Agriculture Reference
In-Depth Information
Ming and Hellekant (1994) report the sweetness of brazzein is retained after
incubation at 80°C for four hours, but the pH was not stated. The same authors
claim 'excellent thermostability' based on tasting after incubating 0.05% brazzein
for two hours at 98°C in buffers at pH 2, 4, 6 and 8 (Hellekant and Ming 1996).
While these fi gures do suggest high stability, there seem to be no long-term,
quantitative, analytical investigations of brazzein's stability under conditions
relevant to foodstuffs.
Metabolism
Brazzein should be metabolised as any other protein and would be accorded an
energy content of 4 kcal/g, but the energy contribution when used as a sweetener
would be negligible. There is no reason to suppose it would have any effect on
blood glucose or insulin, nor should it be cariogenic. However, little has been
published by way of toxicological studies, and this omission may remain a barrier
to brazzein's use as a food additive, despite a long history of human use in Africa.
There it is consumed either raw or in a cooked form, and used as a sweetening
agent in drinks and food.
Sensory properties
Ming and Hellekant (1994) give the potency of brazzein as 2000 at 2%SE and 500
at 10% SE. Its temporal profi le is said to be more sucrose-like than any other
protein sweetener, cleanly sweet, albeit with a slightly slower onset than sucrose
(Hellekant and Danilova 2005). In contrast to sucrose it has a more lasting
sweetness (Hellekant and Ming 1996; Pfeiffer
et al.
2000). There is no detailed
concentration-response curve available in the literature.
Brazzein exists in two forms in the ripe fruit. The major one (~80%) contains
pyroglutamate at its
N
-terminus; the minor lacks this. Taste comparisons show
that the latter molecule is about twice as sweet as the main form (Izawa
et al.
1998).
The protein combines well with most high intensity sweeteners such as
acesulfame-K and aspartame, providing both quantitative and qualitative synergy.
In addition, it improves stability, fl avour and mouthfeel when blended with
acesulfame-K and aspartame, either alone or blended. It typically reduces the side
taste of other sweeteners; for example, a blend of stevioside and brazzein is
superior in taste quality to stevioside alone (Hellekant and Danilova 2005).
There is a substantial literature on sweetness changes arising from modifi cations
of brazzein structure as well as the molecular sites responsible for the protein's
sweetness, but these are beyond the scope of this chapter.
Applications
Brazzein has no applications at present. It has been investigated in beverages,
where it improves mouthfeel when blended with other sweeteners and works
well in both citric acid and phosphate systems (Hellekant and Danilova 2005).
Press announcements in 2007 indicated the imminent launch of fermentatively-
produced brazzein on the US market, but no further information has emerged.
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