GLYCINE AND ITS SODIUM SALT

Introduction

Glycine and its sodium salt, designated as E640, is the simplest amino acid in structure. It occurs naturally in the human body and is found in high-protein foods like meat, fish, and dairy. As a food additive, it functions as a flavor enhancer and a taste modifier, often used to mask bitter or metallic off-notes in products like low-calorie sweeteners.

While glycine itself is a sweet-tasting amino acid, its sodium salt, sodium glycinate, is used where both a savory enhancement and a slight sweetness are desired. It is one of the few amino acids that is specifically authorized for use as a food additive in the EU, with a "quantum satis" level, meaning it can be used as needed.

CAS Number

• Glycine: 56-40-6
• Sodium glycinate: 6000-44-8

Synonyms

Aminoacetic acid; Glycocoll; Sodium Glycinate; E 640; INS 640.

Topic Headings

1. Dual functionality as a sweetener and flavor balancer (paragraph form)

Glycine is unique among flavor enhancers because it possesses a sweet taste. This makes E640 especially useful in products where sweetness is desirable, but you want to avoid the "hollow" or purely sugary taste of refined sugar. In savory applications, its action is more subtle; it doesn't create umami like glutamates or ribonucleotides. Instead, glycine works as a "flavor balancer" by smoothing out harsh notes. It is exceptionally effective at masking the lingering, metallic bitterness of high-intensity sweeteners like saccharin (E954) or the bitterness of potassium chloride, which is often used as a salt substitute. This masking ability allows food technologists to create products with less sugar or sodium without a corresponding loss in palatability.

2. Physical and chemical properties (list form)

• Appearance: White, crystalline powder.
• Odor: Odorless.
• Taste: Sweet (glycine) or slightly savory and sweet (sodium glycinate).
• Solubility: Very soluble in water.
• pH (1% solution): For glycine, approximately 5.5-6.5; for sodium glycinate, it is alkaline (9-11).
• Melting point: Glycine decomposes around 233°C.
• Stability: Very stable in its solid form and in solution.

3. Food applications and typical usage levels (list form)

• Tabletop sweeteners (with saccharin or aspartame) – Used at 0.1-1.0% to mask the bitter aftertaste.
• Low-sodium soups and sauces – Added to mask the bitterness of potassium chloride salt substitutes.
• Processed meats and charcuterie – Enhances the overall "meaty" flavor profile and acts as a taste balancer.
• Alcoholic beverages (wine, liqueurs) – Sometimes added in minute quantities to soften harsh notes.
• Dietary supplements and protein drinks – Used both as a nutritional supplement and to improve palatability.

4. Regulatory status and safety (paragraph form)

Within the EU, E640 is fully approved for use with "quantum satis" limitations, meaning manufacturers can use the amount necessary to achieve its technological effect. It is considered safe by all major food safety authorities (FDA, EFSA, JECFA). Glycine is a naturally occurring, proteinogenic amino acid and is not known to be toxic. Its safety profile is very high because it is a normal component of the human diet and is metabolized efficiently. As it is the simplest amino acid, allergies are essentially unknown. It is commonly used as a flavor enhancer and amino acid supplement in both food and animal feed.

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