CHAPTER I

PROCESS BACKGROUND

1.1CHEMICAL STRUCTURE AND PHYSICAL PROPERTIESMonosodium glutamate is a type of amino acid or known as glutamic acid. The formula of compound salts is C5H8NNaO4[footnoteRef:1]. Glutamic acid is one of famous non-essential amino acid from 20 amino acids of protein group. Monosodium glutamate also known as MSG was discovered by Kikunae Ikeda, professor at the Tokyo Imperial University[footnoteRef:2]. He started to identify the monosodium glutamate salt from his research that related to umami component kelp. The large scale production of the monosodium glutamate began in 1909. Most glutamate found naturally in many foods and present in meat, fish and protein-based food. The production process for the first time was the extraction of monosodium glutamate from the process of adding of hydrochloric acid to vegetable. The best method to carry out the production of monosodium glutamate is fermentation. The fermentation process was done by using Corynebacterium glutamicus bacteria that synthesize the molasses as carbon source. The glutamic acid extracted will undergo a few processes such as filtration, purification and neutralization to form monosodium glutamate. The final step is crystallization or drying to form a crystal white powder of monosodium glutamate. The other name of monosodium glutamate known as MSG, Ve-tsin or E621 [footnoteRef:3]has different salts of glutamic acid such as monopotassium glutamate, calcium diglutamate, calcium inosinate and others but have same taste and effect. The taste of the monosodium glutamate also is known as the fifth basic taste for its salinity. [1: http://www.chemspider.com/Chemical-Structure.76943.html] [2: The American Journal of Clinical Nutrition] [3: http://www.food-info.net/uk/national/msg-report.htm]

The L-glutamic acid then underwent purification process to produce a pure monosodium glutamate. Naturally, the monosodium glutamate salt is It is freely soluble in water and sparingly soluble in alcohol. The pH range is 6.7 and 7.2.

Figure 1: The structure of monosodium glutamate

Table 1.1: Physical properties of monosodium glutamate[footnoteRef:4] [4: http://www.chemspider.com/Chemical-Structure.76943.html]

Molecular weight:169.11 g/mol

Normal boiling point:284.5C

Melting point:195C

Specific gravity:1.635 (referred to water =1)

Appearance:White crystalline powder

Solubility in water:74 g/100 mL

Heat of vaporization:15,625 cal/mol

Heat of combustion:783,946 cal/mol

Flashpoint:152C

Autoignition temperature:580C

Flammable limits:Lower Upper

:1.2 vol%

:9.2 vol%

Minimum liquid temperature to form flammable vapor in air:143C at 1 atm

1.2APPLICATIONS AND USESThe taste of glutamate is also known as umami. . The taste is originated from the combination of sweet, sour, salty and bitter taste. Because of this taste, the monosodium glutamate slat is used as flavor enhancer in most foods. The MSG are widely used as a seasoning around the world. Most of monosodium glutamate salts are used in meat, fish, poultry, many vegetables, sauces, soups, and marinades as additive food-flavoring. Glutamate itself is taste-active compound that enhance the overall taste of foods. There two types of glutamate acid : a single amino acid and a chained form that linked as a protein. The single glutamate form is mainly use as flavor enhancer. The glutamate is added in soup to give a brothy taste. About 0.1% to 0.8%3 of glutamate are estimated to be added in food.Besides, the ingredients that may contained in glutamate salts as flavor enhancer are labeled as the E-numbers series. The structure of the glutamate salts are different but has same taste to glutamate acid.The E-numbers series are listed down as shown in following table.No table of figures entries found.Name

E620 Glutamic acid

E621 Monosodium glutamate

E622 Monopotassium glutamate

E623 Calcium diglutamate

E624 Monoammonium glutamate

E625 Magnesium diglutamate

E626 Guanylic acid

E627 Disodium guanylate

E628 Dipotassium guanylate

E629 Calcium guanylate

E630 Inosinic acid

E631 Disodium inosinate

E632 Dipotassium inosinate

E633 Calcium inosinate

E634 Calcium 5'-ribonucleotides

E635 Disodium 5'-ribonucleotides

636 Maltol

637 Ethyl maltol

E640 Glycine and its sodium salt

Table 1 The E-numbers series for glutamate salt as food additive4

Glutamate contained in monosodium glutamate salts is a key substrate for glutamine and glutathione synthesis[footnoteRef:5]. The glutamine synthesizes are taken part at skeletal muscle, lung, and adiose tissue. The main function of glutamine is for cell immune system. The enzyme used for glutamine synthesis is glutamine synthetase and liver consume lot of glutamine from the gut. The glutathione acts as antioxidant to the human body. The susceptible disease are cancer, Alzheimers disease and Parkinson disease[footnoteRef:6]. Glutathione also acts as a protection to the liver [5: Monosodium Glutamate, A safety Assessment, Food Standards Australia New Zealaand, June 2003] [6: Vitamins and Minerals, Zina Kroner, Library of Congress Catalogingin Publication Data]

Photo 1 : The glutamate help the glutamine synthesis in body[footnoteRef:7] [7: http://themedicalbiochemistrypage.org]

Naturally, most of taste buds on our tongue are sensitive to the glutamate taste. The glutamate acts as neurotransmitter to the glutamate receptors in human body. The active compounds in glutamate will stimulate the receptors by increasing the number of molecules interaction of chemosensory membranes. The chemosensory membranes that located in oral cavity will stimulate the olfactory and limbic system in the brain and promotes immune function[footnoteRef:8]. [8: Walker, R. The significance of excursions above the ADI Case Study: Monosodium Glutamate.Regulatory Toxicology and Pharmacology1999,30, S119-S121.]

Besides, it helps in energy transportation brains neurotransmitter and other specific tissues. The mainly source of glutamate from brain is glucose. The blood in brain acts as a barrier to block the passage of any glutamate to enter the brain. Thus, brain synthesizes its own glutamate. Others functions of glutamate are substrate for protein synthesis and aid nitrogen transportation throughout the body.Overall, the taste of glutamate in Asia is defined as the taste of natural origin like soy or fish sauce that mixed with glutamate as a flavor enhancer.