Effects of different drying conditions on the starch content, thermal properties and some of the physicochemical parameters of whole green banana flour.

Abstract

The physicochemical and thermal properties of whole green banana flour obtained from oven air-drying (ODF) at three temperatures (50, 80 and 110 °C) and freeze-drying (FDF) were compared to wheat flour (WF). Lightness and yellowness were negatively affected by the temperature increment. The FDF samples exhibited higher a* and L* values and had the closest browning index to WF (P-value < 0.01). Also, the ODF50 samples had the highest emulsion activity, whereas FDF had the highest emulsion stability (P-value < 0.05). The oil holding and water holding capacities of the FDF samples were significantly higher than all other samples (P-value < 0.05). A higher resistant starch content was found in the FDF (46.72%) and ODF50 (44.58%) samples. The ODF50 samples had the highest amylose content and degree of crystallinity (P-value < 0.05) as well as the lowest gelatinization temperature amongst the green banana flour samples (4.69 °C). Oven air-drying increased the gelatinization temperature drastically for all GBF samples (P-value < 0.05). In conclusion, drying the whole green banana at 50 °C resulted in the least negative effects on RS content compared to the other drying temperatures investigated in this study and was the closest to the characteristics of the FDF samples.