⚠️ Important Note: E523 has been LIMITED or BANNED in many countries including Europe, Japan, and China specifically due to aluminum content concerns. Always check local regulations where you live—its approval status varies significantly by region.

Why Do Food Companies Use E523?

When used, E523 serves specific functions.

First, it acts as a firming agent, maintaining the texture and firmness of fruits and vegetables during candying, crystallizing, and glazing processes. This prevents mushiness and preserves quality.

Second, it functions as a color retention agent, preserving the natural appearance of processed fruits and vegetables.

Third, it regulates acidity by adjusting pH levels, maintaining product stability.

Fourth, in baking, it acts as an acidic component of baking powder, helping dough rise properly.

However, due to its aluminum content and availability of safer alternatives, it’s increasingly replaced by other additives.

Is It Safe?

The safety picture is complex.

The FDA classifies it as “Generally Recognized As Safe” (GRAS) when used according to good manufacturing practices. The EFSA approved it and conducted a comprehensive 2018 re-evaluation, concluding it “poses no safety concern in current authorised uses and use levels.”

However, this approval comes with major caveats:

– Uses are already very LIMITED—only in specific niche products
– Real-world exposure is “most probably near zero”
– Aluminum content is a concern despite low bioavailability
– BANNED or heavily restricted in Europe, Japan, and China

The Aluminum Concern

The primary health concern with E523 is its aluminum content.

Alums have been controversial due to suggestions of association with Alzheimer’s disease and neurodegenerative diseases. However, several points are important:

– Aluminum from food additives has LOW bioavailability (limited absorption)
– EFSA found NO evidence of carcinogenicity or genotoxicity
– JECFA established a Provisional Tolerable Weekly Intake (PTWI) of 2 mg/kg body weight
– Actual exposure from E523 in food is negligible due to restricted use

For context: the PTWI of 2 mg/kg means a 70 kg adult could tolerate approximately 140 mg of aluminum per week (~20 mg daily) from all aluminum-containing additives without safety concern.

EFSA’s 2018 Safety Re-evaluation

The European Food Safety Authority’s 2018 comprehensive review is important.

EFSA concluded:

– Aluminum sulphates (E520-523) pose no safety concern at current authorised use levels
– Aluminum compounds have low bioavailability and low acute toxicity
– No genotoxicity or carcinogenicity concerns
– Mean exposure: 0.0-0.21 mg/kg body weight per day
– 95th percentile exposure (highest consumers): 0.0-0.88 mg/kg bw per day

Critically, EFSA noted that “real exposure is most probably near the lower end (approximately 0)” because these additives are only authorized in niche products consumed rarely or not at all by most people.

Global Restrictions Reflect Caution

Many countries restrict or ban E523, reflecting an abundance of caution.

Uses are LIMITED or BANNED in:

– European Union (very restricted)
– Japan
– China

These restrictions exist not necessarily because E523 is proven unsafe at approved levels, but because authorities decided the risk-benefit profile favors limiting aluminum exposure from additives when alternatives exist.

Less Common Than Other Alums

E523 is less frequently used than related aluminum-containing additives.

– E521 (Sodium aluminum sulfate): More common in baking powders
– E522 (Potassium aluminum sulfate): Also used in baking products
– E523 (Ammonium aluminum sulfate): Least common of the three

This ordering reflects manufacturers’ preferences and regulatory landscapes—as concerns about aluminum-containing additives have grown, even less commonly used ones like E523 have become increasingly rare.

Manufacturing Process

E523 is synthetically produced through multi-step chemical reactions.

Bauxite ore (containing aluminum oxide) is reacted with sulfuric acid to produce aluminum sulfate. This is then reacted with ammonium sulfate solution to create ammonium aluminum sulfate, which precipitates and is dried and packaged for use.

It’s not extracted from nature—it’s entirely synthetically manufactured.

Vegan, Vegetarian, and Allergen Status

E523 is suitable for:

– Vegan diets ✓
– Vegetarian diets ✓
– Gluten-free diets ✓

Aluminium ammonium sulfate is a chemical compound with no animal products or byproducts involved in its production.

The Bottom Line

E523 (aluminium ammonium sulfate) is an aluminum-containing food additive used as a firming agent and acidity regulator in very limited applications.

Regulatory approval exists from the FDA, EFSA, and JECFA, with EFSA specifically concluding “no safety concern at current authorised use levels.”

However, uses are already extremely restricted—E523 appears in only niche products, and real-world exposure is negligible.

Many countries (Europe, Japan, China) limit or ban its use, reflecting a cautious approach to aluminum-containing additives despite evidence of safety at approved levels.

The declining use of E523 is notable: safer alternatives now exist, and manufacturers increasingly choose non-aluminum options.

As always, food labels must declare E523 when used, enabling informed consumer choice—though finding products containing it requires effort, as it’s one of the rarest food additives available.