Our research featured nutritional bars with banana flour, pumpkin seed flour, and a 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 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 cover 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.
The proximate analysis of pumpkin seed flour, banana flour and newly formulated bars were determined by Tasnim et al. 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.. The cutting probe and compression platen of the texture 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.