Optimization of Protein Recovery from Rapeseed Press Cake

Abstract: Due to the world’s growing population and an increase in food demand, new innovative food products need to be developed to maximize the use of limited farmland. Because of global warming and the fact that plant based products generate less greenhouse gases than meat based products, research should focus on new plant-based protein sources. Rapeseed press cake is a residue from rapeseed oil production and contains around 30 % protein. These proteins can be extracted and possibly be used for food production. However, due to a high concentration of anti-nutrients, the press cake is today mainly sold as animal feed. Previous studies and master students from the Department of Food Technology, Engineering and Nutrition have developed a method for protein recovery from coldpressed rapeseed press cake including a leaching step and a precipitation step. This master thesis focused on two areas: creating a mass balance of the protein distribution in the existing process and to investigate whether the protein yield could be increased by serial recirculation of unextracted proteins. The result of the protein distribution showed that the majority of the proteins the first day (52 %) was located in the final sediment as desired, resulting in a protein yield of 52 %. Protein losses in the process was proteins that was never solubilized during the leaching step and therefore remained in the heavy phase (26 %) and proteins that would not precipitate at the chosen pH remained in the supernatant (18 %). Recirculation of the unextracted proteins resulted in that additionally 9.3 % of the proteins could be collected as sediment increasing the yield to 61 %. Further recirculations only achieved an additional yield increase of 1.0 % and 0.18 % and were not considered economically efficient. The present work shows that recirculation of the unextracted protein should be to perform once.