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Introduction to Wine Producing Process

There are four receiving spots in the wine cellar of "Vrsacki vinogradi AD" enabling a separate receipt of grapes of different varieties, separate receipt of grapes per colour, as well as for a separate processing of grapes that have been covered by grey mould to a great extent. Grapes are delivered by tractor trailers to the weighbridge where the quantities of grapes and sugar are measured. Grapes are unloaded manually or by dumping. The receiving pools are made of concrete with inclined sides that have been insulated by glass panels. The insulation can be achieved by applying a coating of epoxide resin or a thin coating of steel. The panels in the pool are protected from damaging with gum that has been applied for the purpose of attenuating strikes during unloading. Archimedes screw is installed at the bottom of the pool transporting the grapes to the press.


Grapes must undergo a pressing process in order to release grape juice must, and thus ensure alcoholic fermentation. This must be done in such a manner to avoid crumbling of solid parts of grapes and skin tearing. The berries should be just pressed to burst out. Today, the industry of wine production uses the presses with the mechanism for removing stems. The pressed grapes falls into a cylinder that contains an axis with blades in its middle part which rotates and disperses stems around the inner side of the cylinder, while the berries pass through the perforations in the cylinder.

There are two centrifugal presses (separating stems and pressing) in Vrsacki vinogradi AD and one machine for separation of the stems and pressing the grapes with the cylinders. The spout obtained after pressing is transported with the pumps to the presses for filtration.


The pressed grapes - spout should be sulphated by applying the vine-bearing agent (potassium disulphite), whose chemical formula reads K2S2O5. The vine-bearing agent prevents from the action of numerous micro-organisms that may lead the fermentation in the unwanted direction and the faded fragrance of future wine. If the grapes are healthy, 10 grams of vine-bearing agent should be added to 100 kg of the spout, and more vine-bearing agent should be added if the grapes are covered by mould, from 15 to 20 grams to 100 kg of the spout.


Adding enzymes to the sulphated spout enables the increase of yield during filtration, release of fragrant matters in a greater quantity than usual, easier and faster clearing of wine, improvement of colour in less coloured varieties this applies to black grapes. Enzymes, and/or enzyme preparations are natural, and even the grapes contain enzymes to a lesser extent. Ageing of sulphated spout with added enzymes is recommended for Muscat varieties (Traminer, Muscat Ottonel, Sauvignon, Muscat Hamburg) since the fragrant matters are found in the skin and the sulphated spout should age for several hours (2-4 hours), and then filtrated. Wine with a richer taste is obtained in this way.


The filtration of the spout is performed with the pneumatic filtering machine of bigger and smaller capacity. The filtration should be conducted slowly with a light pressure since great pressure releases certain substances from the solid parts of the grapes (skin, stem and seed) to the must and the wine becomes sour later. If the wine is heaven sent gift poured into a glass, then no gulp should be sour. The yield includes the quantity of must that may be obtained from 100 kg of grapes. More than 60 litres of must should be obtained from 100 kg of grapes so that wine could be smooth and not sour. On one hand we will obtain the must that gets fermented into the wine of a better flavour, while on the other hand we can have a better quality brandy from the mash by later distillation that can be very similar to grape brandy loza.

There are two lines for grape processing with 4 impulsive pressing machines of the capacity 2x5 t/h, one line for processing with 2 pneumatic pressing machines of the capacity 20-30t/24 h and one line for processing black grapes of the capacity 5 t/h in Vrsacki vinogradi AD.


In this plant, the must is purified by depositing, clearing and separation. Clearing is performed with bentonite, casein, albumin and gelatine, depending on the need. After filtration and pressing of the spout, the must from the first and the second line is brought to centrifugation. In this operation, big particles causing impurity are separated from the must. The obtained must is introduced to the vessels for fermentation and the separated deposit undergoes vacuum filtration. The capacity of separators is 12.500 l/h causing the must containing 8% of deposit to become a clear must with 2% of deposit. The separator consists of a pre-filter, hydro-cyclone and centrifugal drum with the control panel through which the operations are programmed.

Must depositing
Must depositing is a necessary procedure since the must obtained after the spout filtration is more or less cloudy. The cloudiness comes from the solid parts of grapes (skin, seeds), soil particles, and agents used for spraying, etc. White wine of a better fragrance and lighter colour is obtained by must depositing. This is necessary in case of processing grapes attacked by moulds or dirty with mud. Taking into account that the spout was previously treated by adding the preserving agent (potassium bisulphite), lower temperatures for must depositing should also be used (8 to 12C). Lower temperatures are needed for any case since they will postpone the beginning of the fermentation at least for 12 hours, which would be enough for the must to settle down if the grapes are healthy. Otherwise, if the grape are covered with moulds to a greater extent and the temperature in the room is around 20C, 10g of preserving agent (potassium bisulphite) should be added to 100 litres of must (15 to 20 grams for rotten grapes).

