Fermentation makes waste streams profitable

In a circular economy, it is of great importance to make optimal use of food and to avoid wasting it. Together with its partners in the Zijstromen project, Amsterdam Green Campus has developed a new, patented technology that turns residual fruit and vegetables that would otherwise have to be disposed of as waste into a valuable product. 

Fermentation as part of a circular agricultural system

In a circular agricultural system, we want to avoid food waste and losses and keep organic residual materials in our food system as optimally as possible. In that case, it helps enormously if we upgrade the volume of residual flows of organic products and make them suitable for consumption. Fermentation can offer a solution for this. 

Fermentation of composite residual streams

The request was to develop a fermentation process that is not only suitable for upgrading white cabbage, but also broccoli, peppers, tomatoes and various other products. This was the main challenge in the research, says Professor Jeroen Hugenholtz of the WUR. "When processing residual flows, you are dealing with different types of vegetables and fruit that are offered as a mixture and have to be processed. So the fermentation process has to be able to deal with a mixture, which moreover varies in composition according to the season."

Fresh processing is a prerequisite

Within the framework of the POP3 project, a few additional requirements were placed on the process. Hugenholtz: "Firstly, the process must deliver a high-quality product with retention of vitamins and longer shelf life under all conditions. And secondly, the process must be simple to implement, without high costs for equipment, heating or adding water which you then have to evaporate again later. In the fermentation process we have developed, fermentation takes place at room temperature. So without the need for heating. It also does not require high investments. That makes the process very affordable. And an additional advantage: because there is no heating, there is little damage to the organic material."

The only condition the fermentation process imposes is supply of fresh fruit and vegetables, Hugenholtz continues. "Quick processing of organic material is crucial. The starter culture we have isolated can handle mixtures of varying composition well. But it only works if the material comes directly from the land or from the processing plant."

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