Understanding of the Role of Pretreatment Methods on Rapeseed Oil from the Perspective of Phenolic Compounds.

The thermal pretreatment of oilseed prior to oil extraction could increase the oil yield and improve the oil quality. Phenolic compounds are important antioxidants in rapeseed oil. In this study, we investigated the impact of thermal pretreatment method on the rapeseed oil based on phenolic compound levels. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis showed that the phenolic compound contents in the microwave-pretreated oil were higher than those in the oven- and infrared-treated oils. Sinapic acid (SA) and canolol (CA), which are the top two phenolic compounds in rapeseed oil, exerted well 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with IC50 values of 8.45 and 8.80 µmol/L. The cell experiment uncovered that SA and CA have significant biological activities related to rapeseed oil quality, including increase of antioxidant enzymes superoxide dismutase (SOD), alleviation of reactive oxygen species (ROS), and cytotoxicity of HepG2 cells after the intake of excessive oleic acid. Further investigation indicated that SA and CA reduced cell apoptosis rate through Bax-Bcl-2-caspase-3 and p53-Bax-Bcl-2-caspase-3, respectively. Taken together, our findings suggest that microwave pretreatment is the best method to improve the content of phenolic compounds in rapeseed oil compared with oven and infrared pretreatments.

Evaluation of the functional quality of rapeseed oil obtained by different extraction processes in a Sprague-Dawley rat model.

The nutritional function of vegetable oil is influenced by different oil extraction methods. In this study, the effects of different processing techniques on the quality of rapeseed oil and animal lipid metabolism were evaluated. Results showed that rapeseed oil obtained by the aqueous enzymatic extraction (AEE) method had the highest polyphenol (152.08 ± 11.44 mg GAE per kg), α-tocopherol (208.97 ± 15.84 mg kg-1), and ß-carotene (5.40 mg kg-1) contents and a better oxidation resistance. It was noted in an experiment on rats fed with diets containing rapeseed oils that AEE rapeseed oil reduces total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C), aspartate transaminase (ALT) and alanine transaminase (AST) in high-fat diet rats by 27.09%, 11.81%, 35.52%, 31.02% and 27.61%, respectively, and the body and liver weights of rats were decreased. mRNA expression indicated that AEE could significantly down-regulate fatty acid synthase (FAS) and up-regulate acyl-CoA oxidase 1 (ACOX1) gene expression levels (P < 0.05). These results suggested that the AEE method can increase the content of trace active substances in rapeseed oil and ameliorate chronic diseases induced by a high-fat diet.

Combination of thermal pretreatment and alcohol-assisted aqueous processing for rapeseed oil extraction.

BACKGROUND: The alcohol-assisted aqueous extraction processing (AAEP) of oil has many advantages such as no need for demulsification and relative low cost compared with enzymatic aqueous extraction processing (EAEP). Three kinds of thermal pretreatments including dry-heating, wet-heating and soak-heating followed by the AAEP of rapeseed oil were investigated. RESULTS: Both soak-heating and wet-heating had a higher contribution rate to oil yield than dry-heating due to the enhancement of heat transfer rate owing to the high moisture content in the rapeseed cells. However, oil from soak-heated rapeseeds showed a much lower level on peroxide value (0.41 mmol kg-1 ) than that of wet-heated rapeseeds (5.23 mmol kg-1 ). In addition, transmission electron microscopy images illustrated that promoting effects of soak-heating and wet-heating on oil release were attributed to the coalescence of oil bodies. A relative low concentration of alcohol solution as an extraction medium, the highest oil recovery of 92.77% was achieved when ground rapeseeds (mean particle size: 21.23 µm) were treated with 45% (v/v) alcohol for 2 h at 70 °C and pH 9.0. Both the acid value and the peroxide value are lower than the commercial oil produced by extrusion and hexane extraction. Furthermore, the oil produced from AAEP also had higher content of tocopherols and lower content of trans-fatty acids than the commercial oil. CONCLUSION: AAEP of oil from soak-heated rapeseeds is a promising alternative to conventional oil extraction methods. © 2019 Society of Chemical Industry.

Report-Physicochemical and Antimicrobial properties of canola (Brassica napus L.) seed oil.

Canola oil has been used in the Pakistan for the treatment of various diseases and skin infections. Oil was extracted with n-hexane from the seeds of canola (Brassica napus L.) and was evaluated for free fatty acid value. Four microorganisms namely; Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas originals, and Klebsiella pneumonia, has known to cause some infections treatable with these oils were investigated. The results showed that all oil shown inhibitory effects against Klebsiella pneumoniae, Staphylococcus epidermidis, and Pseudomonas originals but no inhibitory effects was found against Staphylococcus aureus.