A fermented fruit drink is a fruit juice that has undergone alcoholic fermentation by yeasts such as Saccharomyces cerevisae. Products contain varying amounts of ethyl alcohol. Apple cider, plum wine, grape wine, vermouth, etc. are the main fermented drinks.

Different types of Wine

1. Wine: Wine can be defined as an alcoholic fermented beverage prepared from grapes. When other fruits are used to make wine, the name of the fruit is added first such as plum wine, peach wine, etc. There are two types of wine viz. dry and sweet.
   • Dry wines contain practically little or no sugar, while sweet wines contain some sugar and have a sweeter taste. The alcohol content in these wines ranges from 7 to 20 percent.
   • Wines are also classified based on their alcohol content as light, medium, or strong wines.
   • ‘Light wine’ has an alcohol content of 7 to 9 percent.
   • Alcohol in ‘medium wine’ is 9 to 16 percent and,
   • ‘Strong wines’ with 16 to 20 percent alcohol.
   • Wines typically over 12% alcohol are fortified with fruit brandy (alcohol) prepared by distillation of grape wines.
   • Still wines are without any carbon dioxide.
   • Sparkling wine contains carbon dioxide.
2. Champagne: Made mainly from certain grape varieties in France. Champagne is sparkling clear wine and is made in many other countries as well. Generally, the process of fermentation is accomplished in bottles. These bottles are specially made to withstand the high pressure of gas produced during fermentation.
3. Port: This fortified sweet red wine is originally from Portugal, but is now produced in other countries as well.
4. Muscat: Made from grapes of the Muscat variety in Australia, California, Italy, and Spain.
5. Tokay: This is a famous fortified wine from Hungary
6. Sherry: Sherry is a Spanish wine that is matured by placing filled barrels in sunlight at a temperature of 54 to 60°C for 3 to 4 months.
7. Perry: The wine made from pears is called Peri. It is made in the same way as apple cider. It can be prepared from the wastage, culled fruits, and trimmings left over from canaries.
8. Orange Wine: Sweet orange juice is fermented to make orange wine. The method of preparation is similar to that of grape wine. Orange peel oil should be minimal in the juice, otherwise, its presence stops fermentation completely.
9. Berry Wine: Wines made from fruits such as strawberries, blackberries, and elderberries are known as berry wines.
10. Feni: Feni is a liquor made from the fermentation of cashew apples in some places like Goa.
11. Nira: Nira is prepared from the juice of the palm tree.

Method for preparation of wine

Fruits suitable for making wine

Apple, custard fruit, pear, Jamun, berries, cantaloupe, coconut toddy, pomegranate, banana, guava, plum, strawberry, peach, kiwi fruit, raspberry, cherry, pineapple, date apricot, litchi, and mix fruit wine can be made from fruits.

The wine can be red or white depending on the grapes used. Red grapes are crushed and fermented to produce red wine, while white wine is produced by fermenting white grape juice.

Preparation of fruits for fermentation

The grape varieties like Beauty Seedless, Arka Shyam, Concord, etc. are used for making wine. To make wine from white grapes, the juice is taken, whereas, in the case of coloured grapes, crushed grapes without any stem are taken for fermentation. The fruit is crushed to extract the juice or the fruit pulp is used in fermentation.

Addition of sugar

The sugar content should be between 22-24 % and the acidity should be 0.6 to 0.8 %. In low-sugar fruits, cane sugar is added to increase the TSS to 22 %.

pH adjustment

If necessary, the pH of the juice is adjusted. If it is too low, the juice is diluted with water; If it is too much, tartaric acid is added to reduce it. If water is added, more sugar has to be added to increase the TSS. Usually, 0.6-0.8% acidity is maintained.

Addition of preservatives

Potassium Metabisulfite (KMS) @ 1.5 g is added for every 10 kg of grapes and allowed to stand for 2-4 hours. Sulfur dioxide can also be added at a rate of 50-70 ppm to prevent the growth of wild yeast and unwanted bacteria.

Yeast Inoculation

The grape juice after the addition of sugar syrup is fermented by the addition of a culture of the pure wine yeast Saccharomyces cerevisae var. ellipsoideus as a starter @ 2-5% or 20ml for every 5 Kg of grapes. Yeast should be added about an hour after adding the preservatives. If yeast is not available then preservatives should not be added either. The yeast present in the skin of grapes can also ferment for wine but cannot produce good quality wine.

Fermentation

The temperature should be maintained between 27-29 °C for proper fermentation. Temperatures below 10°C and higher than 38°C almost stop the fermentation process. After three days the material is filtered through a muslin cloth and again kept to ferment for another 10 days, so that the yeast cells and other solids settle to the bottom. For other fruits, the time taken to complete fermentation is between 15-20 days.

