Biology Reference
In-Depth Information
a
-limit dextrins). Solution viscosity has also been reported to influence the
enzyme kinetics
(
Uribe & Sampedro, 2003
).
The ionic interactions between starch and gum play an important role on
the viscosity and viscoelasticity characteristics. The strong electrostatic inter-
actions between cationic starch and anionic gum result in an instantaneous
aggregation of granules, whereas nonionic gums form sheet structure and
loosely wrapped the granules (
Chaisawang & Suphantharika, 2005
). These
observations are related to the changes in rheological parameters such as stor-
age modulus (
G
0
) and loss modulus (
G
00
) of the starch-xanthan and the
starch-guar systems (
Chaisawang & Suphantharika, 2005
). However, to
our knowledge, no reports are available on the effect of ionic interactions
of the gums during
in vitro
starch hydrolysis. The addition of some cereal-
based viscous fiber in meals also influences the digestion and absorption
of carbohydrates to a considerable extent. However, the postprandial glu-
cose response may be slightly different as they are physically and functionally
different from the viscous gums.
In addition, it may be difficult to distinguish among the two effects
whether decrease in the rate of hydrolysis occur by the inhibition of enzymes
or by an increase in the viscosity of gastrointestinal contents (acting on the
mass transfer). An inhibitory action of very small concentration (0.5%) of
galactomannan addition on amylase acting on a range of concentrations
of gelatinized starch was observed by
Slaughter, Ellis,
Jackson, and
5. FORMULATED FOODS AND STARCH DIGESTION
5.1. Influence of food matrix composition
on starch digestion
The composition of food matrix also affects the digestion of starch signifi-
cantly (
Singh et al., 2010
). Therefore, the rate of starch digestion differs with
different foods with varying compositions. The presence of protein in the
food matrix may influence the rate of starch digestion. Digestibility of the
starches and proteins in various cereal products is significantly affected by
their interaction with each other. The functional properties and starch
digestibility have been observed to be influenced by the presence of even
Duodu, Emmanbux, & Taylor, 2008
)
. Protein fractions such as albumin,
globulins, and glutenins help in gluing the protein bodies into a matrix sur-
rounding starch granules that may act as a barrier toward starch digestibility
