The major route of rapeseed utilization is by the preparation of rapeseed oil. Different oil preparation technologies have a significant influence on lipid concomitants (including polyphenols, phytosterols, tocopherols, and β-carotene) in rapeseed oil. Lipid concomitants are an important part in rapeseed oil quality, so it is crucial to understand the changes of lipid concomitants during rapeseed oil production. The aim of this review is to summarize the major outcomes of recent research on the influence of different oil preparation technologies on lipid concomitants in rapeseed oil with a focus on pretreatment technologies (including pulsed electric field, microwave, and roasting/steaming), oil extraction technologies (including supercritical carbon dioxide extraction, aqueous enzymatic extraction, and solvent extraction) and refining processes (including degumming, deacidification, decolorization, and deodorization). We hope that this review will provide a theoretical basis for the development of green and efficient technology for rapeseed processing.

Three kinds of silicon dioxide including S655, R92 and R40F were characterized, and their application in low-temperature adsorption refining of fragrant rapeseed oil was studied. The results showed that all three kinds of silicon dioxide had a loose porous structure, but the particle size distribution, specific surface area, pore volume and pore size were obviously different. After being treated with 1.0% silicon dioxide at 45 ℃ for 30 min, the dephosphorization rates of rapeseed oil by S655, R92 and R40F were 90.3%, 99.6% and 88.5%, the lightness increased by 49.9%, 52.5% and 53.9%, the redness decreased by 31.5%, 23.4% and 37.8%, the yellowness increased by 17.3%, 20.0% and 20.6%, respectively. Meanwhile, the retention rate of sterols (above 97.1%) was high, and there were no significant differences in deacidification rate, fatty acid composition or tocopherol retention rate among the three treatment groups. The highest retention rates of total phenol and canolol (98.1% and 99.4%) were found in the samples treated with R92. The contents of glucosinolate degradation products, pyrazines, aldehydes and ketones in fragrant rapeseed oil all increased significantly after refining with the three kinds of silicon dioxide.

In this study, rapeseed seeds were subjected to steam explosion pretreatment (0.4–1.4 MPa) and then coldpressed into oil. The microstructures of the untreated and treated seeds were characterized by transmission electron microscopy (TEM), and the quality of rapeseed oil was comprehensively evaluated by measuring fatty acid profiles, functional components, and antioxidant capacity. The results showed that after treatment, the seeds’ cell structure became incomplete, accompanied by oil accumulation and protein denaturation. As the explosion pressure increased, the moisture content gradually declined from 42.17% to 92.24%, and the oil yield initially increased and then decreased, and the contents of oleic acid, linoleic acid, and α-linolenic acid significantly changed. The energy generated during steam explosion pretreatment could effectively destroy active substance complexes, resulting in the release of more free polyphenols, so that the average content of total phenols in the treatment group was increased by 9.56 folds on average when compared with the control group. Especially, the content of 2,6-dimethoxy-4-vinylphenol reached a maximum value of 2157.95 mg/kg. Phenolic compounds could chelate metal ions, consequently enhancing antioxidant activity of the oil. Specifically, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and ferric ion reducing antioxidant power (FRAP) were increased on average by 13.12 and 12.62 folds, respectively. Meanwhile, the contents of tocopherols and phytosterols increased first due to the dissolution of lipid concomitants, and then decreased due to thermal degradation. Multiple antioxidant components could work together to prolong the induction period of the oxidation of the treated oil up to 22.92 h. In summary, steam explosion pretreatment effectively improved the nutritional and antioxidant properties of rapeseed oil.