Title: Alternative Sweeteners

450 Richards and Dexter
XIII. CARIOGENICITY
The cause of dental caries and the method for intraoral plaque–pH telemetry
have been well documented and discussed in other chapters of this book (Chapters
17, 19). Trehalose was compressed into a lozenge with mint flavor. The change
in pH during consumption of the mint was studied under a standard protocol in
which a plaque-covered pH sensor is integrated into a removable, mandibular,
restorative device (49, 50). The pH did not drop below the critical value of 5.7
in any of the four subjects tested. With regard to nonfermentability, the mints
would, therefore, qualify for the ‘‘toothfriendly’’ claim.
A similar study was performed in Japan where trehalose was incorporated
into a chocolate candy (HBC, unpublished data, 1997). Four subjects dissolved
the chocolate (5.1 g) in their mouths, and the plaque pH was measured by an
indwelling electrode over a 30-minute period. A 10% sucrose solution was used
as a positive control. The pH did not drop below 5.7 in any of the four subjects
consuming the chocolate. This suggests that trehalose taken under these conditions
does not promote dental caries.
In vitro studies on the fermentability of trehalose using Streptococcus mutans
have shown that trehalose can be fermented (British Sugar, unpublished
data, 1998); however, the fermentation rate was lower than that of sucrose. In
vivo plaque-pH assays using the two different trehalose-containing products indicate
that the time during which trehalose is in contact with dental plaque is insufficient
to result in critical plaque acidification. Furthermore, the amount of acid
formed during the period of trehalose exposure was either too small to reduce
the pH below 5.7 or may have been neutralized sufficiently by increased saliva
production during consumption of the mint or chocolate.
XIV. METABOLISM
Humans have long consumed trehalose in various foods, primarily young mushrooms
and baker’s yeast (5, S Miyake, unpublished data, 1997). At present, trehalose
is being used by the Japanese food industry at a rate of more than 1,000
metric tons per month. This will likely increase on an international scale as more
functional applications are found and additional regulatory approvals are granted.
The mechanism by which dietary trehalose is metabolized in mammals has been
studied and appears straightforward. Trehalose is not assimilated intact into the
body and has not been detected in blood. Like other disaccharides, it is hydrolyzed
on the brush border of the intestinal enterocytes. The enzyme that hydrolyzes
trehalose into its two glucose units is trehalase (1, 6). Trehalase is tightly
bound to the surface of the external side of the membrane microvilli in the small
intestine (51, 52). It is highly specific for trehalose, appears to have the highest
concentration in the proximal and middle jejunum, and declines toward the distal