Importance of pressing temperature on protein enrichment by electrostatic separation of rapeseed press cakes

Abstract

Electrostatic separation presents a promising method to concentrate protein from rapeseed. Previous research, with focus on meals neglected, the impact of de-oiling methods on the separation process and protein functionality. Therefore, this study describes the impact of processing history on the electrostatic protein enrichment from rapeseed press cakes pressed at varying temperatures on separation efficiency and hydration properties. A defatted meal was used as control. Pressing temperatures ranging from 60 to 130 °C resulted in varied oil removal, with most removal at 80 °C, yielding final oil and protein contents of 20 and 24 g/100 g dry matter, respectively. Subsequent milling and electrostatic separation produced protein fractions with protein enrichment levels of 17 %–30 % compared to the initial press cakes. Recovery of these fractions was influenced by residual oil content and heat-induced structural changes. The press cake with the least oil demonstrated protein yields comparable to rapeseed meal, recovering 0.4 g protein/g press cake protein. Hydration properties revealed that protein solubility was improved by protein enrichment. No significant effect on water holding capacity was noted due to protein enrichment. These findings demonstrate a promising approach for producing protein-rich ingredients from rapeseed press cakes using tribo-electrostatic separation.