Racking and Filtration

Siphoning out fermented wine from solid deposits is known as racking. After racking it is further clarified with the help of a fining agent like bentonite. When all the colloidal matter settles down with the bentonites, the pure wine is siphoned off and filtered if necessary.

Aging (Maturation)

Pure wines are completely filled in bottles or barrels sealed to exclude air and kept to mature for 6-8 months. During this aging process, the wine loses its raw and harsh flavor and takes on a distinct and distinctive aroma. Generally, oak wood barrels are used for aging because they impart a better aroma to the wine. During maturation, the dissolved carbon dioxide is released and spontaneous clarification takes place. The extraction of oak flavor and limited oxidation also occurs during this process. Astringent tannic substances precipitate and as a result slow smoothing the taste.

Packaging:

The wine is typically pasteurized at 82–88°C for 1–2 minutes, followed by bottling. Alcohol is added in the form of brandy or wine spirits to make fortified wine. Sugar may be added before the final packing of the wine to improve the taste.

Cider

It is prepared mostly by fermentation of special grade apples which are rich in tannin content of 0.1-0.3%. However, very confusing as far as apple cider is concerned. In the United States, apple cider means impure/ non-clarified apple juice, while apple juice is clear and sparkling juice. In other countries such as Europe and India, apple cider is related to fermented apple juice. In India, dessert apples are used to prepare good-quality ciders. The alcohol content in cider ranges from 4 to 6 %.

Fruits like bael, jamun, phalsa, and amla can also be used to make cider. The technology of preparation is almost the same as that of grape wine.

The apple is crushed and pressed to extract the juice, then cane sugar is added to raise its sugar content to 22° Brix. It is preserved with 100 ppm SO₂ and a pure culture of wine yeast is added for fermentation. Sometimes di-ammonium hydrogen phosphate (DAHP) (0.02 to 0.05%) is added as a food supplement for yeast. The method of fermentation is similar to that of other wines. After filtration, the old is aged in oak wooden barrels. Mature cider is bottled, heated to 65°C, crown corked, and pasteurized at 60°C for 30 minutes. Apple cider is also carbonated for better acceptability.

Vermouth

It is a fortified wine in which alcohol contents range from 15 to 21% and flavoured with a mixture of herbs & spices.

Brandy

Brandy is a distillate obtained from the distillation of wine and generally aged in small oak barrels, for example, Cognae and Armagnae.

Vinegar

The word is derived from the French ‘Vinaigre’ which means sour wine (vin meaning ‘wine’, aigre meaning ‘sour’.

Vinegar is a liquid obtained by alcoholic and acetic fermentation of suitable ingredients containing sugar (at least 10% fermentable sugar) and starch. It contains about 5% acetic acid and has disinfectant and antiseptic properties. In trade, vinegar is labeled according to the ingredients used in its manufacture, e.g., malt vinegar (from malt) and cider vinegar (from apple juice).

Types of vinegar

There are two types

A. Brewed Vinegar: Vinegar is made from a variety of fruits, starchy substances, and sugar-containing substances (molasses, honey) by alcohol and subsequent acetic fermentation.

1. Fruit Vinegar: Vinegar is prepared from different types of fruits like apples, grapes, oranges, pears, peaches, etc.
2. Potato Vinegar: Potato starch is used to make it
3. Malt Vinegar: Malt vinegar is obtained entirely from malted barley
4. Molasses Vinegar: Molasses is diluted to 16% TSS, pH corrected with citric acid, and then fermented.
5. Honey vinegar: It is prepared from low-grade honey.
6. Spirit Vinegar: Spirit vinegar is a product prepared by acetic fermentation of a distilled liquid which in turn is produced by fermentation.
7. Spicy Vinegar: It is prepared by steeping leaves or spices in ordinary vinegar.

B. Synthetic Vinegar: Synthetic vinegar is prepared by diluting synthetic acetic acid or glacial acetic acid to the legal standard of 4% and is colored with caramel.

Vinegar Methods

Vinegar is prepared by the following methods

1. Slow process
2. Orlean’s slow process
3. Quick process or generator or German process

1. Slow process

This process is commonly used in India. The juice or sugar solution stored in earthen pots or wooden barrels is kept in a warm, moist room for at least 5-6 months to allow spontaneous alcoholic and acetic fermentation. No special care is taken, but the mouth of the container is covered with a cloth to keep away insects, dirt, etc. The main drawbacks of this method are inferior quality of vinegar, and low yield.

