This study was carried out in Food Technology and Rural Industries Department laboratories, Bangladesh University of Agriculture, Mymensingh, Bangladesh.
2.1.1 Banana flour/powder Uniformly mature ripen bananas were collected from the local market. Then, the bananas were peeled and screened through a mesh to remove off fibrous portion. After that, the foaming agent (albumen) was added at the rate of 5% by weight of the mashed banana and mixed until the fine foam was obtained. This process was done quickly to avoid any browning or discoloration. The fine banana foam was spread on a tray and dried at 55o C in a cabinet drier until it became suitable for making flour. The dried sample ground into fine banana flour and stored at 4oC until further use. 2.1.2 Wheat flour (Maida) Commercially available wheat flour (Maida) was collected from the local market and used in bread preparation. 2.1.3 Formulation for bread from banana flour A different proportion of banana flour replaced the wheat flour.
2.1.4 Procedure for bread preparation The bread was made according to the method described by Kent (1994). The yeast was initially rehydrated (8 ml of water/g of yeast) in warm water (40°C) for 10 minutes to start fermentation. Sugar and salt were dissolved in a measured amount of water. All the ingredients were mixed for about 10 minutes to prepare control and fortified bread. The prepared dough was left 2 hours away to allow the fermentation process. To avoid dehydration, the dough was coated with moistened fabric. Upon two hours of fermentation, the gas involved was “knocked out” so that the temperature could stand, and the thorough mixing could be carried out. After 1 hour of resting, the dough is divided into roughly shaped loaf size (i.e., 200 gm). The dough pieces were rested at around 27°C for 10-15 minutes (1st proof) and shaped into final form to tighten the dough mechanically so that the gas and water could better spread, be stored, and placed in pre-greased baking cups. The dough was again rested in the baking pan for the final tests at 370°C for 60 minutes and then baked for 40 minutes at temperature 230°C in the oven. The loaves were allowed to cool for a minimum of 2 hr. at 24°C before evaluation.
2.2 Evaluation of physical characteristics of bread Initially, the volume of the bread is an important quality parameter. The seed transfer method, defined by Ott in 1987, was used to measure the bread volume. The volume was calculated by subtracting the measured volume of rapeseed mustard seed needed to fill an empty container and fill that same container that holds the bread. The baked bread weight and volume have also been measured following the same method.
2.3 Proximate composition analysis Prepared banana flour and white flour bread were analyzed for moisture, protein, ash, crude fiber, and total sugar content by the method described in AOAC (2010). Carbohydrate content was determined by the subtraction method.
2.4 Sensory evaluation of bread A semi-trained panel did the sensory evaluation. A 1-9-point hedonic rating test was used to assess the degree of acceptability of color, flavor, texture, and overall acceptability of banana bread containing 5%, 10%, and 15% banana flour. The score was arranged in a frequency table and statistically evaluated for variance analysis. However, if any variation existed, Duncan’s New Multiple Range Test procedure was followed.
2.5 Statistical analysis All the analysis were conducted in triplicate, and the data were all subjected to ANOVA (analysis of variance) to determine significant differences among the various samples using statistical software SPSS (version 11.0 SPSS inc. Chicago, IL, USA)) at the 0.05 level.