This article was originally published by Food Ingredients International (IFI HR6 1994) and updated by the author in 2003.
Thaumatin comes from the berry of the plant Thaumatococcus daniellii.

Among sweeteners, natural sweet proteins are unique in that they are natural, often have high sweetness potency compared to sugar and decompose into a normal distribution of amino acids on hydrolysis. To date, thaumatin is the only commercially available ‘natural protein’ sweetener. This versatile ingredient has a wide range of applications in foods and drinks and particularly in the field of taste modification and flavour enhancement. ____________________________________________________________________________________
OVERVIEW Investigation into the isolation and use of taste modifying polypeptides has been largely driven by their high sweetness potency. Natural proteins identified as sweet include miraculin from the “Miracle Fruit” Synsepalum Dulcificum, monelin from the “Serendipity Berry” Dioscorephyllum Cuminsii and thaumatin from the “Katemfe Fruit” Thaumatococcus Danielli. Of these only thaumatin is commercially available. The product has a particularly powerful effect on taste; it has the ability to enhance elements of the flavour and sweetener compounds and simultaneously to mask other elements. Thaumatin’s dramatic effects have their source, as do other flavour enhancers, in the structure and nature of the molecule and the way in which it interacts with both taste and flavour molecules.
HISTORY W F Daniell, in the Pharmaceutical Journal, first documented the existence in Africa of the fruit from which thaumatin is extracted in 1855 in which he referred to it by its local name ‘Katemfe’ and described it as ‘The Miraculous Fruit of Soudan’. He reported considerable trade in the bright red triangular fruit and its use as a powerful sweetener and flavour enhancer in local foods and drinks. Thaumatin is the sweetest substance known to man at approximately 2,500 times sweeter than sugar. Historically this has distracted attention from its more important properties of thaumatin’s taste modification and flavour enhancement.
STRUCTURE AND NATURE Thaumatin, extracted unmodified from the Katemfe fruit using purely physical extraction methods consists of very closely related Thaumatin proteins. These have a single polypeptide chain or 207 “normal” amino acid residues linked with 8 disulphide bridges giving a molecular weight of around 22,000. Thaumatin is completely digested by man and animal, which together with its “normal” amino acid sequence, accounts for its acceptance by regulatory authorities around the world as a safe, natural substance. Thaumatin has the normal calorific value of a protein (4.1 Kcal/g) but in use is essentially non-calorific due to the very low levels required (parts per million). It is very basic with an iso-electric point of around 11.5 and freely soluble in water.
TASTE MECHANISM Thaumatin has a demonstrable effect on various groups of taste receptors, in various species of animal, for which it is used in feeding stuffs, as well as in man and is assumed to operate with the majority of taste receptors. This feature is a result of its particular structure. In the analogy, often used, of flavour molecules being “keys” and the taste receptors being “locks”, thaumatin appears to act as a “master key” in its action with all taste receptors. Thaumatin’s effect in operating with all the taste receptors is the major reason for its wide range of applicability in situations requiring flavour modifications. The electrical charge distribution on the thaumatin molecule is believed to be a major factor in the mechanism of interaction with both the taste receptor and the flavour molecules. This is demonstrated by the specific masking effects on the typically bitter unpleasant taste of metallic ions such as sodium, iron, potassium and its simultaneous enhancement of other free ion, e.g. chloride. Its effect with more complex flavour compounds support the view that thaumatin’s mechanism operates according to the relative nature of the individual molecules present. This is particularly evident in its effect with flavours such as peppermint, ginger, cinnamon and coffee, which it enhances while simultaneously reducing the fiery, peppery or bitter elements associated with them. Thaumatin’s high and rapid solubility in water and its tendency to increase salivation are additional physical features that increase the effect of flavours and aromas, particularly where physical contact with the taste receptors is limited. The strength of the interaction between the thaumatin molecule and the taste receptors is believed to account not only for its potency effects in prolonging the effects of flavours and sweeteners.
STABILITY Thaumatin is remarkably stable considering its proteinaceous nature. It is successfully applied in canning of pet food where it remains stable at temperatures of 120ºC and in coatings subjected to dry temperatures of 140ºC. Thaumatin is stable under pasteurisation and UHT conditions. Further enhancement of its physical and chemical stability can be achieved through reformulation with protective compounds. Its stability under acid conditions, to lower than pH 2, is a useful feature - a result of its molecular structure.
PROPERTIES AND APPLICATION Thaumatin’s properties can be usefully summarised under the headings of: Enhancing Masking Synergism Its applications are however less easy to categorise in the same way because its properties can act simultaneously and in many product applications are utilised together.
