An extended processing strategy for rapeseed: Concentrating homologous phenolics from meal to enhance oil quality

Oxidative-stability and nutritional-enhancement of rapeseed oil are positively related to phenolic content. This study developed a novel approach to improve oil quality by extracting phenolics from rapeseed meal (RSM) and incorporating them into the oil. Firstly, single-factor and response surface methodology were used to optimize the acidic-ethanol extraction condition. Through AB-8 resin purification, the resulting solid extract (RSME) achieved a total phenolic content of 406.63 mg sinapic acid equivalents (SAE)/g. Then, the influences of RSME on the antioxidation capacity of rapeseed oil were explored by POV and TBARS during accelerated storage at 60 °C. RSME at concentrations ≥0.6 g/L demonstrated superior oxidative stabilization of rapeseed oil compared to 0.2 g/L BHT (butylated hydroxytoluene). Although the main component, sinapic acid, exhibited stronger DPPH• scavenging activity than RSME, RSME showed better performance at equivalent concentrations on oil stability. This suggests synergistic contributions from other RSME components, including melanin identified here. In conclusion, a post-process or extensional strategy for rapeseed processing by condensing homologous phenolics from meal into oil for improving oxidative stability was established in this study, as a complementation for improving the protein quality in meal by removing anti-nutritional phenolics. The approach represents a sustainable, value-added utilization of rapeseed processing byproducts. • Phenolics from RSM are homologous to those in rapeseed oil; • Condense phenolics from RSM by acidic-ethanol extraction and resin purification; • Phenolics from RSM significantly improve the oxidative stability of oil by 39.27%; • SA and ME therein play important roles in the fortification of rapeseed oil.