Identification of bitter off-taste compounds in sunflower press cake using sensomics approach

The sunflower (Helianthus annus L.), a member of the Asteraceae family, is cultivated as a crop worldwide for human and livestock consumption. The primary application of sunflower is oil production, and it is the third most widely cultivated oil seed crop in the world, with a production volume of 57.26 million tons. Throughout the oil production process, a large amount of sunflower press cake accumulates, which contains proteins, cellulosic fibres, lignins, phenols, and minerals. The sunflower press cake contains 28–42% of protein, and this high protein value makes the sunflower press cake potential source of global protein demand. The bitterness in sunflower press cake could limit it is usage as protein alternative despite being sustainable and economical alternative to animal protein. However, understanding the underlying reasons for this bitterness could lead to the access of new sources of protein. To identify the specific compounds responsible for the bitter taste in sunflower press cake, an activityguided sensomics approach was employed. The successful application of sequential solvent extraction, solid-phase extraction, High Performance Liquid Chromatography (HPLC), Taste Dilution Analysis (TDA) and 1H NMR, 13C NMR measurements allowed identification of key bitter off-taste compounds. The TDA revealed that two fractions had the bitterest taste, and subsequent identification of those fractions showed that phenolic compounds and lipid oxidation products were the major contributors to the bitterness of sunflower press cake. Lipid oxidation products such as trihydroxyoctadecenoic acid, dihydroxyoctadecenoic acid, hydroxyoctadecadienoic acid and their isomers, as well as stearic acid, were identified as the bitter off-taste compounds in sunflower press cake.