X-ray diffraction, rheological and FT-IR spectra studies of processed amaranth (Amaranthus hypochondriacus)

Abstract

The X-ray diffraction pattern, rheological properties, particle size distribution and Fourier transform-infrared (FT-IR) spectra of native and processed (cooked, germinated and fermented) amaranth were determined using different techniques. The data revealed that the native and processed amaranth flour showed major peak values of the 2θ at 15°, 18° and 23° resembling an A-type X-ray diffraction pattern. The percent crystallinity of fermented and germinated amaranth flour was higher than the native amaranth flour whereas loss in crystallinity was observed for cooked amaranth flour. Fermented amaranth flour showed the highest value while cooked amaranth flour showed the lowest value for storage (G′) and loss modulus (G″). The value of tan∂ was lower than 1 for native and processed amaranth dough. Native amaranth flour showed unimodal size distribution and the size of flour granules were ranged from 0.67 to 98.1 µm in diameter while the germinated and fermented amaranth flour showed bimodal distribution. The FT-IR spectroscopy provides the information about the product composition in the form of peaks. The peak for starch was obtained in the range of 994–1144 cm⁻¹. The proteins bands of native amaranth flour were reported at 1644 and 1545 cm⁻¹. The changes observed in physicochemical properties of amaranth flour after processing treatments provided a crucial basis for its potential applications on industrial scale.