Artificial sweeteners

Aspartame is a kind of artificial sweeteners, belongs to the amino acid dipeptide derivatives, by the chemist developed ulcer drugs found in 1965. With low dosage, high sweetness (sweetness is 150 to 200 times of sucrose), good taste, enhance flavor of citrus and other fruits and reducing heat does not produce dental caries, toxicity than saccharin and other synthetic sweetening agent advantages, is widely applied to beverages, diabetic food and some slimming health food, our daily life to drink cola formula once containing the product. Aspartame in the metabolic processes in the body and the main degradation products are phenylalanine, methanol and aspartic acid, does not enter blood circulation, and does not accumulate in the body, food for the health harmless. But due to metabolic defects in patients with phenylketonuria (PKU), excessive body phenylalanine can influence its development, so in patients with the disease to disable adding aspartame.

Neotame

Neotame is aspartate dipeptide derivatives, is a new product developed at a cost of $80 million by American newt company after aspartame, representing the latest achievements of sweetener research field. It is according to the human sweet receptor double hydrophobic binding hypothesis. In aspartame molecule with a hydrophobic groups and the formation of aspartame derivatives. It can also act on the human sweet receptor of two hydrophobic binding sites and therefore sweetness increased greatly, 6000 to 10000 times sweeter than sucrose, 30 to 60 times than Biasiba sweet . It retains many excellent characteristics such as aspartame, pure sweet taste and good flavor enhancing properties distribution, no energy, no caries, stable in acidic medium. Moreover, it is still a lot better than aspartame in dry conditions, it has a longer shelf life; in neutral medium or instantaneous high temperature sterilization conditions, its stability greatly exceed aspartame, which can be used as a sweetener in baking. Neotame can also be used together with reducing sugar and aldehyde flavor without adverse reaction, its safety is better than aspartame and has been greatly improved. Due to its high sweetness, etc. Sweeter is lower than the cost of aspartame. Therefore, neotame has huge market potential. In December of 1998, neotame as food sweeteners status of application have been proposed in the United States, and some other countries for the certification work is in July 9, 2002 . The U. S. Food and Drug Administration (FDA) confirmed the neotame safety and functional type, currently is in March 10, worldwide more regulatory agency and national review in 2003, China's Ministry of Health approval for neotame as a sweetener used in all kinds of food. The above information is edited by the lookchem Han Ya.

Content analysis

Accurately take sample of about 300 mg, moves into a 150ml beaker, dissolve in 96% formic acid 1.5ml, and glacial acetic 60ml. with crystal violet solution (ts-74), with 0.1 mol/L HClO4 immediately titrate to the end of green. At the same time a blank titration and make necessary correction. Each mI.0.1mol/L perchloric acid is the equivalent of 29.43mg C14H18N2O5.

Toxicity

Entering the human body can quickly metabolic day aspartic acid and phenylalanine, two kinds of amino acids are absorbed, which does not accumulate in the organization. But phenylketonuria patients cannot use. Therefore it is necessary to specially marked. Every year in China about 1500~2000 benzene acetone urine disease in children born, after eating can be in vivo abnormal accumulation caused by brain damage, mental development retardation and epilepsy. The ADI value is 0~40mg/kg (FAO/WHO, 2001). Contains two ketone piperazine ADI value is 0~7.5. GRAS (FDA, 172.804,2000).

Use limits

GB 2760-2001: all types of food (except canned food), are limited to GMP. FAO/WHO (1984): sweets 0.3%, gum 1.0%; beverage 0.1%, 0.5% of breakfast cereals, and used for the preparation of diabetes, hypertension, obesity, cardiovascular patients with low sugar, low calorie health food, dosage depends on the need to set. Can also be used as flavor enhancer.

chemical property

White crystalline powder, odorless, there is strong sweet, sweet and pure, sweetness of sucrose was 100-200 times. Melting point is 235℃ (decomposition). Amino acids is with the general nature. In dry conditions or pH value of 2 to 5 range, it is stability, strong acidic water solution can hydrolyzed to produce amino acid monomer, in neutral or alkaline conditions it can be cyclized to diketopiperazine. Solubility in water (25℃) is relevant to pH value, pH 7.0 was 10.2%, pH value 3.72 is 18.2%. At 25, isoelectric point is pH value of 5.2. Mice by oral LD50 > 10 g/kg Adl is 0~40mg/kg (FAO/who, 1994)

