The effect of drying on the native tocopherol and phytosterol content of Sinapis alba L. seeds

Abstract BACKGROUND Postharvest processing, including drying, has a significant effect on the processability of oil crop seeds. High drying air temperature may significantly affect the levels of bioactive compounds in plant raw materials. We decided to investigate the subject given the lack of data on the drying of mustard seeds. The aim was to determine the effect of drying temperature on free fatty acid, phytosterol and tocopherol levels in the oil obtained from white mustard seeds. Seeds were dried in a thin layer at 40, 60, 80, 100, 120 and 140 °C. Changes in phytosterol levels were assessed using gas chromatography–mass spectrometry and changes in tocopherol levels by high‐performance liquid chromatography. RESULTS The analysis showed that, upon completion of air drying at 40–100 °C, losses of sterols did not exceed 5%, while upon completion of drying at 120 °C and 140 °C these losses amounted to 17–50%. Our investigation also showed that during drying of white mustard seed the total tocopherol levels increased, and the higher the drying temperature, the greater the increment. In seeds air‐dried at 120 °C and 140 °C, the increase in tocopherol amounted to 7–9%. CONCLUSION We also showed that the temperature of the drying agent significantly affects the tocopherol and phytosterol levels. It was found that a maximum temperature of 100 °C provides optimal drying conditions for mustard seeds. Principal component analysis identified two subgroups of oils obtained from seeds dried at 120 °C and 140 °C, which differed considerably from the other samples in terms of their bioactive component contents. © 2019 Society of Chemical Industry