Effects of Hydrolyzed Rapeseed Cake Extract on the Quality Characteristics of Mayonnaise Dressing

Combined fractions (H₂ O and 30% and 50% ethanol) of crude rapeseed cake extracts with 80% ethanol were hydrolyzed with NaOH solution. The hydrolyzed extract showed significantly higher contents of total phenolics (41.8 mg SAE/g) and sinapic acid (425.8 mg/g), as well as higher 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging capacity (91.98 RSC%) than the crude extract (P < 0.05). Antimicrobial activity of the hydrolyzed extract was remarkably higher than that of the crude extract against selected Gram-positive and Gram-negative bacteria as well as yeast, as determined by the minimum inhibitory concentration method. Hydrolyzed extract (100, 250, or 500 ppm) was added to mayonnaise dressing, and several quality characteristics of the dressing were investigated by assessments of microbial, physical, and oxidative stabilities during 8 wk of storage. Microbial stability was higher in the dressing with hydrolyzed extract added (4.3 to 4.6 Log CFU/g) than the control (4.9 Log CFU/g). Physical characteristics of the dressing with hydrolyzed extract added were better than those of the control, based on increased viscosity and reduced emulsion separation. Hydrolyzed extract increased oxidative stability in a concentration-dependent manner, and the dressing with added 500 ppm of hydrolyzed extract resulted in a lower free fatty acid content (4.8% at week 8), peroxide value (13.5 meq/kg at week 6), and 2-thiobarbituric acid-reactive substances value (66.2 μg/100 g at week 8) than the control. Therefore, it is expected that hydrolyzed rapeseed cake extract containing high sinapic acid content can be used in emulsion system as a value-added ingredient.

Crude extract of rapeseed cake was fractionated and alkaline-hydrolyzed to convert sinapine into sinapic acid, and the produced hydrolyzed extract showed higher antimicrobial and antioxidative activities than the crude extract. When the hydrolyzed extract was added to mayonnaise dressing, microbial stability increased along with physical characteristics and oxidative stability, thereby supporting the potential of hydrolyzed rapeseed extract as a food additive for quality management of mayonnaise dressing during storage.