2009_Book_FoodChemistry

258 4 Carbohydrates
Table 4.8. Specific rotation of various mono- and oligosaccharides
Compound [α] D
a
Compound [α] D
a
Monosaccharides
Oligosaccharides
L-Arabinose +105 (continued)
α- +55.4 Kestose +28
β- +190.6 Lactose +53.6
D-Fructose −92 β- +34.2
β- −133.5 Maltose +130
D-Galactose +80.2 α- +173
α- +150.7 β- +112
β- +52.8 Maltotriose +160
D-Glucose +52.7 Maltotetraose +166
α- +112 Maltopentaose +178
β- +18.7 Maltulose +64
D-manno-2- Manninotriose +167
Heptulose +29.4 Melezitose +88.2
D-Mannose +14.5 Melibiose + 143
α- +29.3 β- + 123
β- −17 Palatinose + 97.2
D-Rhamnose −7.0 Panose + 154
D-Ribose −23.7 Raffinose + 101
D-Xylose +18.8 Saccharose + 66.5
α- +93.6 α-Schardinger-
Dextrin +151
Oligosaccharides
β-Schardinger-
(including disaccharides) Dextrin + 162
Cellobiose +34.6 γ-Schardingerβ-
+14.2 Dextrin +180
Gentianose +33.4 Stachyose +146
Gentiobiose +10
α- +31
β- −3
a Temperature: 20–25 ◦ C.
4.2.3 Sensory Properties
Mono- and oligosaccharides and their corresponding
sugar alcohols, with a few exceptions,
are sweet. β-D-Mannose has a sweet-bitter
taste, and some oligosaccharides are bitter, e. g.
gentiobiose.
The most important sweeteners are saccharose
(sucrose), starch syrup (a mixture of glucose,
maltose and malto-oligosaccharides) and glucose.
Invert sugar, fructose-containing glucose
syrups (high fructose corn syrup), fructose,
lactose and sugar alcohols, such as sorbitol,
mannitol and xylitol, are also of importance.
The sugars differ in quality of sweetness and
taste intensity. Saccharose is distinguished from
other sugars by its pleasant taste even at high
concentrations. The taste intensity of oligosaccharides
drops regularly as the chain length
increases.
The taste intensity can be measured by determining
the recognition threshold of the sugar (the
lowest concentration at which sweetness is still
perceived) or by comparison with a reference
substance (isosweet concentrations). The threshold
value is related to the affinity of sweet-taste
chemoreceptors for the sweet substance and is of
importance in elucidation of reltionships between
the chemical structure of a compound and its
taste. For practical purpose, the use of a reference
substance is of greater importance: taste intensity
is dependent on concentration and varies greatly
among sweet compounds.
Saccharose is the reference substance usually
chosen. Tables 4.9, 4.10 and 4.11 list some sugar
sweetness threshold values and relative sweet-