bottle ageing, the process of deliberately maturing a wine after bottling, whether for a few weeks as a conscious effort on the part of the bottler to allow the wine to recover from bottle sickness or, in the case of very fine wines, for many years in order to allow the wine to mature. Fine wines are usually vinified expressly so that they will benefit from ageing in bottle, with generous amounts of acids, phenolics, and flavour precursors extracted from the grape. These can often make them unattractive when consumed young, but provide them with all the necessary ingredients for bottle ageing. In some cases the high sugar, acid, and flavour compound levels, as in great Rieslings which may not contain much alcohol, can also benefit greatly from bottle ageing. However, some winemakers have adapted their winemaking techniques so that their wines have the capacity to age but are nevertheless approachable much earlier. See, for example, micro-oxygenation.