Preservation treatment of fresh raspberries by e-beam irradiation

Abstract E-beam irradiation was studied as a post-harvest treatment for red raspberries (Rubus idaeus L.). Microbial inactivation (natural microbiota and potential pathogenic bacteria) and bioactive properties (phenolic content, vitamin C content and antioxidant activity and cytotoxicity) of these fruits were evaluated before and after irradiation and during storage of 14 days at 4 °C. A reduction of 2 log CFU/g of mesophilic bacteria and 3 log CFU/g on filamentous fungi, and no detection of foodborne inoculated pathogens (3 log CFU/g) was achieved with an e-beam treatment at 3 kGy and during 7 days of refrigerated storage. Regarding bioactive properties, the results suggested that irradiation could preserve the phenolic content and antioxidant activity of raspberries through 7 days of cold storage, even though a decrease of 80% on ascorbic acid concentration was observed. Furthermore, no in vitro inhibitory effect on human cells lines was observed for the extracts from e-beam-treated raspberries. The overall results suggested that use of e-beam irradiation as post-harvest treatment of raspberries as an emergent, clean and environmental friendly process to extend the shelf-life of this fruit with safety and preservation of bioactivity. Industrial relevance Red raspberries are known to demonstrate high bioactivity that could be beneficial to human health, but are highly perishable and often associated with foodborne outbreaks, which makes its safety and commercialization a challenge. The use of a terminal control such as irradiation might reduce the burden of disease transmission and extend the quality of fresh red raspberries. The present research indicated that e-beam irradiation can be used as post-harvest treatment of raspberries, guarantying its safety and quality with the add-value of shelf-life extension.