Certain wines rapidly release their suspended matter (yeast cells, particles from skins and skins, etc.), and the resulting wine is stunning. This is especially so when 50-gallon wooden barrels are used, as they have a more excellent volume-to-surface ratio than larger bottles and are used. Its rough exterior of the wooden cooperage aids in the settling of suspended matter. Other wines, particularly those in warmer regions or when tanks of large size are utilized, can remain slightly cloudy over a long time. The removal of suspended matter from the wine during aging is referred to as clarification. The main steps involved include fining the process, filtration, centrifugation, Ion exchange, refrigeration, and heating.
Fining
Fining is a traditional method in which a substance that helps clarify the wine is added to the wine. The principal techniques involved are adsorption, chemical reactions, adsorption, and possible physical movement. The yeast cells and proteins are adsorbed onto fining agents like bentonite (a type of clay made mostly from montmorillonite) or gelatin. The adsorption of suspended substances can accompany chemical reactions with gelatin and tannins. If an inert component like silica adds silica to cloudy wine, there will be some clarity due to the movement of particles of inert silica around the wine. This process will likely occur when an addition to any fining agents.
Bentonite is mainly replacing the other fining agents. These fining agents include gelatin, casein, isinglass egg white, albumin, nylon, and PVPP (polyvinyl pyrrolidone), which can be utilized for specific purposes, such as removing excess tannin or color.
Metals in excess, including copper and iron, are often present in wine, mainly because of contact with iron or other metal surfaces. They cause persistent cloudiness, which must be removed with particular fining substances such as potassium ferrocyanide (blue fining), widely recommended in Germany. Cufex is a brand-new product containing potassium ferrocyanide and can be utilized throughout the United States under strict supervision. The phytates are used for eliminating iron. In modern winery operations, excessive metal content is not a problem due to using stainless steel equipment.
Filtration
Filtration is a second practice that dates back to the past that was used in the past, and early filters consisted of rough cloth-covered screens over which wine was poured. The modern filter pad comprises cellulose fibers with various porosities or membrane filters available with different porosities. The pore size of a few filters is sufficient to eliminate yeast cells and most bacterial cells. However, filters function not just because of the size of their pores but also due to the amount of adsorptive. Diatomaceous earth-filter aids commonly added to wine in filtration extend the filters’ lifespan by slowing the process of clogging a pore.
Centrifugation
High-speed spinning, also known as centrifugation, utilized to clarify musts, can also be used to describe wines that are hard to make clear with other methods. This procedure requires careful oversight to prevent excessive oxidation or loss of alcohol in the process.
Refrigeration
Refrigeration helps wine clarification in a variety of ways. The reduction in temperature often hinders yeast growth and the formation of carbon dioxide. This is known to keep yeast cells in suspension. Carbon dioxide becomes more soluble when it’s at lower temperatures. One of the leading causes of cloudiness comes from the gradual formation of potassium tartrate (cream of tartar) as wine ages. Rapid precipitation can be caused by decreasing the temperature from 7 to -5 degrees Celsius (19 between 23 and 22 degF) for up to two weeks. If the wine that results is filtered out of the tartrate deposits, it will not typically result in clouding until later.
Exchange on Ion
Another method for stabilizing tartrate is to put a bit of the wine via a machine known as an Ion Exchanger. If the ion exchanger is loaded with sodium and potassium, it replaces the potassium content of potassium acid tartrate with sodium, resulting in an easier tartrate. If the potassium content in the mix of treated or untreated wines is reduced to 500 milligrams/liter, there will be no precipitation. There are exceptions, however, and to ensure safety, the levels of potassium and tartrate, as well as pH, are considered as part of the calculations. Ion exchange is prohibited in several countries.
Heating
Many wines have small amounts of proteins which could cause clouding through precipitation or reaction with other metals or copper to create aggregates which then form clouds. Bentonite is a method of removing some proteins, and it is more effective in absorbing proteins when the wine is heated after being fined. Pasteurization at 70-82 DegC (158 to 180 degrees F) can also remove proteins; however, this procedure is rarely used for clarification in contemporary practice.
The cap of pulp and skins floating over the red wine fermentation hinders flavor and color extraction, can reach unfavorably high temperatures, and could cause acetification if left to dry. These issues can be avoided by submerging your cap in water at least twice daily during fermentation. This process, which is relatively simple for small fermenters, is complex in big, tall fermenters with upwards of 100,000-gallon (380,000-litre) capacity. In larger units, the fermentation must be drained off at the bottom before being pumped back into the cap. Utilizing small vessels for fermentation allows more heat loss to the air, facilitating temperature control.
