Fabrication and physicomechanical performance of κ-carrageenan/casein nanofibers

The low molecular weight of casein proteins (19–25 kDa) and their self-aggregation limit the electrospinnability of casein nanofibers. Here, the influence of ethanol content (0–60 %) and temperature (20–80 °C) on the state of κ-carrageenan dispersions and their subsequent influence on the electrospinnability and physicomechanical attributes of casein-based EMs was evaluated. κ-carrageenan/casein dispersions prepared at 50% ethanol, pH 10, and 60 °C resulted in the formation of EMs with few bead defects. These conditions lead to the dissociation of casein aggregates and the transformation of κ-carrageenan conformation. More uniform fibrous morphologies with minimum bead defects (2.0 x 10⁻³/μm²) were obtained for 1 wt % κ-carrageenan in casein EMs. A maximum strength of ∼0.2 MPa and modulus of ∼12 MPa was obtained for as spun mats with 1 wt% κ-carrageenan in casein. On exposure to a relative humidity of 100% for 48 h, these mats adsorbed 140 % of their weight in water, became solid films, and increased in strength and modulus >10-fold with a 2-fold decrease in elongation at break. This study demonstrates the influence of κ-carrageenan on the electrospinnability of casein proteins to fabricate novel biodegradable casein-based nano-structured mats with potential for food, cosmetic, packaging, and biomedical applications.