A multiplatform metabolomics/reactomics approach as a powerful strategy to identify reaction compounds generated during hemicellulose hydrothermal extraction from agro-food biomasses

Hydrothermal treatment is commonly used for hemicelluloses extraction from lignocellulosic materials. In this study, we thoroughly investigated with a novel approach the metabolomics of degradation compounds formed when hazelnut shells are subjected to this type of treatment. Three different complementary techniques were combined, namely GC-MS, 1H NMR, and UHPLC-IM-Q-TOF-MS. Organic acids, modified sugars and aromatic compounds, likely to be the most abundant chemical classes, were detected and quantified by NMR, whereas GC -and LC-MS-based techniques allowed to detect many molecules with low and higher Mw, respectively. Furans, polyols, N-heterocyclic compounds, aldehydes, ketones, and esters appeared, among others. Ion mobility-based LC-MS method was innovatively used for this purpose and could allow soon to create potentially useful datasets for building specific databases relating to the formation of these compounds in different process conditions and employing different matrices. This could be a very intelligent approach especially in a risk assessment perspective.