What is E628?
Complete guide to understanding E628 (Dipotassium Guanylate) in your food
The Quick Answer
E628 is dipotassium guanylate, a flavor enhancer made from guanylic acid (GMP) bonded with potassium (two potassium ions per guanylate molecule).
It’s used in food to enhance savory, meaty, and broth-like flavors, particularly in snacks, soups, sauces, and processed meats.
Like other guanylate flavor enhancers, E628 doesn’t create umami taste independently but powerfully enhances existing flavors when combined with other ingredients, particularly with glutamate or inosinate.
📌 Quick Facts
- Category: Flavor enhancer, umami intensifier
- Chemical form: Dipotassium salt of guanylic acid (GMP)
- Also known as: Potassium guanylate, potassium 5′-guanylate, dipotassium 5′-guanylate
- Found in: Potato chips, snacks, instant soups, sauces, pre-cooked foods, charcuterie, meat products, olives, dietetic products
- Safety: Approved in EU, Japan, Australia, and most countries
- Acceptable Daily Intake (ADI): None determined; group ADI with guanylic acid
- Flavor potency: Approximately 2 times that of disodium inosinate (E631)
- Source: Commercially prepared from yeast extract or sardines
- Key feature: Enhances natural flavors; allows salt reduction in products
- Important note: Contains purines; metabolizes to uric acid
- Dietary restrictions: Not suitable for vegans (usually from fish); partially suitable for vegetarians depending on source
- Not permitted: In products intended for children under 12 weeks
What Exactly Is It?
E628 is the dipotassium salt of guanylic acid (GMP).
Guanylic acid is a naturally occurring ribonucleotide found in all living cells as part of RNA—the genetic instructions that control life. It’s particularly concentrated in foods like meat, fish, mushrooms, and yeast.
E628 is the concentrated, purified form of guanylic acid, bonded with two potassium ions to create a white crystalline powder suitable for food manufacturing.
Chemical formula: K₂C₁₀H₁₂N₅O₈P – Molecular weight: 439.40 g/mol
Key distinction from related compounds:
• E627 (disodium guanylate): Uses sodium salt instead of potassium
• E629 (calcium guanylate): Uses calcium salt instead of potassium
• E626 (guanylic acid): The base compound without mineral salt bonding
How it enhances flavor:
E628 does not have a taste of its own. Instead, it enhances existing natural flavors in food:
• Guanylate + Glutamate (MSG) = enhanced savory perception
• Guanylate + Inosinate = synergistic umami amplification
• Creates meaty, savory, broth-like taste
• Allows food manufacturers to reduce salt while maintaining flavor intensity
• Particularly effective in “I+G” combinations (E628 with E631)
Important distinction: Unlike glutamates (which create umami taste themselves), guanylates enhance other flavors without contributing their own specific taste.
Where You’ll Find It
E628 appears in various processed foods, particularly savory products:
• Potato chips and corn chips
• Savory snacks and flavored crackers
• Instant soups and powder soups
• Instant noodles and cup noodles
• Sauces and gravies
• Processed meat and charcuterie products
• Pizza toppings and prepared meals
• Spice mixes and seasonings
• Olives and pickled vegetables
• Pre-cooked foods and convenience meals
• Rice-based products
• Fish-derived products
• Canned vegetables
• Breakfast products
• Dietetic products (for low-salt content)
E628 is less commonly used than disodium guanylate (E627), appearing primarily in products where potassium content is strategically important or where different solubility properties are needed.
Why Do Food Companies Use It?
E628’s primary function is enhancing existing natural flavors while reducing salt content.
Food manufacturers use dipotassium guanylate for specific advantages:
• Flavor enhancement without taste contribution: Amplifies existing flavors without adding discernible guanylate taste
• Salt reduction enabler: Allows reduction of sodium while maintaining perceived flavor intensity
• Potassium addition: Provides potassium content alongside flavor enhancement—useful for health-marketed products
• Synergistic effects: Works powerfully when combined with inosinate (E631) or with glutamate (MSG)
• Meaty flavor creation: Helps create authentic meaty, savory taste in plant-based and lower-cost meat products
• Water solubility: Suitable for aqueous food systems
• Appetite stimulation: Enhanced flavor perception encourages greater food consumption
• Cost efficiency: Very small concentrations achieve significant flavor effects
• Flavor potency: Approximately 2 times more potent as flavor enhancer than disodium inosinate (E631)
• Stability: Stable at various temperatures and pH levels throughout processing
The combination of potassium content with flavor enhancement makes E628 particularly attractive in products marketed for cardiovascular health, where reducing sodium while adding beneficial potassium is strategically important.
Is It Safe?
E628 is approved in most major regulatory jurisdictions and is considered safe at approved use levels.
