A New Insight into the Weight Gain Method to Monitor and Evaluate Lipid Peroxidation

The kinetics of change in peroxide value and weight gain were simultaneously studied during the peroxidation of three vegetable oils of various chemical compositions. The initiation and propagation oxidizability parameters O_i (kg mEq^-1 h²) and r_n (h^-1) of the canola, corn, and peanut oils were calculated to be 412 and 0.0894, 160 and 0.0641, and 36.1 and 0.0304, respectively. The weight-based parameter O_iw ranked the oils (103,000, 51,000, and 8000% h², respectively) as the parameter O_i did. However, the equivalent parameter r_nw (0.0680, 0.1198, and 0.1875 h^-1, respectively) provided a reverse order than that of the parameter r_n. This was attributed to the fact that the value of r_n represents the formation and decomposition of lipid hydroperoxides in general, whereas the value of r_nw actually represents the overall tendency of an oil to the formation and polymerization of lipid hydroperoxides.