Rapeseed proteins – Production methods and possible application ranges

Abstract

The worldwide increasing demand in proteins for human nutrition and animal feeding leads to a growing interest in novel protein sources. Therefore, rapeseed as an established raw material for the production of edible oils could be a promising alternative, as large amounts of press cakes and residues of oil extraction are available. Integrated fractionizing processes for simultaneous oil and protein isolation using aqueous-alcoholic extraction or adsorption techniques open many opportunities for new protein ingredients from rapeseed. The present manuscript compares two strategies to identify a suitable process for achieving highly functional ingredients for the use in food applications such as sausages, bakery products or mayonnaise. One process was based on hulling of the rapeseed kernels followed by an aqueous-alcoholic-extraction of the de-oiled flour. Based on this process, protein ingredients with about 60% protein content, but only poor functional properties could be produced. The application concentration of this ingredient was limited to 2%, because of oily and strawy off-flavors. Isolates with protein contents higher than 90% and improved sensory and functional properties could be achieved with an aqueous extraction followed by adsorption of secondary plant metabolites on specific resins and an ultrafiltration of the aqueous extract. This process enables the production of protein isolates with reduced off-flavors and optimized functional profiles. In several food applications a very promising utilization potential of these ingredients could be confirmed