Human consumption of fruits and vegetables are generally below recommended levels. Waste from the production, e.g., of un-used parts such as broccoli leaves and stem when producing broccoli florets for food, is a sustainability issue. In this study, broccoli leaves were analyzed for the content of various dietary fibre and phenolics, applying the Uppsala method and HPLC analyses, respectively. The results showed that broccoli leaves had comparable levels of dietary fibre (26%–32% of dry weight (DW)) and phenolic compounds (6.3–15.2 mg/g DW) to many other food and vegetables considered valuable in the human diet from a health perspective. A significant positive correlation was found among soluble dietary fibre and phenolic acids indicating possible bindings between these components. Seasonal variations affected mainly the content of conjugated phenolics, and the content of insoluble dietary fibre. This study verified the importance of the use of broccoli production side streams (leaves) as they may contribute with health promoting components to the human diet and also socio-economic and environmental benefits to the bioeconomic development in the society.

Global food security faces mounting pressures from climate variability, geopolitical conflicts, price volatility, and diminishing arable land, resulting in chronic hunger for over 724 million people worldwide in 2022. This thesis investigates the potential for extracting valuable nutrients from currently underutilised green leaf biomass from harvested crops and intermediate crops through biorefinery processes. Our findings reveal that broccoli and kale leaves represent significant untapped biomass resources, though economic constraints currently limit commercial harvesting, particularly for broccoli. These leaves contain substantial amounts of dietary fibre but comparatively lower protein levels than intermediate crops. Among biorefinery fractions from intermediate crops, the green protein and white protein fractions yielded protein compositions suitable for human and animal nutrition, predominantly consisting of RuBisCO-rich fractions. Both harvest timing and fertilisation significantly influenced protein content and extractability, highlighting the importance of strategic planning when selecting biomass for protein extraction. Regarding phenolic compounds, the green juice, white juice, and brown juice fractions demonstrated the highest concentrations, primarily in the form of flavonoids. In broccoli, these interannual variations are likely attributable to differences in soil conditions, light exposure and temperature variations. Although not presented as a comprehensive solution to global food insecurity, this research demonstrates that systematic utilisation of currently discarded leaf biomass could significantly contribute to more sustainable food systems. By improving resource efficiency, enhancing the nutritional quality of food products, and providing alternative protein sources, the environmental impact could be significantly reduced compared to conventional animal protein production.