How can it be that zinfandel wines taste spicy (hot?) I experienced this sensation for the first time recently, but never have sensed this before in cabernets, merlots, or other reds. Subsequently I read zinfandels described as "spicy" elsewhere afterwards.
I'm certain that there are no peppers being used in the process of the wine. Is there significant capsaicin present or is it from the alcohol level?
This has to do with esters, which are flavor compounds created during fermentation.
Each grape variety has a unique physiological make up with aromatic compounds found in trace amounts within the grape skin cells. The concentration of each of these aromatic sensations is dependent on the grape type and is mostly undetectable until the juice is fermented. Fermentation magnifies and makes these aromas more easily perceived by the nose, so think of wine as a caricature of the grape.
From winegeeks.com.
about the pepper flavor specifically, although in Shiraz I imagine it's the same or similar to that in Zinfandel:
Australian chemists have identified the compound responsible for the peppery aroma of the country's iconic Shiraz wines - and discovered the same molecule is by far the strongest aroma in peppercorns themselves.
