Natural low-calorie sweeteners - Natural Food Additives, Ingredients and Flavourings - page 47

Applications
D -Tagatose is widely applicable in ready-to-eat cereals, diet soft drinks, health
bars, frozen yogurt/non-fat ice cream, soft confectionery, hard confectionery,
frostings and chewing gum. The sugar also enhances specifi c fl avours in various
applications such as mint and lemon in sugar-free chewing gum. It also boosts
creaminess and toffee fl avour.

Regulatory status
The US FDA has accepted the GRAS notifi cation for tagatose. It was launched in
the US market in May 2003 and is a general-purpose sweetener in Korea, Australia
and New Zealand. It is also permitted in Brazil and South Africa.
Tagatose is a sugar, but foods and beverages in the US are allowed to carry a
'sugar free' claim provided the sugar content does not exceed 0.5 g per serving.
For food labelling purposes in the US, an energy value of only 1.5 calories
per gram may be used for tagatose. In the EU tagatose is regulated as a novel food
but, at the time of writing, bears the full 4 kcal/g regulatory energy content applied
to all sugars.

3.3 Commercial high-potency sweeteners

3.3.1 Steviol glycosides

Structure, source
The steviol glycosides are a group of closely related, potently sweet molecules
produced in the leaves of the stevia plant, Stevia rebaudiana Bertoni. The
glycosides typically amount to about 10-15% of the dry matter of the leaves.
There are ten principal glycosides (Fig. 3.3), although there is some doubt as
to whether steviolbioside and rebaudioside B occur in the plant or are produced by
partial hydrolysis during extraction (Prakash et al. 2008). All are ent -kaurene
diterpenoid glycosides with a common core of steviol ( ent -13-hydroxykaur-
16-en-19-oic acid). Stevioside is the most abundant, followed by rebaudioside A,
and these two are also the most signifi cant commercially. The other glycosides
occur in only minor amounts.
Rebaudioside A is widely accepted to be the best-tasting, a fact that has
encouraged successful conventional plant breeding programmes over many years
aimed at increasing the relative yield of this glycoside. Cultivars now exist where
rebaudioside A accounts for 40% and more of the total glycoside content (Morita
and Bu 2000a, 2000b; Morita et al. 2009).
S. rebaudiana is a native of Paraguay, where its leaves have been used as a
source of sweetness for centuries (Lee 1979; Lewis 1982; Soejarto 2002). The
plant is now grown commercially in South America and Asia. It is a perennial, but
often grown as an annual, especially where the ground freezes, as the plant roots
cannot withstand such conditions. Commercial plantings are largely restricted to
bands roughly between 20° and 40° South and North of the equator because less

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