Developing an Analytical Framework for the Molecular Weight Analysis of Fish-Derived Collagen Peptides in Beverages: A Multi-Method Comparative Study.

Accurate determination of the molecular weight of collagen peptides is crucial for quality control in functional beverages. Current national and industry standard methods for peptide powders face challenges of matrix interference and insufficient comparability when applied to complex beverage systems. In this study, three mainstream chromatographic methods were systematically evaluated for their suitability, reproducibility, and consistency in determining the molecular weight (MW) of fish-derived collagen peptides in beverages. An analytical framework was established by identifying and removing interference peaks from non-peptide excipients, followed by systematic comparison of linear and cubic fitting models. All three methods exhibited good reproducibility. After interference peak removal, the peptide profiles of the beverages were highly consistent with those of pure peptide powder. Cubic fitting reduced inter-method differences, with relative standard deviation (RSD) values below 5% in the bioactive < 1 kDa range. The framework was further validated through beverage formulation optimization, demonstrating compatibility between functional ingredient quality control and sensory flavor adjustability. The proposed approach provides a practical solution for industry quality control and cross-laboratory data comparability of collagen peptide beverages.