Pressing in wine making is the process by which juice is extracted from grapes with the help of a bob, by hand, or even by the weight of grapes and groups. Historically, the whole wine group was stepped on by the feet but in most wineries today grapes are sent through crusher/destemmer, which removes individual grapes from the stems and breaks the skin, releasing some juice, before being pressed. There are exceptions, such as the case of the production of sparkling wine in areas such as Champagne where grapes are traditionally whole-group pressed with sticks included to produce lighter should be low in phenolics.
In the production of white wine, pressing usually occurs immediately after crushing or/and prior to primary fermentation. In red wine production, grapes are also destroyed but the presses usually do not last until after or near the end of fermentation with skin-time contact between the juice and color of grape leaching, tannin and other phenolics of the skin. About 60-70% of the juice available in berry wine, the juice that is managed freely, can be released by the destruction process and does not require the use of the press. The remaining 30-40% coming from pressing can have higher pH levels, lower titratable acidity, potentially higher volatile acidity and higher phenolics than free-running juice depending on the amount of pressure and tearing of the skin and will result in more astringent, bitter.
Grape makers often store free juice and separate wine (and perhaps even further isolate the wine produced by different pressure levels/stages of emphasis) during most of the wine-making processes either bottle separately or then mix each part to make more many wines are complete and balanced. In practice the volume of many wines is made from 85-90% of the juice being managed freely and 10-15% juice is suppressed.
Video Pressing (wine)
When to press and other wine making decisions
Time pressing and the methods used will influence other decisions in the wine making process. In making white wine, pressing usually occurs immediately after harvest and destroys. Here, the biggest decision is how much pressure to apply and how much pressed juice the wine-maker wants in addition to the juice that is sold freely. Some grape varieties, such as SÃÆ' Â © millon and Aurore have a very dilute pulp that releases juice easily without the need for a lot of pressure at risk of tearing the skin. Other varieties, such as Catawba, have a stronger pulp that will require more pressure.
In red wine production when to press is one of the most important decisions in the wine making process because it will be when the maceration and phenolic extraction stop. Some wine makers use a decrease in sugar levels (such as brix measurements) and pressing after the wine has reached complete drought. Often the wine makers will use flavor to determine whether the wine has extracted enough tannins to produce a balanced and pressable wine before the complete drought (as in 3-8 brix). Although removing the skin by pressing often removes some of the solids that wine yeast needs to complete the fermentation and the initial pressing benefits are often offset by the risk of potential stuck fermentation.
The quality of the vintage year and the overall maturity of harvested grapes can also play a role since the cold years when the grapes are often harvested under ripe, tannins in grapes are often very "green" and rough. In recent years wine makers may press early (as in 15 brix), a process that Australians call "short vatting". In warmer years, tannins may be ripe or "sweet" and the wine maker may decide to have an extended maceration period and not suppress the wine for a month after the fermentation is completed.
Usually pressed juice will require some additional treatments, which can be done separately to pressed juices or to whole batches of wine if pressed juice is mixed with free-run. This treatment may include acid adjustment to lower the pH, extend the precipitation period for clarification and additional racking to remove extra suspended solids and use of fining agents to remove extra solids or excess tannins. The wine pulp contains a lot of pectin that creates colloidal coagulation with these solids which will make the wine difficult to stabilize. Some winemakers will use pectolytic enzymes during the maceration process to help break down the cell wall in order to allow the release of more juice freely. This enzyme is also used with white wine to aid clarification. The type of presses used and the amount of suspended solids play a particular role in screening decisions because the high number of suspended solids (especially natural sap) can clog and damage expensive filters.
Maps Pressing (wine)
History
The earliest wine press is likely to be a human or hand leg, crushing and squeezing wine into a bag or container where the contents will ferment. The pressure applied by the means of this manual is limited and this early wine tends to pale in color and body. Eventually humans find that more juice can be extracted and potentially produce better wine if they develop a way of suppressing. It started with the ancient Egyptians who developed "sack press" made of cloth that was squeezed with the aid of a giant tourniquet.
The ancient Greeks and Romans developed a large wooden wine jug using large beams, caps and glasses to suppress pomace. The wine-press style would eventually develop into a basketry machine used in the Middle Ages by wineries of the nobility and the Catholic Church. There are many church records showing feudal land tenants willing to pay a portion of their crops to use the wine press of the landlord if available. This may be due to the increase in the volume of wine (anywhere from 15-20%) that the presses can produce compared to manual stepping large enough to justify the cost.
