African Journal of Food Science Vol. 4(8) pp. 514 - 521, August 2010
Available online http://www.academicjournals.org/ajfs
ISSN 1996-0794 ©2010 Academic Journals
Full Length Research Paper
Glycemic indices of processed unripe plantain
(Musa paradisiaca) meals
Oboh Henrietta Ayodele* and Erema Victor Godwin
Department of Medical Biochemistry, School of Basic Medical Science, College of Medicine, University of Benin, Benin
City, Edo state, Nigeria.
Accepted 9 August, 2010
The glycemic response of processed unripe plantain (Musa paradisiaca) commonly consumed in
Nigeria were assessed using sixty healthy subjects. The post-prandial serum glucose concentration
over a period of 2 h were determined half hourly, after the ingestion of the test foods. Blood glucose
curves were constructed to calculate the glycemic index of the test foods. The results revealed that the
Glycemic Indices (GI) of boiled plantain (Bp), fried plantain (Fp), roasted plantain (Rp), boiled and
pounded plantain (BPp) and plantain flour (Pf) did not show any differences at (p < 0.05). However,
roasted plantain gave the lowest glycemic index and the value was significantly lower than the other
test foods. The processed plantain meal elicit low postprandial rise of blood glucose and can be
recommended for use in the diet of diabetic Nigerians.
Key words: Plantain (Musa paradisiaca), food processing (boiling, roasting, frying, drying and pounding),
Glycemic index, post prandial blood glucose, diet for diabetics.
Plantain belongs to the Musacace family and is cultivated
in many tropics and subtropical countries of the world. It
ranks third after yams and cassava for sustainability in
Nigeria (Akomolafe and Aborisade, 2007). Plantain
(Musa Paradisiaca) is a rhizomatous perennial crop used
as a source of starchy staple for millions of people in
Nigeria.(Adeniyi et al., 2006). Mature plantain pulp is very
rich in iron, potassium, vitamin A and ascorbic acid but
low in protein (Adegboyega, 2006).The proximate
content, functional characteristics and properties of
starch of ripe and unripe plantains have been evaluated
(Izunfuo and Omuaru, 2006; Osundahunsi, 2009). The
processing, utilization and effect of storage have been
reported (Niba, 2004; Onwuka and Onwuka, 2005).
Unripe plantain meal is usually consumed by Nigerian
diabetics to reduce postprandial glucose level. This is
because the propensity of individuals to develop diabetes
and obesity is due to the increased consumption of
carbohydrate rich foods with a high Glycemic index
*Corresponding author. E-mail:firstname.lastname@example.org.
Tel: 234-803-817-1016, 234-802-316-8660.
(Willett et al., 2002; Foster et al., 2003).
The Glyemic index of some Nigerian foods have been
determined (Fasanmade et al., 2007; Jimoh et al., 2008;
Oboh and Agu, 2010). This study aimed to determine the
Glycemic index, load and Glycemic response of
processed unripe plantain in non-diabetic healthy
MATERIALS AND METHODS
Collection of samples
Seven bunches of mature freshly cut unripe green plantain (Musa
paradisiaca) were obtained from a farm at the University of Benin,
Benin City, Edo State, Nigeria. They were separated into five
groups and processed for the experimental diets.
Body weight was measured (to the nearest 0.5 kg) with the subject
standing motion less on the bathroom weighing scale. The weighing
scale was standardized every day with a weight of 50 kg. Height
was measured (to the nearest 0.1 cm) with the subject standing in
an erect position against a vertical scale of portable stadiometer
and with the head positioned so that the top of the external auditory
meatus was in level with the inferior margin of the bony orbit. BMI
was calculated as weight in kilograms divided by squared height in
Preparation of processed samples
Boiled plantain (Bp)
Freshly harvested unripe plantain (Musa paradisiaca) was peeled
and 5 kg quantity was cut into (10 mm long) and was boiled in 5 L
of water containing 1 gm of salt for 1 h. The water was drained and
the plantain was served to the subjects.
Fried plantain (Fp)
The unripe plantain was sliced diagonally into pieces (2 mm thick),
0.5 gm salt was sprinkled on the sliced plantain and it was deep
fried in 2 L of preheated groundnut oil for 20 min, until golden
yellow/brown color developed. The fried plantain were placed on
paper napkins to drain off the excess oil and served to the subjects.
