Journal of agricultural and food chemistry | 8 Nov 2013
JM McRae, S Kassara, JA Kennedy, EJ Waters and PA Smith
The impact of wine pH and closure type on colour, tannin concentration and composition was investigated. A single vintage of Cabernet Sauvignon wine was divided into three batches, the pH adjusted to 3.2, 3.5 or 3.8, the wines bottled under screw caps with either SaranTin™ (ST) or Saranex™ (Sx) liners. After 24 months, the tannin concentration, tannin % yield (relating to the proportion of acid-labile interflavan bonds) and the mean degree of polymerization (mDp) had decreased significantly, all of which can contribute to the softening in wine astringency with aging. The higher pH wines contained less % (-)-epicatechin 3-O-gallate subunits, while the Sx pH 3.2 wines were significantly lower in % yield and mDp than the other wines. Overall, the tannin structure and wine colour of the lower pH wines (pH 3.2) bottled under Sx screw caps changed more rapidly with aging than those of the higher pH wines (pH 3.8) bottled under ST screw caps.
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