Submitted to: Postharvest Biology and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/5/2014
Publication Date: 5/4/2014
Publication URL: http://handle.nal.usda.gov/10113/58771
Citation: Kong, Q., Wu, A., Qi, W., Qi, R., Carter, J.M., Rasooly, R., He, X. 2014. Electron-beam is effective in reducing Escherichia coli on blueberries and extending the shelf life of the fruits. Postharvest Biology and Technology. 95(2014):28-35. Interpretive Summary: De-contamination of fresh fruits is difficult because most conventional methods such as thermal pasteurization and chemical sanitizing procedures do not suit them or have problems concerning residues and environmental pollution. Electron beam irradiation is a potential decontamination strategy to ensure the safety of fresh fruits. In this study, we showed that e-beam irradiation was effective in reducing E. coli on blueberries and extending shelf life of the fruits by controlling microorganisms that cause spoilage. At low levels (< 3 kGy), no changes occurred in nutritional quality of the fruits.
Technical Abstract: Fresh blueberries have become a popular new functional food because of their incredibly high levels of antioxidant phytonutrients and health benefits. However, the potential prevalence of human pathogens on blueberries has become an increased concern because they are consumed with minimal processing. Procedures effective in decontamination and extending shelf life without affecting fruit quality are needed. Electron-beam irradiation was applied to fresh blueberries and its effectiveness for inactivating Escherichia coli (E. coli) K-12 and extending shelf life were investigated. The D10 values of E. coli in bacterial culture and blueberries were 0.43 ± 0.01 kGy and 0.37 ± 0.015 kGy, respectively. Irradiation reduced bacteria inoculated on blueberries from 7.65 x 108 cfu/g to 6 cfu/g at 3.13 kGy and delayed the decaying of blueberries stored at both 4°C and 25°C at doses below 3 kGy, significantly. No significant effect on the total monomeric anthocyanins, antioxidant activity, and L-ascorbic acid content of blueberries was observed from irradiation at doses = 3 kGy. However, significant decreases in the antioxidant activity and L-ascorbic acid content were found in both control and irradiated blueberries after storage at 4°C for 7 and 15 days. Information obtained in this study indicates that low dose electron-beam irradiation is effective in eliminating E. coli and extending shelf life while maintaining the antioxidant properties of blueberries.