Tiếng ViệtMany people wonder: “Why can a drink made only from fermented grapes offer such endless flavors?” The answer lies in the components of wine, a system of biochemical compounds combined with refined craftsmanship.
From both scientific and sensory perspectives, each glass of wine is a harmony of hundreds, even thousands, of different compounds. Understanding the main components of wine not only helps you explain its flavors, but also elevates your tasting experience, taking you from a casual drinker to a true wine enthusiast.
1. Water
Among all the components of wine, water accounts for 80% – 85% of its volume. This water source is completely natural, absorbed by grapevine roots from the soil, transported through the vine and accumulated inside the grapes.
Although it does not directly create aroma or color, water is an essential foundation in the composition of wine. It acts as a solvent that dissolves and harmonizes all other compounds. Water helps soften the sensation of alcohol, balance sweetness and allow flavors to spread across the palate when you take a sip.
2. Sugar
Sugar is one of the main components of wine before fermentation. Grapes contain two natural sugars: glucose and fructose. Under the action of yeast, this sugar is “consumed” and converted into alcohol and CO2.
After fermentation ends, the sugar that remains unconverted is called “residual sugar”. This residual sugar determines the sweetness of the wine. Based on sugar content, wine is divided into different styles:
- Dry wine: Residual sugar is almost zero, creating a clearer sense of tannin and acidity.
- Off-dry wine: Offers a gentle touch of sweetness on the tip of the tongue.
- Sweet wine: Grapes are often harvested late to accumulate very high sugar levels, creating rich sweetness and a smooth, syrup-like texture.
3. Alcohol
Alcohol is the natural result produced when yeast consumes sugar. Alcohol content usually accounts for around 10% to 15% of the wine’s volume, depending on the initial sugar level in the grapes and fermentation time.
In the structure of wine, alcohol creates body and richness. A wine with high alcohol content often leaves slow-moving legs on the side of the glass, creating a full, warm and sometimes slightly spicy sensation in the throat. Alcohol is one of the main components that defines the physical drinking experience. As alcohol evaporates from the glass, it carries aromatic molecules upward, directly awakening your sense of smell.
4. Acidity
Wine is an acidic beverage, with pH usually ranging from 2.5, very acidic, to 4.5, mildly acidic. If sugar brings softness, acidity is the backbone that creates crispness, freshness and prevents wine from feeling heavy or flat.
Grapes and the fermentation process contain weak natural fruit acids such as:
- Tartaric acid: The main acid responsible for wine’s signature sourness.
- Malic acid: A sharp acid similar to green apple, commonly found in underripe grapes or cool-climate regions.
- Lactic acid: A softer, creamier acidity similar to yogurt, converted from malic acid to make red wine structure smoother.
The perfect combination of acidity, sweetness and tannin is the golden standard for evaluating the quality of a bottle of wine.
5. Tannin
Have you ever wondered why red wine can make your gums and palate feel dry, tight and slightly astringent? That is the effect of tannin.
Tannins are natural compounds extracted from grape skins, seeds and stems, and sometimes from oak barrels. Among the components of wine, tannin is like muscle layered over the acidic backbone. Although it creates a slightly bitter and dry sensation, tannin is also an excellent antioxidant that helps protect wine from spoilage. Expensive red wines with high tannin and strong structure can be aged and stored for decades. Over time, the initially rough astringency gradually transforms, becoming softer and smoother like velvet.
6. Natural Aromatic Compounds
This is the most fascinating part that makes so many people fall in love with wine. When experts describe wine as having aromas of strawberry, rose or pepper, it does not mean those fruits or spices were added to the wine. Wine aromas are not added. They form naturally through different stages:
- Primary aromas, from grape variety: For example, Pyrazines create green bell pepper notes, Terpenes bring seductive rose aromas, and Thiols recall fresh grapefruit.
- Secondary aromas, from yeast: Esters produced during fermentation create aromas of green apple, strawberry or buttery toast.
- Tertiary aromas, from aging: When wine is aged in oak barrels, Lactones transfer aromas of vanilla, coconut or warm cedar into the wine.
7. Sulphur Dioxide (SO₂)
Sulphur Dioxide, also known as sulfites, often causes concern among consumers when they see the words “Contains Sulfites” on a wine label. Although controversial, SO₂ remains an important component in wine and is strictly controlled. It is both a natural byproduct of yeast and an essential preservative intentionally added during winemaking.
