IDENTICAL safety concerns with all glutamates (E620-E625) documented in 2017 EFSA re-evaluation—cumulative glutamate exposure EXCEEDS safe levels in infants, toddlers, and children—but distinguished as the RAREST commercial glutamate salt, minimally used compared to E621 (sodium), E622 (potassium), and E623 (calcium) versions.
What Exactly Is It?
E624 is monoammonium glutamate (monoammonium L-glutamate), the ammonium salt of L-glutamic acid with molecular formula NH₄C₅H₈NO₄ and molecular weight of approximately 164.16 g/mol.
Monoammonium glutamate is an ammonium acid salt of glutamic acid—one of the 20 standard amino acids. When provided as a salt, glutamate functions as a taste enhancer, amplifying the perception of umami (savory) taste. E624 is specifically the AMMONIUM SALT version, providing the flavor-enhancing function of glutamate while substituting ammonium for sodium.
Physically, E624 appears as white, practically odorless crystals or crystalline powder. It is freely soluble in water (pH 6.0-7.0 in 5% aqueous solution), allowing easy incorporation into aqueous food systems. The compound is heat-stable and maintains flavor-enhancing activity through food processing and storage.
Chemically, E624 functions through the same mechanism as all glutamates: it activates umami taste receptors on the tongue, enhancing perception of natural savory flavors. Upon ingestion, the glutamate is absorbed in the intestine and presystemically metabolized in the gut wall. The ammonium ions are absorbed and metabolized.
Where You’ll Find It
E624 appears in a LIMITED range of processed foods where flavor enhancement with sodium reduction is desired:
• Soups and broths (limited use)
• Low-sodium processed foods
• Snack foods
• Seasonings and spice blends
• Sauces (limited)
• Pre-cooked foods (limited)
• Spices and seasoning mixes
• Food supplements (limited)
• Specialized low-sodium products
E624 is the RAREST of the commercial glutamate salts. Unlike E621 (monosodium glutamate) which is ubiquitous in processed foods, or E622 (monopotassium glutamate) and E623 (calcium diglutamate) which see increasing use, E624 remains minimally used. Most manufacturers favor E621 (cheapest), E622 (potassium benefit), or E623 (calcium fortification) over E624. This scarcity means exposure to E624 specifically is far lower than to other glutamate salts.
Why Do Food Companies Use It? (Or Rather, Don’t)
E624 performs the same flavor enhancement function as other glutamates but is rarely selected due to specific disadvantages:
Limited commercial appeal: E624 monoammonium glutamate could reduce sodium and provide neutral cation status (unlike E622’s potassium-contribution concern for kidney patients or E621’s sodium contribution). However, E624 faces three significant disadvantages preventing widespread adoption: (1) higher cost than E621, (2) no nutritional benefit like E623 (calcium) or E622 (potassium alternative), (3) ammonia concerns in some applications.
Why E624 is rarely used: Manufacturers prefer E621 (lowest cost, FDA-traditional, ubiquitous), E622 (potassium benefit, increasingly selected for health positioning), or E623 (calcium fortification, dual benefit). E624 offers only sodium reduction without additional benefit, making it uncompetitive. The ammonium cation carries potential smell concerns (ammonia perception) in some applications, further limiting use.
Is It Safe?
E624’s safety status is IDENTICAL to all glutamates (E620-E625)—officially approved but with 2017 EFSA finding that cumulative glutamate exposure EXCEEDS safe levels in vulnerable populations, particularly infants and children, with documented neurotoxic potential.
