Molecular structure and digestibility of banana flour and starch

In this study, the in vitro digestibility of flour and starch from green Musa Dwarf Red banana (MDR), Musa ABB Pisang Awak (MPA) and Musa AAA Cavendish (MC) were examined. The results showed that raw MC flour and MPA starch had the lowest digestion rates, whereas cooked MDR flour and starch had the highest resistant starch contents and cooked MPA starch had the highest slowly digestible starch contents. It was explored that many factors affected the digestibility, including chemical composition, granule morphologies, and molecular structures. The pectin in banana flour could significantly affect the in vitro digestibility of flour. Scanning electron micrographs showed that granules had a flat, oval shape. X-ray diffraction patterns revealed that flour and starch of MDR exhibited the CA-type, whereas those of the other bananas exhibited the CB-type. MPA flour and starch had the highest amylose contents. MC starch had greater proportions of long chains, whereas MPA starch had the highest proportion of short chains. The molecular weight and radius of gyration of MDR starch were the lowest. (C) 2017 Elsevier Ltd. All rights reserved.