Beer filtration

Abstract: with the increasingly fierce competition in beer market and people's higher and higher requirements for beer quality, beer filtration technology has developed rapidly, and a variety of new filtration technologies have been applied to the actual production. In this paper, the current beer filtration technology used in breweries is reviewed and the prospect of domestic beer filtration technology is prospected.

After a period of low temperature storage, most of the cold turbid substances and yeast cells have been precipitated and separated, but a small amount of substances are still suspended in the wine. In order to prevent yeast cells and other turbid substances from separating from beer during the "minimum shelf life", further filtration is necessary before packaging. With the increasingly fierce competition in the beer market and people's higher and higher requirements for beer quality, breweries try to reduce costs and improve beer quality, of which the filtering treatment of beer is the key

The purpose of domestic technical status beer filtration mainly includes the following three points:

(1) remove the suspended matter in the wine, improve the beer appearance, make the beer clear, transparent and lustrous;

(2) remove or reduce the substances, such as polyphenols and proteins, which make beer appear turbid and precipitated, so as to improve the colloidal stability of beer;

(3) remove yeast or bacteria and improve the biological stability of beer

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Beer filtration can be divided into filtration clarification, abiotic stability treatment and biological stability treatment. In terms of beer filtration and clarification, at present, centrifugation, diatomite filtration and cardboard filtration are widely used in China. The main equipment used are centrifuge, diatomite filter (divided into plate and frame diatomite filter, candle type diatomite filter, horizontal disc type diatomite filter), plate filter, etc. In the aspect of abiotic stability treatment, adding PVPP, silica gel, tannin and protease to beer is widely used. In terms of biological stability treatment, pasteurization is mainly used for sterilization, while aseptic filtration has aseptic membrane filtration technology.

1. Centrifugal separation

Because the viscosity of beer fermentation liquid is high, the particle diameter is very small, and the natural sedimentation rate is very slow, the separation rate is greatly improved by using centrifuge instead of natural sedimentation. Centrifuges are generally not used alone, but are mostly used in combination with diatomite filtration. When there are too many turbid particles in the fermentation liquid, the centrifuge is used for pre clarification, and then the diatomite filter is used for filtration. However, the following problems exist in centrifuge pre clarification:

(1) because of the friction between high speed rotating and air, the temperature of the beer that has cooled has been heated up. The foam caused by the leakage of carbon dioxide makes it difficult to filter the next step.

(2) in the process of clarification, a certain amount of oxygen will be mixed in the beer, which will affect the beer quality; (3) when the centrifuge is running at high speed, the noise is large and the maintenance cost is high.

2. Diatomite filtration

Diatomite filtration is the most widely used filtration method in breweries. Diatomite is the remains of marine unicellular algae, and the mineral resources of diatomite in China rank the first in the world. The main component of diatomite is amorphous silicon oxide. At present, diatomite or the mixture of diatomite and quartz sand is the most used filter aid in the primary filtration of beer. A clear beer can be obtained by diatomite filtration. The turbidity is lower than 0.6ebc, and the microbial content is very low. The advantages of diatomite filtration method are as follows: continuous renewal of filter bed; fast filtration speed and large output; large surface area and strong adsorption capacity, which can filter particles below 0.1-1.0 μ m; reduction of alcohol loss by about 1.4%, and improvement of production and operation conditions

However, in 2000, Wang Shuqing proposed that Fe2 + is contained in diatomite. When the beer with acid is filtered by diatomite, Fe2 + will inevitably dissolve in the beer. It can catalyze the oxygen in beer to become hydrogen peroxide rapidly, and cause the oxidation-reduction reaction of some substances in beer to cause the deterioration of beer quality. Therefore, he suggested that diatomite added with iron removal agent should be used as filter aid in beer production.

In addition, there are many other problems in the wide use of diatomite:

(1) when operating diatomite filter for filtration, the labor intensity is high, and diatomite dust is harmful to workers' health;

(2) as a kind of mineral resources, diatomite will be short of resources, which will inevitably lead to cost increase.

(3) diatomite can not be recycled, and the waste diatomite has caused serious environmental pollution

In view of the above problems, it is imperative to find a new process to improve the existing diatomite filtration process in breweries. Now we briefly introduce two methods to improve this process.

(1) recycling of diatomite.

This method is to use hydrocyclone to recycle diatomite. The experimental data show that the recovery of diatomite by this method has a good particle size, and the removal rate of yeast and protein can reach 70% after the first stage washing, which is expected to meet the requirements of industrial application after the third to fourth stage washing. The biggest advantage of this method is less investment and convenient equipment maintenance. If it is successful in industrial production, it will have a profound impact on the recycling of diatomite, reducing the production cost of beer and reducing pollution

(2) perlite, the substitute of diatomite, is a dense glassy rock formed by volcanism. After processing, the white powder product can be used for filtration. It is a new type of filter aid material because of its loose and small density, fast filtration speed and good clarity. Through the comparative test of perlite filtration technology and diatomite filtration technology, it is found that perlite filtration beer has high efficiency, good quality, decreased beer color, made liquor more lustrous, no impact on liquor itself, easy operation and cost saving. In addition, if perlite filter aid and diatomite filter aid are combined for filtration, the soil consumption is obviously reduced and the economic cost is better. However, in the research of Li Haoming and Wang Ruifu, the source and waste pollution of perlite are not mentioned, so there are still some problems whether perlite can be used in actual production

Crossover, which was introduced by BASF company in Germany, is a typical new technology for replacing diatomite filtration and unlimited recycling. The filtration additive of crossover has a granular structure similar to diatomite, which can be used in current filters. The granular material consists of two polymers, polystyrene and PVPP. The new composite materials have high mechanical and chemical stability. On the one hand, the new filter aid can remove the turbid particles in beer, on the other hand, because it contains PVPP, it can absorb the tannins and other polyphenols which lead to the turbid beer. The results show that the clarity, stability and taste color of the beer filtered by this method are equal to the quality of the beer filtered by diatomite + PVPP, and the beer has better polyphenol stability. If it can be widely used in China, the shortage and pollution of diatomite resources can be fundamentally solved.

(3) abiotic stability treatment

In the commercial storage of canned clear and transparent beer, due to the reaction of protein and polyphenol, turbid substance may be produced, which will make the beer lose its original luster and gradually form precipitation. Tannins or protease can be used to solve the problem. However, the small amount of tannin is not enough to affect the filtration performance of beer. A large amount will damage the foam of beer, and may also produce astringency. In addition, if the protease is added, even if the normal amount is added, it will also reduce the foam of beer. The large amount of addition may cause the spewing of beer. In addition, bentonite and silica gel can also be used, but these methods have changed the taste and foam quality of beer protein to a certain extent.

At present, PVPP is a better material. It can adsorb polyphenols such as tannin, and it will not have adverse effects on beer. According to the test, the adsorption capacity of PVPP can reach 80% ~ 90% of the saturation state in 4 ~ 5 minutes, which can be used directly in beer filtration. After treatment, the PVPP filter cake can be regenerated by NaOH solution, and the filtration effect of regenerated PVPP is not different from that of new PVPP.