INTRODUCTION
Lifestyle changes and dietary habits of human all
over the world may affect nutrient intake. Therefore, a
healthy and balanced diet is important to meet the basic
needs of human body. Accordingly, nutrition bars/cereal
bars are the most sophisticated ready-to-eat products due
to the natural ingredients and health concerns [1].
Nowadays, a special attention has been given to byproducts
to utilize raw materials as much as practical
and avoid economic losses and environmental pollution.
Nutrition or energy bars are getting popular among
health aware consumers, school goers, and weight
watchers [2] due to its nutritive value and easy-to-use.
The increasing demand of consumers for nutritious
snacks, results the fastest outgrowth in cereal bars
market more than 20% per year [3] that provide nutrition
and convenience [4].
Health-conscious consumers prefer nutritious foods
to conventional sweets. This tendency driven to the
development of several ready-to-eat, nutritious, and
energy bars containing different fruits and nuts [5–6].
Incorporation of fruit and vegetable by-products in
nutrition bars not only adds the value to products but
also contributes to newly formulated food products and
minimize losses of raw materials by utilizing peels,
seeds, etc. [7].
Modern consumers prefer snacks not only to
satisfy their hunger but also to provide themselves with
essential nutrients. In this regard, food scientists today
are aiming to develop formulations of cereal bars with
various highly nutritious ingredients. Thus, Russian
scientists have developed a cereal bar with rolled oat
flakes, bee honey, walnut, dried cranberry, sunflower
seeds, peanut butter, dates, and prunes [8].
Snacks satisfy hunger, replace a meal, and provide
the body with essential nutrition, including protein,
carbohydrates, fats, and vitamins [9–10]. One of the
popular fruits in Bangladesh is banana [11], which is a
rich source of energy (90 kcal/100 g) [12]. In addition,
banana contains health benefiting antioxidants, crude
fiber, and minerals [13]. Health beneficiary effect of
banana pulp is due to bioactive compounds [14] such
as phenolic acid compounds, flavonoids, carotenoids,
sterols, and antimicrobial compounds. The compounds
make banana a perfect functional food [15].
Russian researchers revealed that main sources of
vegetable protein are seeds of legumes and oilseeds [16].
Pumpkin (Cucurbita pepo L.) seed has also received
considerable attention due to its nutritional value
(200 calories) and high content of amino acids, such as
palmitic, oleic, linoleic, and stearic, as well as dietary
fiber [17]. Pumpkin seed also shows pharmacological
activities including anti-fungal [18], anti-cancer [19],
anti-bacterial, anti-inflammation, and anti-oxidant
effects [20]. The robust flavor of pumpkin seed allows
using it as a valuable ingredient in cooking [21].
Pumpkin seed oil obstructs changes in plasma lipids
and blood pressure together with inadequate estrogen
availability [22].
Recent research on pumpkin seed flour indicated
that it increased reducing sugars, vitamin C, and
carotenoid content in bread [23]. 10% of pumpkin
seed flower in a cake formulation had strong effects
on physicochemical and organoleptic properties of the
cake [24]. Replacement of refined wheat flower with
pumpkin seed flower improved the textural and sensory
qualities of cookies [25]. Addition of 15% of pumpkin
seed flower into biscuit dough had a significant effect on
the rheological and sensory characteristics of the final
product [26].
Searching safe methods to extend the shelf life of
food products is a relevant task for the food industry.
Banana and pumpkin seed demonstrate significant
anti-oxidant properties. Natural antioxidants can be an
alternative to existing preservatives due to its ability
to inhibit oxidation of the main nutrients [27]. An
increasing growth of metabolic diseases and obesity
worldwide is a global problem that makes food scientists
and researchers develop not only tasty but also health
beneficial snacks.
In Bangladesh, mango or peanut bars with glucose
syrup are popular among the population, however, their
nutritional value is low and energy value is high. We
did not find research on the quality of bars enriched
with pumpkin seed flour. The findings of this work will
be beneficial for the local food industry and will reduce
malnutrition problems.
