Precursors and Formation Pathways of Trimethylamine in the Processing of Fragrant Rapeseed Oils

Fragrant rapeseed oil is produced through roasting and hot-pressing. However, the formation of trimethylamine (TMA) during its production can negatively impact the aroma of the oil. This study aimed to find the potential precursors and pathways of TMA formation in fragrant rapeseed oils. A simplified model containing water, oil, and various possible precursors (choline, sinapine, betaine, choline glycerophosphate, phosphatidylcholine, and trimethylamine oxide) was used to quantify the changes in the precursors and intermediates involved in the formation of TMA. The results showed that all of the precursors contributed to the formation of TMA with choline exhibiting the highest conversion rate (24.88%). Choline was found to serve as both a precursor and an intermediate. Sinapine, which was present in rapeseed at a high level (8920.85 mg/kg), was also identified as an important precursor for TMA formation. Furthermore, a higher heating temperature, a longer heating time, and a higher amount of water content were found to potentially lead to increased TMA formation.