Optimized oligochitosan treatment for preserving postharvest quality of Sepia pharaonis during cold storage

Sepia pharaonis is a commercially valuable cephalopod, yet highly prone to quality deterioration during refrigeration. This study optimized the use of oligochitosan (COS) for cold storage preservation of S. pharaonis using a Box-Behnken design with three variables: COS concentration (0.5–1.5%), immersion time (30–150 s), and storage temperature (2–8 °C). The optimal condition (1.14% COS, 60 s, 4 °C) was validated in independent runs after 7 days. The optimal condition (1.14% COS, 60 s, 4 °C) yielded the highest sensory acceptability (8.9 on a 9-point hedonic scale) after 7 days. COS-treated samples showed significantly lower total volatile base nitrogen (TVB-N) (47.58 mg N/100 g DW), ammonia (NH 3 ) (11.32 mg/100 g DW), and peroxide value (POV) (7.84 μmol KOH g −1 dry weight), indicating delayed protein and lipid degradation. Microbial loads, including total plate count and Pseudomonas spp., were also significantly reduced ( P < 0.01). The results support COS as a natural preservative that enhances the shelf life and safety of S. pharaonis , offering a viable alternative to synthetic additives in seafood processing.