Potential of Protective Cultures in Sprout Production

Potential of protective cultures in sprout production

Proceedings of 4th World Congress Foodborne Infections and Intoxications. Federal Institute for Health Protection of Consumers and Veterinary Medicine, Berlin, Germany 1998;Vol 1:631-633.

SkyttS, E.1*, A. Haikara1, A. Siitonen2 and T. Mattila-Sandholm1

'VTT Biotechnology and Food Research, Espoo, Finland

'National Public Health Institute, Laboratory of Enteric Pathogens, Helsinki, Finland

The microbiological risks associated with sprout production are generally recognised. Epidemiological evidence indicates that sprouts have been an important vehicle in a number of Salmonella outbreaks reported. Seeds for sprout production are marketed world-wide as a bulk product and a common source for the outbreaksindifferent countries has often been traced. Because the process conditions favour the growth of mesophilic micro-organisms, the growth risk of Salmonella is alsoincreased when contaminated raw material lots are used. Various kinds of disinfection procedures have been recommended for controlling the microbiological risks in sprouting. All these procedures, however, have negative counter effects which drastically may reduce the germination degree of the seeds. Protective cultures may provide an alternative new biological tool for controlling themicrobiological risks in sprout production. 

In this study, nine Salmonella en/erica ssp. enterica isolates from sprout borne epidemics were used as target organisms for screening of potential protective cultures. One highly antagonistic Lactobadllus plantarum strain was further assessed in the laboratory experiments simulating the germination conditions of Persian clover, and finally tested in production scale. In the simulation assays two inoculation levels (1.2x102cfu/l; 1.2x10'4cfu/l) of Salmonella were used in the soaking water. In the parallel treatments examined the addition of protective culture (109 cfu/ml) was either 10 % (v/v) or 5 % (v/v). After a treatment of five hours no Salmonella growth (< 10 cfu/ml) could be detected in the soaking water when the original inoculation level was 1.2x102 cfu/l. If the inoculation level was higher, a similarly effective result was only obtained by adding 10 % (v/v) of protective culture and extending the duration of the treatment. No Salmonella inoculation was used in the production scale experiments for safety reasons. The protective culture was added in the pre-soaking water before the actual germination phase and thetreatment lasted for five hours. The microbiological quality of the soaking and rinsing water was followed throughout the process by quantitative determinations of aerobic plate "count, enterobacteria and lactic acid bacteria. During the treatment the numberof enterobacteria was significantly reduced in the pre-soaking water. However, in the germination phase their number increased rapidly, and after rinsing for four hours no difference could be demonstrated between the treated and untreated seed batches. The preliminary results gave evidence that in order to obtain a full benefit of protective cultures the treatment has to be optimised in more detail. A singletreatment in the pre-soaking phase is most probably not sufficient and it has to be repeated at a later phase of the germination process. An economic solution would require a recirculation of the culture.