Genotype and roasting conditions determine canolol formation and its partitioning between oil and press cake in white mustard (Sinapis alba L.)

This study presents the complete canolol mass balance for cold-pressed white mustard ( Sinapis alba L.) oil, quantifying the partitioning of canolol between the expressed oil and the residual oil fraction of the press cake. Three cultivars that differ in erucic acid and glucosinolate content (Nakielska, Bamberka, and Warta) were roasted at 140, 160, and 180°C for 5, 10, and 15 min, prior to cold pressing. Roasting significantly increased canolol content in all cultivars, with optimal roasting conditions observed at 140–160°C. Higher temperatures, however, promoted canolol degradation. The majority of total recovered canolol was retained in the press cake lipid fraction rather than transferred to the expressed oil, with transfer rates ranging from 1.1% to 64.2% depending on cultivar and roasting conditions. Canolol net production reached 38.8–54.6 µmol/100 g d.m. across cultivars, values substantially lower than those reported for rapeseed under identical conditions, which is consistent with the markedly different sinapic acid derivative profile of Sinapis alba - characterized by a severe deficit of reactive sinapate esters such as sinapoylglucoside and disinapoylgentiobioside that serve as the primary canolol precursors in rapeseed. Pearson correlation analysis confirmed that the loss of free sinapic acid during roasting was strongly negatively correlated with percentage conversion efficiency (r = −0.920, p < 0.001), indicating that precursor pool composition, rather than free sinapic acid content alone, determines canolol formation efficiency. The pronounced cultivar-dependent variation identified in this study suggests that targeted genotype selection could optimize white mustard processing toward either canolol-enriched oil production or canolol recovery from press cake within a biorefinery framework.