Effect of infrared-assisted spouted bed drying of flaxseed on the quality characteristics of its oil extracted by different methods.

Abstract

Infrared (IR)-assisted spouted bed drying (SBD) has emerged as a potential alternative to the traditional hot air drying for heat sensitive components. The aim of this study was to investigate effect of IR-assisted SBD and application of cold press (CP), solvent extraction (SE) and ultrasound assisted extraction (UAE) on the quality of flaxseed oil. SBD and IR-assisted SBD were performed at air temperatures of 40, 60, 80 °C and their effects on the drying rate, fatty acids composition and oil peroxide and acid values were evaluated. Quality of oil extracted from the dried flaxseeds by CP, SE and UAE methods was then evaluated. Increasing air temperature in the presence of IR increased the drying rate. The peroxide values (PVs) of IR-SBD samples were higher than those of SBD at the same temperature. IR treatment did not notably change the composition of fatty acids in flaxseed oil, except in linoleic acid content. UAE gave higher extraction yield than CP and SE methods. UAE yielded an oil with higher percentage of saturated fatty acids, whereas the percentage of omega-3 and omega-6 fatty acids was higher in the CP method. The oil extracted by CP exhibited lower levels of PV (0.516 meq O2 /kg oil) and acid value (1.36%), as compared to oils extracted by SE and UAE methods. Both UAE and conventional methods did not significantly influence the composition of fatty acids in the extracted oils. Nonetheless, the CP method yielded an oil with a high percentage of omega-3 and omega-6 fatty acids. © 2019 Society of Chemical Industry.