Study the sensitivity of molecular functional groups to bioethanol processing in lipid biopolymer of co-products using DRIFT molecular spectroscopy

To date, there is no study on bioethanol processing-induced changes in molecular structural profiles mainly related to lipid biopolymer. The objectives of this study were to: (1) determine molecular structural changes of lipid related functional groups in the co-products that occurred during bioethanol processing; (2) relatively quantify the antisymmetric CH3 and CH2 (ca. 2959 and 2928 cm−1, respectively), symmetric CH3 and CH2 (ca. 2871 and 2954 cm−1, respectively) functional groups, carbonyl CO ester (ca. 1745 cm−1) and unsaturated groups (CH attached to CC) (ca. 3007 cm−1) spectral intensities as well as their ratios of antisymmetric CH3 to antisymmetric CH2, and (3) illustrate the molecular spectral analyses as a research tool to detect for the sensitivity of individual moleculars to the bioethanol processing in a complex plant-based feed and food system without spectral parameterization. The hypothesis of this study was that bioethanol processing changed the molecular structure profiles in the co-products as opposed to original cereal grains. These changes could be detected by infrared molecular spectroscopy and will be related to nutrient utilization. The results showed that bioethanol processing had effects on the functional groups spectral profiles in the co-products. It was found that the CH3-antisymmetric to CH2-antisymmetric stretching intensity ratio was changed. The spectral features of carbonyl CO ester group and unsaturated group were also different. Since the different types of cereal grains (wheat vs. corn) had different sensitivity to the bioethanol processing, the spectral patterns and band component profiles differed between their co-products (wheat DDGS vs. corn DDGS). The multivariate molecular spectral analyses, cluster analysis and principal component analysis of original spectra (without spectral parameterization), distinguished the structural differences between the wheat and wheat DDGS and between the corn and corn DDGS in the antisymmetric and symmetric CH3 and CH2 spectral region (ca. 2994–2800 cm−1) and unsaturated group band region (3025–2996 cm−1). Further study is needed to quantify molecular structural changes in relation to nutrient utilization of lipid biopolymer.

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► Bioethanol processing-induced changes in molecular structural profiles related to lipid biopolymer.
► Lipid biopolymer structures were studied in the antisymmetric and symmetric CH3 and CH2 region and unsaturated group and carbonyl ester CO regions.
► Different types of cereal grains had different sensitivity to the bioethanol processing.
► The multivariate molecular spectral analyses distinguished the structural differences between grain and co-products.