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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #376148
Research Project: Umbrella Project for Food Safety

Location: Warmwater Aquaculture Research Unit

Title: The efficacy of X-ray doses on Vibrio vulnificus in pure culture and Vibrio parahaemolyticus in pure culture and inoculated farm-raised live oysters (Crassostrea virginica) with different acceleration voltages

Author
item WU, YUWEI - Mississippi State University
item CHANG, SAM - Mississippi State University

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2020
Publication Date: 3/30/2020
Citation: Wu, Y., Chang, S. 2020. The efficacy of X-ray doses on Vibrio vulnificus in pure culture and Vibrio parahaemolyticus in pure culture and inoculated farm-raised live oysters (Crassostrea virginica) with different acceleration voltages. Food Control. 115:107277.

Interpretive Summary: Aquaculture of oysters and radiation sanitation on foods are important industries in the northern gulf area. Vibrio infection of oysters affect marketing of oysters. The FDA only allows only certain amount of radiation for processing oysters. In the application of radiation in oysters, we studied how to improve the efficacy of sanitation. We found that increasing the X-ray voltage can greatly increase the sterilization effect on Vibrios. This result makes the flexible use of X-ray on oysters feasible. For example, x-ray can be applied over a conveyor belt carrying oysters. At the same time, the discovery that the X-ray voltage influences the effect of sanitation is also a novel innovation.

Technical Abstract: Vibrio vulnificus and Vibrio parahaemolyticus are halophilic bacteria and can cause illness associated with the consumption of oysters. In this study, we tested the hypothesis to see if the adjustment of the acceleration voltage can change the efficacy of X-ray doses on V. vulnificus and V. parahaemolyticus in pure culture and inoculated V. parahaemolyticus within farm-raised live oysters (Crassostrea virginica). By using a tailor-made Xray irradiator (Kimtron 350), the acceleration voltage was adjusted to 50, 200 or 350 kV and irradiated on pure culture of V. vulnificus or V. parahaemolyticus and farm-raised live oysters accumulated with a three-strain mixture of V. parahaemolyticus. Inactivation of V. vulnificus and V. parahaemolyticus pure cultures without filter had a lower inactivation when compared with filtered X-ray. With a 1 mm aluminum filter, 250–300 Gy X-ray reduced more than 6 log CFU ml-1 at 350 kV acceleration voltage. When 350 kV X-ray was applied on live oysters with the aluminum filter, 6 log MPN g-1 reduction of V. parahaemolyticus was achieved with 1250 Gy. The V. parahaemolyticus was significantly (p < 0.05) reduced in whole shell oysters from 8.11 ± 0.19 to 6.11 ± 0.19, 3.97 ± 0.47, 4.17 ± 0.17 and 2.77 ± 0.28 log MPN g-1 after processing with 250, 500, 750 and 1000 Gy, respectively. These results showed that the pathogen inactivation can be improved by the optimization of energy level with the adjustment of irradiation filter and acceleration voltage.