The emphasis of the machine became more widespread in the 17th and 18th centuries as the style of wine making in France and other parts of Europe shifted toward better, aging and enduring wines on the journey across the ocean. The text of wine-making begins to recommend the use of mechanical emphasis on the stepped foot in the lagars. Even in Bordeaux, which still use the old lagar after Burgundy, Champagne, and other French wine regions have adopted basketball baskets, seeing the use of winemaking machines become more popular after darker, more full-bodied wine from Ho-Bryan produced by Lord Arnaud III de Pontac began to receive widespread acclaim from British writers.
In the 20th century, grapes pressed forward from the vertical force pressed basket press and ancient wine press to horizontal presses with pressure either applied to one or both ends or from the side through the use of airbag or bladder. The new printing press is categorized as a "batch", which like a press basket must have empty pomace and wine reloaded, and as "sustainable" in which the Archimedes' belt or screw will be subject to wine/pomace to increase the pressure from one end of the tap to that others with new wine added and pomace being removed continuously. Another advance is a complete press enclosure (sometimes called a "tank press") that reduces wine exposure to air. Some forward pressure can even be flushed with nitrogen to create a complete anaerobic environment that can be desired for wine making with white grape wine. In addition, much of today's modernized computerized pressures allow the operator to control exactly how much pressure is applied to the skin of the wine and to how many cycles.
Emphasis type
Pressing wine is generally classified into two types - batch and continuous. Pressing Batch involves pressing a set of wine quantities ("batch") with press needing to be emptied of pomace or "cake" (remaining skin, seeds and stems) between batches. There are many different styles of batch emphasis ranging from simple hand operated basket presses to compress the computer membrane and pressing the "opened" with oxygen can be in contact with the necessity or "closed" in the tank allowing for the manufacture of anaerobic wine. Pressing continuously using a helical screw (such as auger) or a belt that carries grapes from a bait on a cylindrical screen or between a pressure-pressed bear that squeezes the wine, condenses the cake and then removes the cake through the output all in one continuous operation.
In general, batch emphasis is considered more "soft" with less grape skin movement that minimizes the amount of skin tears. The more rotted or polished grape skins, the more phenolic compounds and extracted tannins, which can increase the hardness of the wine. However, batch pressing is much more labor intensive, requiring repeated emptying and charging and can also be time consuming, often requiring between 1 and 2 hours per press cycle. Continuous suppressing, which is often used by high-volume wine producers, can be more efficient, with multiple continuous screw presses that have the ability to perform more than 100 metric tons per hour.
The development of large and closed membranes in the 1970s that can process more grapes with better quality of juices prompted many wineries to transition away from using screw presses. While pressing baskets is still popular among harvester and small milling and some high volume manufacturers still use screws continuously, the most frequently used emphasis in the wine industry tends to suppress the membrane.
Batch press
Press Batches usually operate in mechanized or manual cycles. It involves the following steps:
- Fill a tank or basket with wine
- Apply pressure
- Rotate the tank or break the cake manually
- Apply more pressure on the higher level
- Repeat rotation or breakup when applying further pressure
- Press and clear
The benefit or twisting of the tank or breaking the cake is to promote more pressing and cake forming that would be easier to move. From the moment the grapes are filled into a tank or basket, juice is released and extracted. This juice is usually dried by the tank into a waiting container or "pan press" which is then transferred or pumped into another container.
The amount of pressure applied (and speed) will depend on the wine maker's preferences with additional pressure raising the possibility that the skin and grape seeds will be rubbed and torn, releasing tannins and other phenolic compounds that can make the juice more astringen and bitter.. Mechanically working batch presses will start with less than 1 bar (less than 1 atm) of pressure and gradually increase to a maximum of 4 to 6 bar for 1 to 2 hours. The slower the pressure is applied and gradually increases, the more gentle the overall pressure.
There are several types of batch emphases, each with its own benefits and disadvantages. The most common ones found at the winery are listed below.
- Press cart
- One of the early styles of the mechanical press, this can range from simple wooden baskets with vertical blades and rollers providing pressure for large hydraulic presses that can even be covered to prevent oxygen exposure. The advantages of this compressive force are usually soft ways to suppress the grapes but the disadvantages include the intensity of labor usage, small volume and the tendency to provide uneven pressure to all parts of the cake as well as usually exposing the need for significant amounts of oxygen. Another disadvantage from a time perspective but a gain in other things like softness, is because of its pressing nature with a very slow press basket. Applying too much pressure too fast can break the press.
