HIGH-INTENSITY PULSED LIGHT INDUCES STRUCTURAL AND PHYSICOCHEMICAL CHANGES IN MICELLAR CASEIN

Caseins, the primary milk proteins, exhibit a complex structural organization in the form of micelles, constituting a dynamic colloidal system whose integrity is crucial for the techno-functional and digestive properties of dairy matrices. In addition to contributing significantly to the protein value of various products, casein plays an essential role in digestive behavior, with its micellar structure directly influencing the stability, functionality, and texture of dairy matrices. In this context, the structural modification of micellar casein has been widely investigated as a strategy to optimize its functional and nutritional properties. Non-thermal technologies, such as pulsed light (PL), stand out for their potential to induce conformational changes and supramolecular reorganizations without the adverse effects associated with conventional heating. Therefore, this study aimed to investigate the effects of different PL intensities on the physicochemical and structural characteristics of micellar casein (MC) dispersions. MC was dispersed in a simulated milk ultrafiltrate (SMUF) solution at 0.4% (w/v) and subjected to PL treatments at three intensities (5P, 10P, and 20P). Physicochemical and colloidal properties of the dispersions were assessed through pH, zeta potential, free -SH groups, and particle size measurements. The experiments were conducted in independent triplicates, and the results were evaluated using ANOVA. Changes in pH, zeta potential, free -SH content, and D[4,3] reflected the structural modification of micellar casein under pulsed light. PL treatment induced a decrease in pH, with the lowest values observed at 5P. Concurrently, this treatment (5P) altered the zeta potential, rendering the surface charge more negative. Additionally, the total free -SH content increased significantly in 5P and 10P but returned to control levels in 20P. Regarding particle size, the 5P treatment did not affect the D[4,3], whereas the 10P and 20P treatments induced a progressive increase of this value. These findings demonstrate that pulsed light treatment modifies the structure of micellar casein, offering a promising strategy to modulate its techno-functional properties in food matrices.