Photodynamic inactivation with natural photosensitizers: Impact on camellia seeds and improvement of its oil yield and quality.

Green pretreatments that improve oil recovery while maintaining oil quality are of interest for camellia seed processing. This study compared three separate photodynamic inactivation (PDI) pretreatments, using emodin, resveratrol, or coumarin as the photosensitizer under LED blue light, and evaluated their effects on camellia seeds and the oil obtained after pressing. PDI significantly reduced surface microbial loads, with bacterial and fungal counts decreasing by 0.99-1.31 and 1.04-1.87 log CFU/g, respectively (p < 0.05). It also altered seed microstructure and moisture distribution, increased oil yield by 21.4-43%, maintained the fatty acid profile, and enhanced α-tocopherol by 6.4-12.7%. Emodin and coumarin showed stronger antimicrobial and quality-preserving effects than resveratrol. These results indicate that natural photosensitizer-mediated PDI is a promising pretreatment for improving oil recovery and preserving camellia seed oil quality.