Abstract: To improve the resource utilization efficiency of pufferfish milt, this study systematically investigated the effect of ultrasonic duration (0, 2, 4, 6, 8, and 10 h) on the gel properties and antioxidant activity of pufferfish sperm nuclear proteins. The results demonstrated that 4 h ultrasonic treatment fragmented DNA into small segments, forming a dense crosslinked network with arginine-rich protamines, thereby increasing the gel strength by 55.3%. After 6 h treatment, DNA was further fragmented exposing more active sites, with the resulting product exhibiting a superoxide anion radical scavenging rate of 56.15% and an increased 1,1-diphenyl-2-picrylhydrazyl radical scavenging rate of 73.01%. Rheological analysis confirmed typical gel characteristics (G’ > G”, tan δ ≈ 0.3) in all treatment groups, while 10 h ultrasonic treatment elevated the critical strain from 30% to 400%, indicating severe network degradation. This study elucidates the mechanism by which ultrasonic treatment precisely regulates the degree of DNA fragmentation and protein conformational changes, enabling directed optimization of hydrogel properties. This finding not only establishes a novel approach for the high-value utilization of aquatic processing byproducts but also provides a theoretical basis for the development of functional protein-nucleic acid composite gel materials with potential applications in food packaging and drug carriers.

Key words: milt; nuclear proteins; ultrasonic duration; gel; antioxidant activity