Our work aimed to formulate bars with banana flour
and pumpkin seed flour and evaluate their nutritional,
textural, and sensory quality.
STUDY OBJECTS AND METHODS
Our research featured nutritional bars with banana
flour, pumpkin seed flour, and the mix of banana and
pumpkin seed flours.
Materials. Raw materials, such as brown sugar,
sunflower oil, oats, corn flakes, chickpea, nuts, and
raisins, were purchased from the local supermarket.
All the ingredients were purchased evaluated for safety
standards. The following technical and food safety
information was evaluated: name of the products
with batch number, physicochemical composition,
information about recognized food allergens, sensory
properties (appearance, flavor, and aroma), microbial
information, and shelf life. To store the ingredients,
we used high-density polyethylene and low-density
polyethylene as a packaging material.
Pumpkin seed flour preparation. Pumpkin seed
was collected from the local market as a by-product of
pumpkin processing. Seeds were cleaned with potable
water and sun dried to remove extra water from the
surface of the seeds. After that, the pumpkin seed with
shell was dried in a cabinet dryer (M-1816, Modern
Laboratory Equipment, USA) at 55°C for 4 h, ground
using a grinder (Panasonic Mixer Grinder MX-AC555,
India), and finally sieved through 20 mesh (0.841 mm)
to get fine pumpkin seed flour. Then the pumpkin seed
flour was weighed and vacuum packed for further use.
Banana flour preparation. Ripe banana (Sagor
variety) was collected from the Horticulture center
of Bangladesh Agricultural University, Bangladesh.
Banana was sorted to remove defected banana and
washed with running water. Banana was sliced into
0.5 cm thick pieces with peel. To reduce enzymatic
browning, the slices were then dipped in 10% citric acid
solution for 10 min. The peel was removed and sliced
banana was air dried to remove extra water. Banana
then was dried in a cabinet dryer (M-1816, Modern
Laboratory Equipment, USA) at 60°C for 5 h, ground
using a grinder (Panasonic Mixer Grinder MX-AC555,
India), and sieved through 30 mesh (0.595 mm) to get
fine flour. The banana flour was vacuum packed for
further use.
Bar preparation. Three nutrition bars were
formulated: with banana flour, with pumpkin seed flour,
and with the mixed flours (Table 1). Amounts of banana
flour, pumpkin seed flour, salt, and lecithin were chosen
based on trial and error methods to find the optimum
color and texture of the bars. Similarly, the other
ingredients were chosen based on consumer interest by
survey (data not shown).
Figure 1 demonstrates the production process of
nutrition bars. At first, all the dry ingredients, such
as oats, corn flakes, pumpkin seed flour and/or banana
flour, nuts, raisins, chickpea, and skim milk powder,
were weighed and mixed gently. The heated sugar syrup,
sunflower oil, and lecithin were added into the dry
mixture and mixed. The mixture was heated in a water
bath at 70°C. The mixture then was compressed, dried
in an oven at 110°C for 15 min, and cut into uniform
pieces (12×2.5×2.0 cm) and cooled at room temperature
(25°C) for 30 min. The bars were packed in low and high
density package and then kept in a sealed container at
ambient temperature for further analysis.
284
Habiba U. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 282–289
The proximate analysis of pumpkin seed
flour, banana flour and newly formulated bars were
determined by Tasnim et al. [28] using the guidelines
and methods of AOAC (Association of Official
Analytical Chemists): moisture content ‒ method 950.46;
crude protein, 981.10; crude fat, 922.06; crude fiber,
978.10; and ash, 920153.00. Total carbohydrate contents
in the both flours and nutrition bar were estimated
according to the methods of Food and Agriculture
Organization (FAO) [29]. Mineral contents were
determined following the procedures described in [30].
