Development of on-surface metabolisation systems for food analysis

Abstract

This thesis discusses the progress achieved concerning the potential of on-surface metabolism hyphenated with HPTLC, established as HPTLC-nanoGIT. The developed methods and their wide range of applications offer several advancements in food science and nutrition research. First, the previously published HPTLC-nanoGIT methodology was successfully validated for the quantification of starch digestibility by investigating various grain flours via saccharide release. It provides a novel approach to understand the digestibility of different flour types, as well as the differences between refined and whole grains. The possibility of quantifying each single saccharide provides a new detailed overview of amylolysis, which can help define dietary recommendations for obesity and diabetes management. Furthermore, the HPTLC-nanoGIT method was expanded to a 10D hyphenated technique to investigate the bioactive profiles of vegetable oils via on-surface lipolysis. The developed orthogonal HPTLC×HPTLC method allowed for a detailed metabolic profile. Additionally, the identification of genotoxic and antimicrobial effects of digested oils is helpful in the interpretation of food safety assessments. To further broaden the spectrum, the HPTLC-nanoGIT method was used to evaluate ATI-containing flour extracts and examine the potential as a novel inhibitory assay. This represents a major advancement over traditional spectrophotometric methods, particularly for matrix-rich samples. Finally, the feasibility of the HPTLC-nanoGIT method was investigated in detail and demonstrated enhanced sensitivity in contrast to spectrophotometric assays. However, some limitations were revealed when defining standardised protocols and determining kinetic parameters. Overall, the published results highlight the strong potential of the hyphenation of HPTLC and on-surface metabolisation for the detailed metabolic profiling of food components and their interpretation.