Methods of production

1. By L-aspartate and L-phenylalanine methyl ester condensation. 2. By L-aspartic acid and L-phenylalanine methyl ester hydrochloride condensation. There are two kinds of synthetic and enzymatic synthesis. enzymic synthesis ： Department of chemistry, Wuhan University, Tao Guoliang, gave the following synthetic route: The preparation of I : 0.5mmol benzyloxy carbonyl aspartic acid, 1.5mmol phenylalanine methyl ester hydrochloride and 2.5ml water were added to 25 ml Erlenmeyer flask, with ammonia to adjust the pH to 6, adding 7mg of thermophilic protease, at 40℃mixing reaction for 6h. Filter and washed with distilled water, and drying to obtain white solid (I) 0.29g, 95.6% yield, melting point is 116 to 118 ℃. Elemental analysis results: C 62.96%, H6.09%.N of 6.65%. preparation of II: it will be joined the conical flasks 0.5g sample I and 20mL3mol/L hydrochloride 25ml and 45℃ in the mixing reaction for 0.5h. Filtration and washing with distilled water, drying to obtain 0.32g the product II, yield is 92%, melting point is 129 to 131℃. Elemental analysis results: C 61.45%, H 5.42% , N 6.82%. Preparation of III will 0.2g palladium carbon catalyst (10%), 20 ml of glacial acetic acid, 5 ml of water add 100 ml three necked flask, hydrogenation activation 1.5h. Join 0.6g II 20 ml acetic acid dissolution and, at 30℃ stirring hydrogenated after 6h. the reaction is completed after filtration, catalyst with acetic acid washing 3 times; the filtrate and washings were concentrated under reduced pressure to dry, 15ml of benzene, continue to decompress and concentrate to dry white solid, and drying to obtain 0.38g the product III, and the yield was 92.3%, the melting point is 245 ℃. The elemental analysis results: C 55.63%, H6.23%, N 8.96%. Chemical synthesis method The aspartic acid and phenylalanine as raw material, by amino protection, anhydride, condensation, hydrolysis, neutralization and other steps of the synthesis. Different protecting groups, different methylated sequence can have a variety of different synthesis methods. Such as the use of formyl as protecting groups and after methyl esterification process route.Into a 250ml flask into 27mL 95% of the methanol and 0.2g oxidation of magnesium and magnesium oxide is dissolved, add 100ml 98% of acetic anhydride, at this time, the temperature gradually rose to 40 ℃, adding acid 67gL-aspartic, heated to 50℃, stirring reaction time 2.5h insulation and fill with 15mL98% acetic anhydride, temperature and reaction time 2.5h, join 16ml isopropanol and continue for 1.5h, the reaction after cooling to room temperature. Put the inner anhydride materialized to join 1000ml flask, add 207mL ethyl acetate and 66Gl-phenylalanine, stirring 1.5h in 25 to 30℃, add the glacial acetic acid 126mL, continue to reflect 4.5h, the reaction after the end of the vacuum to remove the solvent and to the temperature of the reaction system 65℃ so far. Then add 35% hydrochloric acid methylmercury, heating to 60 ℃, return at the end of the reaction of the hydrolysis of 2h, atmospheric distillation until boiling temperature of 63℃ (reaction temperature of 73 degrees C) so far, adding methanol 180, to continue the distillation to the system temperature of 85 ℃ so far. After cooled to 25℃, the removal of the vacuum light group. Adding 35% hydrochloric acid 54mL to the hydrolysis liquid, methanol 9mL and water 43mL. In 20 to 30℃for esterification reaction was then filtered, washed separation from α-APM hydrochloride. It dissolves in 600ml distilled water, to 40 to 50 ℃ of 5%~10% NaOH solution and to Ph=4.5. cooling below, filtering, washing to α-APM crude product, and then dissolved in 500 ml of methanol and water (volume ratio of 1:2) mixture. The cooling crystallization, filtration washing, vacuum drying 45% yield in terms of L-phenylalanine. The Japanese scholars put forward a route without protection: 90g phenylalanine methyl ester hydrochloride is dissolved in 450mL water, 24g sodium carbonate neutralization, two vinyl chloride extraction and 2350mL obtained. Adding 9g phenylalanine methyl ester of acetic acid and methanol extracts 8mL, 15.2g aspartic anhydride hydrochloride added at-20 deg.c, stirring for 30min, hot water and sodium carbonate were added to 70~80 350mL C (5.7g) 300mL. solution with 150mL two vinyl chloride 2 remaining after extraction of phenylalanine methyl ester, water with dilute hydrochloric acid to adjust the Ph value to the 4.8. of the aqueous solution of paper electrophoresis measured with 18.2G (molar yield of 60%) and 6.1g (α-APM beta 20% molar yield) β--APM. This solution is vacuum concentration 100mL, plus.36% hydrochloric acid 30mL, set the refrigerator overnight. A-APM-HCl 21.3g Precipitation Crystallization (yield 58%), the crystallization of filtered and dissolved in 200mL water solution. Stirring at 50 ℃, with 5% sodium carbonate solution to adjust the Ph value to 4.8, and then place the refrigerator overnight in the analysis And filtering to obtain alpha APM crystallization) (43% yield). Crystal dissolved in 500ml water. In 45℃ by Dowex 1 x 4 (acetate) columns (1 x 20cm), and 20 ml of water flushing, effluent and washings together vacuum concentration, precipitation of alpha APM crystallization 11.2g. yield of 37%, melting point 235~236℃ (decomposition), than the rotation alpha D22 32.0 ℃ = 1, Cu Suanzhong. Elemental analysis results: 55.30% C, H 6.19%, n 9.36%.

