Due to the presence of its dipeptide structure many variations of reverse proteolysis that employ both kinetically and thermodynamically controlled approaches has been investigated with different enzymes and under various reaction condition. Two Japanese companies have reported one formation route to produce aspartame directly by incubating microorganisms with L- aspartic acid and methyl ester of phenylalanine Ager et al.
Aspartame is a low calorie sweetener used to sweeten a variety of low and reduced calorie foods and beverages including low calorie tabletop sweetener as well as for use in gum, breakfast cereal and other dry products. Aspartame provides energy of 4 calories per gram. Aspartame is unstable if subjected to prolong heating and therefore cannot be used in baking or cooking. It also decomposes in liquids during storage. Upon ingestion, aspartame breaks down into natural residual components, including aspartic acid, phenylalanine, methanol and further break down products including formaldehyde, formic acid and diketopiperazine George et al.
Each of which then metabolized just as it would be if derived from other dietary sources and are safe as consumed in normal diets. Aspartame has been the subject of controversy regarding its safety since its initial approval by the U.
High level of the naturally occurring essential amino acid phenylalanine is a health hazard to those born with phenylketonuria PKU a rare inherited disease. So the phenylalanine level statement or aspartame—sweeten products is for their benefit and has no relevance for general population. Various scientific researches concluded that the effects of aspartame are likely to be attributable to methanol or its metabolites, evidence indicating that fruits and vegetables also contain high level of methanol than aspartame sweetened food and beverage do.
But high intake of fruits and vegetables are associated with decrease rather than increase in cancer risk Heber Carcinogenicity studies of aspartame were conducted by Nalt Toxicological Programme NTP in 2 strains of transgenic mice, and it was concluded that aspartame exposure was associated with increase in cancer in either male or female mice NTP Acesulfame—k Fig. This high intensity sweetener is potassium salt of 6-methylaxathiazine-4 3H -one 2,2-dioxide with molecular formulaC 4 H 4 KNO 4 S and molecular weight of It is a white crystalline powder, approximately times sweeter than sucrose and has high water solubility Rymon Lipinski Acesulfame—k is heat stable, so can be used in cooking and baking Nabors It may have a bitter after taste when used alone to sweeten food or beverage Horne et al.
Early methods for Ace-k synthesis used chlorosulfonyl or flurosulfonyl isocyanate with propyne acetone Clauss and Jensen and with other chemicals give N-chloro or N- fluro-sulfonyle acetoacetamide, which is then cyclized by metabolic potassium hydroxide to give Ace-k.
Alternative method involves the treatment of acetoacetamide with at least two equivalents of sulfur trioxide. This results in formation of N-sulfoacetoacetamide, which is then dehydrated by sulfur trioxide to form oxathiaazinone dioxide.
Neutralization with potassium hydroxide gives Ace-k. Clauss et al. Acesulfame—k is not metabolized in the human body, thus it provides no calories and does not influence potassium intake despite its potassium content ADA One breakdown product of ace-k is acetoacetamide George et al. Sucralose Fig.
Xylitol as Sweetener
This non-nutritive sweetener is made from sucrose by a process that substitutes 3 chloride atoms for 3 hydroxyl groups on the sucrose molecule FDA Sucralose is — times sweeter than sucrose, has a pleasant sweet taste and its quality and time intensity profile is very close to that of sucrose Arora et al. It has a moderate synergy with other nutritive and non-nutritive sweeteners.
Beyts et al. It is very much soluble in water and is stable over a wide range of pH and temperature. It does liberate HCl when stored at high temperature and produce some kind of discoloration Beyts et al. The synthesis of sucralose involves a series of selective protection and deprotection steps so that the 4-hydroxyl group can be converted to a chloro atom with inversion of configuration.
Treatment of the free hydroxyl groups with sulfuryl chloride produce trichlorodisaccharide which is then deprotected to give the sucralose Ager et al. The use of enzymes or microbial cultures to augment synthetic organic chemistry and carry our selected functionalization of complex molecule has been widely documented in the growing field of biocatalysis Wong and Whitesides Although sucralose is made from sugar, the human body does not recognize it as a sugar and does not metabolize it therefore it provides no calories.
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The amount that is absorbed from the gastro intestinal tract is largely removed from the blood stream by the kidneys and eliminated in the urine. As it is an organo chloride and some of which are known to have significant toxicity Patel et al.
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In addition sucralose does not breakdown or dechlorinate. In determining the safety of sucralose, the FDA reviewed data from more than studies in human and animals. Many of the studies were designed to identify possible toxic effects including carcinogenic reproductive and neurological effects but no such effects were found.
Food and Drug Administration FDA approval is based on the findings that sucralose is safe for human consumption. Saccharin Fig. It is a non-nutritive sweetener of 1,2-benzoisothiazol 2H on 1,1 dioxide. Saccharin has an unpleasant bitter or metallic off taste. As the parent compound is only sparingly soluble in water, the sweetener is usually used as the sodium or calcium salt. Both salts are highly water soluble, 0.
