With the development of feed industry in China, the yield of feed is increasing year by year, and the variety, performance and yield of feed machinery are constantly increasing, which increases the development of feed industry. Due to a variety of domestic system of feed production enterprise, the basic no study of premixed feed technology, management, caused by mechanical equipment for the process design of the core is generally, namely in the technology management link is missing "mixed process management" is an important link. Therefore, physical and chemical reactions occur between the materials, the nutrients are destroyed, the quality of the feed decreases, and the cost increases. Now this phenomenon in industry management and feed production enterprise no attention, at least in the school related future managers did not inform students stage in the course of feed enterprises manufacturing process should include "premixed process" and "granulating process", "big raw material preparation" three parts. The granulating process under the influence of mechanical equipment is large, the specialization of equipment and material properties and processing research is more is more in-depth, more professional literature focus on research and application of the equipment. Many feed enterprises are based on the design concept of feed equipment manufacturers. For example, "dry mixing first, then wet mixing", which leads to the inconveniences of feed production; The designer and quality manager of the feed products are out of touch with the product quality management. The production process that the production department of an enterprise usually decides by itself; However, the pharmaceutical and food industry which is adjacent to us has always had strict production process system.
1 what is "technology"
Technology is a combination of equipment and technology. Improve the quality of the product while improving the process level, and improve the rationality and utilization of the equipment.
When the "nutrition formula" is converted to "production formula", the real executable is the "process plan". Therefore, it is often said that feed enterprises should have: "reasonable formulation, good raw materials, scientific technology, high-quality service".
2. Purpose of process
The purpose of the process can be as follows:
The effectiveness of the formula is maintained, and the positive combination effect of various nutrients and additives is played to improve the efficiency of the product in the shelf life.
It is necessary to eliminate and avoid incompatible materials, protect the materials that are vulnerable to loss, and hide the materials that are prone to damage, and prevent the occurrence of feed oxidation.
The influence of the raw materials on impurities and harmful substances is not conducive to the quality of the products.
In order to improve the quality of "secondary" products caused by the process of feed processing.
The specification, chemical form and physical character of the additive are selected rationally, and the appropriate equipment is selected to improve the rationality of equipment and process control.
Key technical problems of pre-mixing process.
In the process of feed processing, first of all, the materials should be treated as chemicals rather than nutrients!
Maximize the "mask" (we call physical means "shielding", the chemical method called "masking") metal trace elements (inorganic), to prevent the direct or indirect damage. Feed is the least "specification" hybrid product, in the pharmaceutical industry and food industry will be carefully deal with metal trace elements that exist in a product, and through various technical means to prevent its negative effects, utmost ground protects the high cost of nutrients, biological activity and additives, maintain or don't reduce the titer of the products. Reasonable application of organic trace elements (compound premix and single additive) can at least on the mixing process from pretreatment, adding sequence, the complexity of the process control, the stabilization of metal trace elements in advance can greatly reduce the destruction of other nutrients in feed, effectively improve the quality of the product.
Premixed process: the main technical issues in REDOX reaction, the dissolution, emulsification, carrier, oxidation technology, the quality of the color problem, evenness, energy consumption and efficiency, equipment not compatibility, etc.
In addition to the above mentioned points, the technology of fat addition and the addition of liquid raw materials are also the key technical problems in the pre-mixing process.
4. Several basic technical problems of pre-mixing process.
4.1 oxidation reduction reaction.
4.4.1 REDOX reaction are the most common chemical reaction occurs in the feed, because can avoid and reduce the influence of illumination and temperature, so the metal trace elements of REDOX reaction achievements seem more important. Under alkaline conditions, Fe2+ and Mn2+ can spontaneously oxidize to high price and then oxidize other nutrients. I- and SeO32- can directly react to the generation of I2, and can react with other nutrients, which directly cause the failure and destruction of nutrients.
4.1.2 metal trace elements is extremely fast catalytic oxidation of fat, lipid peroxide can be generated oxidative damage nutrients (fats), vitamins, carotenoids and has biological activity of additives, enzymes, probiotics (medicine).
4.1.3 the sulfite in vitamin K3 can decompose the vitamin B1, so that the vitamin B2 reduction fails; Vitamin C can reduce vitamin B12 reduction.
4.1.4 feed and environment H2O, CO2, fat, lipid, natural vitamin E(tocopherol) and heme can accelerate the oxidation reduction reaction.
4.2 solvation of water and fat-soluble substances.
