From waste to taste: fermenting rejected tomatoes into a marketable and delicious product

Unwanted tomatoes represent ~20% of the European market, meaning that ~3 million metric tons of tomatoes are wasted every year. On a national scale, this translates to 7000 tons of tomato waste every year. Considering the challenge that food spillage represents worldwide and that the Netherlands wants to be circular by 2050, it is important to find a way to circularize these tomatoes back into the food chain. Moreover, tomatoes are the largest greenhouse crop in the Netherlands, which means that reducing the waste of this crop will positively and significantly affect the circularity and sustainability of the Dutch food system. A way to bring these tomatoes back into the food chain is through fermentation with lactic acid bacteria (LAB), which are already used in many food applications. In this project, we will assemble a unique new mix (co-culture) of LAB bacteria, which will lead to a stable fermented product with low sugar, low pH and a fresh taste, without compromising its nutritional value. This fermentation will prevent the contamination of the product with other microorganisms, providing the product with a prolonged shelf life, and will have a positive impact on the health of the consumers. Up until now, only non-fermented products have been produced from rejected tomatoes. This solution allows for an in-between product that can be used towards many different applications. This process will be upscaled to pilot scale with our consortium partners HAN BioCentre, Keep Food Simple, LLTB and Kramer B.V. The aim is to optimize the process and taste the end result of the different fermentations, so the end product is an attractive, circular, and tasty fermented tomato paste. These results will help to advance the circularity and sustainability of our food system, both at a national and European level.

Out-of-spec tomatoes represent ~20% of the European market, meaning that ~3 million metric tons of tomatoes are wasted every year. Tomatoes are the largest Dutch greenhouse crop, meaning that the national waste translates to 7000 tons of tomato waste every year. Considering the challenge that food spillage represents worldwide and the EU goal of circularity by 2050, it is important to find ways to circularize these tomatoes back into the food chain. One such strategy is through fermentation with lactic acid bacteria (LAB). A project to achieve this was initiated by the Keep Food Simple Foundation (KFS). Proof of principle experiments were performed by doctoral and MSc students from Maastricht and Wageningen University under the guidance of KFS. Building on the results of these studies, the HAN BioCentre, together with KFS and other partners, selected 2-3 LAB strains (from 5 initial candidates) that produced a stable fermented product with low sugar, low pH and a fresh taste. The fermentation, when initially uncontaminated, prevented contamination of the product with other microorganisms, resulting in a prolonged shelf life. Both the heat handling of the tomatoes and the fermentations were upscaled to semi-industrial scale at Kramer B.V. with the assistance of HAN BioCentre. These upscales were done first with ~100kg of tomatoes, and then with ~3000kg, yielding successful fermentations of ~100L. The last fermentations were performed with rejected tomatoes provided by farmers in collaboration with LLTB, showcasing the process’ feasibility. In all, the aim of optimizing the process and taste of the different fermentations has been achieved. Kramer B.V will continue to work on the fermentation results so the end product is an attractive, circular, marketable, and tasty fermented tomato paste. These results will help to advance the circularity and sustainability of our food system, both at a national and European level.