ENHANCEMENT Thaumatin is effective in enhancing a wide range of flavour compounds, including savoury flavours and, in particular, “aggressive” flavours. Due to its ability to reduce the aggressive nature of these complex flavour compounds, thaumatin provides the opportunity to achieve higher levels of flavour in products without these being too aggressive and for instance, in coffee flavoured products, without generating bitter notes. In savoury products enhancement is more complex. In addition to enhancement of flavours directly, thaumatin synergises with naturally present or added flavour enhancers such as 5’ nucleotides and monosodium glutamate (MSG). This adds a unique element of what the Japanese industry describes as “Umami” or, approximately translated into English, ”deliciousness”.
MASKING Thaumatin’s masking effects, particularly of metallic or bitter tastes, are an important feature accounting for it’s widespread use in the human and animal food industry and with high intensity sweeteners and in particular with saccharin. Thaumatin is particularly effective in masking the metallic aftertaste of saccharin, with this combination being used in a wide variety of products from tabletop sweeteners to animal feeds. In citrus fruit products, thaumatin has been shown to be very effective in masking the bitter elements of natural flavours from the fruit hence its application in products such as juices, yoghurts and deserts. A good example of thaumatin’s simultaneous action is to be found in applications with vitamin C, often flavoured with citrus and sweetened with high intensity sweeteners. In this application thaumatin also masks the bitter notes and the sweetener aftertaste, enhances the flavour and also contributes to the sweetening. At high levels of inclusion but still in the parts per million ranges, thaumatin is effective in masking the taste of some pharmaceutical products in chewables and suspensions.
SYNERGISM A clear synergism is shown when using thaumatin in conjunction with intensity sweeteners and with flavour enhancing compounds MSG and 5’ nucleotides. With aspartame for example, a commercial application showed sufficient synergy between thaumatin and aspartame that a thaumatin inclusion of 10 parts per million, the aspartame could be reduced by more than 30% to achieve the original sweetness level. In addition to the synergistic effects thaumatin improved the sweetness profiles of non nutritive sweeteners giving “body” to the sweeteners and masking the associated aftertaste as well as extending the sweetness and flavour profiles.
Thaumatin as the most potent form of sweetness available, and being the only natural high intensity sweetener available, does have some application as a sweetener in its own right, but due to a liquorice aftertaste being contributed at higher levels, its use as the only source of sweetness is limited to applications where the sweetness requirement is less than the equivalent of 10% of sucrose. Above this level a taste contribution from thaumatin can become evident, which although desirable in some products, is not generally acceptable. Applications in conjunction with natural low intensity, non-nutritive sweeteners are of interests in products requiring an “all natural” label. Thaumatin’s application in products in conjunction with added MSG and nucleotide compounds, or where nucleotides are naturally present, for instance in pet food, exhibit a high degree of synergy with these compounds The additional masking effects of metallic flavours provide a range of applications in low sodium products where NaCl has been replaced in part with KCl.
SAFETY AND REGULATION Of the natural sweet proteins, thaumatin is the only one that is widely accepted as safe by regulatory authorities. As a result of its background as a high intensity sweetener, thaumatin has been subjected to the intense scrutiny of regulatory authorities, typical of a high intensity sweetener. Thaumatin is widely approved and has been positively reviewed by the SCF and JECFA, a full toxicological and safety data package. Thaumatin is approved for general use in the USA under FEMA GRAS status, is an approved sweetener in the European sweeteners Directive and an approved flavour enhancer in the European Miscellaneous Additives Directive. It is approved as a natural food in Japan and is also approved for general use in the UK and Canada among other countries. The categories for use allowed under European legislation are currently restricted; however it is intended to broaden these in the future.
FUTURE POTENTIAL When thaumatin was first produced in the late 1970’s great emphasis was placed on the sweetening properties and for some time this defined its regulatory and marketing path. As innovative manufacturers realised that thaumatin’s future lay in its flavour modification ability, its application base and supporting technology have shifted. Thaumatin’s use is thus rapidly developing as a unique and novel means of improving the organoleptic qualities of products and allowing reduction of overall additive levels. As a natural product from an ecologically sound manufacturing regime, applications in “natural” label products are a particular feature of thaumatin’s potential.
REFERENCES 1.    W F Daniell (1855) - Katemfe, or the Miraculous Fruit of the Soudan. Pharm J 14,158 2.    J D Higginbotham, D J Snodan, K Eaton and J W (1983)–Safety Evaluation of Thaumatin (Thaumatin Protein) FD Chem Toxic 21:6 3.    Japan Patent Office (1984) Disclosure No Sho 59 -14764 – Method of improving Dipeptide Sweeteners