|Kim, Hyun Jung|
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2006
Publication Date: 6/1/2006
Citation: Kim, H., Feng, H., Kushad, M., Fan, X. 2006. Effects of ultrasound, irradiation, and acidic electrolyzed water on germination of alfalfa and broccoli seeds and on escherichia coli o157:h7. Journal of Food Science. 71(6):M168-M173. Interpretive Summary: Sprouts are commonly consumed raw in salads and sandwiches because of their nutritional values. However, consumption of sprouts has been linked to a number of foodborne disease outbreaks. Interventions are needed to ensure the microbial safety of the product. In this study, we examined the effectiveness of power ultrasound, gamma irradiation, and acidic electrolyzed water on E. coli O157:H7 inoculated onto alfalfa and broccoli seeds. Results showed that ultrasound or acidic electrolyzed water alone could not completely eliminate E. coli O157:H7 population. Irradiation at 8 kGy achieved a complete elimination of E. coli O157:H7 but resulted in a reduction in germination rate and yield. Combinations of several hurdles were needed to ensure the safety of the sprouts while maintaining acceptable yields. These results are useful for sprouting seed supplier and sprout growers to reduce or eliminate the outbreaks of foodborne illness associate with sprouts.
Technical Abstract: The ability of power ultrasound, acidic electrolyzed water (AEW), and gamma irradiation to inactivate E. coli O157:H7 inoculated onto alfalfa and broccoli seeds was examined. The treatment conditions under which the alfalfa and broccoli seeds treated with sterile deionized water (SW), AEW, ultrasound cleaning tank (UST), ultrasound probe (USP), and irradiation (IR) would retain a germination percentage of more than 85% were first determined for each disinfection hurdle. E. coli O157:H7 inactivation tests were then conducted with the experimental conditions determined in the germination tests to find out the effect of each disinfection hurdle. AEW treatment at 55 C for 10 min reduced E. coli O157:H7 population by 3.4 and 3.3 log CFU/g for the alfalfa and broccoli seeds, respectively. IR at 8 kGy resulted in a 5-log reduction with seed germination of more than 85% for both seed types, but a reduction in the length and thickness of the sprouts was observed. None of the ultrasound treatments achieved over a 2-log reduction in E. coli O157:H7 population without lowering the germination to below 85%. The results of this study demonstrated that AEW and ultrasound, when applied individually or in combination with thermal treatment at 55 C, were not able to deliver a satisfactory inactivation of E. coli O157:H7. A combination of several hurdles must be used to eliminate E. coli O157:H7 cells on alfalfa and broccoli seeds.