Investigating the Biochemical and Structural Evolution of Whey Protein Concentrate Powders Under Storage: Insights from Raman Spectroscopy

Biochemical and structural changes in Whey Protein Concentrate (WPC) powders under various storage conditions were investigated, focusing on the Maillard Reaction (MR) and lactosylation. The Browning Index (BI) and surface hydrophobicity measurements revealed a two-step browning process: a gradual increase followed by a rapid browning phase triggered by lactosylation. Raman spectroscopy provided detailed chemical and structural information, confirming MR and lactosylation processes and highlighting protein structural alterations. Under mild storage conditions, minimal changes in the WPC powder structure were observed, while extreme conditions induced significant protein oxidation and lactosylation. Chemometric analysis using Bayesian Positive Source Separation (BPSS) successfully quantified the freshness and alteration in the powders, revealing three distinct groups based on storage conditions: fresh, moderately altered, and highly altered powders. Raman spectroscopy and chemometric methods are thus valuable tools for monitoring aging at the molecular level and predicting powder quality over time. These insights can directly inform the development of optimized storage protocols and contribute to maintaining the functional and nutritional quality of protein-based food products.