Explosive hazard characteristics

Edible contact dermatitis.

Combustible hazard characteristics

Combustible; combustion produces toxic nitrogen oxide smoke

Storage and transportation characteristics

Combustible; combustion produces toxic nitrogen oxide smoke

Fire extinguishing agent

Dry powder, foam, sand, carbon dioxide, mist water

History

Aspartame was discovered accidentally in 1965 during a search for drugs to treat gastric ulcers. James M. Schlatter, an organic chemist working for G. D. Searle & Company, was using aspartyl-phenylalanine methyl ester (aspartame) in a synthesis procedure and inadvertently got some of the compound on his hands.

Preparation

By coupling the amino acids L-phenylalanine and L-aspartic acid, and the esterification of the carboxyl group of the phenylalanine moiety to produce the methyl ester. This esterification can occur before or after coupling. The crystallized slurry is centrifuged and the resulting “wet-cake” is washed to remove impurities.

Production Methods

Aspartame is synthesized using the L enantiomer of phenylalanine. The L enantiomer is separated from the D enantiomer, the racemic mixture, by reacting it with acetic anhydride (CH32

Manufacturing Process

A solution of 88.5 parts of L-phenylalanine methyl ester hydrochloride in 100 parts of water is neutralized by the addition of dilute aqueous potassium bicarbonate, then is extracted with approximately 900 parts of ethyl acetate. The resulting organic solution is washed with water and dried over anhydrous magnesium sulfate. To that solution is then added 200 parts of Nbenzyloxycarbonyl- L-aspartic acid α-p-nitrophenyl, β-benzyl diester, and that reaction mixture is kept at room temperature for about 24 hours, then at approximately 65°C for about 24 hours. The reaction mixture is cooled to room temperature, diluted with approximately 390 parts of cyclohexane, then cooled to approximately -18°C in order to complete crystallization. The resulting crystalline product is isolated by filtration and dried to afford β- benzyl N-benzyloxycarbonyl-L-aspartyl-L-phenylalanine methyl ester, melting at about 118.5-119.5°C. To a solution of 180 parts of β-benzyl N-benzyloxycarbonyl-L-aspartyl-Lphenylalanine methyl ester in 3,000 parts by volume of 75% acetic acid is added 18 parts of palladium black metal catalyst, and the resulting mixture is shaken with hydrogen at atmospheric pressure and room temperature for about 12 hours. The catalyst is removed by filtration, and the solvent is distilled under reduced pressure to afford a solid residue, which is purified by recrystallization from aqueous ethanol to yield L-aspartyl-L-phenylalanine methyl ester. It displays a double melting point at about 190°C and 245- 247°C.

