Effect of enzymatic and hydrothermal treatments of rapeseeds on quality of the pressed rapeseed oils Part I: Antioxidant capacity and antioxidant content

摘要

Response surface methodology was used to evaluate the quantitative effects of three independent variables: rapeseed moisture content, concentration of the added enzymes and conditioning temperature, on the antioxidant capacity and total phenolic, tocopherol, and phospholipid contents in the enzyme-treated rapeseed oils. The highest antioxidant capacity (1220.0, 964.8 μmolTE/100g) total phenolic (83.3, 74.0 mg SA/100g) and phospholipid (12,532, 12,376 mg/kg) contents reveal two rapeseed oils extruded from seeds contained 11% moisture, treated with cellulolytic and pectolytic enzymes (0.05%), respectively, and heated at 120 ℃. However, the highest content of total tocopherols was determined in rapeseed oils pressed from seeds with 7% moisture, after addition of cellulolytic (0.05%) and pectolytic (0.1%) enzymes, heated at 90 and 105 ℃, respectively. Total phenolic and phospholipid contents in the enzyme-treated rapeseed oils correlated significantly (p < 0.0000001) with antioxidant capacities of oils (R~2 = 0.8710 and 0.6581, respectively). Experimental results of the antioxidant capacity, total phenolic, tocopherol and phospholipid contents were close to the predicted values calculated from the polynomial response surface models equations (R~2 - 0.9727, 0.9870, 0.8390 and 0.9706 for the cellulolytic enzyme-assisted rapeseed oils and R~2 = 0.9148,0.9489,0.9426 and 0.9479 for the pectolytic enzyme-assisted rapeseed oils). The optimum rapeseed moisture content, enzyme concentration and conditioning temperature for the cellulolytic and pectolytic enzyme-treated rapeseed oils were 11% and 9.7%, 0.08% and 0.1%, and 120 ℃, respectively.