Ultrasonic-assisted enzymatic extraction of phenolics from broccoli (Brassica oleracea L. var. italica) inflorescences and evaluation of antioxidant activity in vitro.
An efficient ultrasonic-assisted enzymatic extraction technique was applied to extracting phenolics from broccoli inflorescences without organic solvents. The synergistic model of enzymolysis and ultrasonication simultaneously was selected, and the enzyme combination was optimized by orthogonal test: cellulase 7.5 mg/g FW (fresh weight), pectinase 10 mg/g FW, and papain 1.0 mg/g FW. The operating parameters in ultrasonic-assisted enzymatic extraction were optimized with response surface methodology using Box-Behnken design. The optimal extraction conditions were as follows: ultrasonic power, 440 W; liquid to material ratio, 7.0:1 mL/g; pH value of 6.0 at 54.5 ℃ for 10 min. Under these conditions, the extraction yield of phenolics achieved 1.816 ± 0.0187 mg gallic acid equivalents/gram FW. The free radical scavenging activity of ultrasonic-assisted enzymatic extraction extracts was determined by 1,1-diphenyl-2-picrylhydrazyl·assay with EC50 values of 0.25, and total antioxidant activity was determined by ferric reducing antioxidant power assay with ferric reducing antioxidant power value of 0.998 mmol FeSO4/g compared with the referential ascorbic acid of 1.184 mmol FeSO4/g.
College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, PR China.
Hao
H
Wu
College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, PR China.
Junxiang
J
Zhu
College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, PR China.
Long
L
Yang
College of Horticulture, Qingdao Agricultural University, Qingdao, PR China.
Ran
R
Wang
College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, PR China qauwcr@126.com.
Chengrong
C
Wang
D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D001937:Brassica / Q000737:chemistry*; D002480:Cellulase; D005290:Ferric Compounds / Q000737:chemistry; D005511:Food Handling / Q000379:methods*; D016166:Free Radical Scavengers; D006863:Hydrogen-Ion Concentration; D056626:Inflorescence / Q000737:chemistry*; D010084:Oxidation-Reduction; D010206:Papain; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification*; D010851:Picrates / Q000737:chemistry; D011096:Polygalacturonase; D013696:Temperature; D014465:Ultrasonics
D000975:Antioxidants; D001713:Biphenyl Compounds; D005290:Ferric Compounds; D016166:Free Radical Scavengers; D010636:Phenols; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl; D011096:Polygalacturonase; D002480:Cellulase; D010206:Papain
Broccoli; antioxidant activity; phenolics; response surface methodology; ultrasonic-assisted enzymatic extraction