Effect of the chemical refining process on perilla seed oil composition and oxidative stability

The effect of chemical refining process on the physicochemical characteristics and oxidative stability of perilla seed oil was investigated. We analyzed five samples corresponding to each step of the refining process (degumming, neutralization, bleaching, deodorization, and refined oil). The results indicated that the acid value (2.20–0.24 mg KOH/g) and peroxide value (4.32–1.26 mEq/kg) decreased significantly, while the saponification value (178.81–196.24 mg KOH/g) and p-anisidine value (3.45–9.55) increased dramatically. There was no significant difference in conjugated diene, except in the degummed oil. Additionally, the refractive index did not change throughout the process. Eleven fatty acids were identified in samples, and there was no significant difference observed among them. The refining process resulted in decreases in total tocopherol content (25.0%) and total phenolic content (51.7%). Degummed, neutralized, bleached, and deodorized oils have high primary oxidation stability, whereas refined oils exhibit low secondary oxidation rates. Practical applications The present study was designed to examine the physicochemical properties of perilla seed oil at various phases of refining, as well as its bioactive compounds and oxidative stability during the process. This study provides a good reference for the industrial parameters of the refining process to obtain high-quality products for consumers.