Wine presses are an essential part of the wine making process. They separate the juice from the solid parts of the grapes, such as skins, seeds and pulp. The way the grapes are pressed has a great influence on the taste and aroma of the wine.
A brief History of Wine Presses
The history of the wine press is thousands of years old. The first wine presses were found in what is now Armenia, where grapes were pressed with the feet. The next great steps of development took place in ancient Egypt, Greece and Rome, when the presses became more and more technical and precise. Then, in the Middle Ages, the basket press was invented and became widespread. This type of press, which is still used today, is considered the cornerstone of the development of wine presses.
Today there are three main types of wine presses: screw presses, bladder presses and basket presses.
Wine pressing is an essential winemaking process. It’s not only about the extraction of grape juice, but also about acids, sugars, and flavors that contribute to the aroma and taste of the finished wine. This is also part of the winemaking process where the juice is usually separated from the solids.
Harsh pressing means bigger amounts of grape juice, which is usually of lesser quality and needs more fining. Whereas gentle presses provide a better quality juice, the yield is lower. The first can process greater amounts of fruit at the same time, the second is usually more labor-intensive and slower.
A basket press is usually used for red wines since this type of press can extract softer tannins. For white wines, which are lighter and fruitier, winemakers usually choose the bladder press, which can put less pressure on the grapes.
By controlling the amount and type of pressure, winemakers can produce wines with different tannin levels, flavor profiles, and tastes.
Bladder Press: For a Gentle and Precise Squeeze
Bladder presses or pneumatic membrane presses have been around for about 70 years. They are hailed as the best compromise between yield and quality.
They are a kind of batch press, that is, they can press one batch of grapes at a time.
Bladder presses consist of a large horizontal cylinder closed at both ends. The grapes are fed from the top, through a pusher or from the side. Inside the rotating drum is a bladder that inflates with air and exerts pressure on the grapes. The juice then flows out through small openings on the sides. Some presses have slotted screens, others perforated screens.
During the process, the cylinder rotates so that the pressure is evenly distributed over all the grapes. In the end, all the juice is collected separately from the solid particles that remain inside the cylinder.
They are usually controlled by a computer so that each winemaker can create its own pressing program. This means how much pressure is in the bladder, how long it will hold, and how it will deflate and rotate. Usually, the press spins a few times before the bladder inflates again. A normal press cycle lasts a couple of hours.
Pros and Cons of a Bladder Press
With the bladder press, all the grapes receive the same amount of pressure, so the result is the best compromise between yield and quality. This type of press can also rotate, so more free-run juice is extracted even before the pressing begins.
They are faster per cycle than basket presses, so you can have a smaller press for the same result. This again means you need less space for storing it. They are also easier to move around.
A huge benefit is that they are mostly computerized, so every winemaker can configure their pressing cycle to their preferences. It is considered to be one of the most user-friendly presses.
The biggest downside to a membrane press is the price. They are quite expensive in comparison to other presses. Even though they can be smaller, they still won’t fit in a small cellar and they need an industrial setup.
Basket press: The Artisinal Press that got Modernized
Basket presses have been around for centuries. They are regarded as gentle presses and they extract the highest quality juice.
Nowadays they are made out of stainless steel, but you can still find wooden ones in some cellars.
They work by pressing the grapes from the top and bottom. Grapes are placed inside a basket or a slated cage, then usually two half-moon blocks are placed on the top of the fruit, and heavied down with other blocks. With the help of an iron ratcheting assembly pressure is put on the blocks and via that to the grapes, juices then flow out from the sides.
Nowadays pressure is usually applied with the help of a hydraulic system.
It usually takes about an hour to complete the pressing of one batch. Afterward, the press needs to be cleaned and reloaded.
Pros and Cons of a Basket Press
Because these presses are so gentle and there’s no tumbling of the cake, the extracted grape juice is of the highest quality and usually doesn’t need fining.
But this is also the reason why the yield is usually one of the lowest in comparison to other presses.
Winemakers can decide how much pressure is used in extracting the juice, which influences the taste and aroma of the wine, It is highly regarded for the ability to extract finer tannins. This happens because the pressing is usually lighter, which means grape seeds and skins are not pressed as much.
The downside to this press is also that is not meant for huge wineries. You need a lot of manual work for this type of press. The batches are usually smaller and you need to clean the press in between every batch.
Horizontal Screw Press: For Bigger Batches of Grapes
Horizontal screw press works very similarly to the basket press, the main difference being the orientation, one being vertical and the other horizontal.
A horizontal screw press is made out of a horizontally enclosed cylinder, in which grapes are added. Inside the drum, there’s a rotating screw, which is applying pressure to the grape skins by plates from both ends. Because of the pressure of grapes against the sides, juices start to drain through the slated cylinder.
Pros and Cons of a Horizontal Screw Press
Horizontal screw presses can handle larger amounts of fruit in comparison to the vertical basket press. There is also the possibility of adjusting the pressure on the fruit by tightening or loosening the screw.
Even though the characteristics are similar to the bladder press, the horizontal screw press is not as popular.
Continuous Screw Press: For the Highest Efficiency
The continuous screw press is very similar to the horizontal screw press, but the advancement here is that it can process many batches of grapes at a time. They can provide continuous operation. This happens with the help of an Archimedes screw, that can repeatedly push grapes toward the wall of the press.
This kind of press can also be inclined and the grapes are put in at the bottom of the press.
Pros and Cons of a Continuous Screw Press
They are common in larger wineries, where high efficiency is the prime target. Continuous screw presses can extract the highest amount of juice from grapes in comparison to other presses.
Because of the harsh pressing, there can be a significant amount of extraction from the skins and seeds, which has an undesired influence on the wine. It tends to be lower in quality.
Because of this, some countries even forbade the use of this kind of press for high-end wines.
Every wine press has its benefits and downsides. Winemakers can choose between different pressing methods and equipment to attain the desired result, this can be a fruity and light wine or a bold red one.
The type of winery equipment depends also on the size in production capabilities of a winery, some are smaller and produce more boutique types of wines, so they can choose slower presses, whereas huge wineries will probably choose faster wine presses.