Biology Reference
In-Depth Information
100
90
80
70
60
50
40
30
Cooked beans
Cooked bean starch
Cooked bean flour
20
10
0
0
15
30
45
60
75
90
105
120
135
150
Gastric
Time (min)
Small
intestine
Figure 4.12 Starch hydrolysis (%) during in vitro digestion of cooked navy beans, navy
bean starch, and navy bean flour. Reproduced from
Berg et al. (2012)
with permission from
Elsevier.
gastric simulation period shows that negligible starch hydrolysis occurred
under these conditions.
Under 120 min of simulated intestinal conditions, the rate of starch
hydrolysis of freshly cooked bean paste increased progressively. However,
the percentage of starch hydrolysis rose slowly throughout the digestion
of freshly prepared bean paste compared to the rapid rise seen with samples
of cooked potatoes and pure starch. A very low percentage (
20%) of starch
hydrolysis was observed during the first 15 min of hydrolysis for the cooked
bean paste, whereas it was significantly higher (
>
80%) for cooked potatoes.
The incomplete gelatinization of starch granules ultimately reduced the rate
and extent of starch hydrolysis measured as glucose release during 120 min of
in vitro
digestion with simulated gastric and small intestinal fluids. The sta-
bility of cotyledon cells and the small surface area of the starch granules
which are tightly packed inside the cells also appeared to restrict the free
access of amylolytic enzymes during
in vitro
digestion.
Figure 4.13
A-D shows freeze-dried samples taken throughout the
in vitro
digestion process of freshly autoclaved beans. The regular cellular structure
of cotyledons was observed to be maintained to a good extent during
