Enzyme preparations have been widely used in various fields of the feed industry. With the rapid growth of global feed production, various energy raw materials are relatively tight, and the use of enzyme preparations not only saves energy, but also reduces the use of feed additives that pollute the environment. However, at present, there are still many problems in the application of enzyme preparations, especially the stability of solid enzyme preparations under high temperature and high humidity conditions, which restricts the use of enzyme preparations.
At present, feed companies widely use the technology of spraying liquid enzyme preparation on the surface of pellets after feed granulation to avoid the destruction of enzyme protein and loss of biological function. However, in practical applications, there are many factors that affect the spraying effect of the enzyme preparation. This article describes several factors and solutions for the effect of spraying the liquid enzyme preparation.
1 Several factors spraying effect of liquid enzyme preparations
1.1 The impact of pellet feed
The diameter of the feed pellets, the smoothness of the surface, etc. can all affect the post-spraying effect. The smaller the diameter of the feed pellet, the larger the specific surface area, which is conducive to the adsorption of liquid; the smoother the surface of the pellet, the more unfavorable the penetration of liquid, but the smoothness of the surface can reduce the generation of dust; the pelletized feed of expanded processing, the internal volume expansion of the pellet The increase of the void fraction is very beneficial to improve the absorption capacity of the pellet feed for liquid.
1.2 The impact of liquid enzyme preparations
The storage conditions, biological characteristics, addition ratio, precipitation, etc. of the liquid enzyme preparation can affect the effect of post-spraying.
1.2.1 Preservation of liquid enzymes
The preservation of liquid enzyme directly affects its own quality. Experimental studies have shown that the retention rate of enzyme activity is high at low temperature storage (4 ° C), but the temperature of -20 ° C will cause crystallization of enzymes, enzymes, etc., even liquids. Icing; when the temperature exceeds 25 ° C, the shelf life becomes shorter. When the temperature exceeds 40 ° C, the loss of activity for one month will exceed 10%; direct sunlight will also cause the activity of liquid enzyme preparation to decrease.
1.2.2 Biological characteristics of liquid enzymes
Different liquid enzyme preparations, such as liquid phytase, liquid xylanase, liquid cellulase, liquid mannanase, liquid galactosidase, liquid complex enzyme, etc., the genetic source and enzymatic properties of the enzyme itself, Fermentation processes, etc. are all very different, so the pH, stabilizers, preservatives, etc. used in the liquid enzyme preservation process are also different, especially the compound liquid compound enzyme products, the stability is particularly important, so the use is different. Enzyme preparations, especially enzyme preparations produced by different manufacturers, should pay attention to the preservation conditions and the stability of the compounding, so as to avoid the decrease of the titer and deterioration of the liquid enzyme preparation.
1.2.3 liquid enzyme addition ratio
In the actual production process, the proportion of liquid enzyme preparation is generally 100-200mL per ton of compound feed. Too much addition will cause the feed particles to agglomerate, too little will result in uneven spraying, affecting the effect of enzyme preparation.
1.2.4 flocculating of liquid enzymes
Liquid enzyme preparations may have soluble flocculent precipitates due to different processing techniques, which may affect the appearance of the enzyme preparations, and may block the pipes and nozzles of the spray equipment. Therefore, filtration is required to avoid nozzle clogging and affect the spraying effect. .
1.3 The impact of post-spray equipment
1.3.1 The different pressure sources of liquid spray, different atomization methods of the nozzle, spray pressure and nozzle design can affect the effect of post-spraying.
The liquid spray pressure has a certain influence on the uniformity of the spray of the pellet feed. When the spraying pressure is small, the droplet atomization is not good, making the spraying uneven. As the spray pressure increases, the uniformity between the particles also increases; when the spray pressure is too high, the droplet atomization should be good, but because the nozzle is fixed in position, the flow velocity of the droplet is high, and the ability to penetrate the material is strong. When it is not fully atomized, it is sprayed on the wall of the vacuum mixing chamber, resulting in uneven spraying.
1.3.2 Liquid atomization effect
The effect of liquid atomization is directly related to the structure, number and installation position of the nozzle. The appropriate nozzle structure should be selected according to the movement state of the pellet feed inside the mixer. Studies have found that reducing the nozzle aperture can improve spray uniformity.
1.3.3 Location of the enzyme storage tank placement
Some manufacturers put the enzyme storage tank on the same floor as the nozzle. This needs to consider the temperature problem; some manufacturers are placed in the central control room. This needs to consider the insulation measures and anti-rat measures between the central control room and the nozzle.
