Heating studies
Amino acid salts or amino acids (0.039 mmol) were added as powder in SBO or other oils (6.5 g) in a vial to achieve 5.5 mM concentration. While the solution was stirred with a magnetic bar to form a suspension, 2 grams of the suspension was transferred to a vial (26.2 mm i.d., 60 mm height). Three samples per treatment were prepared. The ratio of surface area to volume of oil in this vial was approximately 2.5 cm2/cm3. The cap of the vial was removed, and the samples were heated in an oven at 180 °C for 8 h. Oil samples were then transferred to 1-dram vials and stored at -20 ℃ until analyses. The oxidation of oil was determined in a week after heating.