E638 - Sodium L-aspartate

At a glance

• What it is: The sodium salt of the naturally occurring amino acid L‑aspartic acid
• What it does: Enhances savory taste so existing flavors seem stronger
• Where it’s found: Seasoning blends, instant soups and noodles, sauces, snack foods, and ready meals
• Other names: E638, sodium L‑aspartate
• Dietary notes: Adds a small amount of sodium; typically used in tiny amounts

Why is Sodium L-aspartate added to food?

Food makers use sodium L‑aspartate as a flavor enhancer. Flavor enhancers make the flavors already in a food taste stronger without adding a strong taste of their own.¹ In the European Union (EU), it is listed as food additive E638 and has official specifications, meaning its identity and purity are defined for use in foods.² Specific permitted uses and conditions are set by EU law.³

What foods contain Sodium L-aspartate?

You may see E638 on ingredient lists for savory products such as dry seasoning mixes, instant soups, snack foods, sauces, meat or plant‑based ready meals, and stock cubes. Allowed uses and levels depend on the food category and the country’s rules.³ Internationally, the Codex General Standard for Food Additives (GSFA) also lists sodium L‑aspartate (INS 638) as a flavor enhancer, and national authorities decide how to apply it in their markets.⁴

What can replace Sodium L-aspartate?

Depending on the recipe and local rules, formulators may consider:

• Other umami enhancers such as monosodium glutamate, disodium inosinate, or disodium guanylate
• Amino acid–type enhancers like glycine and its sodium salt
• Sweet, caramel-like flavor boosters that round out taste, such as maltol or ethyl maltol

The best substitute depends on the target flavor, cost, and labeling needs.

How is Sodium L-aspartate made?

Sodium L‑aspartate is the sodium salt of L‑aspartic acid. In practice, it is prepared by neutralizing food‑grade L‑aspartic acid with a suitable sodium base to form the salt, and it must meet the identity and purity specifications laid down in EU law for E638.²

Is Sodium L-aspartate safe to eat?

E638 is an authorized food additive in the EU; its permitted food categories and conditions of use are set in Regulation (EC) No 1333/2008 and related measures.³ In the United States, flavor enhancers and other food additives must meet federal safety requirements before use; FDA explains how food additives are evaluated and regulated for safety.⁵ When used as intended and within applicable rules, sodium L‑aspartate is considered safe by regulators.

Does Sodium L-aspartate have any benefits?

Its benefit is culinary: it enhances the existing savory flavor profile so foods can taste fuller or more rounded.¹ It does not meaningfully change the nutritional value of the food at the small amounts used.

Who should avoid Sodium L-aspartate?

• People who must limit sodium (for example, some individuals with high blood pressure or kidney conditions) may wish to watch for all sources of sodium, including minor ones from additives like E638.
• Anyone with specific medical or dietary needs should consult a healthcare professional about suitable foods.

Myths & facts

• Myth: Sodium L‑aspartate is the same as the sweetener aspartame. Fact: They are different additives with different roles; aspartame is E951 and is a low‑calorie sweetener, while E638 is a flavor enhancer.⁵
• Myth: All flavor enhancers are MSG. Fact: E638 is not MSG; monosodium glutamate is a different compound.
• Myth: It adds a strong taste on its own. Fact: Flavor enhancers are used to boost existing flavors rather than create a new, dominant taste.¹

Sodium L-aspartate in branded foods

On ingredient lists, look for “sodium L‑aspartate” or “E638.” You’re most likely to find it in savory seasonings, soups, sauces, snacks, and ready meals. Availability and labeling can vary by region; in the EU, E‑numbers are commonly used on labels.³

References

Footnotes

1. 21 CFR 170.3(o)(11) — Definition of flavor enhancer (eCFR). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-170#p-170.3(o)(11) ↩ ↩² ↩³

2. Commission Regulation (EU) No 231/2012 — Specifications for food additives. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩²

3. Regulation (EC) No 1333/2008 — Food additives. https://eur-lex.europa.eu/eli/reg/2008/1333/oj ↩ ↩² ↩³ ↩⁴

4. Sodium L-aspartate (INS 638) — Codex GSFA Online. https://www.fao.org/gsfaonline/additives/details.html?ins=638 ↩

5. Overview of Food Ingredients, Additives & Colors — U.S. FDA. https://www.fda.gov/food/food-ingredients-packaging/overview-food-ingredients-additives-colors ↩ ↩²