Using synchrotron radiation-based infrared microspectroscopy to reveal microchemical structure characterization: frost damaged wheat vs. normal wheat.
This study was conducted to compare: (1) protein chemical characteristics, including the amide I and II region, as well as protein secondary structure; and (2) carbohydrate internal structure and functional groups spectral intensities between the frost damaged wheat and normal wheat using synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIRM). Fingerprint regions of specific interest in our study involved protein and carbohydrate functional group band assignments, including protein amide I and II (ca. 1774-1475 cm(-1)), structural carbohydrates (SCHO, ca. 1498-1176 cm(-1)), cellulosic compounds (CELC, ca. 1295-1176 cm(-1)), total carbohydrates (CHO, ca. 1191-906 cm(-1)) and non-structural carbohydrates (NSCHO, ca. 954-809 cm(-1)). The results showed that frost did cause variations in spectral profiles in wheat grains. Compared with healthy wheat grains, frost damaged wheat had significantly lower (p < 0.05) spectral intensities in height and area ratios of amide I to II and almost all the spectral parameters of carbohydrate-related functional groups, including SCHO, CHO and NSCHO. Furthermore, the height ratio of protein amide I to the third peak of CHO and the area ratios of protein amide (amide I + II) to carbohydrate compounds (CHO and SCHO) were also changed (p < 0.05) in damaged wheat grains. It was concluded that the SR-FTIR microspectroscopic technique was able to examine inherent molecular structure features at an ultra-spatial resolution (10 × 10 μm) between different wheat grains samples. The structural characterization of wheat was influenced by climate conditions, such as frost damage, and these structural variations might be a major reason for the decreases in nutritive values, nutrients availability and milling and baking quality in wheat grains.
Department of Animal Science and Technology, Tianjin Agricultural University, Xiqing District, Tianjin 300384, China.
Hangshu
H
Xin
Xuewei
X
Zhang
Peiqiang
P
Yu
D000577:Amides / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry; D003081:Cold Climate; D003080:Cold Temperature; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D017356:Synchrotrons; D014908:Triticum / Q000737:chemistry*
D000577:Amides; D002241:Carbohydrates