Effect of curcumin-based photodynamic treatment on nutritional properties of strawberry fruit

Abstract

Strawberry is an attractive and highly consumed fruit and can be an important source of essential nutrients as well as polyphenolic compounds such as anthocyanins and phenolic acids. But at room temperature, this fruit is highly vulnerable to physical injury and fungal spoilage. An innovative, cost effective and environmentally friendly photodynamic technique, photosensitization, has been applied with the aim to prevent microbial growth and minimize the loss of nutrients and bioactive polyphenols. Photosensitization works based on the combined action of photosensitizer, light and oxygen, which produce reactive oxygen species that inactivate microorganisms. Curcumin, known for its antifungal activity, was used as the photosensitizer in this study. To assess the effect of photosensitization on the nutritional properties of strawberry fruit, physicochemical parameters, anthocyanins (main polyphenols; UHPLC), total phenolic content (Folin-Ciocalteu assay) and total sugar (HPLC) in fresh (control) and treated strawberries (Cv. ‘Albion’) were determined. There were no changes (p<0.05) in colour, pH, titratable acidity, total soluble solids and moisture content between treated and untreated strawberries. Anthocyanins (20.8 ± 1.15 vs. 20.0 ± 0.54 mg/100 g FW) and total phenolic content (192.9 ± 3.16 vs. 195.8 ± 3.05 mg gallic acid equivalents/100 g FW) were unaffected by photosensitization, whereas the sugar content of photosensitized strawberry was significantly (p<0.05) higher than that of the control (5.29 ± 0.26 vs. 4.12 ± 0.13 g/100 g FW). These preliminary results suggest that photosensitization could be a promising technique that has the potential to be used in the horticulture industry for preservation of strawberry.