2. Orleans slow process

The vinegar prepared by this process is clear and of superior quality. The steps of the process are:

Fruit selection: Grapes, apples, oranges, mangoes, dates, jamuns, and any other fruit of the third category whose juice contains about 10% sugar are taken. Some of the pulp and skins of the fruit discarded during canning and jam making can also be used.

Juice Extraction: Fruits or vegetables are cut into small pieces and then crushed or pressed into a coarse muslin cloth. Fruits that do not juice easily are heated with a small amount of water before pressing.

Addition of sugar: Only juice containing a low percentage of sugar is suitable for the growth of yeast. The sugar concentration is determined by means of a hand refractometer and if the sugar content is high, the juice is diluted with water or added sugar to about 10% TSS.

Fermentation: The juice is heated (pasteurized) to kill microorganisms and then filled to three-quarters of its capacity in a glass carboy, earthen pot, or wooden barrel. Fermentation consists of two important steps:

1. Alcoholic Fermentation: Pure wine yeast powder obtained from the winery or chemist’s shop is taken and dissolved in slightly warm juice and then added to the whole juice at the rate of 1.5 g/L with constant stirring. The mouth of the carboy or barrel is closed with a loose dot of cotton wool to allow the carbon dioxide gas to escape. CO₂ gas must be completely removed otherwise it hinders yeast fermentation. It takes 3 weeks for fermentation to complete. All the sugar is converted into alcohol which can be seen by the test of a refractometer with a TSS of 0-1%. During fermentation, the temperature is maintained at 22 to 27 °C as fermentation stops above 41 °C and below 7 °C. The fermented juice is stored for 1-2 weeks for sedimentation and then filtered with a cloth, or the juice is siphoned off from the top and filled into a clean container that is filled to three-fold of its capacity. Vinegar fermentation should only be done after making sure that the alcoholic fermentation is complete, otherwise, the yeast will slow down the fermentation. For vinegar fermentation, the alcohol content of the fermented liquid is adjusted to 7–8% by diluting it with water, as acetic acid bacteria do not grow in high concentrations of alcohol.
2. Vinegar fermentation: This is done by acetic acid bacteria. Unpasteurized vinegar or “mother” vinegar is thoroughly mixed in a 1:10 ratio to the product of alcoholic fermentation. Thereafter the fluid should not be disturbed otherwise the film of vinegar bacteria breaks down and will sink to the bottom and consume the nutrients of the liquid without producing vinegar. The mouth of the container is sealed with a cork having two holes for proper aeration. The temperature of this liquid is maintained at 21-27 °C and fermentation is completed in 10-15 weeks. Then the vinegar is filtered through a thick cloth.

Aging: The vinegar prepared by the above method is cloudy and does not taste good. It is stored in containers for 4-8 months, during which time the vinegar develops a nice aroma and taste and becomes mellow.

Clarification: Clear mature liquid to be taken out and filtered.

Colouring: Caramel color is added for colouring.

Pasteurization: Vinegar is poured into pre-sterilized bottles and the bottle is heated (pasteurization) in hot water at 71 to 77 °C for 15 to 20 minutes, to prevent further bacterial growth and the strength of vinegar maintained during storage.

 3. Quick process or generator or German process

In this process additional oxygen is supplied for bacterial growth and the surface of bacterial culture is also increased resulting in rapid fermentation, the equipment used in this process is known as the ‘upright generator’, which is cylinder-shaped whose height ranges from 3.66 to 4.22 meters and diameter from 1.2 to 1.5 meters. Which is divided into three compartments distributing, central, and receiving.

Vinegar production problem

1. Wine flower: When unfermented juice is exposed to air, a film/layer of yeast called wine flower forms on the surface of the liquid. The film causes cloudiness and also destroys the alcohol. The growth of wine flower can be stopped by

1. 1. filling the carboy or barrel to the brim,
   2. adding 20-25% unpasteurized vinegar, and
   3. Spreading liquid paraffin on the surface of the fermented liquid.

2. Lactic Acid Bacteria: The presence of lactic acid bacteria in fermented juices is very common. These bacteria interfere with the acidification, cause cloudiness, and produce lactic acid which has an unpleasant foul or musty taste and thus deteriorates the quality of the vinegar. This can be avoided by using 20-25% unpasteurized mother vinegar or a pure culture of yeast.

3. Worms: Among insects, vinegar flies (Drosophila cellaris), vinegar louse, and vinegar mites are important. These can be avoided only by maintaining proper hygiene. Vinegar eels (Anguillula) are thread-like insects found in vinegar, which destroy the acid that can be killed by heating to about 60°C or filtering the vinegar. Vinegar eels are aerobic and do not grow if the container is filled to the brim.