Roasted plantain (Rp)
Fingers of peeled unripe plantain were placed on a wire gauze over
a red-hot charcoal stove and roasted for 30 min with frequent
turning to prevent the plantain from charring. When the plantain
was brown evenly, the plantain was removed and served to
subjects. This is called “bolae” or “bolle” in southern Nigeria.
Boiled and pounded plantain (BPp)
The unripe plantain 5 kg was boiled in 5 L of water for 1 h. The
water was drained and the boiled plantain was transferred into a
wooden mortar and pounded to obtain a smooth consistent paste.
Plantain flour (Pf)
Unripe plantain was sliced and sun-dried for about 3 weeks to a
constant weight, and ground into flour using a warring blender. The
flour was passed through a 0.5 cm mesh sieve, and stored in an
airtight container at room temperature (25°
C). The plantain flour
meal was prepared by stirring continuously 225 g flour in a pot of
250 ml boiling water until well cooked to form a thick, smooth brown
The BPp and Pf were served with a bowl of soup made up of
tomato sauce (containing fresh pepper, tomato, onions grounded to
a smooth paste and mixed with 100 ml of hot red palm oil) and 30 g
of boiled beef meat as eaten in the Nigerian culture.
Proximate analysis for processed plantain
The processed plantains were analyzed for moisture content, ash,
crude protein, and crude fiber by the AOAC (1983) method.
Carbohydrate was determined by difference.
Non-diabetic volunteers (n = 50; 35 males, 15 females, aged 21 –
30 years) were offered a single meal of one of the six test foods on
different days. The other 10 persons were administered 50 g
glucose in 300 ml distilled water. The serving size was determined
Ayodele and Erema 515
by calculating the quantity of the test food that will give 50 gm
carbohydrate when eaten. Blood samples were collected before
feeding (0 min) and at 30, 60, 120 and 180 min after the test meal
was given. The subjects were not allowed to perform strenuous
activities on the day of GI determination.
Determination of blood glucose
Blood glucose was obtained by venipuncture between 9 – 10 am
after an overnight fast of > 12 h. The samples were collected into
sterilized centrifuge tubes and centrifuged for 10 min at 4,000 rpm.
The serum was collected and used. Glucose concentration was
determined in duplicates by the methods of Barham and Trinder
(1972) using Spectrophotomer (GENESYS 10, manufacturer) and
GI was calculated from the blood glucose response curve. The
incremental area under the curve (IAUC) for each test meal for
each subject was calculated as the sum of the surface triangle and
trapezoids of the blood glucose curve and the horizontal baseline
running in parallel to the time axis from the beginning of the curve
to the point at 180 min. This reflect the total rise in blood glucose
concentration after eating the test food.
The IAUC for test and control (50 g of pure glucose - IAUCS) was
obtained in a similar way.
GI for each food was calculated from the formulae:
GI = (IAUC/IAUCS) × 100%.
The average of the two measures for each subject was taken as the
GI for that test food for the subject. The GI for each food was finally
calculated as the mean of the average of the GIs in ten subjects in
Statistical analysis was done by SPSS 15 Statistical programme.
Comparisons between test foods: Boiled plantain (Bp), fried
plantain (Fp), roasted plantain (Rp), boiled and pounded plantain
(BPp) and plantain flour (Pf) and control were done by the student’s
t-test. ANOVA and Duncan multiple range tests were used to
measure significant difference among the GI of tests foods.
Statistical significant was set at p < 0.05.
The Anthropometry of control and test subjects are
represented in Table 1. The volunteers were aged
between 20.00 ± 0.86 to 24.83 ± 0.40. Their estimated
body mass index (BMI) were 20.52 ± 2.20 to 22.85 ± 1.00
kg/m2. The proximate analysis of the processed plantain
meals are represented in Table 2.
The percentage carbohydrate contents ranged from
32% in BPp to 78% in Fp. BPp had the lowest
carbohydrate content while Fp had the highest value. Fp
also had the highest lipid value of 5%, while fibre content
had the highest of 0.94% in Pf. Processing affected the
proximate contents. Percentage lipid was highest in the
fried plantain meal. Boiling (Moist heat treatment),
516 Afr. J. Food Sci.
Table 1. Anthropometry of control and test-groups.
