Method for increasing oligosaccharide content in pellet feed for pigs
By directly enzymatically hydrolyzing starch to generate an oligosaccharide solution during pellet feed production and mixing it with the pellet feed, the drying process is avoided, thus solving the problems of high energy consumption and high cost, and achieving low-cost and high-efficiency preparation of pellet feed containing oligosaccharides.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJINGDEBAOQUNXING TECH CO LTD
- Filing Date
- 2026-03-23
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies have high energy consumption, strict equipment requirements, and high production costs in the production of slow-release metabolizable sugars (oligosaccharides), especially when oligosaccharides are added to pelleted feed, the drying process is difficult, and energy consumption and equipment costs remain high.
After mixing starch raw materials with water, they are enzymatically hydrolyzed using a medium-temperature and high-temperature resistant α-amylase to generate an oligosaccharide solution. This solution is then mixed with pelleted feed raw materials and processed through high-temperature conditioning, extrusion granulation, and ventilation cooling to directly prepare pelleted feed containing oligosaccharides, thus avoiding the drying process.
It reduces the production cost of slow-release metabolizable sugars in pelleted feed by 35-37%, simplifies equipment requirements, reduces energy consumption, and ensures that the oligosaccharide content is between 1.7-2.6%, meeting industry safety standards.
Smart Images
Figure CN122004352A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for increasing the oligosaccharide content in pig pellet feed, belonging to the field of animal feed production. Background Technology
[0002] Oligosaccharides for animal feed are a class of slow-release, metabolizable sugars. These slow-release sugars can promote the growth of lactic acid bacteria (especially strictly anaerobic Bifidobacteria) in the intestines, which has a good effect on the intestinal health of pigs (especially weaned piglets). The most typical product is short-chain dextrin (also known as enzymatically hydrolyzed starch oligosaccharides) made from starch. Their main components are small molecules composed of hexose sugars, with molecular weights concentrated between 3 and 6 glucose units.
[0003] However, the production cost of these slow-release metabolizable sugars is relatively high. Currently, the price of feed-grade oligosaccharides is around 7.2 yuan / kg. Adding 20 kg of feed-grade oligosaccharides to each ton of feed would increase the cost by 144 yuan.
[0004] Referring to the conventional enzymatic starch hydrolysis production process, in the final stage of oligosaccharide production (airflow drying), as the moisture content decreases, the viscosity of the material increases, making drying increasingly difficult. This process not only consumes a lot of energy but also places extremely high demands on the equipment; the drying process is the most costly part of the traditional production process.
[0005] By combining the production processes of oligosaccharides and pelleted feed, this invention integrates starch oligosaccharides with the production process of pelleted feed, avoiding the drying process and directly preparing pelleted feed containing oligosaccharides. Summary of the Invention
[0006] The purpose of this invention is to provide a method for increasing the content of slow-release metabolizable sugars in pig pellet feed. This invention uses high-temperature enzymatic hydrolysis of gelatinized starch to obtain high-concentration liquefied starch, which is then directly added to the raw materials used to produce pig pellet feed. After high-temperature conditioning, extrusion pelleting, and ventilation cooling, the pellet feed is finally obtained.
[0007] The pelleted feed obtained by the method of this invention has a slow-release metabolizable sugar (oligosaccharide) content of 1.7-2.6%, and the production cost is reduced by 35.0-37.0% compared with the conventional method (directly adding feed-grade oligosaccharides). The moisture content of the pelleted feed meets the safety requirements generally recognized in the industry. The method of this invention avoids the difficulties of drying high-viscosity materials. It not only reduces energy consumption but also greatly simplifies equipment requirements, and has great application value.
[0008] The method for increasing the content of slow-release metabolizable sugars in pelleted feed provided by the present invention includes the following steps:
[0009] S1. Mix the starch raw material with water at a mass ratio of 1:1.20; S2, at 68 At 72℃, add medium-temperature α amylase and thermostable α Amylase performs enzymatic hydrolysis; S3. Mix the oligosaccharide solution obtained by enzymatic hydrolysis directly with the pig pellet feed raw materials; S4. After steam conditioning, extrusion granulation, and ventilation cooling, pelleted feed containing oligosaccharides is obtained.
