Читать книгу Wine Faults and Flaws - Keith Grainger - Страница 13

The origin of any fault or flaw in wine may be chemical, microbiological, or physical. During the process of winemaking, thousands of biochemical reactions are taking place, and most of them contribute to the aroma and flavour profile of the wine, but some are unwanted and, if not controlled or inhibited, quality will be compromised and off‐odours or faults may develop. The diverse interactions between yeasts, fungi, bacteria, and chemical compounds begin in the vineyard and continue through the production processes including maturation and even during storage after packaging. The alcohol in wine (ethanol), together with the acids, provide some stability and protection against deterioration – in fact, wine (as opposed to grape must) is a harsh environment for microbes, thereby allowing only relatively few to grow. However, some microorganisms, including unwanted yeasts and bacteria can flourish during winemaking and may remain in a wine that has finished all stages of production and cause off‐odours, off‐flavours, or product deterioration months, or even years, after bottling. Wine may become contaminated and develop such off‐odours and flavours as a result of external factors during the production processes, and even subsequent to bottling or other packaging. Common sources of contaminants include processing aids (e.g. bentonite), the winery or cellar atmosphere and environment, packaging materials (including bottle closures), and transport or storage facilities (including shipping containers).