Physico-chemical characteristics of VitAto™ flour from different drying processes

S. Sabeetha, A. Mohamed Nazim and U. Nor Azmah

Abstract
The physico-chemical characteristics (minerals and vitamins, colour, total sugar, reducing sugar, total starch, solubility, swelling power) and size of flour granules from different drying types (hot-air dried and drum dried) on selected sweet potato variety (VitAto™) were investigated. VitAto™ was collected locally in Malaysia. Calcium, magnesium, phosphorus, potassium, sodium, sulphur, zinc and vitamin C contents in VitAto™ flour using drum dried technique were significant higher (p <0.05) than hot-air dried flour. Drum drier technique showed a higher content of total starch (36.55 ± 0.89) and swelling power and solubility as the temperature increased. Total sugar (76.57 ± 0.67) and reducing sugar (25.02 ± 0.09) contents of VitAto™ flour by drum dried process was also higher than hot-air flour. The colour parameters showed that the L* value that measured brightness (76.57 ± 0.67) and b* values (52.93 ± 5.17) for drum dried flour were significantly higher (p <0.05) than hot-air flour. Scanning electron microscopy (SEM) analysis showed that the granular of flour from drum drier technique had irregular shapes with an average size ranging from 50 – 200 μm. This gives an idea about higher solubility value of drum dried flour than hot-air flour. This study showed that drum dried flour can be promoted as a potential drying technique in the food industry.

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