Introduction of Wine
Wine is an alcoholic beverage made from the fermentation of grape berries. The type and quality of grape used are fundamental to the characteristics of the final wine. Grape berry contain natural sugars, acids, tannins, and aromatic compounds which interact during fermentation to create a complex and flavorful drink.
Types of Grape Berry
There are two types of grape berry.
- Black Grapes : Used for red and rosé wines, contains anthocyanins in the skin which give colour. Examples of black grapes are Cabernet Franc, Cabernet Sauvignon, Gamay, Merlot, Pinot Noir, Syrah, Zinfandel, Pinot Meuniere, etc.
- White Grapes : Used for white wines, lack of colour pigments in the skin and provide more acidity and freshness. Examples of white grapes are Chardonnay, Chenin Blanc, Colombard, Folle Blanc, Thurgau, Muscat, Pinot Blanc, Sauvignon Blanc, Viognier, etc.
Composition of Grape Berry
The grape berry contains the following components.
- Stem
- Skin
- Pulp
- Seed
1. Stem
Stem or stalk holds the grape in bunch. It contains tannins, minerals, acids and cellulose. It is mostly used in the making of big, flavorsome red wine. It is not used for making white and light wines. Tannins is a necessary ingredient as it acts as a preservative and anti-oxidants. Astringency or bitter flavour of the wine is due to tannins only.
2. Skin
It contains tannins, pigment, flavouring materials and cellulose. The skin contains colouring pigments Anthocyanins that contribute colour to the wine. The outer skin has a whitish cloudy coat known as bloom. This waxy substance contains wild yeast, including Saccharomyces Ellipsoideus i.e.wild yeast which contribute to the fermentation process.
3. Pulp
It is a soft flesh behind the skin of the grapes. It provides the juice, also known as must, which is essential for fermentation. The must, which is essential for fermentation. The must consists of 78-80% of water, 10-25% of sugar and 5-6% of acids. The acids present in the must are tartaric, malic, tannic and citrus acids. The acids helps to preserve wine and keep it fresh and brilliant. These acids react with alcohol and produce ester which provide bouquet to the wine.
4. Seeds
They contain tannins, bitter oils and cellulose. Crushed pips impart bitter flavour to the wine. the composition of grape berry changes throughout the ripening process. As the berry ripens, the acid level decreases the sugar content increases in it. Flavours and colours also get developed and become complex as the berry age.
Factors Affecting Quality of Wine
Types of Grapes
- Each type imparts its typical flavour.
- Per acre yield.
- Different varieties demand different soil.
Soil
- Should not be rich & fertile.
- Best is with good drainage-gravel, sand, chalk, lime, etc.
- Should have heavy mineral deposits for an aromatic bouquet.
Climate
- Cool nights and sunny, warm days – right sugar acid balance.
- Too hot weather and less acid – does not age well.
- Too little sunshine – less sugar – less alcohol
- Some rain necessary before harvest.
- Rains during harvest – sugar dilute which encouraged rot.
- Frost/Gale/Hailstorm can ruin whole harvest.
Slope
- Best on sun facing slopes – maximum sun and warmth, both directly and reflected.
Latitude
- Best between 30° and 50° lines.
- Nearer to 50°, better the wine.
Viticulture
- Quality and timing of ploughing, pruning, weeding, spraying, harvesting, etc. Each affect the quality of wine.
Vinification
- It refers to the process of transforming grape juice into wine, encompassing stages like crushing, fermentation.
- It depends upon the skills of the vintner (i.e. a person who makes wine), local traditions and practices