Antioxidant capacity of rapeseed meal and rapeseed oils enriched with meal extract

Abstract

Response surface methodology (RSM) was used to evaluate the quantitative effects of two independent variables: solvent polarity and temperature of the extraction process on the antioxidant capacity (AC) and total phenolics content (TPC) in meal rapeseed extracts. The mean AC and TPC results for meal ranged between 1181-9974 mmol TE/100 g and 73.8-814 mg sinapic acid/100 g of meal. The experimental results of AC and TPC were close to the predicted values calculated from the polynomial response surface models equations (R 2 ¼ 0.9758 and 0.9603, respectively). The effect of solvent polarity on AC and TPC in the examined extracts was about 3.6 and 2.6 times greater, respectively, than the effect of processing temperature. The predicted optimum solvent polarity of e ¼ 78.3 and 63.8, and temperature of 89.4 and 74.28C resulted in an AC of 10 014 mmol TE/100 g and TPC of 863 mg SAE/100 g meal, respectively. The phenolic profile of rapeseed meal was determined by an HPLC method. The main phenolics in rapeseed meal were sinapine and sinapic acid. Refined rapeseed oils were fortified with an extract -rich in polyphenols -obtained from rapeseed meal. The supplemented rapeseed oil had higher AC and TPC than the refined oil without addition of meal extracts. However, AC and TPC in the enriched oils decreased during storage. The TPC in the studied meal extracts and rapeseed oils correlated significantly ( p<0.0000001) positively with their AC (R 2 ¼ 0.9387).Practical applications: Many bioactive compounds extracted from rapeseed meal provide health benefits and have antioxidative properties. Therefore, it seems worth to consider the application of antioxidants extracted from the rapeseed meal for the production of rapeseed oils with potent AC. Moreover, antioxidants extracted from the rapeseed meal were added to refined rapeseed oil in order to enhance its AC. AC was then tested by FRAP assay. FRAP method is based on the reduction of the ferric tripyridyltriazine (Fe 3þ -TPTZ) complex to the ferrous tripyridyltriazine (Fe 2þ -TPTZ), and it is simple, fast, low cost, and robust method. FRAP method does not require specialized equipment and can be performed using automated, semi-automatic, or manual methods. Therefore the proposed FRAP method can be employed by the fat industry laboratories to asses the AC of rapeseed oils and meal.

Octyl sinapate as a new antioxidant to improve oxidative stability and antioxidant activity of rapeseed oil during accelerated storage

“…Only decrease in FRAP (0.89-1.70 μmol TE g −1 ) and TPC (0.09-0.11 mg SA g −1 ) in rapeseed oil enriched with meal extract after 2 (FRAP = 0.66-1.37 μmol TE g −1 , TPC = 0.07-0.09 mg SA g −1 ) and 4 (FRAP = 0.65-1.31 μmol TE g −1 , TPC = 0.06-0.08 mg SA g −1 ) weeks of storage was found previously [15]. Moreover, high amounts (above 75%) of a new caffeic acid amide antioxidants remained in canola triacylglycerols after 5 days of storage in darkness at 60 °C [18].…”

“…The effectiveness of different natural antioxidants present in plants, fruits, vegetables, cereals, seaweeds, macroalgae, essential oils, and by-products for the stabilization of rapeseed oils had been recently estimated [4][5][6][7][8][9][10][11][12][13][14][15]. The protective effect of these natural antioxidants in stabilizing rapeseed oils was evaluated by determining their peroxide values (PV), p-anisidine values (AV), carbonyl values, thiobarbituric acid-reactive substances (TBARS value), conjugated dienes (CD) and conjugated trienes (CT) amounts, TOTOX index, oxidative stability (Rancimat test), antioxidant activity (AA), total phenolic content (TPC), and amounts of volatile compounds during practical and accelerated storage conditions [4][5][6][7][8][9][10][11][12][13][14][15]. The addition of different plant extracts to rapeseed oils revealed efficacy in delaying both primary and secondary oxidative changes (PV = 0-450 and 0-350 meq O 2 kg −1 , CD = 0.3-22.5 and 0.…”

“…The addition of different plant extracts to rapeseed oils revealed efficacy in delaying both primary and secondary oxidative changes (PV = 0-450 and 0-350 meq O 2 kg −1 , CD = 0.3-22.5 and 0. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].0, AV = 3.4-216.9 and 3.4-160.3, CT = 1.1-4.8 and 1.1-4.5, TOTOX = 8.6-1049.6 and 8.6-924.7, induction period = 3.8-53.9 and 4.3-135.0 h for control and enriched oils, respectively) during storage under oxidation conditions [5,[8][9][10][11][12]14].…”

“…Moreover, the supplemented rapeseed oil had higher ferric reducing antioxidant power (FRAP) (0.65-1.70 μmol Trolox (TE) g −1 ) and TPC (0.062-0.11 mg SA g −1 ) than the refined oil without addition of meal extracts (FRAP = 0.37-0.73 μmol TE g −1 and TPC = 0.0039-0.029 mg SA g −1 ) [15].…”

Biologically synthesized silver nanoparticles by aqueous extract of Satureja intermedia C.A. Mey and the evaluation of total phenolic and flavonoid contents and antioxidant activity

“…have been proposed to take role in SNPs formation [29,30]. A majority of such biomolecules known as antioxidants [31,32] are, in fact, successfully employed in the chemical synthesis of SNPs.…”