Ft ir nicolet is50 spectrophotometer

A FT-IR Nicolet iS50 spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) coupled with a crystal diamond attenuated total reflectance (ATR) sampling accessory was used to obtain the FTIR spectra of the studied flours. Flours were equilibrated to 15% moisture content prior to measurements using a saturated humidity Memmert incubator model ICP260 (Schwabach, Germany) at 15 °C. Scanning was conducted in the range of 4000–400 cm⁻¹ with a resolution of 4 cm⁻¹ and the accumulation of 64 scans. Changes to the protein secondary structure were analyzed in amide I bands (1700–1600 cm⁻¹) following an iterative fitting assuming Gaussian band shapes as indicated by Byler and Susi (1986) [20 (link)], using Origin2019b software (OriginLab Corporation, Northampton, MA, USA). Peaks were classified as high frequency β-sheet (1700–1690 cm⁻¹), β-turns (1690–1665 cm⁻¹), random structure and α-helix (1665–1640 cm⁻¹) and low frequency β-sheet (1640–1615 cm⁻¹) according to Fevzioglu et al. (2020) [21 (link)]. Samples were measured in triplicate.

The functional group analysis of anchote starch and control starches (potato and cassava) was performed using an FTIR Nicolet iS50 spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) coupled with an attenuated total reflectance (ATR) device equipped with a diamond crystal. The starch samples were equilibrated at a humidity of 15% following the method previously used by Vela et al. [40 (link)]. The powdered starch sample was placed on a diamond crystal and pressed until the desired level was reached. The spectra were scanned from 400–4000 cm⁻¹ with a resolution of 4 cm⁻¹, and a total of 64 scans were measured and averaged. Each sample was scanned in triplicate, and the obtained spectra were baseline corrected and normalized using OMNIC software (Thermo Fisher Scientific, Waltham, MA, USA).

FTIR spectra of the studied tef flours were recorded by a FT-IR Nicolet iS50 spectrophotometer (Thermo Fisher Scientific, USA) equipped with a crystal diamond attenuated total reflectance (ATR) sampling accessory. The samples’ humidity was set at 15% MC using a saturated humidity Memmert ICP260 incubator (Schwabach, Germany). Measurements were performed in the range of 400–4000 cm⁻¹ with a resolution of 4 cm⁻¹ and an accumulation of 64 scans. The short-range molecular ordered structure of starch (ratios of absorbance 1047/1022 cm⁻¹ and 1022/995 cm⁻¹) and amide I bands (1700–1600 cm⁻¹) were analyzed by Fourier self-deconvolution using OMNIC 9 software (Thermo Fisher Scientific Inc. USA). Two points straight line baseline correction followed by 2nd order derivative of spectra for peak finding and final Gaussian peak fitting at those peak positions were performed in Origin 2019b (OriginLab Corporation, Northampton, MA, USA) to calculate percent contribution by secondary structure components. Peaks were classified as: β-sheet (high frequency) (1700–1690 cm⁻¹), β-turns (1690–1665 cm⁻¹), random coil and α-helix (1665–1640 cm⁻¹), and β-sheet (low frequency) (1640–1615 cm⁻¹) [26 (link)]. Measurements were performed in triplicate.