Abstract
Green banana flour (GBF) is an emerging functional food ingredient derived from unripe bananas, characterized by its nutrient-rich composition. Recognized for its potential health benefits, GBF has gained increasing attention due to its unique blend of complex carbohydrates, dietary fiber, minerals, and bioactive compounds. This novel ingredient's significance lies in its ability to contribute to reduced glycemic index, enhanced gut health, and possible mitigation of diabetes and obesity risks. As a result, comprehensive studies on GBF's nutritional attributes, functional properties, and processing techniques have become essential to harness its potential for innovative food products and improved public health. The first phase of evaluated the nutritional composition (mineral content), functional properties, water absorption capacity (WAC), water solubility index and swelling power of GBF cultivars (Grand Naine, Pisang Awak, Finger Rose, Du Roi and FHIA-01). Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) were used for analysis of the GBF microstructure. The antioxidant activity of GBF cultivars was determined with DPPH and FRAP assays, while the resistant starch (RS) was determined with RS Megazyme-kit.
The study also investigated the effects of micronization on GBF's molecular, microstructural, and in vitro starch digestibility changes, as well as the potential application of micronized GBF in instant breakfast products. For proximate composition, Finger Rose and Pisang Awak had the highest protein and fat content, (4.33 g/100 g) and (0.85 g/100 g), respectively. Potassium (1033.25 mg/100 g) was the most abundant mineral in GBF cultivars, while copper (0.5 mg/100 g) was the lowest. Functional properties varied among cultivars, with Pisang Awak showing the highest water absorption capacity (67.11%) and Du Roi having the highest swelling power of 0.83 g/g at 90 °C. Electron scanning microscopy revealed the irregular shape and dense surfaces of starch granules from all GBF cultivars. The Grand Naine cultivar had the highest TPC, (524.87 mg GAE/100 g), while Du Roi had the lowest TPC at 298.73 mg GAE/100 g. With the DPPH assay, the Du Roi cultivar had the lowest antioxidant activity (301.3 mg TE/100 g d.w), while the Grand Naine cultivar had the highest antioxidant activity (474.23. mg TE/100 g d.w). A similar trend occurred with the FRAP assay with the Du Roi and Grand Naine cultivar showing the lowest and highest
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antioxidant activity, respectively. The second phase of the study evaluated the functional properties, starch molecular structure characterization, in vitro starch digestibility, and bioactive attributes of GBF cultivars grown in South Africa. The Five (5) GBF cultivars were micronized at three surface temperatures (90, 120, and 150 °C for 30 min). The micronization process improved the swelling power of GBF on Du Roi-150 °C, when assessed at 90 °C to approx. 12.21 g/g. Micronization minimally reduced resistant starch (RS) content, Grand Naine-150 °C had the highest RS content (86.50%). X-ray diffraction patterns and Fourier transform infrared spectroscopy indicated that the functional characteristics of GBF were generally unaffected by micronization. Consumer acceptability studies revealed variances in the acceptability of GBF-based instant breakfast shakes (GBF-IBS) among cultivars. Grand Naine had the highest overall acceptability (7.59), while Finger Rose had the lowest (5.14). Storage stability assessments showed varying trends in moisture content, total flavonoid content, total phenolic content, and antioxidant activity over three months. The reconstituted GBF-IBS demonstrated microbiological stability and acceptable pH and sedimentation over a 5-day period. This comprehensive research highlights the diverse attributes of GBF cultivars, the impact of micronization on functional properties, and the potential utilization of micronized GBF in instant breakfast products. The findings suggest that the Grand Naine GBF-IBS holds promise in terms of both consumer acceptability and shelf stability, thereby offering opportunities for successful market penetration and distribution.
Keywords: Green banana flour, functional properties, in vitro starch digestibility, bioactive attributes, micronization, instant breakfast products.