Regulatory Status—Approved Despite Exposure Concerns (Identical to E621-E623, E625):
• FDA (USA): Generally Recognized As Safe (GRAS)
• EFSA (Europe): Approved; ADI 30 mg/kg bw (as glutamic acid)
• JECFA (WHO/FAO): Approved; ADI 30 mg/kg bw
• CRITICAL ISSUE (2017 EFSA): Cumulative exposure from all glutamate sources EXCEEDS ADI in infants, toddlers, children
⚠️ IDENTICAL SAFETY CONCERN TO ALL GLUTAMATES—EXPOSURE EXCEEDS SAFE LEVELS IN CHILDREN: E624 shares all glutamate safety concerns documented in 2017 EFSA:
• Exposure exceeds ADI: IDENTICAL concern as E621, E622, E623, E625—cumulative exposure EXCEEDS 30 mg/kg bw ADI in vulnerable populations
• High exposure documented: At 95th percentile consumption, exposure exceeded not only ADI but also doses associated with adverse effects (MSG symptom complex >42.9 mg/kg bw)
• Adverse effects documented: MSG symptom complex, headache, blood pressure increase, insulin increase—IDENTICAL mechanisms to all glutamates
• Primary sources: Fine bakery wares for children; soups and broths for infants and toddlers—IDENTICAL to other glutamate salts
• Neurotoxic mechanism: Glutamate is neurotransmitter; underdeveloped blood-brain barrier in children creates excitotoxicity vulnerability—IDENTICAL
• 2017 EFSA conclusion: “Exposure exceeded not only the proposed ADI but also doses associated with adverse effects”—IDENTICAL for all glutamates
• Lower exposure risk from E624 specifically: Unlike E621 (ubiquitous) or E622 (increasingly common), E624’s rarity means direct exposure from E624 is minimal; however, cumulative glutamate exposure concern remains identical
Documented findings and concerns (IDENTICAL across all glutamates):
• No genotoxicity: EFSA found no genotoxic concern for all glutamates including E624
• No carcinogenicity: No evidence of carcinogenic potential
• Presystemic metabolism: Glutamate metabolized in gut wall before entering systemic circulation
• Neurotoxic potential: Glutamate as excitotoxin; underdeveloped blood-brain barrier in children raises vulnerability
• MSG symptom complex: Well-documented at doses >42.9 mg/kg bw: burning sensations, facial pressure, chest pain, headache
• Exposure exceeds safe levels: 2017 EFSA found typical exposure in children exceeds safe reference—IDENTICAL across all glutamates
• Vulnerability of infants/children: Blood-brain barrier underdeveloped; cumulative exposure higher relative to body weight
• Hidden sources: Glutamate present naturally (tomatoes, cheese, mushrooms) and as nutrient additions
• Practical exposure risk: E624 scarcity means direct exposure minimal; overall glutamate concern remains if consuming other glutamate salts
E624 vs Other Glutamates—The Rare Option
E624 monoammonium glutamate is the RAREST commercial glutamate salt, sharing identical safety concerns with all glutamates:
• E620 (Glutamic acid): Free acid form; rarely used
• E621 (Monosodium glutamate/MSG): Sodium salt; MOST COMMONLY USED; ubiquitous; adds sodium
• E622 (Monopotassium glutamate): Potassium salt; INCREASINGLY COMMON; reduces sodium; increases potassium
• E623 (Calcium diglutamate): Calcium salt; MODERATELY USED; reduces sodium; provides calcium
• E624 (Monoammonium glutamate): Ammonium salt; RAREST; minimal commercial use; reduces sodium; no additional nutritional benefit
• E625 (Magnesium diglutamate): Magnesium salt; RARE; minimal use
E624 occupies the rarest position in the glutamate family, with minimal commercial adoption.
The 2017 EFSA Re-Evaluation—Applies Identically to E624
The 2017 European Food Safety Authority re-evaluation of all glutamates (E620-E625) applied identically to E624: cumulative glutamate exposure from all sources EXCEEDS safe levels in vulnerable populations.
EFSA explicitly stated: “The Panel noted that the exposure to glutamic acid and glutamates (E 620–625) exceeded not only the proposed ADI, but also doses associated with adverse effects in humans for some population groups” at 95th percentile exposure levels. While E624 specifically is rarely consumed, this assessment applies identically when considering cumulative glutamate exposure from all sources.
Production Method
E624 monoammonium glutamate is produced through fermentation followed by salt formation:
1. Corynebacterium glutamicum bacteria are cultured in fermentation tanks containing molasses or glucose
2. Under controlled anaerobic conditions, bacteria produce glutamic acid as secondary metabolite
3. Glutamic acid is recovered from fermentation broth through precipitation and purification
4. Purified glutamic acid is neutralized with ammonia (NH₃) or ammonium hydroxide, forming monoammonium glutamate
5. The product is crystallized, dried, and standardized for purity
6. Note: Some production uses genetically modified Corynebacterium glutamicum EA-12 strain (approved 2015)
Production is fermentation-based with partially natural origin combined with chemical salt formation.