Therapeutic Function

Sugar supplement

Biotechnological Production

Aspartame is produced from L-aspartic acid and L-phenylalanine and methanol or alternatively L-phenylalanine methyl ester. The standard process uses common chemical methods of peptide synthesis. Enzymatic coupling of the two amino acids is also possible. N-formyl-L-aspartic acid and L- or D.L-phenylalanine methyl ester can be condensed to aspartame by thermolysin-like proteases. The formylated aspartame can be deformylated chemically or with a formylmethionyl peptide deformylase to yield the sweetener.The enzymatic coupling does not require L-phenylalanine but can start from the racemic product obtained in chemical synthesis, and the remaining D-phenylalanine can be racemized again. Production processes based on fermentation are available for the two main components, aspartic acid and phenylalanine.

Pharmaceutical Applications

Aspartame is used as an intense sweetening agent in beverage products, food products, and table-top sweeteners, and in pharmaceutical preparations including tablets, powder mixes, and vitamin preparations. It enhances flavor systems and can be used to mask some unpleasant taste characteristics; the approximate sweetening power is 180–200 times that of sucrose. Unlike some other intense sweeteners, aspartame is metabolized in the body and consequently has some nutritive value: 1 g provides approximately 17 kJ (4 kcal). However, in practice, the small quantity of aspartame consumed provides a minimal nutritive effect.

Biochem/physiol Actions

Asp-Phe methyl ester (Asp-Phe-OMe) is used as a synthetic sweeter, sugar substitute. Asp-Phe methyl ester is being studied for a variety of potential benefits as a nutrition supplement, such as the delay of osteoarthritis and modulation of rheumatoid factor activity. Asp-Phe methyl ester is being studied for its effect on thrombin activity and blood clotting.

Safety Profile

Human systemic effects byingestion: allergic dermatitis. Experimental reproductiveeffects. When heated to decomposition it emits toxicfumes of NOx.

Safety

Aspartame is widely used in oral pharmaceutical formulations, beverages, and food products as an intense sweetener, and is generally regarded as a nontoxic material. However, the use of aspartame has been of some concern owing to the formation of the potentially toxic metabolites methanol, aspartic acid, and phenylalanine. Of these materials, only phenylalanine is produced in sufficient quantities, at normal aspartame intake levels, to cause concern. In the normal healthy individual any phenylalanine produced is harmless; however, it is recommended that aspartame be avoided or its intake restricted by those persons with phenylketonuria. The WHO has set an acceptable daily intake for aspartame at up to 40 mg/kg body-weight. Additionally, the acceptable daily intake of diketopiperazine (an impurity found in aspartame) has been set by the WHO at up to 7.5 mg/kg body-weight. A number of adverse effects have been reported following the consumption of aspartame, particularly in individuals who drink large quantities (up to 8 liters per day in one case) of aspartame-sweetened beverages. Reported adverse effects include: headaches; grand mal seizure;memory loss;gastrointestinal symptoms; and dermatological symptoms. However, scientifically controlled peer-reviewed studies have consistently failed to produce evidence of a causal effect between aspartame consumption and adverse health events. Controlled and thorough studies have confirmed aspartame’s safety and found no credible link between consumption of aspartame at levels found in the human diet and conditions related to the nervous system and behavior, nor any other symptom or illness. Aspartame is well documented to be nongenotoxic and there is no credible evidence that aspartame is carcinogenic. Although aspartame has been reported to cause hyperactivity and behavioral problems in children, a double-blind controlled trial of 48 preschool-age children fed diets containing a daily intake of 38 ± 13 mg/kg body-weight of aspartame for 3 weeks showed no adverse effects attributable to aspartame, or dietary sucrose, on children’s behavior or cognitive function.

