Monosodium Glutamate. What is MSG ?
What is MSG?
Monosodium glutamate (MSG) is a commonly used taste enhancer. When added to food, it gives the product a savory flavor, turning what would be bland packaged food into a delectable meal. It quickly became popular with producers because companies were suddenly able to make anything taste good with the addition of MSG. While it is well known for its use in Chinese food, MSG is used widely today, especially in soups, salad dressings, and low fat foods.
Imine Formation Mechanism
rats. This amount damaged their ability to regulate appetite which can then induce obesity (Hermanussen 2006). One study in China found a positive correlation between MSG intake in humans and an increase in BMI (He 2008) These results are shown in figure 4.
MSG in Our Diet
After consuming food that contains MSG, many people experience adverse reactions to it. The most common reaction is a migraine headache, but reactions vary from person to person. Studies by Schaumburg (1969), Reif-Lehrer (1977), and Kenney and Tidball (1972) have shown that 30% of the population experiences negative effects when fed MSG in a regular diet. The FDA retains that only 2% of the population have adverse reactions. This number is based on a narrow study by Kerr et al (1979), which had narrow requirements for these “adverse reactions”, thereby eliminating a lot of people from the final results.
Many studies on animals have shown that exposure to MSG can cause them to be obese. This is so well known among scientists that MSG has become the “go to” way to attain obese rats for studies (figure 3). In relation to human consumption of MSG, concentrations that only slightly exceed levels in our average diet were given to
Studies by John Olney (1969) showed brain lesions in mice and rhesus monkeys when administered MSG. This led to many studies in the 1970s that replicated and confirmed these results. They concluded that MSG caused brain damage, particularly in the hypothalamus.
Glutamate is found commonly in the body as a neurotransmitter. It causes a reaction in neurons that sends a signal to the brain. If there is too much glutamate in the body, however, neurons can become so overexcited that it causes cell damage or even cell death.
Figure 4 (He 2008)
Monosodium Glutamate has two major functional groups: a carboxylic acid and a primary amine. The two carbons of the carbonyl groups are sp2 hybridized, while the other carbons are sp3 hybridized (figure 5).
To the right (figures 6-8) are the spectra for MSG. The Infrared (IR) spectra has a very distinct, wide peak around 3000 cm^-1 that is evidence of a carboxylic acid. A peak at approximately 1590 cm^-1 suggests a carbonyl group, and the peaks around 1300 suggest an amine. The Hydrogen Nuclear Magnetic Resonance (HNMR) spectra has five peaks, one for each
Hidden Sources of MSG
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To hide the fact that their products contain MSG, companies use synonyms on their ingredients lists. To the right are some of the most common names.
of the chemically equivalent types of hydrogens. Hydrogen “a” is most deshielded because of its close proximity to the carboxylic acid. The Carbon Nuclear Magnetic Resonance (CNMR) spectra has five peaks for each type of carbon. Those of the carbonyl groups are most deshielded.
To the left (figures 1-2) are chemical reactions involving MSG. The first is a synthesis that forms MSG starting with 4-chloro-1,5-pentanol. The second reaction reacts the amine of MSG with a ketone to form an imine.