Using Synchrotron Radiation-Based Infrared Microspectroscopy to Reveal Microchemical Structure Characterization: Frost Damaged Wheat vs. Normal Wheat

Abstract

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.

Univariate and multi‐variate comparisons of protein and carbohydrate molecular structural conformations and their associations with nutritive factors in typical by‐products

“…2 So far, numerous studies have been conducted on the exploration of linkage between nutrient profiles and molecular structural characteristics using mid-IR spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), 6 -8 diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) 9 -11 and synchrotron-based Fourier transform infrared micro-spectroscopy (SFTIRM). 2,12 However, these results were not in a good agreement as some have shown strong associations between nutrient values and molecular structural traits 7,11,13 whereas others reported their correlations to be weak. 8,9 This discrepancy might be due to the limited sample sizes (n = 4-9) or narrow variations existing in both spectroscopic and nutrient information in these studies.…”

“…For instance, the higher percentage of β‐sheet (88%) in the protein secondary structural profile may lead to the low degradation and poor protein quality in feather meal compared with other feed sources containing equivalent protein concentration . So far, numerous studies have been conducted on the exploration of linkage between nutrient profiles and molecular structural characteristics using mid‐IR spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and synchrotron‐based Fourier transform infrared micro‐spectroscopy (SFTIRM) . However, these results were not in a good agreement as some have shown strong associations between nutrient values and molecular structural traits whereas others reported their correlations to be weak .…”

Waste from brewing (trub) as a source of protein for the food industry

“…Nonetheless, the processes used to decrease the bitter compounds in foods may alter the structure and chemical composition of the product. Fourier transform infrared (FTIR) spectroscopy, a fast, direct and non‐destructive technique (Holman et al ., ), has been successfully used to reveal changes in the internal chemical structure of foods (Yu, ; Xin et al ., ).…”

Wheat flag leaf epicuticular wax morphology and composition in response to moderate drought stress are revealed by SEM, FTIR‐ATR and synchrotron X‐ray spectroscopy

“…Fourier transform infrared (FTIR) spectroscopy has become an established method for phenotyping traits associated with stress response, such as identifying cell wall biochemical markers associated with frost damage in spring wheat seeds (Xin et al ), resistance to Fusarium head blight in spring wheat (Lahlali et al , ), selection of superior barley ( Hordeum vulgare L.) cultivars by endosperm protein quality (Liu and Yu ) or differences in grain feed quality for livestock (Walker et al ). On a tissue‐specific level, FTIR spectroscopy can be used to localize total lignin, protein, cellulose, carbohydrates and lipid distributions at spatial resolutions of 1–20 μm (Vijayan et al ).…”