Novel approach to the microbial decontamination of strawberries: chlorophyllin-based photosensitization

This study is focused on the possibility to control microbial contamination of strawberries by chlorophyllin (Na-Chl)-based photosensitization. Moreover, photosensitization-induced effects on key quality attributes of treated strawberries was evaluated.

Strawberries were inoculated with Listeria monocytogenes ATC(L3) C 7644, soaked in 1mmol l(-1) Na-Chl for 5 min and illuminated for 30 min with visible light (λ = 400 nm, energy density 12 mW cm(-2) ). Results indicated that the decontamination of strawberries using photosensitization was 98% compared to control sample. Naturally occurring yeasts/microfungi and mesophiles were inhibited by 86 and 97%, respectively. The shelf life of treated strawberries was extended by 2 days. The total antioxidant activity of treated strawberries increased by 19%. No impact on the amount of phenols, anthocyanins or surface colour was detected.

Photosensitization may be an effective, nonthermal and environmentally friendly microbial decontamination technique which expands the shelf life of strawberries without any negative impact on antioxidant activity, and phenols, anthocyanins or colour formation.

Experimental data support the idea that Na-Chl-based photosensitization can be a useful tool for the future development of nonthermal food preservation technology.