[0010] In the method of this invention, the mass ratio of starch raw material to water is 1:1.20, a figure determined through repeated experiments. From the perspective of production energy consumption requirements, the lower the water content, the better. Less water means a lower load on subsequent cooling and evaporation. However, from the perspective of material viscosity, a higher water content is preferable. Higher water content results in lower viscosity of the enzymatic hydrolysate, making the material easier to transport. Furthermore, there is a minimum moisture content for starch gelatinization enzymatic hydrolysis; if it falls below this limit, gelatinization cannot proceed. The moisture content selected in this invention is higher than this limit (experimental results show that the minimum limit for water content is approximately 80% of the starch raw material mass).
[0011] In the method of this invention, the intermediate temperature α The amount of amylase added is 0.05% of the total mass of the starch raw material. 0.07%, enzyme activity ≥2000 U / g. Enzyme activity is defined as the amount of enzyme required to liquefy 1 gram of starch per hour under conditions of pH 6.0 and 60℃ as one enzyme activity unit U. The high temperature resistant α The amount of amylase added is 0.15% of the total mass of the starch raw material. 0.20%, enzyme activity ≥2400U / g. Enzyme activity is defined as the amount of enzyme required to liquefy 1 gram of starch per hour under conditions of pH 6.0 and 70℃ as one enzyme activity unit U.
[0012] In the method of this invention, the starch raw material is added to the enzymatic hydrolysis tank at a uniform rate over a period of 60 minutes. 80 minutes; After adding the starch raw material, continue at 68 Isothermal enzymatic hydrolysis at 72℃ for 40 minutes 60 minutes.
[0013] The enzymatic hydrolysis tank used in this invention has a water bath jacket (200mm thick) on its outer wall, and the jacket is covered with an asbestos insulation layer. This insulation layer is not only for keeping the water in the jacket warm, but more importantly, for the safety of operators, preventing burns. The temperature of the water inside the jacket is automatically controlled by an electric heating element with a power of 20kW. The water temperature inside the jacket is controlled between 68-72℃. That is, if the water temperature is below 68℃, heating is automatically activated; if the water temperature is above 72℃, heating is automatically deactivated. Although this heating method is more expensive than steam heating, it allows for automatic control, which helps save labor costs and control product quality. The temperature of the material inside the tank is controlled by the water bath in the tank wall jacket, and stirring accelerates heat conduction.
[0014] In the method of this invention, water bath heating is used during the enzymatic hydrolysis process; The enzymatic hydrolysis tank is equipped with a stirring device with a stirring speed of 60. 90 rpm.
[0015] In the method of the present invention, the molecular weight of the oligosaccharides in the oligosaccharide solution is concentrated between 3 and 6 glucose units, and the enzymatic conversion rate is not less than 98%.
[0016] In the method of this invention, during the ventilation and cooling step, the power of the cooling fan is 1.8 times the conventional power. 2.2 times.
[0017] In the method of this invention, the amount of oligosaccharide solution added is 22 mg / ton of feed raw material. 66 kg; The amount added depends on the air temperature and relative humidity of the production workshop. The more moisture the cooling air can remove, the greater the allowable amount can be added. In other words, the drier the cooling air (or the lower the relative humidity), the more moisture can be removed during the cooling process. Compared to the conventional pellet feed production process, this patented technology needs to consider the additional moisture introduced by the starch hydrolysate. More moisture needs to be removed during the pellet feed cooling stage than in conventional production, and the corresponding cooling fan power needs to be greater than that of conventional fans.
[0018] The final pelleted feed contained 1.70% oligosaccharides. The molecular weight is 2.60%, the molecular weight is concentrated between 3-6G (G is glucose unit), and the water content is not higher than 13.5%, which meets the industry's standard requirements.
[0019] In the method of this invention, the starch raw material is corn starch; The raw materials for the pelleted feed include soybean meal, corn, wheat bran, and premix.
[0020] The present invention further provides a pelleted feed for pigs prepared by the method, wherein the oligosaccharide content is 1.70%. 2.60%, with a moisture content not exceeding 13.5%.
[0021] This invention achieves the goal of increasing the slow-release sugar (oligosaccharide) content in pelleted feed by controlling the addition ratio of starch hydrolysate (oligosaccharide solution) to the feed ingredients and evaporating moisture during the ventilation and cooling process of pellet production. The production process of this invention is relatively simple, especially avoiding the drying step in the production of solid dextrin powder, which not only reduces energy consumption but also greatly simplifies equipment requirements. Compared with adding solid slow-release sugar powder, this process significantly reduces the cost of using slow-release sugar in pelleted feed.
[0022] This invention can stably obtain pelleted feed with a slow-release sugar content of 1.70-2.60%, reducing the cost of adding slow-release sugar to pelleted feed by 35-37%.
