Rejects on the Menu: Turning Side Streams into Delicious Foods Through Fermentation
Abstract: ** Lecture will be given in English**
The food industry generates large volumes of side streams that are underutilized or discarded, even though they are food-grade. We aim to keep these streams in their original destination: human food. Using fermentation, we explore how these materials can be transformed into food products while improving safety, generating flavor, and upgrading protein quality in otherwise unappealing substrates. So far, we have developed three products from two side streams of the fresh vegetable processing industry: rejected mushrooms from a canned mushroom factory and leftover mung bean sprouts from a sprouting company.
First, we developed a solid-state fermented (SSF) vegetable block from either substrate, inspired by tempeh. Following a safe-by-design approach, we introduced a dedicated chemical acidification step and validated the process in a challenge test against a pathogen cocktail, demonstrating pathogen reduction within the fermentation window. We then studied microbial dynamics, aroma development, and protein quality. In a consumer test with 420 participants, acceptance scored above the scale midpoint even after minimal preparation, suggesting strong potential for further culinary development, which is now being pursued in collaborations with chefs and leading restaurants.
Second, we explored mung bean sprouts as an alternative kimchi substrate, benchmarked against Napa cabbage. Following starter selection and complete fermentation characterization, we conducted a sensory analysis. Participants could not reliably distinguish the two in a triangle test based on flavor, while hedonic liking was comparable; we are now studying consumption of the product in a real-life environment.
Finally, we are developing a low-salt, soy-free shoyu alternative, using koji grown on European legumes and brewers’ spent grain instead of soy and rice, fermented with rejected mushrooms as an additional flavor source. Having characterized koji performance across substrates and strains, we are now tracking a 90-day moromi fermentation.
Together, these studies show that fermentation can turn overlooked side streams into foods that are technically feasible, safe, and enjoyable to eat.
