Monosodium Glutamate – Properties, Uses and Examples

Mar 17, 2023

Monosodium Glutamate

You must have tasted sweet, sour, salty, and bitter for a long time. Some tastes make you hate them and never try again. But sometimes, when you taste a few food items, you are tempted by them, and you cannot resist swallowing them again and again.

Sometimes you do not like a food item cooked in the kitchen. But then you find that your mom adds a magical ingredient to it, which tastes yummy. Have you ever wondered about what makes you irresistible to such items? Why does the restaurant food taste better than the home-cooked similar delicacies?

That magical ingredient is a naturally occurring substance and can be prepared in laboratories. It is known as monosodium glutamate. Generally, you all know it as ‘Ajinomoto.’ This article lets you understand all about what monosodium glutamate is.

What Is Monosodium Glutamate?

Monosodium glutamate (MSG), a sodium salt of glutamic acid, is a white crystal-shaped substance that enhances flavours in certain food items at room temperature. Generally, MSG is also known as Ajinomoto, monosodium, sodium glutamate, or L-glutamate.

Regarding IUPAC naming, monosodium glutamate or MSG is known as sodium 2-aminopentanedioate. And the monosodium glutamate formula is C₅H₈NO₄Na.

As a compound, MSG does not have any distinct odour. In terms of solubility, monosodium glutamate dissolves better than other salts of glutamic acids, such as magnesium or potassium.

Monosodium Glutamate

History of Monosodium Glutamate

In 1908, MSG was first produced by the Japanese chemist Kikunae Ikeda, a chemistry professor at the Imperial University of Tokyo. As per a tale, once he ate a soup, he found its taste better than ever. After carefully inspecting it, he realised that the enhanced taste was due to its flavouring agent. After that, he got inspired to begin studying its chemical structure.

In 1908, he determined the savoury taste was due to a non-essential amino acid. In 1909, Professor Ikeda filed a patent to produce MSG commercially.

Crystals of Monosodium Glutamate (MSG)

At room temperature, it exists as a crystalline solid, which is white. It does not have any sharp aroma.

Among the sodium, potassium, magnesium, and calcium salts of glutamic acid, only sodium salt of glutamic acid is the most soluble in water. When dissolved in water, MSG dissociates into sodium (Na⁺) cations and glutamate (C₅H₈NO₄^–) anions.

Manufacturing of Monosodium Glutamate

There are three general ways of manufacturing monosodium glutamate.

1. Hydrolysis:

This method adds hydrochloric acid to some vegetables, and after that, hydrolysis is conducted to produce MSG.

2. Chemical Synthesis:

In this method, the chemical use of acrylonitrile takes place. The molecular formula of acrylonitrile is CH₂CHCN.

3. Bacterial Fermentation:

Starch, sugar cane, sugar beets or molasses and ammonium salts are required in this process. Bacterial fermentation happens using Corynebacterium species feeding with ammonia and different carbohydrate sources.

This fermentation process is similar to that utilised to make vinegar, yoghurt, and wine. For commercial or large-scale production, MSG is prepared in monohydrate form.

Monosodium Glutamate Structure

The MSG chemical formula is C₅H₈NO₄Na. It exists in different forms and has different structures in them.

1. In the Solid Form:

In the monosodium glutamate structure, the glutamate ion exists in O(C=O)CH(NH₃⁺)(CH₂)₂(C=O)O^– form. It is the zwitter ionic form of MSG.

2. In Liquid Form:

During hydrolysis, the monosodium glutamate formula breaks into Na⁺ and C₅H₈NO₄^– ions. It happens because they are connected with the ionic bonds.

Monosodium glutamate has the same basic structure as amino acids, with an amine group (-NH₂) and carboxylate ion instead of the carboxylic group (-COO^–). Moreover, monosodium glutamate has another carboxylic group in the side chain. The chemical structure of monosodium glutamate is written below in the common representations used for organic molecules.

Properties of Monosodium Glutamate

There are several characteristic properties of monosodium glutamate that are divided physically and chemically. Some of them are:

Physical Properties of MSG:

At room temperature, monosodium glutamate occurs in solid form.
It has a white and crystal-shaped appearance.
It is odourless or peptone-like and tasteless. But when it is prepared as sodium salt, its taste is referred to as ‘umami’, which means ‘delicious.’
In terms of solubility, it is highly soluble in water.
It is also soluble in organic solvents.
In water, it forms in the shape of rhombic prisms.
The solubility of MSG in water is 740 grams/litre.
With a density of 26.2 g/cm³, MSG forms a saturated solution in water at 20℃.