- Move header
- This press is basically a press basket that has been rotated on its sides with two heads on the opposite end giving a more homogeneous pressure as it moves horizontally toward the compacting cake. Often this press has a linked chain between two heads that breaks the cake between pressing as the head is pulled. Although less labor intensive than pressing traditional baskets and giving more pressure, one disadvantage of moving head presses is that the cake becomes so compact that it is often difficult for the juice to overload the core of the exit cake. It has the effect of creating a dry "pastry" and wet "inner cake" with trapped juice still inside. Juice extracted from the outside cookies can also be very coarse and high phenolic.
- Press the bladder
- Also known as "pneumatic press". To overcome the disadvantages of a moving head press, the bladder press is designed to have a long rubber cylinder ("bladder") sausage mounted through the center of the tank (creating an annulus) inflated by air or water to produce outside pressure on the cake on a hollow screen. The cake becomes like a donut even with the pressure applied almost the same to all parts of the cake. The benefit of this style is usually the amount of pressure applied to the cake as well as the additional ability to help cool the necessity if the bladder is filled with cold water. The disadvantage is the intensity of cleaning and empty work and the potential for high oxygen exposure if the tank is not closed.
- Press membrane
- Instead of pressing from the outlet as with the bladder press, the membrane press membrane is mounted on one side of the press horizontally between the two ends. On the opposite end is a disposal screen that allows juice releases to flow through into the waiting pot pan. As pressure presses the bladder pressure applied by pressurized air (rarely water) which gradually expands the membrane that gently presses the grapes on the sewer screen. The advantages of this compressive force are the gentle pressure and minimal movement of grapes, which minimizes the amount of tear and scrubbing of the skin and grain. This limits the amount of suspended solids and phenolics extracted in pressed wine. Also, much of the membrane is completely closed, allowing for the production of anaerobic wine without oxygen exposure. In addition to the same labor shortage and time (some pressures can take 2 to 4 hours per unit) from other batch printing machines, this computerized and closed computer shutdown is often a more expensive part of the equipment that the winery can buy.
Continuous push
The benefits of continuous emphasis are the "sustainable" order that allows large quantities of wine to be suppressed with minimum labor involvement. Instead of pressing a separate batch that needs to be emptied and recharged, the persisting press usually has an input area and some mechanisms (such as screws or auger belts) that transfer the wine through pressing with the output area for the discarded cake. Throughput is limited by the capacity of the tank and the diameter of the screw or width of the belt. Many continuous screw pressing models can process from 50 upwards of 100 metric tons per hour. This can be a significant advantage for high-volume wines compared to batch pressures that often only process 1 to 5 tons per hour.
Although not as diverse as bundling presses, there are 3 main types of continuous emphasis, each with its own benefits and disadvantages. Although it is often more common in the juice industry than in wine making (and even prohibited for the production of quality wines in some wine regions such as Algeria), the following presses can be found at the winery (usually high volume).
- Screw press - The wine is loaded into the input where a large helical screw wires the wine in a hollow cylinder that allows release juice to escape. As the screw moves further down, the pomace cake is under increasing pressure. While the advantages are high throughput, hard emphasis and a lot of movement causing major tears and grinding on the skin and grape seeds. This causes more minerals (such as potassium, which can affect the pH), tannins and natural sap to be extracted into the juice. 4% v/v of pressed juice from the screw press may be a suspended solid which may be treated by clarification and the fining agent to be stable and filterable.
- Press impulse - Modified screw press that aims to limit the number of grape movements. The first press pulls the screw back into the container as the wine gets loaded in. Then the screw moves forward horizontally acting more like a "batter" of an auger by intermittently pushing the cake in "impulse" towards the tip of the press. Although it produces a slightly less phenolic press fraction, the loss of this pressure is a decrease in efficiency that is almost equivalent to the batch pressure.
- Belt press - This press uses a series of inflated air bearings along the wire belt. Usually a few meters long, fresh wine is loaded to the beginning of the belt where it is transferred by the roller through a series of bearings that apply pressure, hold it for some time and release it with the juice falling through the screen into the waiting pot. Belt buckling has been used by high-volume wineries to suppress whole-group and sparkling wine production but has not been caught in many wine regions due to concerns about the amount of oxidation introduced into the wine as well as a large number of suspended solids. who passed the screen.
