Use of electrolysed water in sprouts production to control microbial contamination.

Ready-to-eat sprouted seeds are widely consumed in Europe because they are convenient and an important source of micro- and micro-nutrients. The production process of the sprouts requires the seeds to be kept in water up to 4-5 days in the presence of high humidity (95%) and a temperature between 22-28°C. These conditions are however suitable for the proliferation of the microbiota on the surface of the seeds, and their levels can vary from 102 to 106 CFU/g. The microbiota is generally represented by yeasts, Pseudomonadaceae, lactic acid bacteria, spore-forming bacteria and enterobacteria, and pathogens may also be present. At the end of the production process, the sprouts have very high cell load levels which can reach values up to 108 CFU/g. This results in both high microbiological risks, as evidenced also by the European recent cases of toxic infection associated with their consumption, and a very short product shelf-life (3-5 days). Electrolyzed water (EW) is an emerging technology with potential applications in various sectors including food and agriculture. EW has strong bactericidal properties comparable to traditional sanitizers such as sodium hypochlorite, with the advantages to be safer. In this context, the objective of this work was to evaluate the effectiveness of EW to reduce microbial contamination of Daikon seeds during 48 hours sprouting. In particular, microbial load of the sprouted seeds using EW was compared to those obtained with tap water or sodium hypochlorite solutions. Furthermore, the possible reduction in the microbial population of the sprouts following washes with EW or sodium hypochlorite for times between 5 and 30 minutes was verified. Results on the use of EW for the sprouting phase showed that contamination levels were about 1.5-2 logarithmic cycles lower than seeds sprouted with tap water. Moreover, no detectable differences in the color and length of the sprouts were observed. On the other hand, sodium hypochlorite, which is the reference sanitizer, showed a higher efficacy than EW against mesophilic and psychrotrophic bacteria, while its activity against Enterobacteriaceae was the same as EW. An important aspect from the application point of view was to evaluate the effects of changing the EW during the sprouting process. Water changes every 6-8 hours improved the microbiological quality of the sprouted seeds. The contamination levels for mesophilic and psychrotrophic bacteria (4-6 log CFU/g) and enterobacteria (2-4 log CFU/g) were lower than sprouts obtained with the same EW solution for 48 hours. This result suggests the importance of maintaining adequate levels of active chlorine to ensure its action during the whole sprouting process. Concerning the sanitization washes of the sprouts before their distribution, results showed that EW has a much higher efficacy than the reference sanitizer (sodium hypochlorite) against mesophilic and psychrotrophyc bacteria.