Environmental Fate

Aspartame is nontoxic. However, individuals with the rare, genetic disease, phenylketonuria (PKU), cannot properly metabolize phenylalanine. Such individuals are detected by testing at birth and placed on special low-phenylalanine diets to control their blood phenylalanine concentrations. Thus, PKU individuals need to be aware that aspartame is a source of phenylalanine.

Metabolic pathway

The rate of aspartame degradation is faster in a phosphate buffer solution than in a citrate buffer solution at the same pH and buffer concentration. The primary mechanism by which aspartame degrades, the formation of diketo piperazine, involves the nucleophilic attack of carbonyl by the free amine, which requires proton transfer.

storage

Aspartame is stable in dry conditions. In the presence of moisture, hydrolysis occurs to form the degradation products L -aspartyl-Lphenylalanine and 3-benzyl-6-carboxymethyl-2,5-diketopiperazine with a resulting loss of sweetness. A third-degradation product is also known, β-L-aspartyl-L-phenylalanine methyl ester. For the stability profile at 258℃ in aqueous buffers. Stability in aqueous solutions has been enhanced by the addition of cyclodextrins, and by the addition of polyethylene glycol 400 at pH 2. However, at pH 3.5–4.5 stability is not enhanced by the replacement of water with organic solvents. Aspartame degradation also occurs during prolonged heat treatment; losses of aspartame may be minimized by using processes that employ high temperatures for a short time followed by rapid cooling. The bulk material should be stored in a well-closed container, in a cool, dry place.

Incompatibilities

Differential scanning calorimetry experiments with some directly compressible tablet excipients suggests that aspartame is incompatible with dibasic calcium phosphate and also with the lubricant magnesium stearate. Reactions between aspartame and sugar alcohols are also known.

Regulatory Status

Accepted for use as a food additive in Europe and in the USA. Included in the FDA Inactive Ingredients Database (oral powder for reconstitution, buccal patch, granules, syrups, and tablets). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.

Composition and Usage

Aspartame is the methyl-ester of the aspartate-phenylalanine dipeptide and is widely used as a sweetener in both the food and pharmaceutical industries. It is found in over 5000 food products globally, including low-calorie beverages, dessert mixes, yogurt, multivitamins, morning cereals, and medicines.

Discovery and Approval

Invented in 1965 by James M. Schlatter during research on antiulcer drugs, aspartame's sweetness was discovered accidentally. Approved by the U.S. FDA in 1981, it is about 200 times sweeter than sugar with almost zero calories.

Acceptable Daily Intake and Labeling

The acceptable daily intake of aspartame is 40 mg/kg body weight in Europe and 50 mg/kg body weight in the United States. Products containing aspartame must be labeled to inform consumers, especially those with phenylketonuria, as it contains phenylalanine.

Metabolism and Risks

Aspartame is hydrolyzed and absorbed in the gastrointestinal tract, releasing methanol, aspartic acid, and phenylalanine. Prolonged consumption may pose risks, especially to phenylketonuria patients.

Applications Beyond Sweetening

Aspartame has been used in encapsulation processes to improve properties like stability, taste, color, and texture, extending storage times. It finds applications in food, cosmetics, agrochemicals, and pharmaceuticals.

Stability and Degradation

Aspartame is stable in solid form but degrades in solution, especially in high temperatures or pH values above 6. It also loses sweetness when reacting with certain flavorings, aldehydes, or ketones.

Usage in Baking and Confectionery

Although decomposed by baking, aspartame salts, and metal complexes can protect it, allowing its use in pastries. Its high sweetness makes it common in confectionery products like chewing gums.

Safety Assessment and Genotoxic Properties

Despite safety assessments by various regulatory bodies, few studies have tested aspartame's genotoxic properties in vivo and in vitro, and none were conducted according to GLP standards.

Category

Toxic substances

Definition

ChEBI: A dipeptide composed of methyl L-phenylalaninate and L-aspartic acid joined by a peptide linkage.

General Description

Asp-Phe methyl ester (aspartame, APM, ASP), a dipeptide ester, is made up of phenyl alanine and aspartic acid. Its genotoxic effects have been investigated. Its interaction with certain hydrocolloids has been studied.