ISS Seed Screening Procedures

ISS Seed Screening Procedures

We have been asked by many, including the International Sprout Growers Association, to make our seed screening procedures available to other seed companies and sprout growers.  We are pleased to do so in the interest of food safety within the sprout industry.

The seed is then screened for human pathogens in the following manner:

  1. Inspect Shipment.  Quarantine the seed and inspect the bags for evidence of contamination.  Such things would include mouse droppings, dead insect parts, holes in the bags that appear to have come from rodents or insects, etc.  In dim light, inspect the bags under black light for traces of urine. Record any findings.

  2. Sample Seed.  Sample 25 grams from of each and every bag in the entire shipment using a seed trier or other procedures described by the ISTA Handbook on Seed Sampling, Second Edition, January, 2004, International Seed Testing Association.  This is 1/1000th of the seed and often comes to 20-22 kg of seed.  If the composite sample does not come to 3 kg, collect additional samples until the composite sample equals at least 3 kg.  Record lot information and sampling information.

  3. Inspect the Composite Sample.  Visually inspect the seed for damage and evidence of contamination.  Such things would include dirt, mouse droppings, glass, metal, live or dead insects or animals, etc.  Then do the same using a magnifying glass.  Pull out anything that is suspicious and inspect it more thoroughly under a microscope.  Record any findings.

  4. Sprout the Composite Sample.  Sprout the sample, without sanitizing it.   

  5. Test Runoff Water.  Collect two samples of the runoff water at approximately 48 hours, or, for slow growing seed, after radical emergence. Record production and collection times and methods.  Enrich and test both samples for Salmonella, E.coli 0157:H7, Listeria monocytogenes, Shigella and E.coli.  If E.coli is present test for Enterotoxigenic Bacteria.  Record lab findings and results of inspection.  If there are human pathogens reject the seed and contact the company that sold you the seed.

  6. Documentation. All steps are recorded along with who was responsible for each step and the results of the tests.  The test results are provided with each seed order.

The first three steps are just to help a person make an educated decision about the safety of the seed.  If, for instance, a seed lot were full of mouse droppings it would be rejected regardless of the results of a pathogen test.  But it is not practical to reject a lot if there are a few damaged seeds, or a dead insect stuck to the outside of a paper bag.  This information is reviewed and the risk evaluated.  

Our procedures are continually changed and improved as we learn more about seed screening.  When purchasing a lot of seed, please ask for a copy of the current seed screening protocol and for the documentation on the lots of seed you are interested in.