Draining the must
The draining of the must from the deposit is performed by the pump. The must is transferred to the vessels for fermentation (vinificators). One should take care to leave around 20% of empty space in a vinificator (the vessel shouldnt be filled up to top) because foam is released under the impact of the isolated CO2. The deposit that was left after draining is processed and used as wine distillate for producing brandy.


Adding bentonite (klarol) to the must separated from deposit is widely used in the production of white wines. It should be noted here also that it is a natural agent bentonite is a type of clay and it is found in the soil. It may be bought as powder or granules of whitish, yellowish or grey colour. Prior to its adding into the must, a suspension (solution) should be prepared first. The suspension of bentonite in the water is prepared in such a way that 100 grams of bentonite in granules (or powder) is poured into 1 litre of water. Bentonite soaked in such a way should stay for 24 hours then it should be stirred until a white solution is obtained. If the grapes are healthy, 1 litre of this solution is added to 100 litres of must. If the grapes were covered with moulds 1,5 to 2 litres of bentonite solution should be added to 100 litres of must. Small quantities of bentonite suspension are added to the must with constant stirring. This agent reacts with albumen that can later blur the wine and turns it into a deposit which means that it facilitates and accelerates wine clearing.


Adding wine yeast to the must is not required, but it is recommended and technologists use it in wine making. Adding the wine yeast ensures a more regular fermentation and its good beginning and completion. Sugar from yeast turns into alcohol (ethanol) and carbon-dioxide and heat is released as well. Fermentation is performed in the rooms with lower temperature due to heat release.


Fermentation starts in two-three days if the temperature in the room is about 20C. Fermentation can take place spontaneously or as a result of adding wine yeast. During the fermentation process, mash rises to the top of the vessel. The production plant of Vrsacki vinogradi AD possesses huge volume vessels of around 100 wagons for conducting alcohol fermentation at the temperature around 18 - 20C, including the concrete cisterns with the cooling system (the total volume of 54 wagons) that contain panel boards letting through cool water, and the water is cooled by Freon system. Around 40 wagons of volume include the tanks in which the temperature is maintained by cooling water. Prior to purification, the must is cooled down so that it could be more efficiently cooled down during fermentation and be subject to fermentation at temperature of around 18C. The fermentation of the must lasts around 14 days until the whole quantity of sugar turns into alcohol.


Storing wine means pouring one from one vessel to another, adding preservation agents and filling up vessels. Pouring one from one vessel to another is the action that is most often performed during wine storing. Upon the completion of alcohol fermentation new wine is cloudy since it contains yeasts that have not deposited yet, albumin matters, parts of skin and seeds of grape, potassium crystals and other compounds that cause its cloudiness. These matters deposit in time at the bottom of the vessel, particularly the yeast cells that start to decay. If the ageing process lasts longer the smell of decayed yeast would be felt in the wine, and this smell resembles rotten eggs. In order to prevent this, wine should be poured from one vessel to another by means of a pump so that the deposit would be separated. Filling up the vessels is the measure to prevent from harmful events that young wine may be subject to. Adding the preserving agent is preferable since it will prevent the wine from spoiling that may be caused by micro-organisms, darkening i.e., colour change, and the faded flavour and fragrance of the wine will be avoided. If the grapes were healthy, around 5g of wine preserving agent is added to 100 litres of wine, and more as appropriate.

In order to have its final look, wine must be filtrated. In ?Vrsacki vinogradi? AD wine is filtrated by filters with panel frameworks ?ZEIS? and micro-filters ?PALLOV?, capacity of which being 5 10 thousands of litres per hour.

Then wine is poured into glasses and undergoes pasteurization in panel pasteurizer.


In order to control all segments of the technological process of producing wine and the quality of the finished product, Vrsacki vinogradi AD established a laboratory with the latest equipment.

Laboratory conducts all routine analyses of the must during processing and analyzing wine on stock (contents of SO2 released and total, alcohol contents, total extraction, quantity of remained sugar,). The laboratory uses the method and device for the analysis of all acids (milk, apple, wine), and there is a drying plant within the laboratory. The laboratory is divided in three separate rooms that ensure a good deployment of machines that require special conditions (humidity, temperature) for uninterrupted operation and successful storage of samples.

Micro-vinification process and experimenting with future products is conducted in the laboratory as well.