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The transition towards a more circular urban food system depends on large-scale changes in citizen behavior. One of these changes it the transition to plant-based protein consumption. As the complex dynamics that drive individual behavior are not well understood yet, this study applies an ecological momentary assessment to collect data of urban citizens’ protein choices in varying physical and social contexts over a period of three weeks. This study theoretically contributes to our understanding of how protein choices are driven by stable personal and varying situational factors. Practically, this study will give policymakers insights into the factors driving urban citizens’ decision-making.

At the end of the annual horticultural production cycle of greenhouse-grown crops, large quantities of residual biomass are discarded. Here, we propose a new value chain to utilize horticultural leaf biomass for the extraction of secondary metabolites. To increase the secondary metabolite content of leaves, greenhouse-grown crop plants were exposed to low-cost abiotic stress treatments after the last fruit harvest. As proof of concept, we evaluated the production of the flavonoid rutin in tomato plants subjected to nitrogen deficiency. In an interdisciplinary approach, we observed the steady accumulation of rutin in young plants under nitrogen deficiency, tested the applicability of nitrogen deficiency in a commercial-like greenhouse, developed a high efficiency extraction for rutin, and evaluated the acceptance of the proposed value chain by its key actors economically. On the basis of the positive interdisciplinary evaluation, we identified opportunities and challenges for the successful establishment of horticultural leaf biomass as a novel source for secondary metabolites.