2009_Book_FoodChemistry

260 4 Carbohydrates
Fig. 4.5. Temperature dependence of the mutarotation
equilibrium of D-fructose, (— β-D-fructo-pyranose, –
–– β-D-fructofuranose, –·–·– α-D-fructofuranose) (according
to Shallenberger and Birch, 1975)
Furthermore, an interrelationship exists between
the sugar content of a solution and the sensory
assessment of the volatile aroma compounds
present. Even the color of the solution might
affect taste evaluation. Figures 4.6–4.9 clarify
these phenomena, with fruit juice and canned
fruits as selected food samples.
The overall conclusion is that the composition
and concentration of a sweetening agent has to
be adjusted for each food formulation to provide
optimum sensory perception.
A prerequisite for a compound to be sweet
is the presence in its structure of a proton
Fig. 4.7. Sensory evaluation of canned cherries prepared
with different sweeteners 1, 2, 3: 60, 50, 40% saccharose,
4: 0.15% cyclamate, 5: 0.05% saccharin, 6:
10% saccharose + 0.10% cyclamate, 7: 10% saccharose
+0.02% saccharin (according to Salunkhe, 1963)
Fig. 4.8. Sensory evaluation of the categories “overall
pleasantness”, “sour” and “bitter” versus sweetness intensity.
B bilberry (◦—◦) andP(•—•) cranberry juice
(according to Sydow, 1974)
Fig. 4.6. Sensory evaluation of the “fruity flavor” of
canned peaches at different ratios of saccharose/starch
syrup (•—•60 ◦ ,◦—◦50 ◦ Brix) (according to Pangborn,
1959)
donor/acceptor system (AH/B-system), which
may be supplemented by a hyrophobic site X.
This AH/B/X-system interacts with a complementary
system of the taste receptor site located
on the taste buds. Based on studies of the taste
quality of sugar derivatives and deoxy sugars, the
following AH/B/X-systems have been proposed