Abstract:
BACKGROUND : The consumption of green banana flour (GBF) products has been linked to reduced glycemic index (GI) and low
risk of type 2 diabetes and obesity. The purpose of this study was to investigate the effect of micronization (high-intensity infrared
heating method) on the molecular, microstructure and in vitro starch digestibility of five GBF cultivars grown in
South Africa. The GBF was micronized at three surface temperatures (90, 120 and 150 °C for 30 min) and the in vitro starch
digestibility was determined with Megazyme kits.
RESULTS : Micronization at the highest temperature (150 °C) increased the swelling power by 6.00% in all five GBF cultivars
when compared to control (unmicronized GBF). Micronization slightly reduced the resistant starch (RS) of the GBF cultivars
by up to 8.63%. The FHIA-01 cultivar showed the highest RS (86.50%), whereas Grande Naine – 150 °C cultivar had the lowest
RS (76.00%). Both micronized and control GBF exhibited similar X-ray diffraction patterns with all cultivars and at all micronization
temperatures. Similarly, the functional properties of the GBF were not altered by micronization when observed with Fourier
transform infrared spectroscopy. Scanning electron microscopy showed changes in the surface morphology of starch
granules after micronization and these were dependent on temperature.
CONCLUSION : Overall, micronization at 120 °C showed the best improvement in functional properties of GBF and this makes it
suitable for potential application for the manufacture of instant breakfast products, baked goods and pasta. In addition, the
micronized GBF cultivars retained high RS, suggesting potential health benefits for people with diabetes and obesity.