Parameter Control group BP FP BPP PF RP
Age (Years) 22.00 ± 0.86 24.83 ± 0.40 23.83 ± 0.70 24.50 ± 1.45 22.00 ± 1.73 19.83 ± 0.90
Height (cm) 172.16 ± 4.07 175.16 ± 1.62 175.00 ± 2.47 167.83 ± 5.13 67.83 ± 6.69 60.00 ± 7.02
Weight (kg) 63.67 ± 3.30 66.00 ± 0.35 61.00 ± 1.60 64.00 ± 2.35 182.00 ± 6.93 169.33 ± 10.34
BMI (kg/m2) 21.44 ± 0.71 21.55 ± 0.64 21.43 ± 0.69 22.85 ± 1.00 20.52 ± 2.20 20.89 ± 1.31
Values are the means ± standard errors of means (SEM) of 10 individuals per group.
Table 2. Proximate analysis of the processed unripe plantain (musa paradisiaca) meals on dry weight percent.
Sample Lipid Ash Fibre Crude protein Carbohydrate Moisture
Boiled plantain (Bp) 1.35 ± 0.024 1.63 ± 0.02 0.81 ±0.00 3.13 ± 0.02 36.28 56.80 ± 0.08
Roasted plantain (Rp) 0.30 ± 0.00 2.0 ±0.00 0.24 ± 0.048 0.47 ± 0.015 45.74 51.25 ± 0.75
Fried plantain (Fp) 5.44 0 ± 0.055
1.84 ± 0.024 0.72 ± 0.004 3.36 ± 0.08 78.40 10.24 ± 0.027
Boiled and pounded plantain (BPp) 1.32 ± 0.012 1.35 ±
0.014 0.49 ±
0.006 3.22 ± 0.18 32.25 61.37 ± 0.095
Plantain flour (Pf) 0.50 ± 0.10 200 ±
0.00 a 0.94 ±0.00 0.90 ±0.05 62.16 33.50 ±0.495
Values are the means ± standard errors of means (SEM) of four (4) determinants.
Table 3. Available carbohydrate in 100 g of the processed unripe plantain (musa paradisiaca) meals and serving sizes used for
glycemic index determination.
Food sample Available carbohydrate in 100 g of
processed food (g) Serving size of processed
Boiled plantain (Bp) 40.25 124.35
Roasted plantain (Rp) 47.28 224.38
Fried plantain (Fp) 79.56 62.85
Boiled and pounded plantain (BPp) 36.17 138.24
Plantain flour (Pf) 63.61 120.96
increased moisture in the boiled and boiled/pounded
plantain. However, moisture was reduced in fried and
plantain flour. The dried/fried product (Pf/Fp) had more
carbohydrate content. The moisture content had an
inverse effect on the carbohydrate content. Fiber was
highest in the plantain flour than the other processed
Table 3 represents the available carbohydrate content
in 100 g of the processed meals and the serving sizes
containing 50 g available carbohydrate. Fp had the
highest available carbohydrate of the processed foods
while Roasted plantain had the highest serving size.
The GI of the five processed plantain meals are shown
in Table 4 and Figure 6.The GI range from 57 for Rp to
67 for BPp. The highest GI is 67 for BPp, while Rp had
the lowest GI of 57. Fp had the highest Glycemic load
(GL) of 50, the lowest is 21 for BPp. The GI of the
processed unripe plantain did not differ significantly but
Rp had a significantly lower GI when compared to other
Figures 1 - 5 shows the blood glucose response curves
for the processed plantain meals Glycemic responses
after ingestion of the processed test meals varied. A
small peak of blood glucose at 60 min was observed for
all the test foods accompanied by a gradual decline in
plasma glucose. The control group showed that blood
glucose concentration rose to a peak at 30 min and
declined rapidly at 90 min until 180 min. In comparison,
the subjects who ate the processed plantain meal,
showed that the blood glucose values rose to a small
peak after 1 h for all the processed foods with a more
gradual decline in blood glucose.
Different factors can influence blood glucose response.
These include the physical form of the food, degree and
type of processing, e.g., cooking method and time,
amount of heat or moisture used (Pi-sunyer, 2002), type
of starch (that is, amylose versus amylopectin), and Co
ingestion of protein (Manders et al., 2005) and fat (Collier
et al., 1984) with test foods. The effect of moist heat
treatment showed that faster rates of digestion were
Ayodele and Erema 517
Table 4. Glycemic indices and load of the processed unripe plantain (Musa paradisiaca).
Food Samples GI GL
Boiled plantain (Bp) 64.944 ± 10a 23.030.49d
Roasted plantain (Rp) 56.87 ± 9b 26.02 ± 0.42d
Fried plantain (Fp) 64.93 ± 9a 50.44 ± 0.84 c
Boiled and pounded plantain (BPp) 66.60 ± 3a 21.15 ± 0.84 d
Plantain flour (Pf) 65.05 ± 1a 40.44 ± 0.84 c
Values are the means + standard errors of means (SEM) of ten individuals per group. Means with
same superscript are not significantly different (P < 0.05).