In wine, SO₂ acts like a protective shield. It binds with oxygen to prevent oxidation, which can cause wine to lose color, similar to how a peeled apple turns brown. It also eliminates harmful bacteria that can spoil wine and turn it into sour vinegar. International law strictly controls sulfite levels to ensure safety for consumers.
8. Calcium Carbonate
Wine is an agricultural product and therefore depends greatly on weather. In very cold years, grapes may not ripen fully, causing acidity levels to become excessively high and making the resulting wine too sharp to drink.
To save the wine batch, winemakers may use Calcium Carbonate (CaCO3), a safe and common food stabilizer. When added, Calcium Carbonate reacts with excess fruit acids, neutralizing them and forming sediment that settles at the bottom of the tank. This is a highly skillful technique that helps “cool down” acidity and restore smooth balance to the finished wine.
9. Concentrated Grape Must
In the commercial wine industry, producers sometimes face the problem of grapes with weak color due to high yields or poor weather. In such cases, concentrated grape must becomes a supporting element in modern wine composition.
Concentrated grape must is extracted from grape varieties with deeply red-colored flesh, then boiled down into a thick syrup. Just a very small amount added to the tank can immediately deepen the red-purple color, add a touch of gentle sweetness to soften rough tannins and mask green vegetal aromas, such as grass or bell pepper, from underripe grapes. This makes the wine more appealing to a wider range of consumers.
10. Yeast
Without yeast, even the most delicious grape juice would remain only a sweet beverage. Yeast is a single-celled organism that acts as the core “engine”, starting fermentation and turning sugar into alcohol and CO2.
Today, winemakers usually face two choices:
- Natural yeast: These are yeast spores naturally present on grape skins, visible as a white bloom in the vineyard, or floating in the cellar environment. Using natural yeast helps wine express a strong sense of place and complex flavor structure, but it is difficult to control and carries a higher risk of spoilage.
- Cultured yeast: Large wineries often prefer laboratory-selected yeast strains. These yeasts tolerate alcohol well, work consistently and allow winemakers to guide specific fruit aromas, such as apple or strawberry, in their wine batches.
11. Potassium Sorbate and Potassium Metabisulfite
For dry wines, high alcohol and tannin are often enough for natural preservation. However, in sweeter wines, residual sugar becomes a potential threat. If a few living yeast cells remain inside the bottle, they may continue consuming that residual sugar, producing gas that can pop the cork or cloud the wine.
To prevent this problem, the pair of compounds Potassium Sorbate and Potassium Metabisulfite is used.
- Potassium Metabisulfite: Removes oxygen and creates an anaerobic environment that suppresses bacteria and mold.
- Potassium Sorbate: Enters yeast cells and prevents them from reproducing, stopping them from continuing to ferment residual sugar.
Thanks to the combined protection of these two safe preservatives, sweet wines can remain stable on store shelves while maintaining excellent quality.
12. Non-Vegan Ingredients
It may sound surprising, but not 100% of wines on the market are suitable for vegans. The issue lies in the final step before bottling, known as fining.
After fermentation, wine is often cloudy because it contains dead yeast cells, proteins and tiny grape skin particles. To make the wine in your glass clear and crystal-bright, winemakers add fining agents to the tank. For hundreds of years, winemaking has commonly used animal-derived materials such as:
- Egg whites: Very common in Bordeaux, France, to soften tannins.
- Gelatin: Extracted from animal collagen.
- Isinglass: Dried fish bladder, highly effective for clarifying premium white wines.
- Casein: Milk protein that helps remove dull color from wine.
After these compounds bind to cloudy particles, they sink to the bottom and are completely removed by filtration. The finished wine has no animal flavor or smell, but the use of these materials during production means the bottle cannot be labeled “Vegan”. Today, to meet the needs of plant-based consumers, many wineries are switching to Bentonite clay or activated charcoal instead.
> Watch the “Hiểu hết về Vang” series here for beginners learning about wine!
Final Thoughts,
Understanding the components of wine does not take away its romance. On the contrary, it helps you appreciate each layer of flavor more deeply.
Wine is not simply fermented grape juice. It is a combination of science, craftsmanship and natural conditions. Every glass is a symphony where water creates the base, alcohol builds structure, acidity brings vitality and tannin adds depth.