Factors affecting the stability of vitamin premix and protective measures
In the production of modern compound feed, the application of compound premix greatly simplifies the production process, saves a lot of equipment investment, and plays an important role in balancing the nutrition of livestock and poultry compound feed, so it is widely used. The premix provides many kinds of nutrients, and the technical content in the formula and production process is high, and the components contained generally account for 1% to 5% of the total price of the material. The premix generally contains vitamins, minerals, etc. Among them, vitamins participate in almost all metabolic reactions in the form of coenzymes and catalysts in animals, and have irreplaceable functions in maintaining cell function and the activity of various enzymes and regulating the metabolism of the three major substances. However, vitamin is the most unstable component in premix because it is rich in unsaturated carbon atoms, double bonds, hydroxyl and other structural parts that are extremely sensitive to chemical reactions, and is easily oxidized and reduced, which reduces its activity or even loses it completely. After the loss of vitamin activity, the nutritional value of the full-price feed will be reduced, which will affect the growth performance of livestock and poultry, and cause some nutritional deficiencies. Therefore, the stabilization of vitamin activity in premixes has a major impact on feed quality, animal growth and health, and it is crucial to maintain its stability during storage and processing.
1 The main factors affecting the stability of vitamin premix
Moisture is considered to be the primary factor affecting the stability of vitamins. In the process of processing and storage, too high ambient humidity or too high water content in the carrier and raw materials will destroy the stability of vitamins. This is because high moisture will cause the matrix of vitamin particles to soften, and the permeability of oxygen on the surface of the matrix will increase, which will accelerate the oxidative denaturation of vitamins and the destruction of vitamins by choline chloride, trace elements and other chemical reactions. According to reports, VB1, VB2, niacin, VE, VC, etc. will still have a high retention rate after 1 year of storage under low moisture conditions; and after 21 days of storage under high moisture conditions, VB1 is only 48% left, and VC is almost All losses, after 3 months of storage, the VB2 content is less than 50%. In order to maintain good stability of vitamins, the moisture content of the premix should not exceed 7%.
The higher the temperature, the greater the loss of the vitamin premix. Studies have shown that when the temperature is lower than 10 °C, the loss of vitamins is less; when the temperature is 15 to 25 °C (room temperature), some of the less stable vitamins will be lost; when the temperature is higher than 30 °C, most vitamins will be destroyed. This is because the vitamin has a low melting point and is easily affected by high temperature, and high temperature can provide energy for redox reactions and accelerate the destruction of vitamins. High temperature will also cause the sulfate in the premix to lose part of the crystal water and increase the water content of the premix, especially the high temperature and high humidity are particularly serious for the loss of vitamins. Studies have shown that when VA is stored under different conditions for 3 months, the retention rate is 88% under low temperature and low humidity conditions, 86% under high temperature and low humidity conditions, and only 2% under high temperature and high humidity conditions.
Therefore, the storage of vitamin premix under high temperature and high humidity conditions must be avoided.
1.3 Trace elements and minerals Trace elements
In particular, copper, iron and zinc have a strong destructive effect on the stability of vitamins, because the redox reaction caused by trace elements can seriously affect the stability of vitamins. It has been reported that in the presence of trace elements Mn2 +, Cu2 +, Zn2 +, and Fe2 +, the vitamin premix will lose more than 80% of VK, more than 40% of folic acid, and more than 20% of VB6 after storage for 3 months. . In particular, its sulfates such as ferrous sulfate, zinc sulfate, copper sulfate, etc. are easy to absorb moisture, have high solubility in water, and are easily ionized by charged ions, which are far more destructive to vitamins than carbonates and oxides. The utilization rate of and oxides is low, and the price of sulfate is cheap, so the widespread use of sulfate in production is also a double-edged sword. Therefore, premix manufacturers will separate vitamins from trace elements and minerals, and process them into vitamin premixes and mineral premixes to ensure the stability of vitamins.
1.4 Carriers and Diluents
Both the carrier and the pH of the premix affect the potency of the vitamin.