Inductively coupled plasma emission spectrophotometer
was used to analyze calcium, iron, magnesium,
phosphorus, and potassium in the samples.
The antioxidant activities of flours and nutrition
bars were determined by using the 2,2-Diphenyl-1-
picrylhydrazyl (DPPH) free radical scavenging modified
method, as described by Brand-Williams et al. [31].
In methanol, DPPH in oxidized form gives a deep
violet color. However, antioxidant compounds usually
denote an electron to DPPH, thus causing reduction. In
reduction form, DPPH turns to yellow. A 0.002% DPPH
solution was prepared in methanol and measured at
517 nm. Sample extracts (50 μL) were mixed with 3 mL
of the DPPH solution and kept for 15 min in the dark.
Then the absorbance was measured again at 517 nm.
The total phenolic content in the banana flour,
pumpkin seed flour, and nutrition bar was determined
using the modified method of Odabasoglu et al. [32].
The total phenolic content of the samples was calculated
as gallic acid equivalents (mg GAE/g) and every
experiment was performed in triplicate. Peroxide
value, free fatty acids, and thiobarbuturic acid (MA/kg
sample), which are generally used to evaluate lipid
oxidation in food products, were measured in
accordance with Rukunudin et al., Sallam et al. and
Schmedes and Holmer, respectively [33–35].
The color characteristics of the nutrition bar were
determined using a Minolta colorimeter (Cr-400/410,
Japan). The CIELB scale with L*, a* and b* was used
to analyze the results, where L* showed the lightness
(L* = 0, black and L* = 100, white) of the product,
a* showed red-green color (+60 to –60), and b* showed
yellow-blue color (+60 to –60) [36].
The textural parameters of the nutrition bar under
the study (12×2.5×2.0 cm) were determined using a
texture analyzer (Stable Micro Systems, UK) and the
modified method described by Momin et al. [37]. The
cutting probe and compression platen of the texture
Table 1 Formulation of nutrition bars with banana flour,
pumpkin seed flour, and mixed flour, g/100 g
Ingredient Banana
flour
Pumpkin
seed flour
Mixed
flour
Oats 10 10 10
Corn flakes 10 10 10
Pumpkin seed flour 0 15 10
Banana flour 15 0 5
Sunflower oil 10 10 10
Nuts 7 7 7
Raisins 6 6 6
Water 6 6 6
Salt 0.2 0.2 0.2
Lecithin 0.8 0.8 0.8
Glucose syrup 10 10 10
Brown sugar 10 10 10
Chickpea 5 5 5
Skim milk powder 10 10 10
Figure 1 Flowchart of nutrition bars production process
Heating in a water bath (70°C)
Pressing
Drying in an oven (110°C, 15 min)
Cutting (12×2.5×2.0 cm)
Cooling (room temperature, 30 min)
Packaging
Oats, corn flakes, pumpkin seed flour
and/or banana flour, nuts, raisins,
Chickpea, skim milk powder
Sunflower oil, salt, brown sugar,
lecit hin, glucose syrup
Dry ingredients Aglutina te syrup
285
Habiba U. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 282–289
analyzer were calibrated at a 20 cm distance using data
acquisition software. The following parameters were
used for the analysis: pre-test speed 1.0 mm/s, trigger
5 g, and post-test speed 10 mm/s. Each sample was
texted in three replications.
Three different types of the nutrition bars were
evaluated by 10 semi-trained panelists for color, flavor,
texture, and overall acceptability. For statistical analysis,
the 9-point hedonic rating test [38] was used to access
the sensory quality of the newly nutrition bar. The
analysis was performed three times. The significant
difference of mean values was assessed by the analysis
of variance (ANOVA) using a software STATISTIC
version 8.1. For the significant difference, DMRT was
applied.
