Curcumin-Mediated Photodynamic Treatment Enhances Storage Quality of Fresh Wolfberries via Antioxidant System Modulation

Photodynamic inactivation (PDI) is an innovative non-thermal sterilization and preservation method that has recently emerged as a safe, effective, cost-effective and environmentally sustainable alternative for biomedical applications. Curcumin (Cur), a commonly used food additive, possesses photosensitizing properties. In this study, we investigated the effect of curcumin-mediated photodynamic treatment (Cur-PDT) on the preservation of fresh wolfberries. Our experimental data revealed that a Cur-PDT treatment using a cur concentration of 500 μmol/L for 30 min, with 20 W irradiation, achieved the best preservation effect on fresh wolfberries. This intervention significantly slowed the decline in post-harvest hardness and delayed the progression of decay. It also reduced the accumulation of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and superoxide anion (•O₂^-). Notably, at day 3, the enzymatic activities of catalase (CAT) and ascorbate peroxidase (APX) in Cur-PDT-treated wolfberries were 1.12 and 1.88 times higher, respectively, than those in the control group. These elevated enzyme activities promoted the biosynthesis and recycling of ascorbic acid (AsA) and glutathione (GSH), leading to their substantial accumulation under oxidative stress conditions. By modulating the antioxidant defense system, Cur-PDT has the potential to extend the shelf-life of post-harvest wolfberries and enhance their overall quality attributes, thereby maintaining physiological homeostasis during storage.