Pre‐processing effects on cold pressed rapeseed oil quality indicators and phenolic compounds

Abstract

This study exposed seven rapeseed cultivars to various seed pre‐processing practices. The aim of the study was to investigate the effect of pre‐processing on cold pressed rapeseed oil parameters associated with health and flavor. Results showed the pre‐processing in this study were not a significant factor regarding oil quality. The total phenols of oils from unprocessed seeds ranged from 0.005–2.468 mg/kg oil. The phenolic acids investigated in the roasted group averaging 10.386 mg/kg and the microwaved group averaging 8.015 mg/kg. Part of this increase was due to the formation of canolol in these groups. Microwaved and roasted groups had significantly higher DPPH radical scavenging potential than the other groups. The thermal pre‐processing techniques also significantly altered the volatile composition of the roasted and microwaved groups. Ultrasound pre‐processing had no significant impact on any of the parameters studied.Practical applications: The regulations surrounding cold pressing means that there are restrictions regarding extraction procedures and the treatment of the oil after cold pressing. This means that the main opportunity to alter cold pressed oil is pre‐processing of the seed (in this case rapeseed). Pre‐processing of rapeseed can alter the composition of cold pressed rapeseed oil without impinging on cold pressing regulations. This study shows how pre‐processing techniques can increase the attributes of cold pressed rapeseed oil in relation to antioxidant activity and phenolic acids. This work shows that pre‐processing has a much greater effect on these parameters than varietal selection.Rapeseed pre‐processing and subsequent analysis of cold pressed rapeseed oil compounds associated with flavor and health.