2 methods to improve the application of liquid enzyme preparations
2.1 Improve the physical quality of liquid enzyme preparations through advanced equipment
Ultrafiltration and microfiltration are advanced membrane separation technologies developed by materials science. In recent years, ultrafiltration and microfiltration manufacturing technologies and application technologies have rapidly developed and matured, and are increasingly being applied to feed enzyme preparations. Production area.
Both ultrafiltration and microfiltration utilize the intercepting ability of porous materials to remove a certain amount of impurity particles in water by physical retention. Under pressure, the small water, organic low molecular weight, inorganic ions and other substances in the solution can reach the other side of the membrane through the micropores in the fiber wall, and the large size such as bacteria, colloids, particulate matter and organic macromolecules in the solution. The substance cannot be trapped through the fiber wall to achieve the purpose of sieving the different components of the solution. The process is normal temperature operation, no phase change, no secondary pollution.
In the actual production of liquid enzyme preparations, the microfiltration equipment is used for further sterilization and purification, and the ultrafiltration equipment is used for further concentration and enzyme activity enhancement, and the concentrated liquid enzyme preparation is diluted accordingly, and then added with a protective agent. The transparency, stability, and viscosity of the liquid enzyme preparation.
2.2 Improve the stability of liquid enzyme preparations by adding stabilizers
The addition of a stabilizer to improve the stability of the enzyme preparation is a convenient, economical and effective method, and is effective for a wide variety of enzymes of the existing variety. Stabilizers mainly include 10 kinds of substances such as preservatives, polyhydroxy compounds, edible gums, salts and amino acids. According to its stabilizing effect, there are the following major types of substances:
2.2.1 Preservatives and Protease Inhibitors
In enzyme engineering operations, the enzyme is extracellular, the protein concentration is much lower than in the cell, and is in an oxidative environment. Cell disruption causes cell rupture, especially lysosomal rupture releases a large amount of protease and acidifies the solution. The hydrolysis reaction takes place under the influence of the protease. In order to prevent this, a protease inhibitor may be added or the pH, ionic strength or polarity of the extract may be adjusted to protect the enzyme coexisting by inhibiting the activity of the protease. Some cosolvents such as glycerol, sugar, PEG, etc. can also effectively reduce the hydrolysis of proteases.
During the production, preparation and application of the enzyme, the hybrid protein coexisting with it provides good nutrient conditions for the growth of microorganisms, which may cause the bacteria to grow in large quantities and destroy the enzyme molecules. The addition of a preservative can inhibit the growth of microorganisms and stabilize the enzyme. Sodium benzoate, potassium sorbate, parabens and the like are commonly used preservatives. The effects of the first two types of acid preservatives on the pH are greatly related to the pH, and it is advantageous to appropriately lower the pH.
2.2.2 buffer solution
Extreme pH is an important cause of molecular instability of the enzyme. Since the enzyme protein is in a neutral environment in the cell, a pH 6-8 buffer solution can effectively prevent pH changes. Most enzyme molecules remain relatively stable over a wide pH (pH 5-9 or greater). Which range of buffers to use in practice can be determined based on the pH stability of the particular enzyme.
2.2.3 co-solvent
Sugars, polyols, amino acids and derivatives thereof, inorganic salts, glycerin, polymers such as polyethylene glycol, etc. are generally referred to as protein cosolvents. A high concentration of co-solvent stabilizes the protein, and the synergistic effect of enhancing the protein stability when the co-solvent is mixed is much greater than the sum of the single stabilizing abilities.
2.3 Improve the storage environment to ensure the quality of liquid enzymes
The storage of liquid enzyme preparations should be maintained at an appropriate temperature to ensure protection from light and ventilation. The feed mill should set up a special liquid enzyme preparation storage room, pay attention to antifreeze in winter and high temperature in summer.
2.4 The details that should be paid attention to during the use of
2.4.1 Purchasing liquid enzyme preparations should be used in small quantities, first-in-first-out when used, and used up as soon as possible within 1~2 days after opening. For example, if using vat (200L) liquid enzyme preparation products, the extractor should be kept clean and avoid bacteria. .
2.4.2 Maintenance of post-spraying equipment: Regularly check the nozzles and pipelines to prevent clogging; timely replace the corroded filter screen; timely remove the sediment or impurities at the bottom of the tank; and regularly check the gauge.
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