Approval status:
• Approved: European Union (E628), Australia, Japan, South Korea, and most countries worldwide
• Regulatory consistency: Unlike some additives with regional variations, E628 enjoys broad international approval
Safety profile:
• No ADI (Acceptable Daily Intake) specifically determined for E628
• Group ADI established with guanylic acid and all guanylate salts
• EFSA has evaluated guanylic acid and guanylates and found no safety concerns at reported use levels
• No evidence of carcinogenicity, mutagenicity, or reproductive toxicity in scientific studies
• No impact on reproductive function confirmed
• The body metabolizes guanylates the same way it handles guanylate compounds from natural foods
• Decades of extensive use without documented widespread safety incidents
• Generally considered safe among flavor enhancers
• Restricted use: Not permitted in products intended for children under 12 weeks
Population-specific concerns:
• Asthmatic individuals: Some asthmatic people should avoid guanylic acid and guanylates, as these additives may trigger symptoms
• Purine metabolism concerns: Critical issues exist (see below)
Critical consideration—purine metabolism:
Like all guanylate flavor enhancers, E628 contains purines that the body metabolizes to uric acid. This creates specific health concerns:
⚠️ Important Health Consideration:
E628 is metabolized to purines, which convert to uric acid. This creates potential problems for:
• Gout sufferers: Higher purine intake increases serum uric acid levels, worsening symptoms and increasing attack frequency
• Hyperuricemia: People with elevated uric acid levels should limit purine consumption
• Chronic kidney disease: Impaired kidney function makes purine metabolism problematic
• History of kidney stones: Uric acid contributes to certain types of kidney stone formation
• People on uric acid-lowering medication: Should limit purine intake to maintain medication effectiveness
Important note: While concentrations used in food are generally very low, people with gout should avoid guanylic acid and guanylates according to food safety resources. For these groups, E628 may not be appropriate despite being “approved as safe” for the general population. Consult your healthcare provider if you have any of these conditions.
Natural vs Synthetic Version
E628 can be derived from natural sources or synthetically produced:
Production methods:
• Natural extraction (most common): Extracted from yeast extract or sardines; potassium is then chemically bonded
• Bacterial fermentation: Can be produced via fermentation using microorganisms
• Chemical synthesis: Laboratory synthesis of the nucleotide from chemical precursors
Vegetarian/vegan status: Complex and variable. Guanylic acid and guanylates are generally produced from yeasts, but partly also from fish. Production method and source vary significantly. Fish-derived sources are not suitable for vegetarians or vegans. Yeast-derived sources can be vegetarian/vegan. Always verify source with manufacturers, as labels don’t always specify.
Chemically identical: Regardless of production method, E628 is the same compound. Your body metabolizes it identically.
Natural Alternatives
Want to avoid E628 or manage purine intake?
Some alternatives include:
• Disodium guanylate (E627) or Calcium guanylate (E629) – Similar guanylate-based enhancers with different mineral salts
• Disodium inosinate (E631) or other inosinates – Similar inosinate-based enhancers; also purine-based; often combined with E628 as “I+G”
• Monosodium glutamate (MSG, E621) – Umami flavor but different mechanism than guanylates
• Disodium 5′-ribonucleotides (E635) – Mixture of guanylate and inosinate; similar combined effect
• Natural yeast extracts – Contain natural guanylates; more expensive
• Fish sauce and fermented fish products – Traditional umami enhancers; contain natural guanylates
• Mushroom extracts – Natural umami and glutamates with lower purines
• Aged cheeses – Natural umami from glutamates
• Tomato extracts – Natural glutamates without nucleotide-based compounds
For people with gout or hyperuricemia, alternatives must also be evaluated for purine content—most umami-rich foods contain some purines.
The Bottom Line
E628 (dipotassium guanylate) is a flavor enhancer that amplifies existing natural flavors, particularly savory and meaty tastes.
It’s found in potato chips, snacks, instant soups, sauces, processed meats, and pre-cooked foods—particularly in products marketed for low-sodium content.
E628 is approved by regulatory bodies in the EU, Australia, Japan, and most countries worldwide.
Key health considerations: E628 contains purines that metabolize to uric acid. While approved as safe for the general population, it may be inappropriate for people with gout, hyperuricemia, chronic kidney disease, or those managing uric acid levels. Additionally, some asthmatic individuals should avoid it, and it’s not permitted in infant formula.
E628’s advantage over disodium guanylate (E627) is that it provides potassium content alongside flavor enhancement—potentially beneficial for products marketed for cardiovascular health. However, the sodium form (E627) remains more widely available and commonly used.
For healthy individuals without purine metabolism concerns or asthma, E628 at approved levels is considered safe by regulatory bodies. If you have metabolic concerns related to uric acid or respiratory sensitivity, consult your healthcare provider before regularly consuming products containing E628.