Natural vs Synthetic Version
E624 is fermentation-derived with partially natural origin—produced through bacterial fermentation but with chemical salt formation making it technically semi-synthetic.
While glutamic acid is naturally produced by bacteria through fermentation (a natural biological process), E624 is created by isolating the bacterial product and forming an ammonium salt—making it technically a synthesized/extracted compound. The distinction is that glutamic acid originates from biological fermentation, but the final product requires synthetic salt formation.
Commercialization and Market Rarity
E624 remains the rarest of the commercial glutamate salts despite regulatory approval, due to competitive disadvantages:
• Cost disadvantage: E624 costs more than E621 (monosodium glutamate) but offers no cost savings
• No nutritional benefit: Unlike E623 (calcium) or E622 (potassium), E624 provides no additional nutritional positioning
• Ammonia concerns: The ammonium cation can create ammonia-like smell in some formulations, limiting sensory appeal
• Marketing disadvantage: No health positioning (“low-sodium” alone is insufficient when E622 offers potassium benefit or E623 offers calcium fortification)
• Manufacturer preference: Most select E621 (cost), E622 (potassium), or E623 (calcium) over E624
This commercial rarity means E624 exposure is minimal compared to other glutamate salts.
Environmental and Sustainability
E624 production through fermentation is relatively sustainable—uses renewable carbohydrate substrates (molasses, glucose), generates minimal waste, and does not rely on petroleum. Fermentation-based production is more sustainable than purely synthetic synthesis. However, agricultural inputs carry environmental costs.
Consumer Actions to Minimize E624 and Glutamate Exposure
For consumers concerned about glutamate exposure, particularly protecting children:
• Limit soups and broths (primary source)
• Reduce fine baked goods and bakery products for children
• Check labels for “glutamate,” “flavor enhancer,” “E624,” “E621,” “E622,” “E623”
• Avoid products combining multiple glutamate additives with natural glutamate sources
• Prepare home-made foods without added glutamates to reduce cumulative exposure
• Pay special attention to products marketed for children; these commonly exceed safe levels
• Understand that complete avoidance is impractical (glutamate naturally present) but reducing added forms helps
• Recognize that E624 scarcity means direct exposure is minimal; focus on more common glutamates (E621, E622, E623)
• Monitor cumulative glutamate exposure across all sources
The Bottom Line
E624 (monoammonium glutamate) is a fermentation-derived ammonium salt of glutamic acid used as a flavor enhancer providing the umami (savory) taste, officially approved by FDA, EFSA, and JECFA, but sharing IDENTICAL safety concerns as all glutamates (E620-E625) documented in 2017 EFSA re-evaluation: cumulative glutamate exposure from food additives, natural sources, and nutrients EXCEEDS the safe level (ADI of 30 mg/kg bw as glutamic acid) in infants, toddlers, children, and adolescents, with documented neurotoxic potential and MSG symptom complex at high doses—distinguished as the RAREST commercial glutamate salt, minimally used compared to E621, E622, and E623, meaning direct E624 exposure is low but cumulative glutamate concern remains if consuming other glutamate salts.
E624 is the ammonium salt form of glutamic acid, functioning as a flavor enhancer that amplifies perception of umami (savory) taste. It is produced through bacterial fermentation followed by chemical salt formation. At 0.1-1% concentrations, E624 enhances natural food flavors while reducing sodium compared to E621.
The critical distinction of E624 is that it shares ALL safety concerns documented for glutamates while being the RAREST commercial glutamate salt. The 2017 EFSA re-evaluation finding that cumulative glutamate exposure EXCEEDS safe levels applies identically to E624, even though E624 direct exposure is minimal due to commercial scarcity.
E624’s rarity reflects commercial disadvantages: it offers sodium reduction like E622 but without potassium benefit; it offers sodium reduction like E623 but without calcium fortification; and it costs more than E621 (the industry standard). Manufacturers prefer competing formulations.
For consumers, E624 exposure is minimal due to commercial scarcity. However, cumulative glutamate concern remains if consuming other more common glutamate salts (E621, E622, E623) where the 2017 EFSA finding of excessive exposure in children applies.