Preparation, structure characterization and improved thermo-reversible gel properties of covalent conjugation of marine oligosaccharides/salt-soluble pea protein induced by cold plasma treatment

Plant protein-based thermo-reversible gels are essential for meeting the dietary nutritional needs of the elderly and individuals with dysphagia. However, high hydrophobic globulin content and heat-induced denaturation often hinder gel formation. In this study, salt-soluble pea protein isolate (SPPI) was extracted via ammonium sulfate precipitation, and cold plasma (CP) was used to conjugate SPPI with marine oligosaccharides, including chito-oligosaccharides (COS), carrageenan oligosaccharides (CAS), alginate oligosaccharides (AOS) and agaric oligosaccharides (AGS). This approach achieved a maximum grafting degree of 17.89 % and facilitated the thermo-reversible gelation of SPPI. The interaction mechanisms between SPPI and marine oligosaccharides and their effects on the thermo-reversible gels' functional properties were investigated. COS/SPPI-CP exhibited enhanced solubility, conductivity, reduced particle size. Structural analyses revealed increased environmental polarity, enhanced hydrogen bonding, stronger disulfide bonds and reduced hydrophobic interactions, hence indicating a shift towards a more hydrophilic SPPI structure after oligosaccharide conjugation. CP treatment improved gel thermo-reversibility while reducing hardness, adhesiveness, and chewiness, with COS/SPPI-CP showing the lowest values for these properties. Adding 0.3 % NaCl maintained thermo-reversibility, supporting safe swallowing and adequate nutritional intake. These findings contribute to developing pea protein-based supplements for individuals with dysphagia.