0 30 60 120 180
Concentration in mg/dl
Time in mins.
Figure 1. Graphical representation showing the glucose response area for boiled plantain (BP) and control (glucose D).
achieved with boiled (Bp) and boiled and pounded
plantain (BPp) than roasting. Cooking of the plantain
meals allowed the starch granules to swell, gelatinize and
increase the availability to amylase digestion and thereby
increasing starch digestibility (Bahado-sigh et al., 2006).
The tests foods (boiled and pounded plantain and
plantain flour) were swallowed without chewing. Chewing
would have reduced particle size and increased the
surface area of exposure and facilitate salivary amylase
digestion of carbohydrate (Omoregie and Osagie, 2008)
The results revealed no significant difference (P < 0.05)
in the GI among the test foods studied except Rp which
was significantly lower in comparison to other processed
meal. Roasted and baked foods have a higher GI than
fried/boiled meals (Bahado-sigh et al., 2006). However,
our results revealed otherwise. The roasted plantain meal
had the lowest GI. This could be due to the fact that
although dry heat was utilized and could have caused
518 Afr. J. Food Sci.
0 30 60 120 180
Concentration in mg/dl
Time in mins
Figure 2. Graphical representation showing the Glucose Response area for roasted
plantain (RP) and control (Glucose D).
0 30 60 120 180
Concentration in mg/dl
Time in mins.
Figure 3. Graphical representation showing the glucose response area for fried plantain
(FP) and control (glucose D).
Ayodele and Erema 519
0 30 60 120 180
Concentration in mg/dl
Time in mins
Figure 4. Graphical representation showing the glucose response area for pounded plantain
(BPp) and control (glucose D).
0 30 60 120 180
Concentration in mg/dl
Time in mins
Figure 5. Graphical representation showing the glucose response area for plantain flour (Pf)
and control (glucose D).
520 Afr. J. Food Sci.
BOILED PLANTAIN (Bp)
ROASTED PLANTAIN (Rp)
FRIED PLANTAIN (Fp)
BOILED & POUNDED
PLANTAIN FLOUR (Pf)
GLYCEMIC INDEX (%)
Figure 6. Glycemic indices of plantain meal.
loss of water, the heat applied by roasting with hot coals,
may not be sufficient to fully gelatinize the starch
granules thus making it resistant for amylase digestion
and release of glucose into the bloodstream.
Processing of the unripe plantain meals alters the
physical form of the carbohydrate and thus may influence
the Glycemic Index of the test foods. The greater the
changes of the physical form of the meal, the higher the
glycemic response (Wolever et al., 1986). One of the
processing methods utilized involved pounding of boiled
plantain with a wooden mortar and pestle with intermittent
addition of water. This gives a softer and finer texture
thus increasing the surface area for enzyme digestion
leading to rapid glucose absorption.
Although, roasted, boiled and fried plantains were
chewed, roasted plantain (Rp) still gave a significantly
lower GI than the other meals. The oil associated with
fried plantain could have contributed to the lowering of
the GI. The GI values of the test foods did not show a
significant difference at P < 0.05.
The roasted plantain (Rp) meal showed lesser glucose
response than other processed test meals in the
experimental subjects probably because the unripe
plantain starches have only small concentrations of free
sugars and rapidly digestible starch (Ramdath et al.,
2004).The slow digestion of unripe plantain starch is
probably related to properties of the starch granule (e.g.,
amylose: amylopectin ratio) and its physical association
with the plant cell wall (fiber), which could contribute to
reducing total starch gelatinization.
The amount of carbohydrate as well as the type of
carbohydrate in a food will influence its effect on blood
glucose level (Sheard et al., 2004). The specific type of
carbohydrate present in a particular food does not always
accurately predict its effect on blood glucose (Wolever,
The roasted plantain (Rp) meal had the lowest Glycemic
index of all the processed test meal. The knowledge of an
effective processing method for dietary staples to control
and reduce hyperglycemia is essential in the treatment of
diabetes. This is because diet management is crucial to
control spikes in blood glucose levels. The findings of this
study are useful for health care providers and nutritionists
in Diabetes Education
The Authors are grateful to Dr. S. I. Obahiagbon of the
Central Laboratory National Institute for Oil Palm
Research (NIFOR), Edo State, Nigeria for his assistance
in carrying out the proximate analysis of the test
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