As wine rises on the inside of a glass when the glass is swirled, the alcohol in the wine evaporates because it has a lower vapor point than water. Thus the “legs” are made up of the water that remains. While high sugar levels can be associated with legs that run down slower because of the increased viscosity, water is is still the predominant compound.

Wine that has not been degassed from the original fermentation can have a cloudy appearance due to the tiny, diffused bubbles in the wine and they can make a wine taste more acidic than it actually is. The bubbles tend to be evenly distributed throughout the wine rather than arising from the bottom and sides of the glass.

In general, paler wines indicate higher acidity levels in white wines and deeper golden colors indicate lower acid levels. Deep gold can also indicate oxidized wine but not always.

Blueish or deep purple tints in wine are usually associated with lower acidity in red wine whereas a bright red color is associated with higher acid levels. Brownish red (garnet colors) or browning of red wine takes place as more oxygen combines with the wine. This usually produces aldehydes but does not change acidity much.

Holding your nose usually blocks odors from circulating and reaching the olfactory sensors. Smelling your own arm only reestablishes a baseline when you are judging odors in rapid succession.

Vanilla smells come from the chemical vanillin, from oak barrels or other oak additives used in aging wines. The other odors listed are usually primary odors that can be detected from tasting the grapes alone before fermentation.

Individuals whose threshold detection for certain odors are extremely low (supertasters) or a thousand times higher (refractory tasters) need to recognize they are at the extremes so they do not unduly influence other tasters who have markedly different thresholds.

There are many odors which some individuals cannot smell at all, i.e., they have selective anosmia.

Odor detection thresholds can vary by 5 fold or more from day to day.

Recognizing that something smells different (odor threshold or perception threshold) is not the same as identifying or naming that odor. Usually, a higher concentration of the chemical(s) causing the odor is needed to identify it.

While sulfites can have an effect on bacteria, yeast and oxygen, they are primarily used to kill spoilage bacteria. In normal doses they do not reliably kill all fermenting yeast. They do tend to kill wild yeast when added to fresh grapes for an initial soak. They can replace some oxygen, but most oxidized wines have so much exposure to oxygen that the sulfites cannot protect them.

Odor threshold means one can tell an odor is present but not necessarily “recognize” or identify what the odor is.

Glycerol does provide sweetness, fullness and a smoother “mouth feel” in wine but it has no effect on alcohol perception. It is much different than glycol (diethylene or ethylene glycol), which has been added to wine in the past by unscrupulous wine sellers. Ethylene glycol, as used in anti-freeze, is a toxic poison causing organ damage and possibly death if the dose is high enough.

Glycerol is a by-product of the yeast used, the grape variety and how much sugar is present. It is not a product of any fault or flaw.

Less than 0.5 gm% is considered “dry” by almost everyone. Between 1.5 gm% and 3.0 gm% is usually labelled as “off-dry” by almost every one. Between 0.5 gm% and 1.5 gm% depends on your sensitivity threshold to sweetness as to how you might label a wine, since it is the sensitivity range for sweetness detection in the general population.

When young, a wine has more “short chain” tannins whose “ends” can be thought of as causing more astringency and drying of saliva in the mouth. As a wine ages, the tannin chains link together and produce a less astringent, softer, finer mouth feel.

Grape sugar sucrose molecules are hydrolyzed (separated) by the enzyme invertase into glucose and fructose. The glucose is preferentially fermented into alcohol so if the process is incomplete, more fructose remains. Fructose tastes sweeter than glucose, gram per gram.

A higher alcohol level tends to make wine taste fuller and slightly sweeter, but if too high, it can make wine taste bitter or give a burning mouth feel.

Malic comes from the Latin malum meaning “apple”. Grapes high in malic acid like Pinot Noir, Norton, Baco Noir, Chambourcin and some other red hybrid grapes often need to undergo malolactic fermentation to smooth out the sharp green taste.

The sorbate stops yeasts from fermenting sugar so that the wine bottle does not explode or the wine does not develop “frizzante” bubbles in the bottle. Also, potassium sorbate is added to grape concentrates in wine making kits to make sure the juice does not start fermenting in the can in case there is any yeast contamination.

Malolactic bacteria can metabolize citric acid as well as malic acid. Diacetyl, a buttery tasting compound is produced from the citric acid. In small amounts it adds a buttery taste; however, in large amounts it can cause a fault like rancid butter.

Balance means that the taster does not perceive any taste component as excessively high or low for that particular type of wine. Sweetness needs high acidity to balance a wine, otherwise the taste  seems “cloying.” Firm tannins with a long aftertaste may be desirable in a red wine, but it only means the wine has a good finish, not necessarily in balance with respect to mouth feel.