[0023] This invention eliminates the independent drying process and removes the additional moisture from the starch hydrolysate by increasing the cooling and ventilation volume during feed pelleting, which has great application value. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of a starch enzymatic hydrolysis tank. Detailed Implementation
[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0026] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0027] Example 1 Location of implementation: A feed production enterprise in Liaoning Province.
[0028] The ambient temperature is 14-28℃ and the relative humidity is 29-56%.
[0029] The raw materials for production are shown in Table 1: Table 1 Raw material distribution between the experimental group and the control group
[0030] The proportions of raw materials for producing pig pellet feed are shown in Table 2.
[0031] Table 2 Composition of Pelleted Feed Ingredients
[0032] The moisture content of the feed ingredient mixture is 12.6%.
[0033] The moisture content of the corn starch is 13.5% (Liaoning Yihai Kerry Starch Technology Co., Ltd.).
[0034] The moisture content of the feed oligosaccharide powder is 13.3% (Liaoning Kangpulide Biotechnology Co., Ltd.).
[0035] Medium-temperature α-amylase: Enzyme activity ≥2000u / g (produced by Shandong Longket Enzyme Preparation Co., Ltd.). Enzyme activity is defined as the amount of enzyme required to liquefy 1 gram of starch per hour under conditions of pH 6.0 and 60℃, which is one enzyme activity unit U.
[0036] Thermoresistant α-amylase: Enzyme activity ≥2400u / g (produced by Shandong Longket Enzyme Preparation Co., Ltd.). Enzyme activity is defined as the amount of enzyme required to liquefy 1 gram of starch per hour under conditions of pH 6.0 and 70℃, which is one enzyme activity unit U.
[0037] Production equipment: Starch hydrolysis tank: See Figure 1 The nominal volume is 1.5 cubic meters, and the stirring motor power is 7.5 kW. The outer wall has a water bath jacket, which is covered with an asbestos insulation layer. The water temperature inside the jacket is automatically controlled by an electric heating element. The water temperature inside the jacket is controlled between 68-72℃. If the water temperature is below 68℃, heating is automatically activated; if the water temperature is above 72℃, heating is automatically deactivated and stopped.
[0038] Two sets of pellet feed production equipment were used, both manufactured by Jiangsu Muyang Group, with a capacity of 10 tons / hour. The first set (referred to as the "experimental group") had a 45kW cooling fan for enzymatically hydrolyzing starch to produce pellet feed. The second set (referred to as the "control group") had a 22kW cooling fan for adding oligosaccharide powder to produce pellet feed. Apart from the difference in the cooling fan configuration, all other supporting equipment was identical.
[0039] The mixing tanks used in the production of pelleted feed all have stainless steel inner walls.
[0040] The experimental group used enzymatic hydrolysis of starch to produce oligosaccharides, and the process flow for producing pelleted feed is as follows: Starch hydrolysis and liquefaction → uniform mixing with feed ingredients → conditioning → pelleting → ventilation and cooling → obtaining pelleted feed.
[0041] The control group directly added feed-grade oligosaccharide powder, and the process for producing pelleted feed was as follows: Feed oligosaccharide dry powder → uniformly mixed with feed ingredients → conditioning → pelleting → ventilation and cooling → obtaining pelleted feed.
[0042] The experimental group's operation procedure is as follows: Starch hydrolysis process: Add 720 kg of water to the hydrolysis tank, start the water bath heating and stirring motor, and set the stirring speed to 60 rpm (60 revolutions per minute). After the water temperature in the tank reaches 68℃, add 300 g of mesophilic α-amylase and 900 g of thermosophilic α-amylase, followed by corn starch. The corn starch is added at a rate of 7-8 kg / min for 80 minutes, for a total of 600 kg of corn starch. Then maintain a constant temperature water bath (68-72℃) for 60 minutes.
[0043] Chromatographic analysis showed that the starch in the enzymatic hydrolysate was basically degraded into oligosaccharides with a molecular weight of 3-6G, with a conversion rate of over 98%.
[0044] Because viscosity changes rapidly during gelatinization and liquefaction, this embodiment uses rapid viscosity analysis (RVA) to determine the starch dextrin content. This method uses a viscosity analyzer to measure changes in solution viscosity to estimate the starch dextrin content, making it particularly suitable for rapid online industrial detection. Finally, liquid chromatography is used to determine the molecular weight distribution of oligosaccharides in the enzymatic hydrolysate.
