⚠️ Critical Finding: The European Food Safety Authority concluded that actual consumer exposure to E520 is “most probably near zero” because uses are limited to only two food categories that are “not captured in dietary surveys.” This is one of the most heavily restricted food additives.

How E520 Works in Food

E520 serves specific preservation and texture functions.

First, it acts as a firming agent. When fruits or vegetables are candied or crystallized, proteins and starches can break down, making the product mushy. E520 chemically coagulates and precipitates these proteins and starches, causing them to flocculate (clump together). This process hardens the product and preserves crispness.

Second, it acts as a color retention agent, preserving natural pigmentation during processing.

Third, it regulates acidity by adjusting pH levels.

Its mechanism—coagulating proteins and starches—makes it particularly useful in specialized candy and preserve applications where texture must be preserved through complex processing.

Why Do Food Companies Use E520?

E520 solves specific technical problems in specialized food production.

When processing candied fruits or crystallized vegetables, traditional methods can break down natural proteins and starches, resulting in mushy, undesirable texture. E520’s protein-coagulating properties maintain firmness and prevent degradation.

However, due to its declining use and availability of alternatives, fewer products contain E520 over time. The Mintel Global New Products Database shows consistent decrease in products containing aluminum sulphates since 2014.

Is It Safe?

Regulatory authorities consider E520 safe at approved use levels—but with exceptional caveats.

The FDA lists E520 as “Generally Recognized As Safe” (GRAS) with no concentration limit. The EFSA’s comprehensive 2018 re-evaluation concluded that aluminum sulphates (E520-523) “are of no safety concern in the current authorised uses and use levels.”

However, this approval comes with extraordinary restrictions:

– Uses authorized in ONLY TWO food categories
– Further restrictions beyond those two categories
– Real-world consumer exposure: “Most probably near zero”
– Products containing E520: Increasingly rare
– Industry no longer submitting use data

The Aluminum Concern

The primary health concern with E520 is its aluminum content.

Alums have been historically controversial due to suggested associations with Alzheimer’s disease. However, important distinctions apply:

– Aluminum from E520 has LOW bioavailability (limited absorption)
– EFSA found NO evidence of carcinogenicity or genetic damage
– EFSA found NO adverse reproductive or developmental effects
– EFSA found NO evidence supporting disease associations at food additive levels
– Actual human exposure is negligible

Aluminum sulfate is nontoxic and nonflammable in its food-grade form. While concentrated forms can theoretically generate extremely corrosive sulfuric acid if ingested, this risk doesn’t apply to trace food additive amounts.

EFSA’s 2018 Comprehensive Safety Assessment

The EFSA’s thorough 2018 evaluation provides critical context.

Key findings:

– Aluminum sulphates pose no safety concern at current use levels
– No genotoxicity (genetic damage)
– No carcinogenicity (cancer)
– No reproductive/developmental toxicity
– Low bioavailability of aluminum
– Mean exposure: 0.0-0.21 mg/kg body weight per day
– 95th percentile (highest consumers): 0.0-0.88 mg/kg bw per day
– Actual exposure “most probably near zero”

Most critically, EFSA noted that these additives are “only authorised in specific products which consumption is not captured in dietary surveys,” meaning they’re so niche that standard health surveys can’t even measure exposure.

E520’s Dramatic Decline in Use

E520’s use has dropped significantly since 2014.

The Mintel Global New Products Database shows consistent decrease in products containing aluminum sulphates following February 2014 legislative changes. Additionally, industry no longer submits use level data to EFSA, suggesting manufacturers have largely abandoned these additives in favor of alternatives.

Non-Food Industrial Uses

E520’s primary uses are outside of food.

Aluminum sulfate’s largest applications are:

– Water and wastewater treatment (primary use)
– Drinking water purification (coagulant)
– Paper manufacturing
– Textile dyeing (mordant)
– Tanning agents
– Sewage treatment
– Oil refining

This demonstrates that aluminum sulfate is a well-understood chemical with extensive industrial use beyond food.

The Alum Distinction

An important chemical distinction exists.

E520 is often called “alum” but technically differs from true alums:

– E520 (Aluminum sulfate): Formula Al₂(SO₄)₃—simple sulfate
– E521-E523 (True alums): Formula XAl(SO₄)₂·12H₂O—double sulfates

This distinction is chemical and regulatory, though all four (E520-E523) are aluminum-containing additives with similar safety profiles and use restrictions.

Manufacturing and Chemistry

E520 is synthetically produced through chemical reaction.

Aluminum hydroxide is reacted with sulfuric acid to produce aluminum sulfate. The resulting white powder is dried and packaged for industrial and food use.

It’s entirely synthetic with no natural source.

Vegan, Vegetarian, and Allergen Status

E520 is suitable for:

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

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

The Bottom Line

E520 (aluminum sulfate) is an aluminum-containing food additive used as a firming and acidity-regulating agent in extremely niche products.

Regulatory authorities approve it as safe at current use levels, with EFSA specifically finding “no safety concern in current authorised uses and use levels.”

However, uses are already so severely restricted that actual human exposure is negligible—EFSA estimates it as “most probably near zero.”

Most notably, use has declined significantly since 2014, reflecting both regulatory tightening and industry preference for aluminum-free alternatives.

The vast majority of consumers will never encounter E520 in food because it appears only in highly specialized candied and crystallized products that most people don’t regularly consume.

As always, food labels must declare E520 when used—but finding products containing it requires considerable effort, as it’s one of the rarest food additives available in modern commerce.