NMR-Based Quantification of Collagen Content in Protein Hydrolysates

Certain functional food and dietary supplement ingredients contain bioactive peptides whose bioactivity is determined by their chain length, composition, and specific sequence of the amino acids. This study investigated collagenous peptides from the valorization of poultry side streams, which, for example, have inhibitory activities against therapeutic targets for the management of blood pressure and blood glucose. To overcome the specificity challenges of conventional amino acid analysis, the aim was to establish and validate a quantitative ¹H NMR (qHNMR) method for the quantification of hydroxyproline as a marker of collagen content in poultry hydrolysates. Indeed, qHNMR provides a rapid structure-specific quantification, and it is highly informative, reproducible, and accurate. The effect of different acidic solvents was investigated using quantum mechanics (QM)-based ¹H iterative functionalized spin analysis (HifSA). Comparison of conventional integration (int-) with QM-qHNMR revealed limitations of the former approach and highlighted the increased accuracy and specificity of QM-qHNMR.