RESULTS AND DISCUSSION
Table 2 shows the nutrient composition of pumpkin
seed flour and banana flour. It is remarkable that the
pumpkin seed flour contained significantly (P < 0.5)
higher amount of protein and fat but lower amount of
water, crude fiber, and carbohydrate, compared to the
banana flour. Among the minerals, calcium, magnesium,
and phosphorus concentrations were higher in the
pumpkin seed flour and iron and potassium was higher
in the banana flour (Table 2). The energy value of the
pumpkin seed flour (604.44 kcal/100 g) was also higher
than that of the banana flour (385 kcal/100 g).
The nutrition bars developed (Fig. 2) were analyzed
to determine their nutritional value (Table 3). Dietary
protein is one of the vital nutrients for human due to
its functional properties, including the improving of
health growing of muscles [28, 39]. All the nutrition
bars under study may easily supply recommended daily
allowance for protein. The mixed nutrition bar contained
significantly higher amount of protein compared to the
others.
The fat content of the mixed bar sample was
significantly higher than of the sample with banana flour
and the bar with the pumpkin seed flour. The ash content
was higher in the pumpkin seed flour bar, which did not
significantly differ from the mixed flour sample.
The total carbohydrate content solely depends on
the other nutrient components of the nutrition bars. The
mixed flour nutrition bar had the lowest carbohydrate
(66.11%) content compared to the pumpkin seed flour
(73.19%) and banana flour (80.20%) nutrition bar. The
banana flour and mixed flour nutrition bars had the
lowest and highest energy values, respectively (398.60
and 424.94 kcal/100 g).
Table 2 Nutrient content of pumpkin seed flour and banana
flour (per 100 g)
Ingredients Pumpkin seed flour Banana flour
Moisture, % 1.20b ± 0.05 3.00a ± 0.75
Carbohydrate, % 14.47b ± 1.00 78.30a ± 1.50
Protein, % 29.54a ± 1.50 3.9b ± 0.50
Fat, % 47.6a ± 2.35 1.8b ± 0.45
Crude fiber, % 2.13b ± 0.25 9.9a ± 1.15
Calcium, mg 30.07a ± 2.00 22.96b ± 2.50
Magnesium, mg 1103.19a ± 10.50 108.05a ± 5.25
Phosphorus, mg 3205.13 a ± 11.20 74.54 a ± 3.50
Iron, mg 0.31 a ± 0.01 1.22 a ± 0.04
Potassium, mg 809.03 a ± 3.25 1491.88 a ± 8.50
Energy, kcal 604.44 385.00
Values are expressed as mean ± SD. Means in the same row with
different superscripts were significantly different (P ≤ 0.05)
a b c
Figure 2 Appearance of nutrition bars with banana flour (a),
pumpkin seed flour (b), and the mix of banana and pumpkin
flour (c)
Table 3 Nutritional composition of nutrition bars with banana flour, pumpkin seed flor, and mixed flour
Composition Banana flour Pumpkin seed flour Mixed flour
Moisture content, % 6.94a ± 1.0 6.61a±1.25 6.82a ± 1.55
Ash content, % 1.16b ± 0.05 1.46a ± 0.35 1.32a ± 0.50
Protein content, % 5.50c ± 0.75 9.74b ± 1.15 14.25a ± 1.55
Fat content, % 6.20c ± 0.50 9.05b ± 0.45 11.50a ± 0.75
Carbohydrate content, % 80.20a ± 2.50 73.19b ± 3.05 66.11b ± 3.00
Energy content, kcal 398.60b ± 3.00 412.72a ± 2.75 424.94a ± 1.80
Calcium (Ca), mg 3.75b ± 0.05 3.10c ± 0.25 4.90a ± 0.75
Iron (Fe), mg 0.04b ± 0.02 0.2a ± 0.05 0.05b ± 0.03
Magnesium (Mg), mg 15.20c ± 0.05 153.45a ± 5.00 118.25b ± 4.25
Phosphorus (P), mg 10.20c ± 1.10 450.75a ± 2.55 345.20b ± 2.35
Potassium (K), mg 115.20c ± 5.20 220.45a ± 5.55 150.79b ± 4.75
Values are expressed as mean ± SD. Means in the same row with different superscripts were significantly different (P ≤ 0.05)
286
Habiba U. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 282–289
Iron is an essential element whose deficiency causes
anemia [40]. According to Institute of Medicine, Food
and Nutrition Board, iron and calcium contents in 100 g
of the nutrition bars would contribute less than 4 and
10%, respectively, of recommended daily allowance
for men aged 19–50 years reported in 2001 [41]. Our
results also indicated that 100 g of the nutrition bars
with pumpkin seed flour, banana flour, and mixed flours
would provide more than 45, 32, and 10% of phosphorus,
respectively [42].
