Measuring the Molecular Dimensions of Wine Tannins: Comparison of Small-Angle X-ray Scattering, Gel-Permeation Chromatography and Mean Degree of Polymerization

Jacqui McRae, N Kirby, Haydyn Mertens, Stella Kassara, Paul Smith

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)

    Abstract

    The molecular size of wine tannins can influence astringency, and yet it has been unclear as to whether the standard methods for determining average tannin molecular weight (MW), including gel-permeation chromatography (GPC) and depolymerization reactions, are actually related to the size of the tannin in wine-like conditions. Small-angle X-ray scattering (SAXS) was therefore used to determine the molecular sizes and corresponding MWs of wine tannin samples from 3 and 7 year old Cabernet Sauvignon wine in a variety of wine-like matrixes: 5-15% and 100% ethanol; 0-200 mM NaCl and pH 3.0-4.0, and compared to those measured using the standard methods. The SAXS results indicated that the tannin samples from the older wine were larger than those of the younger wine and that wine composition did not greatly impact on tannin molecular size. The average tannin MWs as determined by GPC correlated strongly with the SAXS results, suggesting that this method does give a good indication of tannin molecular size in wine-like conditions. The MW as determined from the depolymerization reactions did not correlate as strongly with the SAXS results. To our knowledge, SAXS measurements have not previously been attempted for wine tannins.

    Original languageEnglish
    Pages (from-to)7216-7224
    Number of pages9
    JournalJournal of Agricultural and Food Chemistry
    Volume62
    Issue number29
    DOIs
    Publication statusPublished - 23 Jul 2014

    Keywords

    • depolymerization
    • GPC
    • SAXS
    • tannin molecular weight
    • wine matrix
    • wine tannin

    Fingerprint

    Dive into the research topics of 'Measuring the Molecular Dimensions of Wine Tannins: Comparison of Small-Angle X-ray Scattering, Gel-Permeation Chromatography and Mean Degree of Polymerization'. Together they form a unique fingerprint.

    Cite this