|BREARD, ANNA - University Of Maine|
|Hwang, Cheng An|
|WU, VIVIAN - University Of Maine|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2016
Publication Date: 10/4/2016
Citation: Lacombe, A.C., Breard, A., Hwang, C., Hill, D.E., Fan, X., Huang, L., Yoo, B.K., Niemira, B.A., Gurtler, J., Wu, V.C. 2016. Inactivation of Toxoplasma gondii on blueberries using low dose irradiation without affecting quality. Journal of Food Protection. 73:981-985. https://doi.org/10.1016/j.foodcont.2016.10.011
Interpretive Summary: The Food and Drug Administration has recently identified fresh fruits and vegetables as commodities with a high potential risk of Toxoplsama gondii contamination. These commodities are frequently consumed fresh, ready-to-eat, or used as ingredients, and are generally minimally processed to maintain freshness, nutritional value, and sensory quality. Increasing consumption of produce has resulted in more outbreaks of foodborne illnesses linked to parasites. The Center for Disease Control and Prevention has recognized Toxoplasma gondii as an emerging food safety threat due to the increasing complexity of the food supply. Toxoplasma gondii is a common protozoan parasite, whose environmentally-resistant stage, the oocyst, can contaminate irrigation water and fresh edible produce. Current washing steps in produce processing may not be effective for eliminating T. gondii from at-risk varieties of produce. The objective of this study was to evaluate low-dose irradiation as a means to inactivate T. gondii oocysts on blueberries. We found conditions that dramatically reduced viable parasite contamination to well-below detection limits without compromising the quality of the berries (as measured by compression firmness, anthocyanins, or color). Results of this study indicated that low-dose irradiation is a potential intervention measure for controlling T. gondii contamination on blueberries without affecting product quality. These data will be of interest to public health authorities, food scientists, epidemiologists, and produce processors.
Technical Abstract: Blueberries (10 g) inoculated with T. gondii (5 log oocysts/g) were exposed to an absorbed dose of 0 (control), 0.2, 0.4 or 0.6 kGy gamma radiation at 4°C. After treatment, oocysts were recovered from berries by washing, and excysted sporozoites were enumerated using a plaque assay. Vero cells were maintained as monolayers in a 6-well microplate, exposed to sporozoites recovered from berries, and incubated for 7 days to determine plaque-forming units (PFU). Immediately after treatment, blueberries without inoculated T. gondii were analyzed for compression firmness, surface color, and total anthocyanins. The results from this experiment demonstrate that the viability of T. gondii oocysts was significantly reduced after an irradiation treatment of 0.2 kGy. All treatments produced reductions of 4 log PFU/g beyond the detection limit of 1 log PFU/g. Quality analysis showed that there was no significant change in compression firmness, anthocyanins, or color in berries after the irradiation treatment. Results of this study indicated that low-dose irradiation is a potential intervention measure for controlling T. gondii contamination on blueberries without affecting product quality.