LC-DAD-ESI-MS/MS-assisted elucidation of the phenolic compounds in shalgams: Comparison of traditional and direct methods

Abstract

Shalgam is a beverage which is produced by lactic acid fermentation of black carrot juice. Two commercial methods (traditional method - TM and direct method - DM) used to produce shalgams were compared with respect to their effects on the general compositions, bioactive phenolic compounds and antioxidant potentials for the first time. A total of 25 phenolic compounds comprising anthocyanins, flavonols, and phenolic acids were identified and characterized by LC-DAD-ESI/MSn. Cyanidin-3-xylosyl-galactoside and cyanidin-3-xylosyl-glucosyl-galactoside accounted for the highest amount of the total anthocyanins. Also, seven newly-identified anthocyanins including cyanidin 3-xylosyl-(caffeoyl-glucosyl)-galactoside, cyanidin 3-xylosyl-(p-hydroxybenzoyl-glucosyl)-galactoside, cyanidin 3-xylosyl-galactoside+vinylphenol, cyanidin 3-xylosyl-galactoside+vinylcatechol, cyanidin 3-xylosyl-(feruloyl-glucosyl)-galactoside+vinylcatechol, cyanidin 3-xylosyl-galactoside+ vinylguaiacol, cyanidin 3-xylosyl-(feruloyl-glucosyl)-galactoside+vinylguaiacol were found in the shalgam samples for the first time. Phenolic acids and flavonols of shalgam samples were studied for the first time. The major subclass of the chlorogenic acids was identified as 5-caffeoylquinic acid in the samples. Antioxidant capacities of the samples screened using ABTS and DPPH assays were in accordance with their total phenolic content. Principal component analysis (PCA) revealed clear discrimination between the two production methods (TM and DM). This study demonstrated that the DM provided higher phenolic and antioxidant potential than the TM in the shalgam samples.