4.2.1 the increase of water is the basis of chemical reaction enhancement. The distribution of water in the feed is not uniform, and some "water" is distributed in the cell and the compound crystals. Some "moisture" is distributed on the surface of the material; Some of the "water" is latent, the water that is "released" by chemical reactions. We usually refer to the moisture content of the feed product as "dry weight loss", which is the average calculated amount, which does not represent the activity of water (transferable water). Even when the moisture content reaches the standard material, in the mixing, can have the solvent effect, causes the reaction to occur. At least the moisture on the surface of the material (relative to the air relative humidity) can support the chemical reaction, and the water produced by the reaction speeds up the reaction.
4.2.2 fat-soluble substances in feed: fats and lipids also have the function of "organic solvents", at least in favor of organic chemical reactions. Some materials with surfactants (choline chloride, betaine, phosphatide) increase the emulsification of the system. Protein materials are the most widely used emulsifiers in the world, and the emulsifying effect strengthens and expands the "solvation" of water and fat.
4.2.3 because of the principle of "surface chemistry", any change in the surface free energy of any feed material is conducive to the development of a biochemical reaction in the case of "low solvation".
4.2.4 moisture and fat-soluble substances "solvent" effect also had a positive effect, such as antioxidant effect, enhances the seasoning has increased, the effect of some additives on the gas phase diffusion (mould) diffusion way has increased.
4.2.5 powdered feed raw materials, because of larger than surface area, easily absorb moisture in the air, and the surface is wet, which is called hygroscopic property. The relative humidity of moisture absorption is called "critical relative humidity" (CRH), which refers to the relative humidity of a large amount of moisture absorption. The general materials absorb less moisture when relative humidity is less than "critical relative humidity", and vice versa. The larger the CRH value of the material is, the less it is likely to absorb moisture, and vice versa. The relative humidity of the production environment in the vast area of south China is very large, because the process of crushing and mixing increases the moisture absorption of the material, and the moisture absorption material also produces various chemical reactions.
4.3 uniformity problem.
The mixed materials are mostly "powders". From the perspective of physical pharmacology, "powder" belongs to the solid - gas dispersion system. The dispersed phase is a solid, and the dispersed medium is a gas, mainly air. In design of solid material mixing process and other process, not only to guarantee the quality of products, from the aspects of chemical processes should also master the basic properties of powder and in the nature of the show, at least need to know about powder particle size, shape and particle size distribution, surface characteristics, liquidity, compressibility, filling, porosity, hygroscopic, electrical, force between particles, density, etc., in the process of product transportation, storage and should understand some basic properties of the powder, these properties to improve the quality of products and product uniformity are important.
4.3.1 in simple terms, the homogeneous degree of the feed to be reasonable, the homogeneous degree of the whole, is conducive to improve the quality of feed products, partial evenness increased, to all sorts of chemical reaction (or even physical reaction: electrostatic enhancement).
4.3.2 many feed enterprises "according to the requirements" multi-stage premix, the first several premix are the performance and efficiency of various small pre-mixing equipment.
4.3.3 the drug additive should not only consider the uniformity of the preparation, but also consider the uniformity of the application and the stability of the preparation.
4.3.4 has biological activity of enzymes, small peptide additive, probiotics more to consider the stability of the "uniform distribution in the feed, usually think they add less on it is wrong of premix. The additive is unstable because of high concentrations of chemicals.
4.4 discoloration
4.4.1 premix discoloration is a very common problem, mostly due to the impurities and moisture on the high side feed additives, carrier or ingredients in the carbonate on the high side, alkaline materials caused by the improper use or add.
4.4.2 of copper sulfate crystallization water with five more copper sulfate is given priority to, because the crystal of copper sulphate pentahydrate free water surface will be exist, there are often laboratory personnel in the process of testing, to weigh the copper sulphate samples "waiting for" the volatilization of the free water in order to balance the reading "stable", so that the result of the operation of copper content is easy to "qualified", and free water is not removed during production, can promote the dissolution and produces a series of reaction and make the material change color.
4.4.3 feed grade ferrous sulfate, is produced by ti * * * more scraps, without direct drying "purification" techniques, including the basis of residual oxygen titanium sulfate as the discoloration, Fe3 + in feed premix color change is the main factor.
4.4.4 feed grade of the preparation of zinc sulfate is according to the chemical industry standards, in order to remove the iron to make products more "beautiful", generally used hydrogen peroxide in addition to iron process, because of the addition of hydrogen peroxide is excessive, the end product of residual hydrogen peroxide, on the one hand, has brought the feed system strong oxidant, on the other hand, hydrogen peroxide and oxygen titanium sulfate reaction produces non-ferrous material.
