E640 - Glycine and its sodium salt

At a glance

• What it is: The simplest amino acid, used as a flavor enhancer; the sodium form is its salt.
• What it does: Softens sharp tastes and supports overall flavor.
• Where it’s found: A wide range of processed foods where a smoother taste is desired.
• How it’s made: Food-grade glycine is produced and purified to meet official specifications; the sodium salt is formed by neutralizing glycine.
• Safety: Approved for use in the EU (as E640) and considered GRAS (Generally Recognized As Safe) in the U.S. when used under good manufacturing practice.
• On labels: Look for “glycine,” “sodium glycinate,” or “E640.”

Why is Glycine and its sodium salt added to food?

Food makers add E640 to fine-tune taste. Glycine provides a mild, slightly sweet note and helps reduce bitterness or metallic edges in some formulas, acting as a flavor enhancer or adjuvant (a helper for flavor systems). In the United States, glycine is affirmed as GRAS as a flavoring agent and adjuvant when used in line with good manufacturing practice.¹ In the European Union, glycine and its sodium salt are authorized food additives categorized as flavor enhancers.²

What foods contain Glycine and its sodium salt?

You may find E640 in products where a rounder, smoother flavor is desirable, such as seasonings, sauces, soups, beverages, and some confectionery or dessert mixes. Because it is used at relatively low levels to tweak taste, it often appears alongside other flavoring ingredients or enhancers.

What can replace Glycine and its sodium salt?

Depending on the goal, formulators might choose:

• Other flavor enhancers for umami or savory depth, such as monosodium glutamate, disodium inosinate, or disodium guanylate.
• Acids to brighten or balance taste, like citric acid.
• Sweet polyols to soften bitterness and add body, such as sorbitol or xylitol. The best substitute depends on the specific flavor problem and the food matrix.

How is Glycine and its sodium salt made?

Regulators describe identity and purity specifications for E640 rather than a single mandated manufacturing route. In the EU, glycine and its sodium salt must meet the specifications set out for food additives, including limits for impurities.³ In practice, food-grade sodium glycinate is made by neutralizing glycine with a food-grade sodium base, then purifying and drying the salt. In the U.S., use is governed by good manufacturing practice standards under the Code of Federal Regulations.¹

Is Glycine and its sodium salt safe to eat?

Yes, when used as intended in foods. In the U.S., glycine is affirmed as GRAS (Generally Recognized As Safe) as a direct food substance used as a flavoring agent or adjuvant, provided it meets applicable specifications and is used at levels consistent with good manufacturing practice.¹ In the EU, glycine and its sodium salt are included in the Union list of permitted food additives and have official identity and purity criteria.³²

Does Glycine and its sodium salt have any benefits?

Technologically, E640 can:

• Smooth out harsh or bitter flavor notes and improve overall taste integration.
• Support flavor systems without adding a strong character of its own. Glycine itself is also a naturally occurring amino acid present in proteins, but when used as E640 its primary role is flavor enhancement rather than nutrition.⁴

Who should avoid Glycine and its sodium salt?

• Individuals with physician-directed restrictions related to rare metabolic disorders involving glycine handling (for example, nonketotic hyperglycinemia) should follow medical advice on protein and amino acid intake.⁵
• People on strict sodium-restricted diets may prefer products without the sodium salt; however, E640 is typically used at very low levels, so the sodium contribution is usually minor.

Myths & facts

• Myth: E640 is an artificial chemical unrelated to real food. Fact: Glycine is an amino acid that naturally occurs in proteins found in many foods.⁴
• Myth: If an ingredient has an E-number, it is unsafe. Fact: E-numbers in the EU indicate the additive passed a safety assessment and is approved for use in specific ways.²
• Myth: E640 always makes foods taste sweet. Fact: Glycine may taste mildly sweet on its own, but in foods it is primarily used to round off flavors and reduce harsh notes, not to sweeten.

Glycine and its sodium salt in branded foods

On ingredient lists, look for “glycine,” “sodium glycinate,” or “E640.” Because it works behind the scenes to adjust flavor, it may appear alongside other flavorings, spices, and enhancers such as monosodium glutamate or nucleotides like disodium inosinate. If you prefer to avoid it, check the label—manufacturers must list additives by name or E-number in regions that use E-numbers.

References

Footnotes

1. 21 CFR 184.1318 — Glycine. U.S. eCFR. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-184/subpart-B/section-184.1318 ↩ ↩² ↩³

2. Commission Regulation (EU) No 1129/2011 — Amending Annex II to Regulation (EC) No 1333/2008 to establish a Union list of food additives. EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32011R1129 ↩ ↩² ↩³

3. Commission Regulation (EU) No 231/2012 — Specifications for food additives listed in Annexes II and III to Regulation (EC) No 1333/2008. EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32012R0231 ↩ ↩²

4. Glycine — PubChem, National Institutes of Health. https://pubchem.ncbi.nlm.nih.gov/compound/Glycine ↩ ↩²

5. Nonketotic hyperglycinemia. Genetic and Rare Diseases Information Center (GARD), NIH/NCATS. https://rarediseases.info.nih.gov/diseases/7437/nonketotic-hyperglycinemia ↩