1.5 Feed processing methods
The production process of compound feed includes mixing, pelleting and cooling, etc. The temperature, friction, pressure, time, etc. during the production process will affect the stability of vitamins. Studies have shown that VA, VD3, VK3, VB1 and VC have the worst stability in pelleted feeds. The powder and pellet feed were stored under the same conditions for 3 months, and it was found that the retention rate of VA of the powder feed in the low temperature environment was 50%, but the retention rate in the high temperature environment was 39%; The retention rate of VA in a low temperature environment is 65%, but the retention rate in a high temperature environment is 20%. This shows that the vitamins in the pellet feed are resistant to low temperature, while the vitamins in the powder feed are resistant to high temperature.
1.6 Other factors
Choline chloride has strong water absorption and alkalinity, and has a destructive effect on other vitamins. This effect is more intense in synergy with trace elements. Among them, VK, VB1, VB6, pantothenic acid and biotin are very sensitive to choline chloride. . There are anti-vitamin factors in some feeds, such as lipoxygenase in raw soybean meal can indirectly destroy VA and carotene, and flaxseed has anti-VB6 factor. Some drugs can also affect the stability of certain vitamins, such as amproline anti-VB1, sulfa synergist anti-folate; light or ultraviolet light on vitamins VA, VD3, VE, VK, VB1, VB2, VB6, VB1 2, VC, Folic acid has a strong damaging effect. With the extension of storage time, various vitamins show a certain loss. When the feed storage period is more than 3 months, the loss of some unstable vitamins such as biotin, VB12, and folic acid can reach 10% to 15%.
2 Measures to improve the stability of vitamin premix
2.1 Selection of stable vitamin species
Selecting more stable vitamin raw materials can effectively reduce the loss of vitamins during production and storage. For example, VA recommends using VA palmitate and acetate; VK3 uses dimenaquinone sulfite (50% MPB); VB1 uses nitro Thiamine; pyridoxine hydrochloride for VB6; calcium L-ascorbate for VC; nicotinamide for niacin; calcium pantothenate for pantothenic acid; riboflavin acetate for riboflavin.
2.2 Correct choice of carrier and diluent
When choosing a carrier and diluent, close attention should be paid to its bulk density, water content, particle size, separation characteristics, pH value, lipid content, flow and agglomeration. In production, the pH value of the carrier should be controlled at 6-8, and the water content should be less than 12%. Because the density and particle size of most vitamins are similar to those of pulverized grains, bran, corncob, corn kernels, and rice husks are usually chosen as carriers or diluents for vitamin premixes.
2.3 Appropriate over-addition
In order to ensure the stability of vitamins in compound feeds, excessive amounts of vitamins should be added in production according to specific conditions such as storage conditions, turnover cycle, production type, and environmental conditions. For example, when the compound premix is made and the storage time exceeds 3 months, the commonly used vitamins generally need to be added in excess. , folic acid is 10%. In general full-price feeds, the excessive addition of vitamins is 5% to 10%.
2.4 Add antioxidant and antifungal agent
Adding an appropriate amount of antioxidants to the vitamin premix can slow down the oxidation of vitamins and maintain their potency. Commonly used antioxidants include ethoxyquin, butylated hydroxytoluene, butylated hydroxyanisole, and citric acid. At the same time, the feed is prone to mildew in a humid environment. It is also very important to add an appropriate amount of mildew inhibitor to the feed to maintain the stability of vitamins. Commonly used mildew inhibitors include propionic acid, sodium propionate, and sorbic acid.
2.5 Reduce storage time and improve storage environment
The storage environment of vitamins should be kept low temperature, dry, dark and airtight. The suitable temperature is 15-26°C, the humidity should be controlled within 70%, and it should be used immediately after unsealing. Minimize the storage time of premix or compound feed. Vitamin premix is generally required to be used up within 1 month, and the longest shall not exceed 3 months.
In summary, there are many factors that affect the stability of vitamin premixes. In the process of production and storage, the influence of various factors on the stability of vitamins should be minimized according to the actual situation, which can not only prevent the waste of vitamins, but also save a certain amount of time. The production cost is of great significance to the actual production of premix and compound feed.