Elucidation of the role of oleosin in off-flavour generation in soymeal through supercritical CO2 and biotic elicitor treatments

• Phospholipids (PLs) and oleosin proteins are responsible for off-flavor generation in soymeal.
• SC-CO2 oil extraction from soybean seeds resulted in reduced residual PLs in soymeal.
• Biotic elicitor treatments of soybeans before oil extraction enhanced the oleosins’ PLA2 activity.
• Enhancement of PLA2 activity of oleosin reduced the off-flavor generation in soymeal.

Defatting soybean by sophisticated oil extraction method utilising supercritical CO2 resulted in a significant decrease in the residual phospholipids (PLs) compared with soymeal obtained by conventional cold percolation method utilising hexane as the extraction solvent. Interestingly, the levels of residual PLs showed a proportionate relationship with thiobarbituric acid (TBA) number, an indicator of lipid peroxidation responsible for off-flavour generation. Furthermore, two oleosins (18 and 24 kDa) were isolated from the oil bodies extracted from soybean seeds and positively characterised for phospholipase A2 (PLA2) activity, suggesting their plausible involvement in off-flavour generation in soymeal. The treatment of soybean seeds, before oil extraction, with different concentrations of biotic elicitors such as chitosan and jasmonic acid also significantly reduced the levels of residual PLs as well as the TBA number. The biotic elicitor treatment could thus prove to be an important strategy for the reduction of off-flavour in protein-rich soymeal.