Physico-chemical, structural, functional and powder flow properties of unripe green banana flour after the application of Refractance window drying

Abstract

In this work, unripe green banana flour (UGBF) was dried by using Refractance window (RW) drying and Hot Air (HA) oven drying, and various properties were evaluated. The water activity of RW and HA dried UGBF was 0.28 ± 0.05 and 0.39 ± 0.07, respectively. The RW drying showed a higher whiteness index (WI) of 90.26 ± 0.30, whereas HA drying showed 87.04 ± 0.45. The SEM analysis showed the presence of oblong and sphere-shaped starch granules with a smooth surface in the case of RW dried UGBF. The crystallinity of RW and HA dried UGBF were found to be 9.61% and 8.73%, respectively by using x-ray diffractograms. The gelatinization temperature and enthalpy of UGBF obtained by RW and HA drying were found to be 80.92 °C and 2.05 Jg−1K−1; 75.74 °C and 2.64 Jg−1K−1, respectively. The presence of different functional groups in UGBF was observed from FTIR analysis. The TPC, DPPH, and TFC for RW dried flour were found to be 0.85 ± 0.04 mg GAE/ g, 19.04 ± 1.03%, and 7.68 ± 0.05 µg quercetin/ g. The compressibility index and compressibility ratio of RW and HA dried UGBF are 26.49% and 1.36; 36.18% and 1.41, respectively which proves that RW dried flour has a fair flowability and intermediate cohesiveness. This study shows that RW dried flour had better quality of the product than HA drying.