Wine a bit , You will feel better ?!

What is wine ??

Do you try drinking wine before?
In pubs, bars, party or celebration...
What feeling you feel after drinking it?
Must be very excited and your face turned red ~!

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

Today, an enormous variety of wines are available!

In, the production of all wine, chemistry is important!!

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

It is converted to alcohol when the yeasts consumed the sugars in the grapes.

''Wine cheers the sad, revives the old, inspires the young, make weariness forget his toil.''

Wine Grape

Composition of grape

The quality of the wine is determined by the composition of grape.

In general, grapes consist of clear juice(80%), skins(8%), seeds(4.5%), pulp(4.5%) and stem(3%)

In terms of chemical component, the constituents of grapes are carbohydrates, water, alcohol, aldehyde, 

 organic acids, phenolic, nitrogenous, and minerals.

CARBOHYDRATES

Carbohydrates are molecules with the general formula of C_x(H₂O)_x

and sugars are a sub-group of carbohydrates.

Sugars are sweet-tasting, water soluble and good energy sources.

The most important sugars in grape juice are the two six-carbon sugars glucose and fructose

These are the sugars that make the juice sweet and are fermented to alcohol by the yeast.

ORGANIC ACIDS
Three main organic acids found in grapes :
i) malic acid

ii) tartaric acid

iii) citric acid

The acids give the juice its acidity 
They also act as an effective buffer in order to maintain a stable pH at around 3.2-3.3
And contribute to the flavour balance of the juice and wine, 
resulting the sharp acidity.

PHENOLICS
These compound contributes to the bitterness of the grapes and wine
Besides that, they also responsible for most of the colour
There are 6 main classes of phenolics found in grapes :
i)catechins

ii)procyanidins

iii)anthocyanins

iv)flavonols

v)hydroxycinnamates

vi)hydrobenzoates

The difference types of phenolics will result in red and white wines.
hydroxycinnamates and hydrobenzoates occur in the flesh of the berry
and so occur in both red and white wines

AROMA COMPOUNDS
Actually, the character of the wine is provided by the volatile aroma compounds.
The most important volatiles in the grape are monoterpenes.
They give a range of smells ranging from floral or fruity to resinous or solvent effects
Monoterpenes exists in 2 forms :
i) free volatile form
Examples :
Citronell 

 α-Terpineol 

Geraniol 

Linalool

ii)bound glycosides 
they are not responsible to the aroma as they are not volatile
they hydrolysed slowly in the acid conditions of the wine and contribute volatiles as the wine ages
During process of aging, they also converted to other more complex volatiles
For examples :TDN and Vanillin
1,1,6-Trimethyl-1,2-dihydro napthalene (TDN)

Vanilin

ESTERS

Ester also responsible to the wine aroma.

For instance ethyl acetate and hexyl acetate

Formed from interactions between the alcohols and acetic acid

Ethyl acetate

hexyl acetate

VITAMINS

They are present in very low level but they do contain some vitamins in large enough concentrations for human nutrition.

Vitamins that present in grape are inositol, nicotinamide, pantothenate, pyroxine, riboflavin and cobalamin

The Wine Manufacturing process

STEP 1 : Harvesting

STEP 2 :Crushing and destemming

STEP 3 :  Juice preparation

STEP 4 : Fermentation

STEP 5 : Purification

In a nutshell , making good wine is a skill and it needs some complicated process! Fine wine is an art, Wine is also inspiring and adds greatly to the joy of living :)