Evening primrose (Oenothera paradoxa) cake as an unconventional protein source.

An efficient procedure of a protein isolate production from the evening primrose cake was developed. The cake is a by-product of oil extraction from seeds by using the cold pressing method. The evening primrose cake contains 22.7% of protein. Its content in the protein isolate derived from the cake is 74%. Proteins present in evening primrose seeds are rich in Trp (7%) and Met (3%), but Lys-deficient (1.3%) as compared to the FAO protein standard. Apart from the proteins, the protein isolate contains 8.5% (w/w per s.s.) dietary fiber, that negatively affects its digestibility. To enhance the bio-availability of the protein isolate, it was partially hydrolyzed with commercial preparations of trypsin and other proteases (Alcalase and Flavourzyme, Novozymes. Denmark). The most advanced proteolysis (52%) was achieved by 6 h digestion of 2% protein suspension with a mixture of Flavourzyme and Alcalase (350 and 600 U per g of protein, respectively) at 50 degrees C and pH 9.0.