Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
with FAME catalyzed by Na metal to produce highly substituted polyesters at lower
temperatures because they are nonreducing sugars. Glycosylation converts the reducing
C-1 anomeric center to nonreducing, the alkyl glycosides become substrates for
transesterification with FAME, and the remaining hydroxyl groups can be esterified
as described for sucrose polyester to produce alkyl glycoside fatty acid polyesters.
Fatty acid esters and ethers of saccharides are nonionic surfactants commonly
used as wetting, dispersing, or emulsifying agents and as an antimicrobial and
protective coating for fruits. Fatty acid polyesters of saccharides function as fat
replacers and provide the characteristic functional and physical properties of fat but
have lower caloric contents because of reduced digestion and absorption. Their
properties depend on the type and number of sugar units in carbohydrate moiety as
well as the number, type, and length of attached alkyl chain or fatty acid residue.
3.7 PHYSICOCHEMICAL PROPERTIES AND
APPLICATIONS
3.7.1 SUGAR ALCOHOLS
All polyols exhibit negative heats of solution, resulting in a cooling of the solution
and consequently a cooling sensation when the dry powder of polyols is dissolved
in the mouth. The intensity of the cooling effect depends on the magnitude of the
heat of the dissolution. For example, maltitol and isomalt show no cooling effect
and xylitol imparts a strong cooling sensation. This cooling property has found
applications in food and pharmaceutical products in which a cooling sensation is
desired.
Because of the absence of carbonyl group, polyols exhibit a good stability against
the exposure to heat, alkali, and acid, and do not take part in nonenzymatic browning
(Maillard) reactions (Chapter 18). They exert freezing point depression because of
their small molecular weight. They have low hygroscopicity with, in increasing
order, mannitol, isomalt, lactitol, maltitol, xylitol, and sorbitol (Table 3.1).
Polyols are low-calorie bulk sweeteners with applications where calorie reduction
is desired, such as diabetic products, table-top sweeteners, chocolate, hardboiled
candies, jellies and jams, chewing gum, and ice creams. Some polyols may
require the addition of intensive sweeteners to provide the right sweetness to certain
applications. Polyols also function as humectants and emulsifiers to provide freshness
and extend shelf life to bakery products and confectionery where products tend
to dry or harden during storage. Because of their small molecular weight, they also
have a plasticizing effect to improve the texture of the products. Sugar alcohol syrups
can function as antifreeze to preserve the functionality of products such as fish
protein. The selection of polyols depends on the sweetness profile, cooling effect,
and aftertaste, and combinations of polyols often have a synergistic effect.
3.7.2 POLYDEXTROSE
The highly branched structure of polydextrose renders it water soluble and gives it
reduced-calorie (1 cal/g) properties. It has no sweetness and its viscosity is slightly