Influence of hydrothermal processing on functional properties and grain morphology of finger millet

Effect of drying technique on physiochemical and nutritional properties of Eleusine coracana () porridge powder

Eleusine coracana (Finger millet, ragi) is one of the cereals which can cultivate in higher altitudes. This study analysed the effects of various drying techniques such as spray, tray and freeze drying on the retention of micronutrients and structural changes in ragi. Minerals, such as iron and calcium were determined using atomic absorption spectroscopy (AAS) and water-soluble vitamins, such as vitamin B1, B2 and B3 were determined by high-performance liquid chromatography (HPLC). The micronutrient content of freeze-dried ragi powder was observed to be 349.6 ± 0.6 mg/100 g of calcium, 0.550 ± 0.1 mg/100 g of iron, 0.421 ± 0.01 mg/100 g of vitamin B1, 0.193 ± 0.05 mg/100 g of vitamin B1 and 1.103 ± 0.05 mg/100 g of vitamin B3. Along with micronutrients analyses, proximate and various important physiochemical properties were also analysed. Structure analysis of dried ragi using scanning electron microscopy (SEM) indicated that both tray and spray dried ragi show variations in their structure when compared to freeze-dried porridge powder. Crystallisation of starch during drying was determined using Fourier transform infrared (FTIR) spectroscopy. Selected physiochemical properties were also analysed for all dried samples. The results of this study showed that freeze-drying to be the best technique to preserve nutrients over spray and tray drying methods.

Graphical abstract

Effect of grain moisture content during milling on pasting profile and functional properties of amaranth fractions

Evaluation of functional properties of milled fractions of grain amaranth may be useful to decide the end uses of the grain. Hence, pasting profiles of amaranth fractions obtained by milling the grains at different moisture contents were studied in relation with their starch profile and also with their swelling power and solubility indices. It was observed that, for flour fraction, the viscosity parameters were lowest at 14-16 % moisture content. Swelling power and solubility indices of the samples varied as a function of grain moisture content. The middling fraction also showed similar pasting pattern with the variation of grain moisture content. The seed coat fractions showed higher gelatinization temperature compared to that of fine flour and middling fractions. However, starch content of the fine seed coat fraction was comparable with that of the flour and middling fractions. The coarse seed coat fraction showed lower viscosity parameters than the other samples. Viscosity parameters correlated well among themselves while, they did not show significant correlation with the starch content. However, the viscosity parameters showed negative correlation with the soluble amylose content. The study revealed that, the fractions obtained by milling the grains at different moisture content show differential pasting profiles and functional properties.