The total phenolic content was found to be highest in
the mix flour bar (8.55 ± 0.05 mg GAE/g), compared to
that in the banana flour and pumpkin seed flour samples
(7.10 ± 0.03 and 6.45 ± 0.07 mg GAE/g, respectively
(Table 4). Phenolics combat with free radicals, which are
harmful to human, and stop their further activity [43].
DPPH inhibition level indicates free radical scavenging
property and is a measure of antioxidant potential. The
DPPH radical scavenging activity of the nutrition bars
depended on an amount of phenolics in the banana
flour, pumpkin seed flour, chickpea, and raisins.
Food materials rich in phenolics exhibit a high DPPH
inhibition level as reported by Abu El-Baky, who studied
phenolic compounds in spirulina and their protective
properties [44]. In our research, the mixed flour nutrition
bar demonstrated the highest DPPH inhibition level
(45.35 ± 0.10%) and, consequently, better antioxidant
activity. The lowest one was found to be 38.25 ± 0.45%
(pumpkin seed flour).
The textural properties of the bar samples were
measured using a texture analyzer and included
hardness and fracturability (Table 4). The mix sample
had the highest hardness, while the pumpkin seed flour
bar showed the lowest hardness. Fracturability of banana
flour bar was the lowest but it did not significantly
differ from that of the banana sample, so their textural
properties were close. Among the other samples, the
pumpkin seed flour bar had the least hardness.
The color of food products is a critical parameter,
especially for bars, which are potentially targeted
on children and women. Figure 3 shows the color
parameters for the nutrition bars. There was a significant
difference (P < 0.05) in L* values among all the samples.
This could be due to the presence of polyphenols in
banana flour, pumpkin seed flour, and chick pea. The
pumpkin seed flour bar showed a lower L* value than the
other bars.
All the nutrition bars demonstrated positive a*
(redness) and b* values (yellowness). The pumpkin seed
flour sample had significantly (P < 0.5) higher a* value
than the other nutrition bars, which can be explained
by the presence of higher polyphenol concentrations in
the raw materials such as pumpkin seed flour and chick
pea. The positive b* value of all the nutrition bars could
be due to the presence of cornflakes, chickpea, and
pumpkin seed flour.
