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Phenolic Compounds, Volatiles and Antioxidant Capacity of White Myrtle Berry Liqueurs

Serreli, Gabriele, Jerković, Igor, Gil, Katarzyna Angelika, Marijanović, Zvonimir, Pacini, Viviana, Tuberoso, Carlo Ignazio Giovanni
Plant foods for human nutrition 2017 v.72 no.2 pp. 205-210
gallic acid, myricetin, gas chromatography, headspace analysis, cineole, 2,2-diphenyl-1-picrylhydrazyl, liquid-liquid extraction, high performance liquid chromatography, Myrtus communis, liqueurs, solid phase microextraction, mass spectrometry, antioxidant activity, shikimic acid
The aim of this research was to evaluate the antioxidant capacity and physical-chemical characteristics of commercial white myrtle berry (Myrtus communis L. var. leucocarpa DC) liqueur (WMBL). The total phenolic (TP) content was measured spectrophotometrically, applying a modified Folin-Ciocalteu’s method, and phenolic compounds were identified by high-performance liquid chromatography (HPLC) coupled with electrospray mass spectrometry, and quantified by HPLC coupled with ultraviolet/visible detection. The antioxidant capacities were evaluated by FRAP, CUPRAC, DPPH•, and ABTS•⁺ assays. The volatiles were assessed by gas chromatography and mass spectrometry (GC-MS/FID) after headspace solid-phase microextraction (HS-SPME) and liquid-liquid extraction (LLE). WMBL showed lower TP levels (636.3 ± 39.2 mg GAE/L) than in purple myrtle berry liqueur (PMBL). Nevertheless, WMBL exhibited better antioxidant capacities, potentially due to high concentrations of gallic acid (294.2 ± 14.2 mg/L) and its derivatives (58.3 ± 2.1 mg/L). Other phenolic compounds detected by HPLC-DAD and LC-MS/MS were flavonols like myricetin and its derivatives (myricetin-3-O-galactoside and myricetin-3-O-rhamnoside) with concentrations similar to those found in PMBL. GC-MS/FID analysis revealed 44 compounds (terpenes, higher aliphatic compounds and shikimic acid pathway derivatives). 1,8-Cineole was the most abundant terpene in the liqueur (26.5% (HS-SPME) and 9.6% (LLE)).