Food-Grade Phosphoric Acid (E338): Uses and Selection

Food-grade phosphoric acid is the same molecule as the industrial acid – H₃PO₄, CAS 7664-38-2 – but it is made and controlled so that arsenic, fluoride and heavy metals stay inside food limits. In the EU it is known as the food additive E338, and it is one of the most widely used acidulants in the beverage and food industry. This article covers what food-grade acid is, how it differs from industrial acid, where it is used, and what to check when buying it.

1. What food-grade phosphoric acid is

Food-grade phosphoric acid is a clear, colourless aqueous solution of H₃PO₄ supplied at 85%. It is produced from high-purity (thermal-process) acid so that the impurity profile meets the food monograph limits. It functions in food as an acidulant, a pH regulator and, in some applications, a sequestrant for metal ions.

Property	Typical value
Name / E number	Phosphoric acid / E338
CAS number	7664-38-2
Formula / MW	H₃PO₄ / 98.00 g/mol
Supplied concentration	85% (food grade)
Appearance	Clear, colourless, odourless solution

2. Food grade vs industrial grade

The chemistry is identical; the difference is the impurity control and the paperwork. Food grade is defined by strict limits on arsenic, fluoride and heavy metals, and is supplied against a food-grade specification with a per-batch certificate of analysis. Industrial grade meets an industrial specification and is used where those food limits are not required. This is why food grade carries a premium even though it is the same acid.

3. Why food grade is supplied at 85%

The standard commercial strength for food and beverage use is 85%. Food grade is not normally supplied at 75%: manufacturing and shipping the food grade at its standard strength keeps the impurity profile consistent and simplifies traceability. If your process needs a weaker acid, you dilute the 85% material to your working strength, so buy on an 85% basis and dose accordingly.

4. Where food-grade phosphoric acid is used

Application	Role of phosphoric acid
Cola-type soft drinks	Acidulant giving the characteristic tart taste; also a mild preservative effect through pH
Jams, jellies and fruit preparations	pH adjustment for set, colour and shelf life
Processed cheeses	Acidulant and emulsifying-salt component
General food processing	pH control, acidulant and metal-ion sequestration
Yeast and fermentation nutrition	Phosphate source and pH control for fermentation
Animal feed and feed phosphates	Phosphorus source and acidulant (feed grades)

5. Regulatory and quality points

E338. In the EU, phosphoric acid is authorised as food additive E338; confirm the authorised use and level for your product and market.
Monograph limits. Food-grade material must meet the limits for arsenic, fluoride and heavy metals set in the applicable monograph.
Per-batch COA. Ask for a certificate of analysis per batch so the impurity profile is documented for each delivery.
REACH. For EU supply, the substance should be supplied as a REACH-registered substance; confirm the status with your supplier.

Always confirm the permitted use and maximum level for your specific product and market against the current regulation; this article is general information, not a compliance opinion.

6. Packaging, storage and handling

Packaging. Food-grade acid is supplied in food-contact-appropriate drums, IBCs and bulk. Keep food-grade packaging separate from industrial stock.
Storage. Store in closed, acid-resistant containers, clearly labelled, away from strong bases and reactive metals.
Handling. Concentrated acid is corrosive; use goggles, gloves and protective clothing. Always add acid to water when diluting.
Traceability. Retain COA and SDS per batch for your records and audits.

7. How to choose a supplier

Supplies food grade at the standard 85% strength and states the grade clearly.
Provides a food-grade specification plus a COA and SDS for each batch.
Confirms E338 compliance information for your market.
States REACH status for EU purchases.
Offers food-appropriate packaging and delivery.

Frequently Asked Questions

What is food-grade phosphoric acid?

Phosphoric acid (H₃PO₄, CAS 7664-38-2) supplied at food-grade purity, corresponding to the food additive E338, with strict limits on arsenic, fluoride and heavy metals.

What concentration is food grade supplied at?

85% is the standard commercial strength. Food grade is not normally supplied at 75%; if you need a weaker acid, dilute the 85% material to your working strength.

What is E338?

E338 is the EU designation for phosphoric acid when used as a food additive, where it acts as an acidulant and acidity regulator.

Is food-grade phosphoric acid the same as industrial grade?

It is the same molecule, but food grade meets much tighter limits on arsenic, fluoride and heavy metals, and comes with food-grade documentation.

Do you supply food-grade phosphoric acid with REACH registration?

Yes – food-grade phosphoric acid (85%, E338) is supplied as a REACH-registered substance. Confirm the exact status and documents you need when you request a quotation.