Food safety risks of seeds and the production process of sprouted seeds (SEGERI)

Sprouts such as alfalfa (lucerne) or leek and their seeds are the main topic of this food safety research. We aim to answer the following questions: how does Salmonella and verotoxin producing E. coli (VTEC) survive on seeds intended for sprouting? How effective are the current sampling plans? How effective are the current detection methods for Salmonella and VTEC on seeds intended for sprouting and sprouts? What is the efficacy of different decontamination techniques to reduce the Salmonella and VTEC-level on seeds, and what is the effect on the natural background microbiota? Finally, the project has also the goal to investigate the development of Salmonella and VTEC in combination with the naturally present competitive background microbiota throughout the production chain of sprouting seeds, taking into consideration indicator organisms such as generic E. coli.

In collaboration with the project coordinator (Ghent University), the focus was on alfalfa and leek sprouts as they are the most-sold sprouted seeds in Belgium. In the first part of the research the methodology was defined (detection, isolation, quantification of the pathogens (STEC O157 and Salmonella) on seeds, sprouted seeds and spent irrigation water. Subsequently, the survival of both pathogens on artificially inoculated seeds was investigated over a period of two years. We have followed the survival of STEC O157 and Salmonella as well as the naturally present background microbiota during the production process and distribution of the sprouted seeds. In order to simulate professional production conditions, ILVO has designed a pilot scale sprouting device with rotating drums. The effectiveness of diverse decontamination techniques on seeds was investigated, as well as the effectiveness of antimicrobial compounds added to the irrigation water in order to reduce the pathogen load. We also evaluated the effectiveness on the background microbiota. In all instances, the influence of these decontamination techniques on the germination capacity of the seeds was taken into consideration.

The most important conclusion is that the initial microbiological quality of the seeds is fundamental for a food safe germination process in the sector of sprouted seeds. This is caused by the observation that the zoonotic pathogens can survive for many years on the seeds used for production of sprouted seeds and hence, they have a large chance of growing during the germination process. Unfortunately, no effective antimicrobial treatment during the germination process has been found which is able to reduce substantially the growth of the pathogens (and at the same time does not harm the germination of the seeds). This means that the monitoring of the germination process remains pivotal to trace at an early phase any contamination problems and to prevent that contaminated final products are put on the market. Our research results have been presented at various international congresses and to the European Sprouted Seeds Association. Several scientific publications are planned. A practical valorization is that ILVO now has a pilot scale sprouting device with three drums which complies with biosafety demands and the machinery directive. The amount of germinated seeds which can be produced is about 1/100 of an industrial rotating installation.

Funding provider(s)
FOD Volksgezondheid, Veiligheid van de voedselketen en Leefmilieu

External partner(s)
UGent