Printer Friendly

High pressure has potential for inactivating E. coli O157:H7 on alfalfa seeds.

Alfalfa sprouts eaten raw are increasingly being perceived as hazardous foods. They have been implicated in some E. coli O157:H7 outbreaks in which the seeds were the likely source of contamination. Sprouts follow a complex path from farm to table that includes growing, harvesting, processing and shipping seeds. This is followed by sprouting and distributing the finished product.

Applying high hydrostatic pressure as a seed decontamination technology has been evaluated by scientists at the University of Delaware. Their research demonstrates that high hydrostatic pressure holds promise as an intervention technology for eliminating pathogens from alfalfa seeds while having minimal adverse effects on seed germinability.

In experiments, alfalfa seeds were inoculated with approximately [10.sup.5] CFU per g of E. coli O157:H7. The seeds were subjected by scientists to oscillatory pressure treatments of 600 MPa at 20 C for up to five cycles with a holding time of 2 minutes per cycle.

However, oscillatory pressurization was not able to completely eliminate the E. coli. So, the researchers tried applying pressure at 600 MPa for 2 minutes at 20 C in the presence of some chemicals, including calcium hypochlorite, calcium hydroxide, lactic acid or sodium acid sulfate. They found that even this multiple hurdle approach did not completely decontaminate the alfalfa seeds.

The researchers found that soaking seeds prior to treating them with pressure plays a critical role in enhancing the pressure inactivation of E. coli O157:H7. Seeds soaked in water for 60 minutes followed by a treatment of 600 MPa for 2 minutes at 20 C were completely decontaminated and had a germination rate of 91%, which was 4% lower than that of the untreated seeds.

Investigators also found that soaking seeds in water for more than 10 minutes, then treating them at 600 MPa for 15 minutes at 20 C, was equally effective with respect to both microbial safety and the viability retention of the seeds.

Further information. Haiqiang Chen, Associate Professor, Food Science, 020 Townsend Hall, Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716; phone: 302-831-1045; fax: 302-831-2822; email:

Contamination can occur at any point in the production and distribution channel.
COPYRIGHT 2010 Food Technology Intelligence, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2010 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Publication:Microbial Update International
Date:Oct 1, 2010
Previous Article:Sodium chloride reduces microbial levels on lettuce, radishes and green onions.
Next Article:Strong adherence promotes retention of strains on processing equipment.

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters