Protective Cultures for Controlling of Microbiological Risks in Sprouting

Protective Cultures for Controlling of Microbiological Risks in Sprouting

In: Abstracts of the ASM 99th General Meeting, Chicago, Illinois. American Society for Microbiology 1999:522-523.

E. SKYTTA1*, A. HAIKARA'.A. SIITONEN2,M. SAARELA1 AND T. MATTILA-SANDHOLM1

'VTT Biotech. Food Res.,Espoo,Finland2 Natl. Publ. Hlth Inst., Helsinki, Finland

 

Contaminated alfalfa seed lots have been identified as the causative vehicle in a number of sprout-borne Salmonella and EHEC outbreaks. Several disinfection procedures have been recommended for the treatment of seeds intended for sprouting. All these procedures have negative counter effects which can drastically reduce the germination degree of the seeds. A range of LAB strain candidates applicable for protective cultures in sprouting were screened. The LAB strains were either isolated from a production scale sprouting process of Mung bean and Persian clover (Lactobacillus plantarum, Pediococcus pentosaceus, Lactococcus lactis subsp. lactis), or selected from a culture collection (Lactobacillus plantarum, Pediococcus parvulus, Lactococcus lactis). Antimicrobial activity of the cell free culture filtrates of LAB was tested by automated turbidometry using Salmonella iso­lates from sprout borne outbreaks (Salmonella enterica serovars Java, Bovismorbificans and Stanley) as the target organisms. The most efficient of the LAB strains were further as­sessed in a pilot scale experiment using seeds contaminated with a mixture of Salmonella strains. Protective culture was added into the soaking water at three inoculation levels (10 , 107 or 108 cfu/ml) and the growth of Salmonella was followed up for 48 h. To evaluate the potential of the selected LAB strain in production scale, the experiments were repeated un­der normal processing conditions without contamination with Salmonella. In the pilot scale experiments the growth of Salmonella was efficiently inhibited if the duration of the treat­ment was a few hours longer than the normal presoaking phase. In the production scale, the treatment with protective culture did not disturb the germination of seeds. The treatment re­sulted first in a significant reduction of enterobacteria in soaking water, but the effect was stepwise diminished due to the serial rinsing periods during the process. The process is cur­rently being further optimized by repeated treatments providing a long term effect still not affecting the germination. Protective cultures may provide an alternative biological tool for controlling the microbiological risks in sprout production.