[0045] Mixing process: The starch hydrolysate is pumped into a mixing tank using a centrifugal pump and mixed evenly with the feed ingredients. The mixing ratio of hydrolysate to feed ingredients is 6.6:100. Intermittent mixing is used, with one intermittent mixing cycle using 33 kg of starch hydrolysate corresponding to 500 kg of feed ingredients. The time for one mixing unit operation (including feeding, mixing, and discharging) is 3 minutes and 30 seconds.
[0046] Granulation process: Conditioning: The conditioning steam pressure is 0.2-0.3MPa, the material temperature is 82-85℃, and the average duration is 30 seconds.
[0047] Extrusion granulation: The steam pressure of the ring die is 0.2-0.3 MPa.
[0048] Ventilation and cooling: ventilation volume is 60-80m³ 3 / min.
[0049] The control group produced pelleted feed under the same conditions, and the specific process is as follows: Mixing process: Mix 15 kg of feed oligosaccharide powder evenly with 500 kg of feed ingredients. The mixing time for one unit is 3 minutes.
[0050] Granulation process: Conditioning: The conditioning steam pressure is 0.2-0.3 MPa, the material temperature is 82-85℃, and the average duration is 30 seconds.
[0051] Extrusion granulation: The steam pressure of the ring die is 0.2-0.3 MPa.
[0052] Ventilation and cooling: ventilation volume is 30-40m³ 3 / min.
[0053] Table 3. Differences in key procedures between the experimental and control groups.
[0054] In this embodiment, the experimental group underwent 10 enzymatic hydrolysates, consuming 6000 kg of corn starch and 200 tons of feed ingredients, yielding a total of 13200 kg of starch hydrolysate. The control group consumed 6000 kg of feed oligosaccharides and 200 tons of feed ingredients, and the following results were obtained: Table 4 Production Results
[0055] The finished pelleted feed is produced in batches of approximately 200 tons, with a slow-release oligosaccharide content of about 2.60%. The moisture content of the pelleted feed is below 13.0%, meeting safe storage standards.
[0056] The loss of dry matter was mainly concentrated in the cooling and ventilation stage. The experimental group lost 354 kg more dry matter than the control group (896-542=354), which is equivalent to 405 kg of finished pelleted feed (moisture content 12.5%).
[0057] Note: The oligosaccharide content in the experimental group was slightly higher than that in the control group, possibly because amylase was still working during the mixing and granulation process, and the raw materials still contained a large amount of starch.
[0058] Table 5. Increase in energy expenditure in the experimental group compared to the control group
[0059] Table 6 Comparison of Increased Costs (Yuan)
[0060] The price of corn starch is 3,000 yuan / ton, and 6 tons of corn starch is worth 18,000 yuan.
[0061] The price of feed-grade oligosaccharides is 7,200 yuan / ton, and 6 tons of feed-grade oligosaccharides are worth 43,200 yuan.
[0062] Compared to conventional pelleted feed production processes, the increased consumption is as follows: 3.0 kg of medium-temperature α-amylase is worth 20 × 3.0 = 60 (yuan).
[0063] 9.0 kg of heat-resistant α-amylase is worth 40 × 9.0 = 360 (yuan).
[0064] The price of clean water is 5 yuan per ton, so 7.2 tons of clean water is worth 36 yuan.
[0065] The enzymatic hydrolysis process consumes 1458 kWh of electricity.
[0066] Increased power consumption during pelleted feed production: 512 kWh.
[0067] Assuming the electricity price is 1.2 yuan / kWh, the total increase in electricity cost is 1.2 × (1458 + 512) = 2364 yuan.
[0068] The increased steam consumption is 1.8 tons, which is worth 250 × 1.8 = 450 yuan.
[0069] The experimental group suffered an additional yield loss of 405 kg, valued at: 405 × 3.6 = 1458 (yuan). Note: The ex-factory price of finished pelleted feed is 3600 yuan / ton.
[0070] Increased equipment depreciation costs (mainly reflected in the depreciation of the enzymatic hydrolysis tank): 1500 yuan.
[0071] Increased labor costs: 3,000 yuan.
[0072] The experimental group used enzymatic hydrolysis of corn starch, which cost 27,198 yuan.
[0073] The control group used feed oligosaccharides directly, which cost 43,200 yuan.
[0074] The difference between the two is 43200-27198=16002 (yuan).
[0075] The decrease was 16002 / 43200 = 37.0%. That is, the cost of directly adding 30 kg of feed oligosaccharides to each ton of feed raw materials is about 216 yuan, while the cost drops to about 136 yuan after using starch enzymatic hydrolysis technology, a reduction of about 37.0%.
