Optimization of Protein Extraction from The Novel Oil Crop Field Cress Press Cake

Abstract

This study investigated the sustainable extraction of protein from field cress (Lepidium Cam-pestre) press cake, an underutilized by-product of oil extraction from a novel oilseed crop, which is currently being domesticated in Sweden. Field cress is recognized for its resilience in Nordic climates and its potential as a source of sustainable aviation fuel (SAF), yet the protein and fibre-rich cake generated during the oil extraction has historically been relegated to low-value uses such as animal feed or discarded as waste.
The pH-shifting method was carried out to establish the baseline of field cress press cake protein extraction. The baseline of protein extraction only yielded approximately 3%. This result led to a further extraction using the enzyme-assisted protein extraction method. The enzyme-assisted protein extraction method was used to optimise the protein recovery yield. The enzymatic hydrolysis facilitated the disruption of the plant cell wall matrix and released the trapped protein. Among the five enzymes used, cellulase (Cellic® Ctec 3 HS) was identi-fied as the most effective enzyme, in which its relatively low dosage of 1.2 millilitres per extraction batch significantly improved the protein yield. The dosage not only enhanced the process efficiency but also reduced the operational cost and energy input, making the method suitable for industrial upscaling.
The optimized protocol involved mixing the press cakes with water, enzymatic treatment, and a two-step pH adjustment-first to solubilize protein and then to precipitate and recover it. The extraction pH at 12.0 yielded higher values than lower pH, approximately 40%, while the precipitation pH at 5.0 led to a higher precipitation coefficient, around 80%. When tak-ing all steps into account, the highest protein recovery yield (39%) was achieved at alkali pH 12.0 and precipitation at pH 4.0.
Beyond technical optimization, this study situates its work within the broader context of the global food system and climate change. With agriculture and food processing contributing substantially to greenhouse gas emissions, the valorisation of agricultural by-products like field cress press cake is essential for advancing circular bioeconomy principles and reducing food waste. Moreover, this study aligns with the UN Sustainable Development Goals for zero hunger and responsible production.
The outcomes of this study demonstrate that field cress press cake can be efficiently convert-ed into functional protein ingredients. This study contributes to environmental stewardship and the diversification of protein sources for a growing global population by unlocking the potential of what was considered waste.

Popular Abstract

Unlocking the Hidden Gem of Ignored Press Cake
What if the leftovers from biofuel production could help to feed the world? This study shows how a high-protein, but fibrous, side-stream of oil extraction can be turned into valuable plant-based protein.
Every harvest season, large amounts of crop waste are generated, often discarded, burned, or used as animal feed. Field cress, a winter-tolerant crop now being developed in Sweden, is no exception. If you are checking out a flight ticket, and they offer you "green fuel", that fuel can in the future be based on oil from field cress. It is just like rapeseed, while the seeds are pressed for oil, the leftover cake is packed with protein and fibre. Yet until now, humans have ignored this valuable press cake in their food chain.
Our project aimed to change that; we wanted to find out how to extract protein from field cress press cake sustainably and on a scalable basis. However, we have a problem with this press cake having very high viscosity, making it harder for us to extract the protein. We dis-covered that using an enzyme called cellulase helped to break down the plant's cell wall, liberating the trapped protein inside. This enzyme cuts down the long chain of carbohydrates to smaller parts, making the slurry less viscous and flowing more easily. But here is the in-teresting part: by using a smaller volume of enzymes rather than a larger volume, we could get more protein out from the press cake. This counterintuitive result may help reduce costs and energy usage in future applications.
How is the magic recipe? Mix the cake with warm water, add the enzyme, adjust the acidity, then increase the alkali to dissolve the protein from the cake. Finally, put more acid again to get the "real" protein that can be collected and dried. And Bum! This simple method gave us nearly 40% of the original protein content.
Why does this matter? Because we are facing global challenges, including food insecurity, rising population, and climate change. By reusing agricultural leftovers into food-grade pro-tein, we can reduce waste, support a circular bioeconomy, and feed more people using fewer resources.
Imagine tomorrow's plant-based burger containing protein from what used to be discarded press cake. That is the kind of future this work makes possible, “one where waste becomes resources, and problems become solutions.”
Authors:
Luthfi Fathul Huda & Abdull-Wahidi Hamad Salim
Lund University, Faculty of Engineering (LTH)

• author: Salim, Abdull-Wahidi Hamad and Huda, Luthfi Fathul
• supervisor: Karolina Östbring
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLTM02 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Field cress press cake, oilseed crop, viscosity, protein extraction, enzymatic hydrolysis, cellulase, pH adjustment, protein yield, sustainable process, food engineering nutrition and food chemistry
• language: English
• id: 9197787
• date added to LUP: 2025-06-16 13:42:09
• date last changed: 2025-06-16 13:42:09