Influence of drying techniques on milk thistle (Silybum marianum) protein isolate: Characterization, structural, and techno-functional properties.

Unraveling alternatives to animal-based protein is an urgent global demand, and milk thistle seed protein isolate (MSPI) represents an underexploited and promising plant-based protein source for food applications. Therefore, the effects of spray (S-MSPI), freeze (F-MSPI), and oven-drying (O-MSPI) on the nutritional, physicochemical, structural, thermal, and functional attributes of MSPI have been investigated. Remarkably, F-MSPI had the highest amino acid scores in comparison with the WHO/FAO reference pattern. Morphologically, the particles of F-MSPI sample appeared as irregular porous flakes, while S-MSPI had spherical particles with smooth and uniform surfaces; however, O-MSPI showed large, compact, and aggregated particles. Structurally, O-MSPI showed significant changes compared to F-MSPI and S-MSPI, as manifested by its lower α-helix and β-sheet levels. Nevertheless, the thermal stability of O-MSPI was greater than that of F-MSPI and S-MSPI. Intriguingly, F-MSPI possessed outstanding structural integrity and functionality because of its highest foaming stability (71.7%), denaturation temperature (98.9 °C), and solubility (97.2%). In conclusion, our study underscores that F-MSPI maintains the protein's native structure and functional performance, which boosts its potential incorporation in sustainable plant-based food systems.