Key phytochemicals contributing to the bitterness of quinoa

Despite its nutritional components and potential health benefits, the bitterness of quinoa seed limits its utilization in the food industry. Saponins are believed to be the main cause of the bitterness, but it is still uncertain which specific compound is responsible. This study aimed to isolate the main components contributing to the bitterness in quinoa seed by solvent extraction and various column chromatography techniques guided by sensory evaluation. Five compounds were identified by mass spectrometry and nuclear magnetic resonance analyses, with the dose-over-threshold factors from 29.03 to 198.89. The results confirmed that triterpenoids are responsible for the bitter taste in quinoa seed, with phytolaccagenic acid derivatives being the primary contributor. Additionally, kaempferol 3-O-(2″, 6″-di-O-α-rhamnopyranosyl)-β-galactopyranoside (namely mauritianin), was demonstrated for the first time to be associated with the bitterness of quinoa. This study could provide new insight into the bitter compound identification in quinoa.