1, improper or insufficient sanitary treatment during brewing.
With the continuous development of brewing technology and the continuous updating of brewing equipment, the bitterness caused by such problems has rarely appeared at present.
2. There are too many tannins in wine, which are probably inferior tannins from grape stems or grape seeds.
This situation usually exists in low-priced wine, which may be due to insufficient brewing equipment, resulting in broken grape seeds and inferior tannins dissolved in wine; It may also be caused by excessive squeezing by manufacturers in order to achieve a certain output.
3. After over-impregnation, there are too many high-quality tannins produced by oak barrel fermentation and its impregnation process.
Second, excessive oxidation.
Oxidation means that wine is exposed to too much air. If a bottle of wine is not finished after opening, it will be oxidized. After oxidation, the color and aroma of wine will also change accordingly.
Third, the overall performance of wine is unbalanced.
This may be due to the high acidity or tannin content, resulting in bitterness. Generally speaking, too low acidity will make wine taste too fatty, while too high acidity may produce bitterness, especially for people who are sensitive to acid and bitterness.