Thaumatin

Preparation

Thaumatin I and II proteins can be produced recombinantly in a wide range of hosts, including microorganisms such as bacteria and yeast, and in GM plants to enhance the organoleptic properties.

Production Methods

Thaumatin is a naturally occurring intense sweetener isolated from the fruit of the African plant Thaumatococcus daniellii (Benth). Commercially, thaumatin is produced by aqueous extraction under reduced pH conditions followed by other physical processes such as reverse osmosis.

Health Hazard

Thaumatin is the only natural high-intensity sweetener, and products containing it do not require to be labelled 'artificially sweetened'. It has a low calorific value and is non-cariogenic (Higginbotham, 1986). The report of the Joint F AOfWHO Expert Committee (1987) recorded no mutagenic, teratogenic or allergenic effects of thaumatin, and concluded that the lack of toxicity, together with its ready digestion to normal food components, indicated that its only dietary effect was to make an insignificant contribution to the normal protein intake.

Pharmaceutical Applications

Thaumatin is a naturally occurring intense sweetening agent approximately 2000–3000 times as sweet as sucrose. It has a delayed-onset taste profile and long (up to one hour) licorice-like aftertaste. It is used extensively in food applications as a sweetening agent and flavor enhancer, and has potential for use in pharmaceutical applications such as oral suspensions. The typical level used in foods is 0.5–3 ppm, although higher levels are used in certain applications such as chewing gum. Synergistic effects with other intense sweeteners such as acesulfame K and saccharin occur. The extensive disulfide crosslinking within thaumatin maintains the tertiary structure of the polypeptide: cleavage of just one disulfide bridge has been shown to result in the loss of the sweet taste of thaumatin.

Safety

Thaumatin is accepted for use in food products either as a sweetener or as a flavor modifier in a number of areas including Europe and Australia. It is also used in oral hygiene products such as mouthwashes and toothpastes, and has been proposed for use in oral pharmaceutical formulations. Thaumatin is generally regarded as a relatively nontoxic and nonirritant material when used as an excipient. In Europe, because of its lack of toxicity, an ADI has been set of ‘not specified’. LD50 (mouse, oral): >20 g/kg LD50 (rat, oral): >20 g/kg

Regulatory Status

GRAS listed. Accepted for use as a food additive in Europe. Included in nonparenteral medicines licensed in the UK.

Regulations

Thaumatin has been permitted as a natural food in Japan since June 1979. It was awarded GRAS status for use in chewing gum in the USA in October 1984 and, in the UK, was permitted for use in foods, drinks and dietary products, excluding baby foods, by the Sweeteners in Foods Regulations in 1983. The Joint F AOjWHO Expert Committee declared an ADI 'not specified' for thaumatin in 1985 (Joint F AOjWHO, 1987). Approval has also been gained in many countries world wide for use of thaumatin as a sweetener and flavour enhancer, particularly in chewing gum. These include Australia, Belgium, Spain, Switzerland, Mexico and Denmark (Higginbotham, 1986).

Physical properties

Thaumatin occurs as a pale-brown colored, odorless, hygroscopic powder with an intensely sweet taste. Also see Thaumatin b-recombinant.

Application

Thaumatin is a flavor enhancer that is a protein which is approxi- mately 3,000 times as sweet as sucrose. the onset of sweetness may take several seconds and can be affected by heat. It is a potential low-calorie sweetener that used in chewing gum.

Who Evaluation

Evaluation year: 1985