Optimization of Sample Preparation and Phloroglucinol Analysis of Marselan Grape Skin Proanthocyanidins using HPLC-DADESI- MS/MS

Abstract

Proanthocyanidins are a group of oligomeric or polymeric flavan-3-ols that are highly significant contributors to astringency in grapes and wines. An orthogonal L9(3) 4 test was adopted to determine the optimal extraction conditions and acid-catalysis cleavage of proanthocyanidins in the presence of excess phloroglucinol. The qualitative and quantitative analyses were done using HPLC-DAD-ESI-MS/MS. The results showed that the maximum extraction was obtained using 0.3 mol/L of HCl and 0.005 g of ascorbic acid with incubation at 70°C for 20 min. The precision and accuracy of this method were acceptable. The composition of free flavan-3-ols and proanthocyanidins in the skins of 'Marselan' grapes (Vitis vinifera L. cv.) was investigated. (-)-Epigallocatechin was found to be the most abundant free flavan-3-ol monomer and terminal subunits, whereas the extension subunits were mainly (-)-epicatechin-3-O-gallate in the early developmental stages, and primarily (-)-epigallocatechin and (-)-epicatechin in the middle and late stages.

Flavonoid and aromatic profiles of twoVitis viniferaL. teinturier grape cultivars

“…In the skin, the PAs comprised polymers with the mDP of 12 for Kolor and 14 for Yan73. When the PAs from the skin and the seeds were compared, the mDP was higher in the skin PAs in both cultivars (mDP, 12–14.3 vs 2.7–3.0), similar to that of previous reports (Hanlin et al , Liang et al , Rebello et al ). These polymers consisted of predominantly EC extension subunits, while the terminal subunits and flavan‐3‐ols were characterised by C. This was also the case for Shiraz grape skin previously reported (Bogs et al ).…”

“…The residues were re‐extracted again and the supernatant was collected for subsequent LC/MS analysis. Flavan‐3‐ol was extracted according to Liang et al (). To determine the content of various flavan‐3‐ol units, grape sample powder (0.10 g) was mixed with 1 mL of phloroglucinol buffer (0.5% ascorbate, 300 mmol/L HCl and 50 g/L phloroglucinol in methanol), incubated at 50°C for 20 min, neutralised with 1 mL sodium acetate (200 mmol/L, pH 7.5) and finally centrifuged at 8000 g for 15 min.…”

Accumulation Pattern of Flavonoids in Cabernet Sauvignon Grapes Grown in a Low-Latitude and High-Altitude Region

“…With regard to the isolation of flavan-3-ols, we directly adopted acid degradation at 70°C to cleave proanthocyanidins into flavan-3-ol units in the presence of excess phloroglucinol (Liang et al, 2012a). In this situation, the data acquired should represent the total content of various flavan-3-ol units in the grape skins, including free monomers and the component units of their oligomers and polymers.…”

Tissue-specific Accumulation of Flavonoids in Grape Berries is Related to Transcriptional Expression of VvF3′H and VvF3′5′H

“…The sum of flavan-3-ol monomers and polymers was determined after acid catalysis in the presence of excess phloroglucinol (Liang et al, 2012). The catalytic solution was composed of 50 g/L phloroglucinol in methanol, 5 g/L ascorbic acid and 0.1 M HCl.…”

“…Flavan-3-ols extracts were filtered through 0.22 μm nylon membrane filters and then separated by an Agilent 1100 series LC-MSD trap VL, equipped with a DAD detector and reversed phase column (Lorbax SB-C18 column 4.6 mm × 250 mm, 5 μm) (Liang et al, 2012). The mobile phase was composed of (A) aqueous 0.2% acetic acid and (B) acetonitrile and aqueous 0.2% acetic acid mixed at 4:1.…”