- Why wine needs to be filtered
Wine should be colorless and transparent, no suspended solids, no turbidity, no precipitation, but a variety of factors in the production process will bring the above substances to the wine, mainly as follows:
(1) In the distillation and liquor flowing operation, the fermented grains and rice husk residues are accidentally dropped into the liquor receiving container; the koji powder is flying when the koji is scattered; the fermented grains residue and dust are flying when the site is cleaned, and they will also fall into the liquor receiving container.
(2) Dust on the road during the transportation of the wine produced in the workshop to the wine storehouse; unclean wine conveying pipeline; unclean wine storage container; unclean air quality;
Dust and dregs in wine storehouse or poor sanitation of wine storehouse.
(3) With the decrease of alcohol content, the amount of water added to the pulp increases. If the water quality is poor, or sometimes the content of metal salts in the water is too high, the salts gradually precipitate after adding into the wine, resulting in turbidity and precipitation.
(4) The ethyl esters of higher fatty acids will precipitate and cause turbidity.
Therefore, liquor (especially low alcohol liquor) must be filtered before it can be packed out of the factory.
- Main filtration equipment
(1) Sand filter rod filtration
The shell of the filter is a metal closed container, in which there are several to dozens of sand filter rods on a fixed sieve plate. The sand filter rods are made of diatomite or glass or sintered into a rod core with an open end. It can be used for water treatment and liquor filtration. It has been widely used in distilleries since the 1970s. It has a good effect on removing suspended solids and precipitates in wine, but a poor effect on turbidity removal.
Working principle: the raw water (or wine) is pumped into the filter, so that the organic matter and microorganism in the water or the suspended solids and precipitates in the wine are intercepted on the surface of the sand filter rod by the micropores of the sand filter rod, and the water (or wine) enters the rod core and is discharged from the outlet. The general working pressure is 100-200 kPa. The filter needs to be cleaned after being used for a period of time and operated according to its instructions.
(2) Diatomite filter
The commonly used mobile stainless steel filter is composed of chamber shell, hollow shaft, filter plate, filter cloth, spacer ring, clamp, buffer plate, and other components, including horizontal type, vertical type, candle type, etc.
The most popular is the candle diatomite filter with a wedge wire candle filter element.
Working principle: diatomite has the dual functions of the filter medium and filter aid. First, the diatomite filter layer is precoated. After the liquor is clear, it can be formally filtered. Generally, it can filter 20 ~ 50 tons at a time.
(3) Wine purifier
Its core is a purification medium, which is a composite material composed of a variety of adsorbents. Different adsorption materials have different adsorption objects, such as turbidity removal, impurity removal, etc., which have considerable flexibility. The structure of the wine purifier is simple. The absorption tower is made of stainless steel plate. The tower is filled with granular purification medium and can be used. It can be used for a single tower or several towers.
Working principle: adsorption principle, deodorization, and impurity removal of wine to prevent flocculent precipitation. Another feature of the wine purifier is that the contact between the medium and the wine is sufficient and balanced. The wine liquid is forced to pass through the purification medium layer 1 to several meters high by the pressure of the wine pump to complete the effective contact. In order to ensure high efficiency and no dead angle, the adsorption tower of the purifier also adopts multiple technologies such as fluidized bed adsorption and filtration. At present, it is widely used, such as the production of all kinds of finished wine, the same end of the wine, alcohol deodorization and impurity removal, etc.
The wine purifier needs a wedge wire filter element as the first filtration link to carry out the coarse filtration process.
(4) Membrane filtration
The filter cake is made of stainless steel shell and a mixture of high molecular polyethylene by cold pressing sintering. It is characterized by abundant micropores and tiny intermittence. The minimum number of solid particles that can be intercepted is 0.4 μ m, and the filtration effect can reach 100%.
Working principle: using molecular sieve principle, using permeability in the physical phenomenon, that is, when solution passes through a microporous medium
The larger solute molecules in the solution are blocked on the surface of the membrane, and the smaller solute and solvent molecules penetrate through the membrane, so as to play the role of separation and purification. In this way, the higher alcohols and esters in the wine, as well as the large particle solids and impurities in the wine are blocked on the surface of the filter, which has the effect of removing impurities and purifying the wine.