Wine Composition, Chemistry, And Wine Faults

Ethanol is indeed the primary alcohol found in wine. It is produced through the fermentation process, where yeast converts sugar into ethanol and carbon dioxide. This process is responsible for the alcoholic content in wine. Ethanol is the most common type of alcohol found in alcoholic beverages, including wine.

Grapes contain two main sugars, glucose and fructose. These sugars are naturally occurring and contribute to the sweet taste of grapes. Glucose is a simple sugar that is easily metabolized by the body for energy, while fructose is a naturally occurring sugar found in fruits and has a sweeter taste than glucose. Together, these sugars make grapes a delicious and naturally sweet fruit.

Phenolic compounds are indeed commonly referred to as 'polyphenols'. This is because they are organic compounds that contain multiple phenol groups, hence the term 'polyphenols'. These compounds are known for their antioxidant properties and can be found in various plant-based foods such as fruits, vegetables, and beverages like tea and wine. Therefore, the statement that phenolic compounds may also be referred to as 'polyphenols' is true.

Polymerization is the process in which smaller molecules, such as tannins and pigments, combine to form longer chain molecules. This reaction leads to the formation of polymers, which have different properties and characteristics compared to their individual components. Therefore, tannins and pigments forming longer chain molecules is the most suitable explanation for the result of polymerization.

The olfactory epithelium is responsible for detecting aromas in wine. This specialized tissue lines the nasal cavity and contains olfactory receptor cells that are sensitive to different odor molecules. When we inhale the aroma of wine, these cells send signals to the brain, allowing us to perceive and identify the various scents present in the wine. Therefore, the statement that we detect the aromas in wine through our olfactory epithelium is true.

Acidity and tannin are two components in wine that can affect the perception of sweetness. Acidity can make a wine taste less sweet, even if it has a high sugar content, while tannin can give the perception of dryness, making a wine seem less sweet. Therefore, it is true that acidity or tannin can alter the perception of sweetness in a wine.

It is not found in grapes; it is created in wine through malolactic fermentation.

Brettanomyces is a type of yeast commonly found in wine and beer that can cause off-flavors and spoilage. Tannins, resveratrol, and flavonol are all phenolic compounds commonly found in plants. Tannins are responsible for the astringent taste in red wine, resveratrol is a compound found in grapes and red wine that has antioxidant properties, and flavonol is a type of flavonoid that is abundant in fruits and vegetables. Brettanomyces, on the other hand, is not a phenolic compound but rather a type of yeast.

Tannins are organic compounds commonly found in plants, particularly in the stems, seeds, and oak barrels used for aging wine. They contribute to the taste, texture, and color of wines. Sulfites, on the other hand, are sulfur-based compounds used as preservatives in wine production. While sulfites are commonly found in wines, they are not considered tannins. Therefore, the correct answer is sulfites.

Anthocyanins are responsible for the red, purple, or blue pigment found in wine. These pigments are a type of flavonoid compound that are present in the skin of grapes. During the winemaking process, anthocyanins are extracted from the grape skins and contribute to the color of the wine. The specific type and concentration of anthocyanins present in the wine can vary depending on factors such as grape variety, ripeness, and winemaking techniques.

Tartaric acid is the most prevalent acid found in wine. It is naturally present in grapes and is responsible for the sharp, tart taste in wine. Tartaric acid also helps to stabilize the wine and prevent it from spoiling. Other acids such as acetic, malic, and succinic acid may also be present in wine, but in lower concentrations compared to tartaric acid.

Acetic acid is present in most wines in small quantities and contributes to the overall complexity of aroma. However, it is important to protect the wine from oxygen so that higher levels do not occur and create vinegar aromas.

Ruby-orange tints indicate a low pH, or a wine likely to hail from a cool to moderate climate. Red wines with a blue-purple tint indicate high pH, or warm climate. (See FYI Box on Page 18 for further explanation)

All wines contain trace amounts of sulfites as a byproduct of fermentation. Vanillin is a polyphenol derived from oak barrels, thus not all wines contain this compound.

A wine's aroma is derived from the grape variety; the bouquet is a result of winemaking, such as aging in oak or on the lees.

Bitter taste is generally considered to be the most sensitive taste for humans. This is because our taste buds have more receptors for bitter taste compared to other tastes. Bitter taste is often associated with potentially toxic substances, so our sensitivity to it helps us avoid consuming harmful or poisonous foods. Additionally, bitter taste can also be an indicator of certain healthy compounds, such as antioxidants, which our bodies may need in smaller quantities. Therefore, our heightened sensitivity to bitter taste serves as a protective mechanism and helps us make better food choices.

Esters are the largest group of odiferous compounds; they are formed by the joining of an acid and and alcohol molecule. Aldehydes are formed by the oxidation of alcohol and create the characteristic aroma of fino sherry.

The recognition threshold for TCA is 2 to 7 parts per trillion. The detection threshold is the smallest amount of stimulus required to trigger an unidentifiable sensation, while the recognition threshold is the smallest amount of stimulus required to trigger an identifiable sensation.

Ethyl acetate is a wine fault that is caused by bacteria. Bacteria can produce ethyl acetate through the process of fermentation, where they convert ethanol into acetic acid and then into ethyl acetate. This wine fault is characterized by a fruity or nail polish-like aroma and can negatively impact the overall quality and taste of the wine.

H2S occurs in a reductive state (absence of oxygen). Exposing the wine to oxygen (such as racking) usually fixes this wine fault.