The effect of a novel photodynamic activation method mediated by curcumin on oyster shelf life and quality

In this paper, the effect of photodynamic method mediated by curcumin (PDT) on the shelf life and quality of pacific oysters during storage at 5 +/- 1 degrees C were analyzed. In our previous study we investigated the optimal treatment conditions of photodynamic method mediated by curcumin to sterilization were 10 uM photosensitizer concentration and 5.4 J/cm(2) light energy density. Under these conditions, the effect of a novel photodynamic activation method mediated by curcumin on oyster shelf life and quality was researched. The total bacterial counts, TVB-N content and sensory analysis were used to evaluate the effects on oyster shelf life. The oyster shelf life was prolonged from 8 days to 12 days after photodynamic treatment and the oysters in the treatment group displayed notable odor retention, produced fewer odor corrupting substances when the control group oysters reached the end of their shelf life (day 8). Texture, free amino acid contents and fatty acid levels were applied to estimate the quality of the treated oysters. The texture had no significant change after treated with PDT. At the end of oyster shelf life, compared PDT group (PDT) with control group (control), total free amino acid contents (control: 234.30 mg/100 g, PDT: 813.02 mg/100 g) was higher and free fatty acid levels (control: 0.071 mEq/L, PDT: 0.0455 mEq/L) displayed lower in PDT group. This indicated that the treated oysters oxidized minimally, decayed slowly, decomposed fewer nutrients and had lower metabolic levels of spoilage microorganisms. PDT has a positive effect on prolonging oyster shelf life and its quality. (C) 2016 Elsevier Ltd. All rights reserved.