About 80% of the grown grapes are used annually for the manufacture of various products of the wine industry. It belongs to the most valuable type of plant material. Its processing is quite simple, and the resulting products are distinguished by high taste and nutritional qualities.
Technological stages of grape processing
After the crop is harvested, it is delivered to the wineries for processing. This process consists of several stages:
- acceptance, where the average sample is taken from each batch of raw materials received;
- primary processing, during which the grapes are washed;
- comb separation intended for the separation of berries and ridges;
- crushing, providing processes by which juice from grapes stands out at an accelerated pace.
Features of crushing grapes
This process takes place in crushing and pressing shops. The main type of equipment used in them is grape crushers designed for processing it into pulp and must. Whatever the degree of crushing of the berries, it should minimize the violation of the integrity of the seeds.
Since light natural wines, champagne and cognac wine materials have a small extractivity, the degree of grinding of berries for their production should be the lowest. Therefore, crushers for grapes in this case work in easy mode.
As for full extractive wines, which include thick, sufficiently strong red wines, the berries for them are crushed more intensively.
As a rule, the process of crushing grapes is combined with the separation of ridges. This is due to the fact that during processing they can saturate the wort with substances that will subsequently give the wine a rather unpleasant herbal taste. An exception is the production of Kakheti wines, when the crests are not separated at all.
Modern enterprises use crushers for grapes of two types: centrifugal and roller. Their difference consists in the intensity of crushing berries and the different nature of the impact on the grape cluster. Each of them has its own special design and differs in operational and technical characteristics. But both of these types are united by the fact that it is a crusher for grapes with a comb separator.
Centrifugal crusher
This type of crusher is characterized in that the crushing of the berries occurs due to the centrifugal force, which ensures the impact of the bunches on the inner walls of the casing. In this case, the berries are subjected to a rather severe mechanical impact and are substantially saturated with atmospheric oxygen. In the process, the unit crushes the berries, while separating them from the ridges.
Such a mechanical crusher for grapes consists of a case equipped with a cover with a drive, a blade shaft, a hopper and a tray along which the ridges are diverted.
It operates according to the following principle:
- the grapes entering the bunker are subjected to the blows of the scourge of the shaft;
- the berries are separated from the ridges and come with them to the surface of the cylinder, equipped with perforations;
- after that, with the help of the rowing blades they are rubbed and through the holes fall into the mezzanine;
- the ridges are then separated into the tray located in the upper part of the crusher, and from it fall onto the conveyor belt.
Roller crusher
Such grape crushers are designed to separate ridges from clusters with subsequent crushing of berries. The design of the roll crusher consists of a ram shaft, a perforated cylinder and 4 food rubber rolls that work in pairs.
The principle of action is as follows:
- grapes enter the unit where the crests under the blows of the gross beaters are separated from the berries and removed from the perforated cylinder;
- after that, the berries fall through the perforations onto the rolls, with the help of which the crushing takes place.
The unit has additional devices that adjust the distance between the rolls within 3–8 mm. This makes it possible, if necessary, to use a gentle regime for crushing berries, depending on their variety and physical parameters.
Pulp pressing
In order to isolate the so-called wort (grape juice) from the pulp obtained during crushing, special presses are used. They are of two types - periodic and continuous operation.
Batch devices, in turn, are divided into basket devices, where the pulp is loaded into baskets, after which it is pressed, and pneumatic. Such a grape press has a cylinder for loading the pulp and a pipe through which air is pumped. With the expansion of the pipe, the pulp is pressed.
Aggregates continuously press the pulp in the process of moving it. They have great productivity due to the automation of the process. Such a grape press works by means of a screw, which both moves and presses the pulp.
Grape Crusher
For those who are engaged in the preparation of wine at home, a hand crusher will be an indispensable tool. It is a bunker with a stirrer that pushes berries between the rollers. By adjusting the distance between the latter, it is possible to obtain crushing of varying degrees, without damaging the bones.
Thanks to a productivity of up to 500 kg / h, a sufficiently large volume of grapes can be processed in order to immediately begin pressing the pulp.