Homebrewer here as well. There's plenty of chemical compounds that yeast produce that give various notes that kind of resemble something else. For instance alde

Homebrewer here as well. There's plenty of chemical compounds that yeast produce that give various notes that kind of resemble something else. For instance aldehydes (notably acetaldehyde) is a yeast byproduct that gives off a "green apple" flavor. Usually in beers this is considered a flaw, but I notice that some wines promote that aspect as positive if it's not overwhelming. Diacetyl is another one -- this has a "buttery" flavor. This is considered a flaw in some styles, but is naturally present in others (English ales notably often have a little bit of this in it). Some wines are very "buttery", I understand in particular those that use a process called malolactic fermentation (where diacetyl is a byproduct) are prone to it. From what I can Google you can get chocolate notes in wine either from the tannins in grapes, or the charring process used on barrels. However, I haven't been able to Google specific chemicals. In beer, "chocolate notes" can come from some of the toasted / roasted malts out there (IMHO more on the pale end of the "chocolate malt" spectrum -- darker "chocolate malts" taste more "coffee" like to me). A fair bit of places offer a "off flavor" kit for beers that allow you to train your tastebuds on at least the common "faults".