[0076] Example 2 Location of implementation: A feed production enterprise in Liaoning Province.
[0077] The ambient temperature is 16-32℃ and the relative humidity is 35-69%.
[0078] Similar to Example 1, in order to demonstrate the advantages of this patented technology, an experimental group and a control group were set up for comparison.
[0079] See Table 7 for raw materials used in production: Table 7 Raw material distribution between the experimental group and the control group
[0080] The ratio of raw materials for producing pig pellet feed is the same as in Example 1 (see Table 1).
[0081] The moisture content of the feed ingredient mixture is 12.6% (same as in Example 1).
[0082] Corn starch: Same as in Example 1.
[0083] Feed oligosaccharide powder: Same as in Example 1.
[0084] Mesophilic α-amylase: Same as in Example 1.
[0085] Thermoresistant α-amylase: Same as in Example 1.
[0086] Production equipment: Same as in Example 1.
[0087] The process flow for producing pelleted feed is the same as in Example 1.
[0088] The experimental group's operation procedure is as follows: Starch enzymatic hydrolysis process: Add 720 kg of water to the enzymatic hydrolysis tank, start the water bath heating and stirring motor, and set the stirring speed to 90 rpm (90 revolutions per minute). After the water temperature in the tank reaches 68℃, add 420 g of mesophilic α-amylase and 1200 g of thermosophilic α-amylase, and then add corn starch. Control the addition rate of corn starch between 9-11 kg / min, and continue adding for 60 minutes, for a total of 600 kg of corn starch. Then maintain a constant temperature water bath (68-72℃) for 40 minutes.
[0089] Chromatographic analysis showed that the starch in the enzymatic hydrolysate was almost entirely degraded into oligosaccharides with a molecular weight of 3-6G, achieving a conversion rate of over 98%. The determination method was the same as in Example 1.
[0090] Mixing process: The starch hydrolysate is pumped into a mixing tank using a centrifugal pump and mixed evenly with the feed ingredients. The mixing ratio of hydrolysate to feed ingredients is 4.4:100. Intermittent mixing is used, with one intermittent mixing cycle using 22 kg of starch hydrolysate corresponding to 500 kg of feed ingredients. The time for one mixing unit operation (including feeding, mixing, and discharging) is 3 minutes and 20 seconds.
[0091] Granulation process: Conditioning: The conditioning steam pressure is 0.2-0.3 MPa, the material temperature is 82-85℃, and the average duration is 30 seconds.
[0092] Extrusion granulation: The steam pressure of the ring die is 0.2-0.3 MPa.
[0093] Ventilation and cooling: ventilation volume is 55-70m³ 3 / min.
[0094] The control group produced pelleted feed under the same conditions, and the specific process is as follows: Mixing process: Mix 15 kg of feed oligosaccharide dry powder with 500 kg of feed ingredients evenly. The mixing time for one unit is 3 minutes.
[0095] Granulation process: Conditioning: The conditioning steam pressure is 0.2-0.3 MPa, the material temperature is 82-85℃, and the average duration is 30 seconds.
[0096] Extrusion granulation: The steam pressure of the ring die is 0.2-0.3 MPa.
[0097] Ventilation and cooling: ventilation volume is 30-40m³ 3 / min.
[0098] Table 8. Differences in key procedures between the experimental and control groups
[0099] In this embodiment, the experimental group underwent eight enzymatic hydrolysis cycles, consuming 4800 kg of corn starch and 240 tons of feed ingredients, yielding a total of 10560 kg of starch hydrolysate. The control group consumed 4800 kg of feed oligosaccharides and 240 tons of feed ingredients. The final results are as follows: Table 9 Production Results
[0100] The finished pelleted feed is produced in batches of approximately 240 tons, with a slow-release oligosaccharide content of about 1.74%. The moisture content of the pelleted feed is below 13.0%, meeting safe storage standards.
[0101] The experimental group lost 431 kg more dry matter than the control group (1073-642=431), which is equivalent to 493 kg of finished feed (moisture content of 12.5%).
[0102] The same phenomenon as in Example 1 occurred in this embodiment, namely, the oligosaccharide content in the experimental group was slightly higher than that in the control group. The reason may be the same: amylase is still playing a role in the mixing and granulation process.
[0103] Table 10. Increase in energy expenditure in the experimental group compared to the control group
[0104] Table 11 Comparison of Increased Costs (Yuan)
[0105] The price of corn starch is 3,000 yuan / ton, and 4.8 tons of corn starch is worth 14,400 yuan.
