title: Determination of total phenolic content and antioxidant activity of garlic (Allium sativum) and elephant garlic (Allium ampeloprasum) by attenuated total reflectance-Fourier transformed infrared spectroscopy.
abstract: The total phenolic contents and antioxidant activities of garlics from California, Oregon, Washington, and New York were determined by Fourier transform infrared (FT-IR) spectroscopy (400-4000 cm(-1)). The total phenolic content was quantified [Folin-Ciocalteu assay (FC)] and three antioxidant activity assays, 2,2-diphenyl-picrylhydrazyl (DPPH) assay, Trolox equivalent antioxidant capacity (TEAC) assay, and ferric reducing antioxidant power (FRAP), were employed for reference measurements. Four independent partial least-squares regression (PLSR) models were constructed with spectra from 25 extracts and their corresponding FC, DPPH, TEAC, and FRAP with values for 20 additional extracts predicted (R > 0.95). The standard errors of calibration and standard error of cross-validation were <1.45 (TEAC), 0.36 (FRAP), and 0.33 μmol Trolox/g FW (DPPH) and 0.55 mg gallic acid/g FW (FC). Cluster and dendrogram analyses could segregate garlic grown at different locations. Hydroxyl and phenolic functional groups most closely correlated with garlic antioxidant activity.
authors.affiliation: School of Food Science, Washington State University, Pullman, Washington 99164-6376, United States.
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Lu
authors.forename: Carolyn F
authors.initials: CF
authors.lastname: Ross
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Powers
authors.forename: D Eric
authors.initials: DE
authors.lastname: Aston
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Rasco
mesh_terms: D000490:Allium / Q000737:chemistry*; D000975:Antioxidants / Q000032:analysis*; D005737:Garlic / Q000737:chemistry*; D016018:Least-Squares Analysis; D010636:Phenols / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D000975:Antioxidants; D010636:Phenols