As an experienced sommelier and brewer, I can assure you that red wine can indeed taste yeasty, but it's not a desirable characteristic. When it comes to winemaking, the presence of yeast flavors in a finished wine can indicate that the winemaker may have pitched too small a colony of yeast during fermentation.
During the fermentation process, yeast consumes the sugars in the grape juice and converts them into alcohol. Ideally, winemakers want a healthy and vigorous fermentation, with a sufficient number of yeast cells to efficiently convert the sugars. However, if the winemaker under-pitches the yeast, meaning they add too little yeast to the fermentation vessel, the yeast cells may struggle to fully ferment the sugars, resulting in a slower and less efficient fermentation.
When yeast is stressed or underpopulated, it can produce off-flavors and aromas, including a yeasty or bready character. This can manifest as a subtle, dough-like taste in the wine, similar to the flavors found in freshly baked bread. It's important to note that this yeasty taste is different from the natural yeast-derived flavors often associated with specific wine styles, such as in sparkling wines or certain white wines like Chardonnay.
The presence of yeast flavors in red wine is generally considered a flaw or a sign of a winemaking error. It can detract from the overall quality and enjoyment of the wine, as it masks the true fruit flavors and can give the impression of an unfinished or faulty product. It's something that winemakers strive to avoid and is generally seen as a technical fault rather than a desirable characteristic.
In my own experience, I have come across red wines with a slight yeasty taste, usually in wines from smaller, less-experienced wineries where the winemaking process may not have been as carefully controlled. These wines often exhibit other signs of fermentation issues, such as excessive volatile acidity or a lack of clarity. It's always disappointing to encounter these off-flavors in a wine, as they can overshadow the potential qualities that the wine might have had.
To summarize, while it is possible for red wine to taste yeasty, it is generally considered a flaw rather than a desirable characteristic. A properly made red wine should showcase the fruit flavors and complexities of the grapes, without any intrusive yeast-derived flavors. When encountering a yeasty taste in a red wine, it suggests that the winemaker may have made an error during fermentation, such as pitching too small a colony of yeast.