physicochemical

PARIMALAVALLI and KAVITHA
dough ball was rolled and flattened to chapathi and
roasted on a preheated non-stick hot plate for 20
seconds on one side, 10 seconds on an other side,
and held over flame until complete puffing occurred
(Rao and Bharathi, 1996).
SUBJECTS: Six healthy non – medicated women
aged from 40 to 50 years were selected and consent
was obtained from all the selected subjects. The
fasting blood glucose level of the group was within
the normal range (94.33±5.01 mg/dl) and gave normal
2 h response to glucose tolerance test. Glucose (50g)
was administered for conducting Glucose Tolerance
Test on the first day. After the GTT, test foods such
as broken wheat porridge, whole wheat flour porridge,
whole wheat flour chapathi were given on the second,
third and fourth day respectively. Blood samples were
drawn before and at 30, 60, 90 and 120 min after
consumption of the test foods. The blood samples
were collected through finger prick using a hypodermic
needle. Each blood sample was placed on a test strip
which was inserted into a calibrated glucometer
(Optimum/one touch) which gave direct readings after
5 seconds.
CARBOHYDRATE BASIS FOR GLYCAEMIC
INDEX (GI) DETERMINATION
GI of foods such as broken wheat porridge,
whole wheat flour porridge and whole wheat flour
chapathi was measured. The test foods contained
significant amount of available carbohydrate that
means total carbohydrate minus dietary fiber. A 50 g
available carbohydrate load had been proposed as a
reference amount for GI testing.
CALCULATION OF GLYCAEMIC INDEX
Incremental Area Under Curve (AUC) was
recommended by the Food and Agriculture
Organization (1998), and it is calculated as AUC using
the incremental AUC, ignoring area under the baseline.
Assuming that at times t 0
, t 1
, …. t n,
the blood glucose
concentrations are G 0
, G 1
, ….G n
, respectively:
AUC =
x=1
Ax
n
where Ax is the AUC for the xth time interval, and
the xth time interval is the interval between times
t x-1
and t x
.
The results were expressed as mean and
standard deviation.
RESULTS AND DISCUSSION
Glucose tolerance test was carried out in the
selected healthy women (n=6). The blood glucose
level was estimated in the empty stomach at zero
hour, after that, broken wheat porridge was given.
After 30, 60, 90 and 120 minutes, the blood glucose
levels were recorded. The next day, whole wheat flour
porridge was served and the same procedure was
followed. The mean blood glucose levels were shown
in figure – 1.
Figure 1. Mean blood glucose concentration of wheat based foods with reference to processing
Blood Glucose Concentration
(mg/dl)
160.00
140.00
120.00
100.00
80.00
60.00
40.00
20.00
0.00
140.50
127.00
123.00
117.00
94.33 120.00
98.00 96.50
109.80
94.50
92.30
96.00
81.00 83.80
86.50
Fasting 30 min 60 min 90 min 120 min
Time (Minutes)
Glucose
Broken w heat
porridge
Whole w heat flour
porridge
The mean fasting blood glucose level of the
selected healthy women was 94.33+5.01 mg/dl and
it was increased to peak level 140.5+ 6.47 mg/dl
within 30 minutes after ingestion of 50g glucose. The
blood glucose level was declined to 127+5.22,
117+3.89 and 86.5+12.82mg/dl at 60, 90 and 120
minutes respectively. The glucose concentration after
ingestion of 50g carbohydrate from the broken wheat
porridge was increased to 120+5.83 mg/dl within 30
minutes and 109.8+5.12 mg/dl at 60 minutes and
slightly increased to 96.5 ± 6.56 mg/ dl at 120 minutes.
The glucose concentration after ingestion of 50g
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