Optimising the heat moisture treatment of Morado banana starch by response surface analysis

Heat moisture treatment (HMT) was considered to modify the characteristics of Morado banana starch. Morado banana starch was isolated to a purity of 84 g/100 g dry sample (ds) with an amylose content of 31.5 g/100 g ds. Response surface analysis was used to estimate the best moisture content and heating time to obtain the optimal treatment conditions at 100°C. The optimised conditions were 32.2% for moisture content and 6.5 h of heating time to achieve the highest slowly digestible starch (SDS) and resistant starch (RS) content. Gelatinised HMT starch contained 12.1 g/100 g ds of SDS and 30.7 g/100 g ds of RS. Differential scanning calorimetry in excess water indicated structural changes, as reflected by increased phase transition temperatures and enthalpy. Fourier transformed infrared spectroscopy showed an increase in the 995/1022 cm^-1 ratio, which indicated the rearrangement of the double helices' packing within the crystalline lamella. The X-ray diffraction pattern showed that HMT increased the crystalline content from 28.9 to 31.5% compared to the native counterpart.