Wine production

 

Wine production

 

    Wine is an alcoholic beverage typically made from fermented grapes. Yeast consumes the sugar in the  grapes and converts it to ethanol and carbon dioxide and releasing heat in the process.

Wine making practice is one of the oldest ancient civilizations.

Otherwise called vinification and the study called as oenology. 

Archaeological evidence suggests that wine was being made at least 8,000 years ago, and there are indications that viticulture was carried on in Mesopotamia (the region that is now Iraq and eastern Syria) about 5,000 years ago.

Wine was a popular beverage as well as a sacred drink. In Greek mythology, Dionysus was the god of wine, overseeing all matters pertaining to the cultivation of grapes and wine production. 

The production of wine that begin from crushing of fruits, its fermentation into alcohol and the bottling of the finished alcoholic beverage. 

Wine is a product of alcoholic fermentation of fruit juice that are rich in fermentable sugars. During fermentation the yeast digest sugar found in fruit juice, producing alcohol and carbon dioxide in the process. Most wines are made from grapes only.

Wine naturally contains 85-89 % water, 10-14 % alcohol, < 1% fruit acids and hundreds of flavour and aroma compounds in very small amounts. 

 Four elements act as a vital role to tasting wines – acidity, tannins, alcohol and sweetness.

Nutrient content of wine

·       Riboflavin (Vitamin B12)

·       Niacin (Vitamin B3)

·       Pyridoxine (Vitamin B6)

·       Vitamin K

·       Minerals – Calcium, Iron, Magnesium, Manganese, Phosphorus, Potassium, Zinc, Copper.

·       Antioxidants- Flavonoid, Polyphenols, Resveratrol,

·       Sugar

·       Calories- Depends on the types of grapes, sweetness of alcohol and percentage of alcohol.

 Types of wine

Four broad categories of wine – Table wine, Sparkling wine, Fortified wine and Aromatic wine.

Table wines

·       Table wine also known as natural wine.

·       It contains 10 and 14 % of alcohol. The grape sugar has been turned to alcohol by the yeast.

·       It includes red, rose and white wine.

Red wines

·       Red wine made from pulp of red or black grapes.

·       Red wine is prepared by fermentation of red grape juice along with the grape skins.

·       Red colour was given by the presence of red pigments called anthocyanins in the skin of grapes.

Rose wine

·       Light pink in colour and is produced from red grapes not fermented with the skins.

·       A little pigment is released when the red grapes are crushed, but not to the same extent as during fermentation.

·       Pink colour was produced by the presence of tannin compound in the skin of red grapes.

White wine

·       White wine is actually looks like straw to golden-yellow in colour.

·       The white juice is separated from the skin and kept for fermentation.

·       The clear white colour was produced by using of grape juice and the skin was removed before fermentation. 

Sparkling wines

·       Sparkling wine called as “bubbly wine”. 

Sparkling wine is made from table wine that has undergone a second fermentation.
·       The yeast ferments the added sugar, but this time the carbon dioxide gas remains in the sealed bottle, creating carbonation. When the sparkling wine is poured into a glass, the gas bubbles are released to the surface of wine.
·      In sparkling wine considerable carbon dioxide is present arising from final fermentation.

Aromatic wine

·       Aromatic wine is white wine with dominant aroma.

·       It contains fruits, plants extract, flowers.

·       The floral aromas found in wine are similar to rose petal, violet colour, orange blossom, red, jasmin and white flower.

Wine making 

Raw materials - Fresh and fully ripened wine grapes, yeast, water, sugar.

Selection of grapes

Refractometer is a small, hand-held device that allows to check the sugar content of grapes. The grapes are picked after maturation using suction picker.

Fully ripened grapes with sweet taste and optimum flavour are selected and washed with clean water. The stem and stalks of the grapes are removed as they contain tannin.

Crushing of grapes

·       A roller-crusher may also be used to crush grapes.

·       Ancient methods of crushing with the feet. sometime crushing is accomplished by pressing with hands and produce white juice.

·       The crushed juice called “Must” has a pH of 3.0.

·       If the sweetness of Must is low (< 20), sugar is added.

·  SO2 and potassium meta bisulphite is added as preservatives that remove wild yeast contaminants.  

·       The must is transferred into new tank and then closed.

·       The resulting respiration in the fruit, consuming oxygen and producing carbon dioxide that kills the skin cells, which lose their semi-permeability, allowing easy colour extraction.

Fermentation of must

•  After six hours of adding SO2 the starter culture is added. The Must is inoculated with 3% yeast starter culture, Saccharomyces cerevisiae var ellipsoideus.
• Nutrients like, ammonium sulphate is added as nitrogen source.
• Anaerobic condition, a temperature of 21 – 27 °C and pH at 3.0 – 3.6 are maintained during fermentation.
• Partially fermented wine is decanted and again allowed to ferment for 7 – 10 days.
• After fermentation is completed, the wine is decanted from sediment of yeast and particles of grape tissues.
•  Fermented Must is filtered and fining agents such as casein, gelatine, egg white, tannin may be added for clarification. Clearing of wine and development of flavour take place during aging of at least 8 – 10 months.
•  The characteristic wine flavour develops due to production of various volatile aroma substances such as (ethyl formate, methyl acetate, ethyl acetate), aldehydes (acetaldehyde, propionaldehyde, butyraldehyde), ketone (acetone, acetoin, diacetyl) and acids (formic acid, acetic acid, propionic acid). 
• Among them, esters and ketones are well known “flavourants agents” in wine.
• The aged wine is again filtered, pasteurized and bottled before consumption. 
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  Aging of wine ·       
• The aging of wine generally takes between 3 and 9 months

  ·       But which may be extended up to three years for high quality wines.

  ·       The maturation or aging is an important step in the manufacture of wine that produces desirable changes such as sweetness, alcoholic content, aroma or flavour of wine.

  ·       While aging of wine, the finished fermenting, yeast cells die off and settle to the bottom of fermenter vessel, it is called as “Lees”.

  ·       During maturation some chemical reactions takes place, the flavour of wine is developed through oxidation and esterification.

  ·       The wine is allowed for aging in new oak casks or bottles.

  ·       Oak wood has several complex chemical compounds, each of it contributes its own flavour or textural note to wine.

  ·       The colour also changes during aging from purple to carmine in red wine and yellow to gold in white wine.

  ·       The tannin settles and acids are converted into ether, and gives the beautiful taste of wine.

  
  
  

Application of wine

·     Wine, helps to decreasing low-density lipoprotein (LDL) also known as bad cholesterol which may cause artery damage while increasing the body’s high-density lipoprotein (HDL) which is also known as good cholesterol which may reduce the risk for heart disease.

·       Prevents the formation of blood clots.

·     Powerful antioxidant that can be found in grape skin and red grape juice. Antioxidants help the body fight off free radicals that can damage our cells and organs.

·       Preventing congestive heart failure (CHF). Antioxidants may help prevent coronary artery disease

·       Preventing diabetes (type 2) and heart disease in people with diabetes. 

·       Preventing ulcers caused by a bacterium called Helicobacter pylori.

·       Preventing Alzheimer's disease. 

·       Reducing the risk of cancer. 

·   Antioxidants in red wine, such as flavonoid, resveratrol, and tannin, help to slow down the ageing process by preserving collagen and elastic fibres.

Greeting

Dr.K.Amala,

Assistant Professor,

Department of Microbiology,

Sacred Heart College (Autonomous), Tiruppattur.

Tamil Nadu, India.