Press the
There is a trade-off between high volumes and the pressing throughput can continue to manage versus the overall quality of the press juice compared to the more subtle potential ways of batch emphasis. However, there are striking differences in the composition of pressed juices from continuous pressures taken from the beginning of the press (press section 1) with the least pressure and movement compared to fractions that come farther down the road. Often the winemakers will have a separate press pan under each section that they will keep separate and separate apart.
Below is a table of differences in the Riesling juice composition between free-run juice and juice coming out from different parts of the persistent press from a comparatively low press 1 compression portion to compressive parts of 3 more compact and higher-pressure presses.
Free-run versus pressed juice
During the emphasis it has been used, the wine makers have known the characteristics of different colors, bodies and aromas of grapes made from "free" juice compared to pressed juice. Free-runs are juices that have been extracted through the process of destruction, the natural breakdown of wine cell walls during maceration and fermentation and by the weight of the grapes themselves as they are loaded on top of each other in the press. Even between press juices there is a difference in composition between the various "fractions" of juice resulting from the initial emphasis through subsequent (and usually more severe) emphasis. Often the winemakers will store free and pressed juices separately for most of the wine making process including malolactic fermentation and barrel aging with the option to then blend between them to make the most complete, balanced, bottled wine separately under different label and price levels or to dispose/sell pressed fractions to other manufacturers.
The main difference between free and pressed juice is that pressed juice often has lower levels of acidity, potassium and higher pH levels, more phenolic compounds such as tannins and more suspended solids such as chewing gum and natural proteins. Some of these attributes can be a positive influence on grapes with increased phenolics offering more body, aroma characteristics (such as varietal scents of terpenes) and potential aging. Other attributes may have more negative effects such as increased astringency and bitterness, precursors to browning pigments in white wine issues, mouth and balance (as well as potential microbial instability) of increased pH and increased need for finance agents to aid in clarification. and wine stabilization with increased suspended solids.
The extent of this difference will be enlarged or minimized based on the initial condition of the fruit after harvest (with moldy, damaged, sun-baked or cultured wine producing striking differences between free-run and pressed juice), the type of press used, the amount of pressure involved and the overall amount of movement influenced by grapes that can affect how much skin and seeds are rubbed and torn.
Pressed fraction
Below is a table of Riesling juice composition differences between free juice and various press fractions using a compressed membrane.
Debt all over
Whole-cluster pressing is where instead of sending grapes through a destemmer/crusher, whole grapes that are directly pressed are still attached to the stem. This is a widely used method for the production of white wine, rosÃÆ'Â © and sparkling as it usually produces finer grapes, less phenolic and less colorful. Even some red wine producers (especially Pinot noir) will use this type of pressure to avoid the harsh or "greenish" tannins that may come from ripe grapes. This method is different from the "stem pressing" in which the wine is destroyed and destroyed but part of the stem is stored and thrown onto the wine press to add some phenolics as well as make the "duct" for the juice flowing between the skins, which can limit how often the drain is clogged.
Under the whole-group method, the first press fraction is essentially a "free-running" fraction because the grapes are only damaged and release the juice when the press cycle begins. However, as with the crushed grape presses the juice composition changes with each subsequent emphasis and this fraction is often kept separate. Unlike suppressing destroyed grapes, where normally the most free juice is the most valuable, the whole cluster pressing the second fraction is often the most valuable for the balance of phenolic content and the potential for aging.
In Champagne, where the whole-pressed group in shallow press baskets is very common, the tradition of separating the press faction dates back to Dom PÃÆ'Â © rignon with guidelines recorded in 1718 by his biography Canon Godinot. According to PÃÆ' Â © rignon (Godinot), the free run vin de goutte is considered too complicated and lacks itself to make good Champagne and it is sometimes discarded or used for other wines. The first and second pressure (called tailles or cut because the pomace cake is actually cut with a string, chain or paddle to remove it between presses) is the most ideal for the production of sparkling wine. The third pressing juice is quite acceptable but the fourth pressing (called vin de taille ) is rarely used and all other pressures after it (the vins de pressoirs ) are considered too rough and colorful to be of any value in the production of Champagne.
References
Source of the article : Wikipedia
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