Grape chemistry makes wine tasty!

Have you ever thought of why wine tastes so good?

Wine is indeed an indispensable part of any celebration at the same time

Wine is an alcoholic beverage made from fermented grapes or other fruits.

The natural chemical balance of grapes lets them ferment without the addition of

• Sugars
• Acids
• Enzymes
• Water

Wine production was started dates back 6000 BC in Georgia

Wine Quotes

"Penicillin cures, but wine makes people happy” – 'Alexander Fleming’

 "Where there is plenty of wine, sorrow and worry takes wing” – 'Anonymous’

Types of wine

General categories of wines

• White wines (made from white grape varieties)

               Example: Chardonnay

• Red wines (made from red grape varieties)

              Example: Merlot

• Rose wines (made from red grape varieties)

             Example: Zinfandel

• Sparkling wines

            Example: Rose Champagne

• Sweet or Dessert wines

            Example: Eiswein

• Fortified wines

           Example: Madeira

Based on taste wines can be classified as

• Dry wines
• Medium Wines
• Sweet wines
• Table wines

Winemaking

Winemaking or vinification is the production of wine. It contains the following categories

• Still wine production (it doesn’t include carbonation process)

• Sparkling wine production (it includes the carbonation process)

“The science of wine and winemaking is known as oenology”

Which factors contribute to the taste of wine?

Chemical composition of wines:

Enzymes

Pectinase; Hemicellulase; Glycosidase; Glucanase

Sugars

Glucose; Fructose; Sucrose

Acids

Tartaric acid; Malic acid; Lactic acid; Citric acid; Acetic acid; Ascorbic acid; Butyric acid; Sorbic acid; Succinic acid

Alcohols

Ethanol; Methanol; Polyalcohol

Aldehydes and ketones

Acetaldehyde; Acetoin; Diacetyl

Esters

Heart Healthy Nutrient Content of Wine

• Resveratrol
• Flavonoids (Quercetin, Anthocyanins)
• Bioflavonoids
• Tannins

Nitrogen compounds

Catechin

Phenolics

Vanillin ; 4-Ethylphenol ; 4-Ethyl Guaiacol

Inorganic constituents

Vitamin Content of Wine

• Thiamin
• Riboflavin
• Niacin
• Vitamins A, B, K & G
• Folate
• Choline
• Betaine
• Lutein
• Zeaxanthin

Mineral Content of Wine

• Sodium
• Calcium
• Iron
• Magnesium
• Phosphorus
• Potassium
• Zinc
• Copper
• Manganese
• Fluoride
• Selenium

What kind of chemistry involved in wine preparation?

The following stages is involved in winemaking

• Harvesting grapes - Grapes must be harvested when the sugar, acid, phenol and aroma compounds are optimized for the style of wine desired.

• Destemming & Crushing grapes - Grapes are removed from the stems and gently crushed to break the skins and Sulfur dioxide can be added to prevent oxidation and inhibit microbial activity.

• Pressing the grapes

• Fermentation

The process of fermentation can be explained by the following reaction

            C₆H₁₂O₆ + Yeast → 2C₂H₅OH + 2CO₂

             Sugar                     Ethanol (alcohol)

Once the fermentation process is done the following step is the Fehling reaction – for monitoring specific gravity

                RCHO _(aq)   +   2Cu ²⁺ _(aq)   +   4OH ^- _(aq)   →   RCOOH _(aq)   +   Cu₂O_(s)   +   2H₂O _(l)

• Purifying and refining
• Preserving
• Premarketing aging
• Bottling

Reference

[1] © From http://www.all-about-wine.com/types-of-wine.html

[2] © From http://www.whitman.edu/environmental_studies/WWRB/winemaking.htm

[3] © From http://nzic.org.nz/ChemProcesses/food/6B.pdf

Image reference

[1] © From http://www.benefits-of-resveratrol.com/chemical-composition-of-wine.html

To contact the author mail: articles@worldofchemicals.com

© WOC Article