Detecting carbohydrate molecular structural makeup in different types of cereal grains and different cultivars within each type of grain grown in semi-arid area using FTIR spectroscopy with uni- and multi-variate molecular spectral analyses

Various cereal grains including barley (three varieties: moderate (MT), cold (CT), and dry (DT)), corn (two hybrids: early (EM) and late maturity (LM)), and sorghum (two varieties: new type (NT) and conventional type (OT)) were used to characterize carbohydrate molecular structural features in cereal grains using Fourier transform infrared spectroscopy (FTIR). Molecular spectral peak bands assessed included: A_860 (non structure carbohydrate: ca. 880–818 cm−1), A_928 (non-structure carbohydrate: ca. 946–881 cm−1), total carbohydrate (TCHO: ca.1186–947 cm−1) with three major component peaks (ca. 1017, 1074, and 1152 cm−1), and cellulosic compounds (ca. 1291–1186 cm−1). The results showed carbohydrate molecular spectral features differed among cereal grains. The infrared absorbance intensities of A_860, A_928, TCHO component peaks, and cellulosic compounds were greater for barley than those for both corn and sorghum grains which were similar to each other. These spectral intensities were greater for EM than those for LM in corn hybrids, and greater for OT than for NT in sorghum cultivars. These structural differences may impact the carbohydrate utilization and availability of cereal grains. Results from multivariate spectral analysis indicated that there were still structural similarities in cereal grains and varieties within each type of grain.