[0106] The price of feed-grade oligosaccharides is 7,200 yuan / ton, and 4.8 tons of feed-grade oligosaccharides are worth 34,560 yuan.
[0107] Compared to conventional pelleted feed production processes, the increased consumption is as follows: 3.36 kg of medium-temperature α-amylase is worth 20 × 3.36 = 67.2 yuan.
[0108] 9.6 kg of heat-resistant α-amylase is worth 40 × 9.6 = 384 yuan.
[0109] The price of clean water is 5 yuan per ton, and 6.0 tons of clean water is worth 30 yuan.
[0110] Increase in power consumption: 1165 kWh + 410 kWh = 1575 kWh.
[0111] Assuming the electricity price is 1.2 yuan / kWh, the total increase in electricity cost is 1.2 × (1165 + 410) = 1890 yuan.
[0112] The increased steam consumption is 1.5 tons, which is worth 250 × 1.5 = 375 yuan.
[0113] The increase in dry matter loss is: 1073-642=431 (kg), which is equivalent to 493 kg of finished feed (assuming a moisture content of 12.5%), with a value of: 493×3.6=1775 (yuan).
[0114] Note: The ex-factory price of finished pelleted feed is 3600 yuan / ton.
[0115] Increased equipment depreciation costs (mainly reflected in the depreciation of the enzymatic hydrolysis tank): 1200 yuan.
[0116] Increased labor costs: 2400 yuan.
[0117] The experimental group used enzymatic hydrolysis of corn starch, which cost 22,521.2 yuan.
[0118] The control group used feed oligosaccharides directly, which cost 34,560 yuan.
[0119] The difference between the two is 34560 - 22521.2 = 12038.8 (yuan).
[0120] The decrease was 12038.8 / 34560 = 34.8%.
[0121] That is, the cost of directly adding 20 kg of feed oligosaccharides to each ton of feed raw materials is about 144 yuan, while the cost drops to about 94 yuan after using starch enzymatic hydrolysis technology, a reduction of about 35.0%.
Claims
1. A method for increasing the oligosaccharide content in pelleted feed, comprising the following steps: S1. Mix the starch raw material with water at a mass ratio of 1:1.20; S2, at 68 At 72℃, add medium-temperature α amylase and thermostable α Amylase performs enzymatic hydrolysis; S3. Mix the oligosaccharide solution obtained by enzymatic hydrolysis directly with the pig pellet feed raw materials; S4. After steam conditioning, extrusion granulation, and ventilation cooling, pelleted feed containing oligosaccharides is obtained.
2. The method according to claim 1, characterized in that: The intermediate temperature α The amount of amylase added is 0.05% of the total mass of the starch raw material. 0.07%; The high temperature resistant α The amount of amylase added is 0.15% of the total mass of the starch raw material. 0.20%.
3. The method according to claim 1 or 2, characterized in that: In step S2, the starch raw material is added to the enzymatic hydrolysis tank at a uniform rate over a period of 60 minutes. 80 minutes; After adding the starch raw material, continue at 68 Isothermal enzymatic hydrolysis at 72℃ for 40 minutes 60 minutes.
4. The method according to any one of claims 1-3, characterized in that: In step S2, water bath heating is used during the enzymatic hydrolysis process; The enzymatic hydrolysis tank is equipped with a stirring device with a stirring speed of 60. 90 rpm.
5. The method according to any one of claims 1-4, characterized in that: In step S3, the molecular weight of the oligosaccharides in the oligosaccharide solution is concentrated around 3. Between 6 glucose units, the enzymatic conversion rate is no less than 98%.
6. The method according to any one of claims 1-5, characterized in that: In step S4, during the ventilation and cooling process, the power of the cooling fan is 1.8-2.2 times that of the conventional power.
7. The method according to any one of claims 1-6, characterized in that: In step S3, the amount of oligosaccharide solution added is 22 mg / ton of feed raw material. 66 kg; The final pelleted feed contained 1.70% oligosaccharides. 2.60%, with a moisture content not exceeding 13.5%.
8. The method according to any one of claims 1-7, characterized in that: The starch raw material is corn starch; The raw materials for the pelleted feed include soybean meal, corn, wheat bran, and premix.
9. A pelleted feed for pigs, characterized in that, By claim 1 The oligosaccharide content is 1.70% when prepared by any one of the methods described in any one of the eight methods. 2.60%, with a moisture content not exceeding 13.5%.