Chemical Properties of MSG:

The IUPAC name of monosodium glutamate is (2S)-2-amino-5-hydroxy-5-oxo-pentanoate.
The molecular monosodium glutamate formula is C₅H₈NO₄
Its molecular mass is 169.11 g/mol.
This compound crystallises as a pentahydrate when cooled to temperatures below -8℃.
Its melting point is 225℃.
The solutions of monosodium glutamate show pH values ranging from 6.7 to 7.2.
It is highly soluble in water.
When heated above 232℃, it decomposes and releases toxic fumes of nitrogen and sodium oxides.
MSG tunes with deprotonation of the 𝛼-carboxylic group. This group contains the most acidic hydrogens.

Uses of Monosodium Glutamate

Monosodium glutamate was first prepared in Japan, where the meat-like taste is present in many dishes. MSG occurs naturally in certain types of cheese, tomatoes, grape juice, mushrooms, salami, potatoes, and many other foods.

It is highly utilised in the food industry as a flavouring agent.
It gives umami, i.e., delicious taste and intensifies strong flavours when added to specific foods.
It is used in several spice blends and canned food products.
Monosodium glutamate is often added to tobacco to increase its taste.
In the treatment of hepatic coma, monosodium glutamate also plays a role.
MSG is a major component of several instantaneous ramen noodle products.
Glutamic acid is naturally present in raisins, onions, mushrooms, cheeses, and other foods.
You can store it for long periods at ambient temperature without changing its appearance or quality.

Monosodium glutamate has been associated with tingling sensations, headaches, and burning sensations. These manifestations are collectively cited as the “Chinese restaurant syndrome”. Nevertheless, the data from many studies suggest no link between this syndrome and monosodium glutamate. This compound is used as a permitted food additive in many countries.

Other Names for Monosodium Glutamate

MSG, known as monosodium glutamate, is highly responsible for that tempting taste. The other names for MSG include:

Sodium 2-aminopentanedioate
Monosodium glutamate or sodium glutamate
L-Glutamic acid, monohydrate, monosodium salt
Glutamic acid, monohydrate, monosodium salt
Monohydrate monosodium L-glutamate
Monohydrate L-monosodium glutamate
Monohydrate sodium glutamate
MSG monohydrate
Flavour enhancer E621
UNII-W81N5U6R6U

Monosodium Glutamate-Containing Products

Some products that ‘consistently’ contain MSG are:

Hydrolysed protein: (plant, vegetable, or any kind)
Calcium or sodium caseinate
Yeast extract and autolysed yeast
Yeast food and yeast nutrients
Textured protein
Glutamic acid
Monopotassium glutamate
Gelatin

Summary

Monosodium glutamate has been found to revive the palate’s taste bud receptors that gaggle a brain signal. As a result, the taste of a food item gets enhanced or intensified. It is added to the concoction of many food items.

Some people do not advocate using it in food as they believe it can affect their health or the child’s development. There is no convincing proof that MSG is a noteworthy factor in causing systemic reactions that result in acute illness or mortality. Therefore, it is important to thoroughly understand compounds that are so popular and common in our day-to-day lives.

Frequently Asked Questions

1. How does monosodium glutamate function in the body?

Monosodium glutamate is a sodium salt of glutamic acid and is a type of non-essential amino acid. Glutamic acid itself is colourless and tasteless. But its sodium salt is used to enhance the taste of food. In food, monosodium glutamate invigorates glutamate receptors in the palate’s buds. These receptors relay signals to recognisable brain regions, activating the typical taste.

2. Does organic food also contain monosodium glutamate?

Yes. Usually, things like yeast and yeast extract contain monosodium glutamate. But you can also add it to organic food. But there is no prohibition stating that organic food cannot have MSG, only that the ingredients must be organic.

3. Why is it said that monosodium glutamate affects a person’s health?

There is a lot of debate within the natural health culture surrounding monosodium glutamate. Headaches, asthma, and even brain damage are reported. Side-effects reported by various studies can be summarised as the appearance of anomalies in metabolic/digestive, respiratory, circulatory, and nervous systems. Most official sources, like the FDA, announce it is safe for limited usage and raise several potential side-effects connected to increased MSG consumption.

4. What are the natural sources of monosodium glutamate?

Glutamate occurs naturally in virtually all foods, including fish, meat, breast milk, poultry, and vegetables. Various processed and prepared foods, such as sauces, traditional seasonings, and certain restaurant foods, can also contain significant levels of free glutamate, both from natural sources and from added MSG.