It is about times sweeter than sucrose. Chemical synthesis of saccharin involves the oxidation of the o-toluenesulfonamide with variety of agents like potassium permanganate Tarbell and Tarbell , chromic acid, electrochemically Bennett et al. The ortho isomer is dehydrated to give the sweetener. Bennett et al. Another process involves diazotization of methyl anthranilate and then treatment of the diazonium salt with sulfur dioxide and chloride gas to give the sulfonyl chloride which is then treated with ammonia to give saccharin Tarbell and Tarbell The FDA tried to ban saccharin in because animal studies had showed that it caused cancer in rat mainly bladder cancer.
Many studies have since been performed on saccharin.
Artificial sweeteners have toxic effects on gut microbes -- ScienceDaily
No study has ever shown a clear casual relationship between saccharin consumption and health risks in human at normal doses. Though some studies have shown a correlation between consumption and cancer incidence Weihrauch and Diehl Saccharin is currently permitted for use under an interim regulation that specifies the amounts of saccharin permitted in beverages, processed food, and sugar substitute and requires that the product level must state saccharin in the ingredient declaration and specify the amount used Kroger et al.
Cyclamate Fig. It was used as a low calorie sweetener in the United States in s and s. It is a salt of cyclohexylsulfamic acid. Sodium cyclamate is used as non- nutritive sweetener and the analogous calcium salt used specially in low sodium diets. Cyclamate is 30 times sweeter than sucrose. It has a bitter off taste, but has good sweetness synergy with saccharin. It is soluble in water and its solubility can be increased by preparing the sodium or calcium salt Bopp et al.
This process begins with the trisaccharide raffinose followed by chemical chlorination to form tetrachloro raffinose TCR. This TCR is then enzymatically treated with a galactosidase to move the 6-chlorodeoxygalactosyl moieties from the 6th position to yield cyclamate Bennett et al. There are another two methods available for synthesis of saccharin like bioorganic synthesis Drasar et al.
Cyclamate itself shows very low toxicity but is metabolized by the gut bacteria to cyclohexylamine which shows greater toxicity Bopp et al. It would be inappropriate to assume that the total daily intake of cyclamate is metabolized to cyclohexylamine. For cyclohexylamine in rats assuming that The plasma concentrations of cyclohexylamine following cyclamate intake will depend on both the extent of metabolism by the intestinal flora and the extent of elimination of cyclohexylamine from the circulation.
Scientific research on cyclamate is continuing. Recent studies have provided new data on the extent to which individuals convert cyclamate to cyclohexylamine during long term consumption Renwick et al. This study gives first true indication of possible exposure to cyclohexylamine from cyclamate metabolism in humans over a period that is toxicologically relevant to the establishment of ADI for cyclamate. Neotame Fig. Neotame has been developed as a sweetener with a high degree of sweetness and is obtained by N-alkylating aspartame.
Its degree of sweetness varies according to the kind of food and blend composition. It is to 13, times and about 30 to 60 times sweeter than sugar and aspartame respectively Prakash et al. Neotame is an odorless white to gray-white powder with a strong sweetness and is readily soluble in alcohols and slightly soluble in water. The 0. A chemoenzymatic method used for preparing N-[N- dimethylbutyl -L-a aspertyl]-L-phenylamine 1- methyl ester via the enzymatic regioselective hydrolysis of neotame ester using lipases or estarages Prakash and Zhao Neotame is rapidly metabolized, completely eliminated and does not accumulate in the body.
The major metabolic pathway of neotame is hydrolysis of the methyl ester by esterase which is present throughout the body. This yields deesterified neotame, the major metabolite and a significant amount of methanol. Due to the presence of the di-methylbutyl group, peptidases which would typically break the peptide bond between the aspartic acid and phenylalanine moieties are essentially blocked, thus reducing the availability of phenylalanine. The amount of methanol derived from neotame is exceedingly small Neotame Alitame Fig.
It is a dipeptide of L-aspartic acid and D-alanine with a terminal N-substituted tetra methylthietanyl-amine moiety. Alitame is prepared by a multi step synthesis involving the reaction between two intermediates S -[dioxo- 4-thiazolidine ] acetic acid and R —2- amino-N- 2,2,tetramethylthietanyl propanamides. Alitame is readily absorbed in the GI tract and then rapidly metabolized and excreted.
It has two main components, aspartic acid and alanine amide. The aspartic acid component is metabolized normally and the alanine amide passes through the body with minimal metabolic changes. In humans the glucoronic derivative of D-alanine tetramethylthietane amide is the major urinary metabolite. JEFCA reviewed safety data on alitame in The committee concluded that there was no evidence that alitame is carcinogenic.
Rare sugars, which are defined as monosaccharides and their derivatives that are rare in nature Izumori have recently attracted a great deal of attention mainly concerning their application. This could provide an alternative to the other sweetener due to its lack of calories. Rare sugars are either not metabolized by the body or metabolized to a lesser extent than natural sugar.