Mass and functionality based exergy analysis of different rapeseed protein production routes

Rapeseed proteins are among the outstanding plant-based proteins due to their favorable interfacial functionality. This study evaluates the resource use of the most common rapeseed protein production routes – acidic precipitation, ultrafiltration and wet mild fractionation – using an exergy-based approach. The exergy consumption is normalized based on both product mass and protein functionality. Mass-based assessment indicates that the routes producing dry rapeseed protein concentrate exhibit relatively low exergy efficiencies (12.3 – 20.7%), mainly due to production of a single useful stream and dilute processing conditions that intensify the drying-related exergy demand. Wet mild fractionation shows the highest exergy efficiency at 47.3%, by distributing resource inputs across two useful products, oleosome cream and proteins. When evaluated based on protein functionality, however, ultrafiltration-based recovery of proteins from rapeseed meal and acid precipitation from cold-pressed cake emerge as the least exergy-intensive options to produce rapeseed protein-based emulsifiers. Therefore, the study shows that the resource use efficiency of a process is strongly dependent on the chosen evaluation criterion and highlights the importance of functionality-oriented valorisation of useful streams to enhance the efficiency of resources use.