Sweetener Aspartame Lab Report

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The novel sweetener aspartame was discovered in the United States in 1965 (Romanovski, 2009). James Schlatter, a chemist and a medical researcher, working for G.D. Searle and Co., was developing a new anti-ulcer treatment. One of the possibilities was to find an inhibitor of the gastrointestinal secretory hormone gastrin. Because the drug discovery at that time was a trial-and-error method, Schlatter had to synthesise C-terminal tetrapeptide (Trp-Met-Asp-Phe-NH2), usually found in the stomach, in his laboratory (Filer, 1984, pp. 3-4). One of the steps in the process was to create a dipeptide intermediate (Asp-Phe-OMe), aspartyl-phenylalanine methyl ester (Walters, 2001). In the course of the work, Schlatter inadvertently spilled a small amount…show more content…
1151-1152). Prior to the synthesis of aspartame from two α-amino acids, L-phenylalanine (orange on the image) is treated with methanol (blue on the image) in the presence of hydrochloric acid. This causes an esterification reaction, forming the methyl ester of phenylalanine. The bond between L-phenylalanine and methanol is called an ester bond. The next step includes joining aspartic acid’s negatively charged polar side chain (-COO-) to phenylalanine’s positively charged amine group (-NH3+) by following the Fischer’s projection formula. The joining of one α-amino acid’s carboxyl group to another α-amino acid with the release of water is called the hydrolysis reaction (Obhardt, 2003). The newly made bond between the amino acids is called a peptide linkage (Schmid, 1996, p. 1152). As said earlier, the formed molecule of aspartame has a peptide linkage between aspartic acid and phenylalanine molecules, and ester bond between phenylalanine and methanol molecules. This results in a rigid and planar molecule with delocalized electron structure in the bonds, benefitting to its function and sweetness (Schmid, 1996, p.…show more content…
In addition, enhanced satiety and the release of dopamine are achieved with the help of intestinal osmoreceptors [a receptor that responds to an increase in the concentration of the extracellular fluid (Hine, 2008, p. 464)] and gastric chemoreceptors (a receptor that detects the presence of a particular chemicals and transmits this information to sensory nerves (Hine, 2008, p. 124)]. Beverages containing aspartame have low energy content and osmotic load. Moreover, diet drinks have lower energy density and empty from the stomach more quickly. This means that the gastric emptying rate is increased with lower osmotic challenges. For a person to stop eating, both intestinal nutrient indicator and gastric stretch are needed, in order to result in full satiety. However, aspartame does not possess these properties. Therefore, scientists suggest that aspartame containing diet drinks suppress overall satiation and increase appetite (Mattes,

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