Research On Polyphenolics Of Rapeseed

Polyphenol is a wild spread secondary metabolites which unique occur in plant kingdom. Its general antioxidant activity, antibacterial and antitumor properties of have triggered increasing research interests on polypehnol. Based on the reported data, rapeseeds have higher total polyphenol content than other oil crops seeds, such as soybean and peanut. Understanding the content and distribution of polyphenol in different varieties of rapeseeds will be helpful for better utilization of polyphenol from rapeseeds. For this purpose, the following studies in this thesis have been done:1. The extraction condition such as solvents and extraction time have been optimized based on the total pholyphenol content (TPC) and antioxidant (DPPH radical scavenge capability (RSC) and FRAP value) capabilities. Under this condition, we found that TPC, DPPH RSC, and FRAP value in industry high temperature pressed rapeseed cake were decreased by 11.8%, 9.57% and 5.7% compared with laboratory solvent defatted rapeseed meal.2. The TPC, DPPH SRC and FRAP value in defatted meal, hull and endosperm from 10 different varieties Brassica napus rapeseed were compared, the results showed that TPC content ranged from 25.08 to 31.53mg/g , tannins content ranged from 0.71 to 1.06mg/g in these 10 varieties rapeseed meals. The TPC and tannin content of in defatted endosperm were 4.47-6.24 and 6.41-11.11 times higher than that of defatted rapeseed hull, respectively.3. The species in rapeseeds polypehnol extracts were analyzed by HPLC/MS and MS/MS method, and 7 phenolics species such as sinapine, sinapic acid, sinapine glucoside, disinapic glucoside and disinapic gentiobioside were identified. Besides these, seven glucosinolates, which including progoitrin, gluconapin, 4-hydroxyglucobrassicin, glucobrassicicanapin, gluobrassicin, glucoisatisin and neoglucobrassicin were identified in the extracts as well.4. The major polyphenols species in defatted rapeseed meal, hull and endosperm from 10 different varieties Brassica napus were quantified. The results showed that sinapine was the major species in all extracts. The sinapine content in these 10 defatted rapeseed meal ranged from 10.52 to 16.31mg/g, account for 65-83% of TPC (13.91-21.46 mg/g). In defatted endosperm, the sinapine content was 10-20 times higher than that of defatted rapeseed hull, respectively. The TPC from defatted endosperm (ranged from 13.91-21.46 mg/g) is much higher than that of defatted hull (1.37-2.46 mg/g) based on the HPLC results.5. The insoluble phenolics in defatted rapeseeds meal, rapeseed hull and endosperm were extracted by alkaline hydrolysis combined with ethyl acetate extraction. The major species of insoluble phenolics were analyzed by HPLC/MS and MS/MS. Nine phenolic acids in rapeseeds hull, which are sinapic acid ang isomer, protocatechuic acid, p-hydroxybenzoic acid, caffeic acid, syringic acid, p-coumaric acid were identified. While, only sinapic acid and protocatechuic acid were detected in rapeseeds endosperm.6. The content of insolube phenolics in defatted rapeseed meal, hull and endosperm from 10 varieties Brassica napus were quantified. The results showed that sinapic acid and protocatechuic acid are the major insoluble phenolics in rapeseed hull, the content of sinapic acid and protocaechuic ranged from 0.076 to 0.234 mg/g and 0.028 to 0.612 mg/g respectively, which account for 18.07-47.05% and 8.57-58.09% of insolube TPC in defatted rapeseed hull. The TPC in defatted rapeseed hull ranged from 0.133 to 1.05 mg/g based on the HPLC method. Sinapic acid was the major insoluble phenolics in rapeseed endosperm, which rage from 0.432 to 0.801 mg/g and in hull is 0.432-0.801mg/g. The content of sinapic acid in defatted rapeseeds endosperm was 2.9-5.7 times higher than that of defatted rapeseed hull, respectively.