High pressure has potential for inactivating E. coli O157:H7 on alfalfa seeds.
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: firstname.lastname@example.org.
Contamination can occur at any point in the production and distribution channel.
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|Publication:||Microbial Update International|
|Date:||Oct 1, 2010|
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