Title: Alternative Sweeteners

238 Embuscado and Patil
growth of the microorganism and its efficiency to produce erythritol. The resulting
concentrated fermentation broth facilitates the isolation and purification
of erythritol. The separation process is simpler and less energy-intensive. Conversion
yields of 40–50% have been reported using the fermentation process.
Cerestar, a company of Eridania Béghin-Say, is producing erythritol commercially
with an entirely biotechnological process (17).
Several methods of improving erythritol productivity have been carried out.
Strains of Trichosporonoides sp. have been isolated from honeycomb that can
give high erythritol yields and low amounts of glycerol from glucose or sucrose
substrates (19). A high erythritol-producing strain of Trichosporon sp. was also
isolated from honeycomb (20). The strain produced 141 g of erythritol per liter
of medium at 35°C after 3 days of incubation. The fermentation medium consisted
of 30% glucose and 4% corn steep liquor. Induced mutation has also been
used to improve the strain of Aureobasidium sp. so its conversion ratio would
increase (18). This method resulted in yields between 43–52%. Using this microorganism,
the fermentation broth did not foam, substrate as high as 83.3% can
be used, and only small amounts of by-products were synthesized. Using this
microorganism and under certain fermentation conditions by-products were eliminated
(18). Another study dealt with the effect of increased osmotic pressure on
the rate of erythritol production using Trigonopsis variabilis (21). The rate was
increased from 0.09–1.9 g/g-day when the osmotic pressure was increased from
1.3–3.9 Kpa. It is most likely that more research studies will be undertaken in
the future to improve erythritol production. This can be done either through the
use of bioengineering to improve the present strains of erythritol-producing osmotolerant
yeasts or fungi or through formulation of enzyme cocktails that would
be more efficient in converting glucose or other sugars to erythritol.
III. PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES
A. Sweetness
Tables 2 and 3 summarize the properties of erythritol, other polyols, and sucrose.
The sweetness of erythritol is around 65% that of sucrose. Its sweetness profile
is similar to sucrose with slight acidity and bitterness but with no detectable
aftertaste. Most polyols have sweetness levels less than sucrose. Xylitol is the
only polyol that has the closest degree of sweetness to sucrose, but its cooling
effect is more intense than erythritol. Maltitol is another polyol, which has a
higher degree of sweetness than erythritol. The rest of the polyols have levels
of sweetness less than or equal to erythritol. It must be remembered that sweetness
in itself is not the only important taste criteria but also persistence of sweetness,
presence or absence of aftertaste, and the sweetness profile (i.e., how close it is
to sucrose). For bulk sweeteners like erythritol, other nonsweet flavor attributes