Modulation of Functional and Allergenic Properties of Bovine Casein via Cold Plasma-Assisted Glycation

• Cold plasma unfolds the CN structure, exposing more available amino groups. • Cold plasma enhanced the glycation efficiency of conjugates to 25.8%. • The conjugates exhibit a more uniform and dispersed structure. • The conjugates show better solubility, emulsifying properties, and thermal stability. • Cold plasma-assisted glycation reduces the allergenicity of CN. For the past few years, consumer demand for milk proteins that combine superior functional properties with health attributes has been steadily increasing. However, the native functionality of casein (CN) is highly affected by pH, temperature, and ionic strength, thereby limiting its applicability in food processing. The traditional Maillard reaction can enhance protein functionality, but its efficiency is hindered by limited amino accessibility and stringent temperature requirements. To overcome these constraints, CN was first pre-treated with cold plasma (0–5 min, 75 W, Ar) and subsequently reacted with galacto-oligosaccharides (GOS) at 60°C and 79% relative humidity for 3 h, producing a series of CP-assisted Maillard conjugates with unique structural and functional characteristics. After a 3 min pre-treatment, the degree of glycation reached 25.8%, which was significantly higher than that achieved by the conventional method. All conjugates exhibited markedly greater emulsifying activity (316.54 m²/g) and emulsion stability (28.47 min) than native and traditionally glycated casein. Meanwhile, foaming properties, water-holding capacity, and solubility under various pH conditions were also improved. DSC analysis indicated an increase in denaturation temperature by 16–19°C, signifying enhanced thermal stability. A 29.6% decrease in IgE binding was observed, along with a reduction in the release of various cytokines by KU812 cells, suggesting a reduction in allergic response. Particle size analysis further revealed that the conjugates formed after the combined treatment were finer and more uniform, indicating improved dispersion behavior. In summary, plasma-assisted glycation modification is a mild strategy that simultaneously enhances the techno-functional properties and safety of CN, offering significant potential for novel dairy ingredient processing for the future.