Innovative approach to sterilising process water for ready-to-eat salads

KRONEN GmbH, together with its partners, is currently developing a new solution for reducing germs in the process water used during the washing cycle of Fresh-cut salads. The goal is to increase the microbial safety of packaged ready-to-eat products without using chemical additives. The project named SiMoHyP is one of three research projects KRONEN is conducting at the moment.

The demand for ready-to-eat leaf lettuce has been increased massively over the last years. 

All bigger retail chains have completed their fresh food assortment by
offering these kind of products. Microbial innocuousness is one crucial quality criterion when it comes to consumer safety and has to be guaranteed when producing Fresh-cut products.

During the production process for packaged leaf lettuce the salad is cored and tired leaves are removed, then it is cut, washed, dried and packaged in plastic films. The washing process is usually organized in two steps. The first washing cycle makes sure that heavy dirt is removed, such as adherent soil as well as liquids leaking from the damaged salad cells after cutting the salad. The second cycle is made for thorough cleaning.

Washing vegetables with potable water leads to a reduction of microorganisms from tenfold to a hundredfold only. Since, depending on the kind of product, it must be assumed that the number of germs is up to 107 KbE/gFM at the beginning, the washing result has to be evaluated as critical considering these high germ numbers at the beginning. And the washing cycle implies the risk of cross-contamination whenever microbial safe salad batches follow on batches contaminated with pathogens. Adding chemicals is one way to meet this problem, but this is sometimes rejected.

The project KRONEN is working on together with its partners, the ATB Leibniz Institute for Agricultural Engineering and Bioeconomy, aquagroup AG und Havita Berlin Frischgemüse GmbH, is answering this fact. The so-called SiMoHyp project targets to develop an innovative method to hygienize the process water for ready-to-eat salads without using additives. For that reason, the partners want to make use of the fact that bacteria are killed within seconds, when the redox potential is higher than 650 or 700 mV. 

Concretely, this means that an electrolysis cell is developed and implemented in a salad washing plant, which can cope without any additives. Using the ingredients of the potable water only, a redox potential is realized in the process water which is high enough to decontaminate it. Besides, the water can be returned to the washing cycle without any risk of cross-contamination.

Hence, there are several benefits for the producers of Fresh-cut products:
  • Increased consumer safety due to a new method of hygienization without additives.
  • Reducing potable water consumption and thus decreasing costs, which is due to an optimized water use during the washing process by deploying cycle management.
  • Improvement of hygiene and reducing the danger of cross-contamination during the washing process
“In February 2017 we started the project SiMoHyP together with our partners
ATB, aquagroup and Havita. When you look at the project stage we are at around half-time. We are very confident we'll reach the planned targets by the beginning of 2019,” says Eric Lefebvre, Technical Director and the person responsible for the project at KRONEN.

“The project is a worthwhile contribution for increasing the safety and quality of food products and for saving resources at the same time. Our motivation is to develop innovative solutions for our customers. So, currently two other research projects are ongoing at KRONEN: Aquafresh and DEKONWA. 

The three projects deal with very different approaches to contribute to one and the same target: improving food safety without using chemical additives”.

The project SiMoHyp was funded by the Federal Ministry of Food and Agriculture by a decision of the German Bundestag.

Learn more about the current research projects at:

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