Substance that Gives Rapeseed a Bitter Taste Has Been Discovered

Rapeseed does not just contain oil but high-quality protein, too. However, protein extracts from rapeseed have an intense, bitter off-taste, which prevents it from being a protein source for human nutrition. In a step towards developing rapeseed for the human protein supply, food chemist Thomas Hofmann and his team at the Technical University of Munich (TUM) identified the substance that is pivotal for the bitter taste in rapeseed.

The researchers investigated three different protein isolates using mass spectrometric analysis methods and taste tests. All three isolates had a protein content of 80 to 90 percent. The researchers show for the first time that a compound called kaempferol 3-O-(2'''-O-sinapoyl-ß-sophoroside) is the key substance that makes protein extracts from rapeseed inedible. The cruciferin isolate, in particular, contained a large amount of this bitter substance with 390 milligrams per kilogram. The rapeseed meal and napin isolate had less than a tenth of the quantity, but still tasted bitter in the sensory test.

"Since we now know the cause of the bitter off-taste, it is much easier to develop suitable technological processes or breeding strategies that can be used to produce tasty, protein-rich foods from rapeseed," said co-author Corinna Dawid, who heads the Phytometabolomics research group at TUM.

For more details, read the TUM news article.