Textural properties and characteristics of whole green banana flour produced by air-oven and freeze-drying processing

Abstract

Structural properties of flour play a functional role in bakery products. Different heat treatments during flour production can affect the structural properties of the produced flour. Therefore, this study investigated the production of whole green banana flour (GBF) air-oven drying at 50, 80 and 110 °C as well as freeze-drying (ODF50, ODF80, ODF110 and FDF, respectively) to determine the method with least negative effects on functional properties of the flour. Results from particle size distribution indicated that drying at 50 °C generated smaller flour particles compared to ODF80 and ODF110 treatments. Freeze-dried flour (FDF) samples had significantly higher bulk density, viscosity and firmness compared to the GBF samples and the reference sample, wheat flour sample (WF) (p 0.05). While the ODF110 samples presented the highest pasting temperature (81.23 °C) and breakdown viscosity (7118.67 cp) amongst the GBF samples, ODF50 samples were the only heat-treated samples that showed similar hold, final and setback viscosity values to those found in the FDF. FTIR spectroscopy confirmed the stability of β-sheet, α-helix and amide structures in the freeze-dried samples and better granular starch structure compared to heat-treated samples. In terms of mineral contents, all GBF samples had higher concentrations of K, Mg, Ca and Zn compared to the WF which makes GBF as a better source of these nutrients.