by D. Eric Walters, Ph.D.
Artice of the week:
Thaumatin
Other names:
Talin®
Taste:
Thaumatin is sweet, with a slow onset, lingering sweetness and a licorice after-taste. Sweetness potency relative to sucrose is about 2000 x on a weight basis, and about 100,000 x sucrose on a molar basis.
Calories:
Thaumatin has 4 calories per gram, since it is a protein. Since it has such high potency relative to sucrose, the amount used is extremely small, and so it does not provide measurable caloric value at use levels in foods.
Safety:
The Food and Drug Administration (FDA) in the USA has classified thaumatin as GRAS (Generally Recognized as Safe). Thaumatin is digested like any other protein, so there is no concern about toxicity. Thaumatin-like proteins in other plants are known to be allergenic[1], so there is the potential for development of thaumatin allergies. Thaumatin has been tested for toxicity, digestibility, teratogenicity, and allergenicity[2]; it is non-toxic, it is readily digested, it is not teratogenic, and it is allergenic, but less so than house dust mites.
Source:
According to van der Wel ("Developments in Food Proteins -- 4", B.J.F. Hudson, Ed., Elsevier Applied Science, London, 1986, pp. 219-245), the katemfe plant (Thaumatococcus daniellii Benth, also called "the miraculous fruit of the Sudan") is common in the West African rain forest zone. The fruit contains 1-3 black seeds surrounded by a gel, and capped with a membranous sac, the aril, which contains the sweet material. This is used as a sweetener in cooking, in flavoring palm wine, and in making confections for children.
Thaumatin is a protein which is isolated from the katemfe fruit. There may be several related proteins in the plant, but there are two main forms: thaumatin I and thaumatin II. Thaumatin I is composed of 207 amino acids, with molecular weight 22,204. Thaumatin II is synthesized as a precursor protein of 235 amino acids; the first 22 amino acids and the last 6 amino acids are apparently cleaved to produce a protein the same size as thaumatin I (207 amino acids) and 98% identical to thaumatin I.
Thaumatins have an isoelectric point around 11-12. Their tertiary structures are maintained by 8 disulfide linkages.
Properties:
Thaumatin is very water-soluble and heat-stable.
References:
1. Breitender, H. Thaumatin-like proteins--a new family of pollen and fruit allergens. Allergy 59:479-481 (2004). PubMed
2. Higginbotham, J.D.; Snodin, D.J.; Eaton, K.K.; Daniel, J.W. Safety evaluation of thaumatin (Talin protein). Food Chem. Toxicol. 21:815-823 (1983). PubMed
Other links:
Thaumatin on Wikipedia
SweetenerBook.com
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