Several years ago to use potassium iodide as a source of iodine 4.4.5 (now mostly use calcium iodate or potassium iodate, there are still a few companies in the use of potassium iodide) at the same time, the use of sodium selenite selenium source, ingredients and thought "homologous" premix directly, both the two REDOX reaction (iodine in potassium iodide ion can react and Fe3 +, Cu2 +). The resulting I2 sublimation and halogenated reaction can be seen directly, and the "red selenium" formed by the reduction of selenium is directly visible. In addition, due to the improper addition of raw sugar, the reaction with sodium selenite will also be reduced. It also brings the market to organic selenium.
4.4.6 carrier of trace element premix improper selection is a major cause of the premix discoloration, someone with calcium carbonate or containing carbonate "zeolite powder as the carrier," "show acidic sulfate and carbonate reaction, Fe2 + and Mn2 + in alkaline oxidation under the condition of present yellow or brown, the generated water acceleration response.
4.5 carrier problem
4.5.1 some people have been interested in discussing the problem of "carrier" and "diluent" (dispersant). In fact, the application of "carrying" method is very common in additive production. Material in the form of liquid adhesive on the surface of the "carrier" or internal, or in the form of physical and chemical adsorption on the "carrier", after drying of material with solid or semisolid carrier exists in the distribution proportion. In feed premix (material) production, and the enrichment of material, the production process of compound feed, due to the added fat, vitamins and enzymes after application of spraying process, feed ingredients and feed itself in the "identity" of the carrier, so you can think of feed premix technology used in the carrier, is actually a dispersing agent, diluent, the effect of anticaking agent.
4.5.2 of raw materials in the premixing process is often each other between "carrier", this increases the reactivity between raw materials, use less "carrier" of the matter and to consider the chemical stability, bulk density (density), color, ash content, cost factors, many people are concerned about the "water" of the carrier and the carrier of oxidizing, the principle of the selection of carrier: Portland, starch, low fat, high fiber, amino acids and other additives.
4.5.3 the premix (material) carrier used by the enterprise shall be dominated by the stability of the product, and the factors of product density, cost and color shall be neglected. In a variety of application object of premix (material) as an example, the proposal USES zeolite powder, powder "standard time" (don't type protein high bran powder), dicalcium phosphate, silica, talcum powder, amino acid as a "carrier".
4.5.4 the carrier of the premix (material) of external sales and self-use shall, under the premise of product quality stability, consider the commodity factors such as the application object, cost, bulk density and color, etc.; It is suggested to use zeolite powder with starch, rice husk powder, corn kernel powder, bean skin powder, and the whole grain corn and wheat. Do not recommend using defatted rice bran, corn germ meal, rice bran, fish meal etc to oxidation of high fat content (former) material carrier, do not recommend use strong alkaline calcium carbonate, "" high carbonate zeolite powder, strong adsorption with ion exchange properties of bentonite for carrier.
4.5.5 pretreatment of the carrier: the production enterprises often select and preprocess the carrier for the particle size, moisture, color, and "adsorption capacity" of the carrier. The particle size selection should be close to the particle size of the main raw material, and the reason is that the particle size of organic carrier is larger than that of inorganic carrier. Due to the mill feed companies use is not suitable for the "processing" of the carrier, users are generally require suppliers again fine some, smashing organic carrier and inorganic carrier does not require the supplier to product do thick some, then some of the main raw material granularity fine makes sense.
Due to the variety of mineral carrier, geological reasons, iron content, chemical structure and oxidation degree can lead to the outside of each batch of raw material have differences, can be directly mixing different batches of the carrier to ensure consistent color.
The bulk density difference of silica gel carrier (white carbon black) is very large (160 -- 250g/L). The amount of iron that is obtained by crushing method is also increasing, which will affect the quality of the product and will not decrease. The weight and granularity should be compatible when choosing.
Water is a problem that is often paid attention to, and the method of trying to dry is not worth promoting. Organic carriers such as rice husk powder (chaff) are used to dry, which both consume thermal energy and cause fat oxidation. The better way is to test the relationship between water and quality, or to measure the water activity of the carrier, and to analyze the influence degree of water, and do not have "water phobia". The "adsorption capacity" of the carrier does not need to be considered unless it is to take advantage of the chemical and physical chemistry of the adsorption principle to carry the material at the sub-level.
4.6 energy consumption, efficiency and non-compatibility of equipment.
4.6.1 feed enterprises directly used for "hybrid" process itself of equipment, energy consumption is acceptable, but companies often look forward through the "primary" mixer disposable efficiency (artificial, power consumption per unit of time). Most of the process design of material physical properties, basic does not consider mixing process of chemical reactions can occur, in improving the mechanization and automation processing ability and ignore the quality problem. On this basis, the company will feel that the processing cost is rising, the efficiency is declining, at least "troublesome", and even the production department is unwilling to accept the "science".