Table 4 Total phenolic content, antioxidant activity, and textural properties of nutrition bar with different types of flour
Nutrition bar Total phenolic
content, mg GAE
DPPH
inhibition, %
Texture analysis
Hardness, gf Fracturability, s
Banana flour 7.10b ± 0.03 40.50b ± 0.35 41254.00b ± 210.80 17.85b ± 2.10
Pumpkin seed flour 6.45c ± 0.07 38.25c ± 0.45 39806.00c ± 205.07 17.50b ± 1.35
Mixed flour 8.55a ± 0.05 45.35a ± 0.10 47453.00a ± 195.70 18.95a ± 2.45
Values are expressed as mean ± SD. Means in the same column with different superscripts were significantly different (P ≤ 0.05)
Figure 3 Color parameter of nutrition bar with banana
flour (a), pumpkin seed flour (b), and the mix of the flour (c)
a b c
Table 5 Sensory evaluation of nutrition bars
Nutrition bars Sensory attributes
Color Flavor Texture Taste Overall acceptability
Banana flour 6.60a ± 0.50 5.80a ± 0.65 5.80a ± 0.85 5.20a ± 0.50 5.20a ± 0.85
Pumpkin seed flour 6.90b ± 0.43 7.20b ± 0.50 6.80b ± 0.65 6.20a ± 0.80 6.60b ± 0.95
Mixed flour 7.80c ± 0.72 8.20c ± 0.95 7.20b ± 0.45 7.60b ± 0.75 7.80c ± 0.55
LSD value 0.96 0.94 0.94 1.16 0.96
Values are expressed as mean ± SD. Means in the same column with different superscripts were significantly different (P ≤ 0.05)
L* a* b*
287
Habiba U. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 282–289
Sensory assay of the newly nutrition bars included
color, flavor, texture, taste, and overall acceptability
(Table 5). The analysis showed that there was a
significant (P < 0.5) difference in the sensory attributes
among banana flour, pumpkin seed flour, and mixed
flour bars. However, the sample with mixed flour
demonstrated better sensory properties compared to the
other nutrition bars.
We assessed changes in lipid peroxidation in the
nutrition bar with the mix of banana flour and pumpkin
seed flour during two months of storage at room
temperature (25oC). Peroxide value, free fatty acids,
and thiobarbuturic acid values of the bar sample are
demonstrated in Table 6.
On day 60, the moisture content in the sample
slightly increased, regardless of the packaging
material used. Between the packaging materials (lowdensity
polyethylene and high-density polyethylene),
a significant difference (P < 0.5) was observed in the
moisture content. Chemical changes in the mixed bar
were found low in the samples packed in the highdensity
polyethylene compared to those packed in the
low-density polyethylene. After two months of storage,
peroxide value, free fatty acids, and thiobarbuturic acid
in the mixed nutrition bar became 7.5, 2.1., and 1.5 times
higher, respectively.
CONCLUSION
We evaluated the quality of nutrition bars containing
banana flour, pumpkin seed flour, and mixed flour. The
samples with both banana flour and pumpkin seed flour
(mixed flour) showed good nutritional quality, with
higher amount of protein (14.25 ± 1.55%), fat (11.50 ±
0.75%), and calcium (4.90 ± 0.75 mg/100 g) content
compared to the other bars. However, the sample based
on pumpkin seed flour demonstrated higher amount
of ash (1.46 ± 0.35 mg/100 g), magnesium (153.45 ±
5.00 mg/100 g), potassium (450.75 ± 2.55 mg/100 g), and
phosphorus (220.45 ± 5.55 mg/100 g) content.
Antioxidant activity (45.35 ± 0.10% DPPH
inhibition), total phenolic content (8.55 ± 0.05 mg GAE/
bar), and textural properties (47453 ± 195.70 gf hardness
and 18.95 ± 2.45 s fracturability) were significantly the
highest in the mixed flour nutrition bar. Sensory analysis
found that the mixed flour nutrition bar was attributed as
the best formulation.
Thus, banana flour and pumpkin seed flour showed
considerable potential as ingredients in the formulation
of nutrition bars and improved their nutrient value.
Further studies are needed to determine the shelf life
and in vivo metabolism of nutrition bars enriched with
banana flour and/or pumpkin seed flour.
CONTRIBUTION
U. Habiba: conceptualization, methodology,
investigation, visualization, and drafting manuscript.
M.A. Robin: conceptualization, investigation,
visualization, and drafting manuscript. M.M. Hasan:
conceptualization, investigation, and drafting
manuscript. M.A. Toma: data analysis, methodology,
drafting manuscript, and writing. D. Akhter:
data analysis and writing. M.A.R. Mazumder:
conceptualization, methodology, project administration,
writing, and supervision.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGMENTS
The authors gratefully acknowledge Department
of Food Technology and Rural Industries, Bangladesh
Agricultural University, Bangladesh for project work
research grants.
