Utilizing atmospheric pressure plasma-modified soy protein isolate as a phosphate substitute to improve the rheological properties of meatballs (kung-wan).

This study explores the potential of plasma-modified soy protein isolate (SPI) as a phosphate replacer to reduce the use of food additives in meatballs (kung-wan). Our findings demonstrate that plasma treatment altered SPI's physicochemical properties, decreasing surface hydrophobicity, free sulfhydryl content, particle size distribution, zeta potential, and thermal stability. Circular dichroism spectroscopy demonstrated an elevated α-helix content in air and nitrogen plasma-treated SPI, alongside a reduction in random coil contents. In addition, air plasma treatment for 90 s and nitrogen plasma treatment for 60 s and 90 s led to reductions in β-sheet content by 3.1 %, 0.6 %, and 4.51 %, respectively. Nitrogen plasma-modified SPI (60 s) exhibited improved solubility (16.62 %) and water holding capacity (7.57 %), alongside enhanced emulsification (0.77-1.15 %). Kung-wan made with nitrogen plasma-modified SPI (90 s) showed an 8.8 % reduction in cooking loss and improved emulsion stability compared to unmodified SPI. Across all groups, plasma-modified SPI reduced cooking loss, with the RPN2 group exhibiting the lowest rate (7.28 ± 1.87 %), significantly lower than the control group (P group). Dynamic rheology indicated better gel integrity in kung-wan with plasma-modified SPI, while appearance, particularly color, remained unaffected by the phosphate replacement. These findings suggest that nitrogen plasma-modified SPI enhances the quality of kung-wan by improving gel structure, water retention, and emulsion stability without compromising sensory characteristics. Our study introduces a novel strategy for replacing phosphates in meat products by employing plasma-modified SPI, thereby improving the overall quality and reducing the additive content of processed meat products.