The effect of there fining process on the physicochemical properties, fatty acid composition, bioactive components, and antioxidant properties of evening primrose oil (EPO) was investigated. The results showed that the peroxide value, acid value, and p-anisidine value changed significantly throughout the refining process (p < .05). Twelve fatty acids were identified in oil samples, while their percentage contents were not significantly different during the refining process. Contents of tocopherol and total phenols were removed by 23.5% and 79.4%, respectively, after refining. The refining process resulted in losses of campesterol and β-sitosterol of approximately 16.0% and 13.8%, respectively. Moreover, squalene was detected in evening primrose oil for the first time, and its content decreased by 20.2% during the refining process. Furthermore, during the whole refining process, the DPPH free radical-scavenging ability of EPO decreased by 10.6%, and the FRAP reducing capacity dropped by 56%, meanwhile, its antioxidant stability was affected. How to cite this article: Pan F, Li Y, Luo X, et al. Effect of the chemical refining process on composition and oxidative stability of evening primrose oil.

For the increase in oxidative stability and phytonutrient contents of walnut oil (WO), 5, 10, 20 and 30% blends with almond oil (AO) were prepared. The fatty acid compositions and the micronutrients of the oil samples such as tocopherol, phytosterol and squalene were measured by GC-MS and HPLC. It was found that the proportions of PUFAs/SFAs in blended oils with high AO contents were lowered, and the blends contained higher levels of tocopherols, phytosterols and squalene than those of pure WO. The 60 °C oven accelerated oxidation test was used to determine the oxidative stability of the blended oil. The fatty acid composition, micronutrients and oxidation products were determined. The results showed that the oxidation stability of the blended oil increased with an increasing proportion of AO. In addition, a significant negative correlation between micronutrient and oxidation products was observed as the number of days of oxidation increased.

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.

The effect of chemical refining process on the bioactive composition, in vitro antioxidant capacity, and their correlation of perilla seed oil (PSO) were investigated. In this paper, seven samples corresponding to each step of the refining process (degumming, neutralization, bleaching, deodorization, winterization, crude, and refined oils) were studied. The results showed that phenolic compounds and tocopherols were removed from PSO to a degree of 19.4% and 5.4%, respectively. In addition, the carotenoid content of PSO decreased during the refining process. The main carotenoid of PSO was found to be lutein, and the compound was lost completely during the bleaching step of the refining process. In this paper, we analyzed the variation of carotenoid content in PSO during the refining process for the first time. Neutralization affected the contents of phytosterols the most, followed by the effects of degumming and bleaching. The demonstrated results of Pearson product-moment correlation indicated that total tocopherols were significantly correlated with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorption capacity (ORAC) values, whereas carotenoids were significantly correlated with the DPPH value. However, phenolic compounds and phytosterols have no significant difference with DPPH, 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, ORAC, and ferric reducing antioxidant power values. The collected information can be applied to seeking out optimum factors needed to suffice the fundamental requirements for PSO production and minimize micronutrient losses to enhance its market value.Practical Application: The present study aimed to determine influence of chemical refining in the bioactive composition of perilla seed oil (PSO) as well as its antioxidant capacity in vitro. Moreover, we also intend to find the correlation between them. Results indicated that this study supplies a good reference for the industrial parameters of the refining process to minimize micronutrient losses and further obtain high-quality PSO products for consumers.