What is E524?

Complete guide to understanding sodium hydroxide in your food

The Quick Answer

E524 is sodium hydroxide, commonly known as caustic soda or lye.

It’s used in food production to regulate acidity, improve texture, and process food appearance.

Most people consume trace amounts in pretzels, olives, processed dairy, and other convenience foods without realizing it.

What Exactly Is E524?

E524 is sodium hydroxide (NaOH), commonly known as caustic soda or lye.

It’s a white solid that comes as flakes or pellets and readily dissolves in water, releasing significant heat—a reaction so intense it’s used in self-heating food containers and emergency cooking kits.

Sodium hydroxide is synthetically produced through electrolysis of common salt, making it an industrial chemical. However, it’s also been used in traditional food preparation for centuries—most famously in German pretzels, Chinese moon cakes, and olive processing.

In technical terms, it’s a prototypical strong base (opposite of an acid) with powerful pH-regulating and alkaline properties.

Where You’ll Find E524

E524 appears in numerous processed and traditional foods:

– Pretzels (distinctive brown glaze and taste)
– Olives (softening, removing bitterness)
– German lye rolls and bagels
– Chinese moon cakes
– Chinese yellow noodles (containing lye-water)
– Cocoa and chocolate products
– Caramel coloring
– Dairy products (cheese, puddings, condensed milk)
– Butter and whey products
– Fat spreads and emulsions
– Sweet creams and ice cream
– Processed and preserved fruits
– Meat and fish products
– Poultry products (scalding)
– Soups and broths
– Sauces and salads
– Bakery and confectionery products
– Soft drinks and beverages

If you’ve ever eaten a pretzel, olives, or instant cocoa, you’ve likely consumed trace amounts of E524.

Why Do Food Companies Use E524?

E524 serves multiple critical functions in food production.

First, it’s a powerful acidity regulator. By increasing pH and adjusting alkalinity, it extends shelf life, prevents spoilage, and maintains optimal flavor and quality. Without pH control, products spoil or develop unpleasant tastes.

Second, it improves texture and appearance. In olives, it softens the fruit and removes bitter compounds. In pretzels, it creates the characteristic brown glaze and distinctive taste. In chocolate and cocoa, it improves processing and appearance.

Third, it serves as a processing agent. In poultry, it’s used for scalding. In fruits and vegetables, it chemically peels skins. In cocoa and tea, it creates fine powders.

Fourth, it acts as a stabilizer in dairy and frozen products, preventing separation and maintaining consistency.

So food manufacturers use E524 because it solves real production challenges while being cost-effective and approved worldwide.

Is It Safe?

Regulatory authorities confirm E524 is safe for food use.

The FDA classifies it as “Generally Recognized As Safe” (GRAS) when used according to Good Manufacturing Practices. The EFSA approves it under Commission Regulation (EU) No 231/2012. Most remarkably, it’s even approved for organic food—the highest safety designation possible.

The UK Health & Safety Executive states: “Low level exposure from the correct use of products that contain sodium hydroxide would not be expected to cause any adverse health effects.”

No Acceptable Daily Intake (ADI) was established—indicating no safety concern at approved food use levels. E524 is used under “Quantum Satis” authorization, meaning manufacturers use only necessary amounts with no absolute maximum specified.

At trace amounts found in finished foods, sodium hydroxide is completely safe for all populations, including children and pregnant women.

The Stark Difference: Concentrated vs. Food-Grade

This distinction is absolutely critical to understand.

In chemical manufacturing and industrial settings, concentrated sodium hydroxide is classified as extremely hazardous:

– Causes severe chemical burns to skin
– Causes serious eye damage and potential blindness
– Corrosive to respiratory tract if inhaled
– Can cause fatal gastrointestinal damage if ingested
– Decomposes proteins at room temperature
– Classified with hazard signal word: DANGER

However, these hazards apply exclusively to workers handling concentrated industrial solutions—not to consumers eating foods containing trace amounts of E524.

In food manufacturing, E524 is used in tiny quantities and is further diluted, processed, and transformed during production. By the time food reaches your table, any sodium hydroxide present is in negligible amounts that pose zero risk.

Think of it this way: water is essential for life, but drowning is dangerous. The dose makes the poison.

Traditional Uses Demonstrate Long Safety History

E524 isn’t a modern food chemical—it has centuries-long culinary history.

German pretzels have been treated with sodium hydroxide solution for as long as they’ve been made, creating their distinctive brown color and unique taste. Chinese moon cakes have used lye-water for centuries. This traditional use, combined with modern safety approvals and regulatory oversight, demonstrates sustained confidence in its safety.

The fact that sodium hydroxide is even approved for organic food—the most stringent food safety designation—shows how confident regulatory agencies are in its safety at food additive levels.

Why Sodium Hydroxide Over Potassium Hydroxide?

Both sodium and potassium hydroxide are approved for food.

Food manufacturers prefer sodium hydroxide because:

– It’s cheaper to produce from common salt
– Less quantity is needed to achieve the same effect
– More cost-effective for food production
– Sodium is a naturally occurring dietary mineral

However, both are equally safe at food additive levels when properly managed.

Manufacturing and Synthetic Status

E524 is synthetically produced through electrolysis.

Common salt (sodium chloride) undergoes electrolysis to produce sodium hydroxide. This modern industrial process is standardized, controlled, and creates pure food-grade product. While “synthetic,” this means it’s manufactured in a controlled facility—it doesn’t make it unsafe. Many beneficial substances are synthetically produced.

Distinctions from Related Hydroxides

Don’t confuse E524 with other hydroxide additives:

– E524 Sodium hydroxide: Sodium-based (caustic soda)
– E525 Potassium hydroxide: Potassium-based (caustic potash)
– E526 Calcium hydroxide: Calcium-based (slaked lime)
– E527 Ammonium hydroxide: Ammonia-based (ammonia water)
– E528 Magnesium hydroxide: Magnesium-based

These are all different compounds with distinct functions. Only sodium hydroxide is approved for organic food production.

Vegan, Vegetarian, and Allergen Status

E524 is suitable for:

– Vegan diets ✓
– Vegetarian diets ✓
– Gluten-free diets ✓
– Those with most allergies ✓

Sodium hydroxide is a synthetic chemical with no animal products or byproducts involved in its production.

The Bottom Line

E524 (sodium hydroxide) is a synthetically produced food additive used for acidity regulation, texture improvement, and food processing.

Regulatory authorities worldwide classify it as safe for approved food uses.

The FDA considers it GRAS, and the UK Health & Safety Executive confirms that proper use poses no adverse health effects.

Remarkably, it’s even approved for organic food—the highest food safety certification available.

At trace amounts found in pretzels, olives, cocoa, and other processed foods, E524 poses no documented health risks to any population.

While concentrated sodium hydroxide is hazardous in industrial settings, food-grade applications use only microscopic amounts that pose zero consumer risk.

As always, food labels must declare E524 when used, enabling informed consumer choice.