Natural low-calorie sweeteners - Natural Food Additives, Ingredients and Flavourings - page 64

Sensory properties
The R,R isomer is the most interesting for commercial development, as it has the
highest potency, in the range 2500-3000 at 5% SE. However, any of the isomers
could be employed.
R,R monatin has an excellent sweetness. In quality and temporal behaviour it
is close to sucrose, with a rapid onset, a very clean sweet taste and a complete
absence of side-tastes. It is one of the fi nest zero-calorie sweeteners ever tasted by
the author. This combination of high potency and high quality suggests that
monatin could be used widely as a sole sweetener and need not be blended with
others - a unique attribute among plant-derived HPS.

Applications
There are no commercial applications of monatin yet, but the patent literature
reveals interest in the sweetener for use in a wide range of products including
foods, all types of beverages as well as powders and concentrates for preparing
them, confectionery, dairy products, chewing gum, table-top sweeteners and
pharmaceuticals.

Regulatory status
Monatin has no regulatory status at the time of writing.

3.4.2 Brazzein

Structure, source
Brazzein is a small protein (6473 Daltons), isolated from the fruit of the African
climbing shrub Pentadiplandra brazzeana Baillon growing mainly in Gabon and
Cameroon (Ming and Hellekant 1994; Hellekant and Ming 1996).
Each fruit is globular, about 5 cm diameter and has a reddish epicarp, rather
like a nutshell, surrounding three to fi ve seeds embedded in a thick, red, sweet
pulp that contains brazzein at concentrations of 0.05-0.2% of ripe fruit (Hellekant
and Danilova 2005). Only laboratory-scale extraction methods have been
published (Hellekant and Ming 1994, 1996).
The protein is a single chain polypeptide of 54 amino acid residues with four
intramolecular disulphide bonds, no free sulfhydryl group, and no carbohydrate
(Hellekant and Danilova 2005).
Genes to express brazzein have been successfully used to create a production
system in bacteria (Assadi-Porter et al. 2000). Brazzein has also been expressed
in yeast (Guan et al. 1995), fruits and vegetables to increase their sweetness and
in grains to be economically extracted and used as a sweetened fl our (Faus 2000).

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Physico-chemical properties
Brazzein is very water soluble (at least 5%) and is claimed to be the most heat
stable of the sweet proteins, a fact that has made it a target for the investigation of
sweet protein structure (Jin et al. 2003).