A method for preparing acidified milk pellets for veal calves

Abstract

The present application relates to the technical field of livestock raising, and particularly relates to a preparation method of acidified milk granules for beef calf. The steps comprise: mixing first component raw materials, second component raw materials and third component raw materials to obtain initial adhesive mixture; determining target gelatinization degree according to water content, and controlling the material to reach the target gelatinization degree through conditioning time length control to obtain gelatinized denatured material; determining conditioning completion degree by taking insoluble polymer content and peak viscosity as double determination indexes, and adjusting the granulation density to prepare pre-prepared granules; after first stage drying, determining pre-cooling temperature according to the particle surface hardness, and then performing high-temperature one-pass brittle treatment to form a surface dense hard shell layer, and the finished product is obtained. The present application realizes the cooperation of stage drying and surface instantaneous high-temperature shell forming, and effectively retains the nutritional components of the granules while ensuring the particle hardness and the pulverization rate.

Description

Technical Field

[0001] This invention relates to the field of animal husbandry technology, and in particular to a method for preparing acidified milk pellets for beef calves. Background Technology

[0002] The feeding and management of beef calves is a crucial aspect of the beef cattle industry, as their growth and development during the calf stage directly impacts their adult production performance and economic benefits. In calf farming practice, supplementing calves with acidified milk pellets in the early stages helps promote rumen development and alleviate weaning stress.

[0003] Chinese Patent Publication No. CN113455590A discloses a calf pellet feed. By adding fresh milk to the feed, manual feeding of calves is eliminated, significantly reducing workload. Adding formic acid and sodium benzoate to the fresh milk improves the shelf life of the pellet feed, ensuring calf health. Adding premix ensures sufficient nutrition in the pellet feed. Adding binder solvent increases the viscosity of the raw materials, improving the pelleting rate. The patent also discloses a method for preparing calf pellet feed. By selecting appropriate parameters such as corn powder particle size, mixing time, and compression ratio, good mixing of raw materials is ensured, achieving high mixing uniformity. A small flat die pellet mill can be used to increase the pelleting rate to over 98%, making it suitable for small-scale production on family farms. However, this technology has drawbacks. Insufficient conditioning and gelatinization during pellet preparation can lead to high pellet powdering rate and poor water resistance. Furthermore, prolonged high-temperature treatment can denature and inactivate heat-sensitive nutrients such as whey protein and vitamins. In addition, plant proteins and starches in the raw materials are prone to excessive cross-linking during conditioning, forming insoluble polymers that affect the digestion and absorption of calves.

[0004] Therefore, how to balance the relationship between the degree of gelatinization, particle hardness, and nutrient preservation is an urgent problem to be solved in the industry. Summary of the Invention

[0005] Therefore, the present invention provides a method for preparing acidified milk pellets for beef calves, overcoming the problem in the prior art that it is impossible to balance the degree of gelatinization, pellet hardness and nutrient protection.

[0006] This invention provides a method for preparing acidified milk pellets for beef calves, characterized by comprising: Prepare the first component raw material, the second component raw material, and the third component raw material according to the preset ratio, and mix them evenly in sequence to obtain the initial viscous mixture; The moisture content of the initial viscous mixture is obtained to determine the target degree of gelatinization in the conditioning process; The conditioning time is determined based on the target degree of gelatinization in order to condition the initially viscous mixture and obtain the gelatinized modified material after conditioning. An insoluble test is performed on the gelatinized modified material to obtain insoluble polymerization characteristics. Based on the insoluble characteristics and gelatinization modification characteristics, the degree of conditioning completion is determined to adjust the granulation density of the granulation process in order to granulate and form pre-formed granules. The porosity and moisture content of the pre-formed granules are obtained, and the drying correction temperature is determined in combination with the degree of conditioning completion. The pre-formed granules are then subjected to a first-stage conditioning and drying process to obtain the conditioned granules. The surface hardness of the conditioned pellets is obtained to determine the pre-cooling temperature for the one-pass embrittlement treatment of the conditioned pellets. After cooling the conditioned pellets, a high-temperature one-pass embrittlement treatment is performed to obtain acidified milk pellets for beef calves.

[0007] Furthermore, the first component raw material is one or more of milk powder or whey protein powder, and the particle size of the first component raw material is such that the passing rate through a 60-80 mesh standard sieve is greater than or equal to 95%; The second component raw material is one or more of soybean meal or fermented soybean meal, and the particle size of the second component raw material is greater than or equal to 90% passing through a 40-60 mesh standard sieve; The third component raw material is one or more of corn, soybean hulls, molasses, wheat bran, and wheat middlings, and the particle size of the third component raw material is such that the passing rate through a 30-40 mesh standard sieve is greater than or equal to 85%.

[0008] Further, obtaining the moisture content of the initial viscous mixture to determine the target degree of gelatinization in the conditioning process includes: The degree of gelatinization that can be achieved by initial viscous mixtures with different moisture contents under fixed conditioning conditions is determined in advance, and the pulverization rate of each sample prepared into granules is detected. Using a powdering rate below a preset threshold as the standard condition, and based on the gelatinization degree corresponding to the standard sample, the target gelatinization degree at the corresponding moisture content is determined to establish the correspondence between moisture content and target gelatinization degree. Based on the moisture content of the material to be processed, the target degree of gelatinization for the conditioning process is determined according to the aforementioned correspondence.

[0009] Furthermore, the step of determining the conditioning time based on the target gelatinization degree to condition the initially viscous mixture includes: Set the initial duration, temperature, and steam addition amount for conditioning treatment to condition the initially viscous mixture; During the conditioning process, the conditioning parameters are adjusted based on the real-time gelatinization degree of the material, including one or more of the following methods: extending the conditioning time, increasing the conditioning temperature, and increasing the amount of steam added, until the real-time gelatinization degree reaches the allowable deviation range of the target gelatinization degree, thereby obtaining the gelatinized modified material.

[0010] Further, the gelatinized modified material after conditioning treatment is dissolved and dispersed in warm water at 40-60°C, the insoluble matter is separated by centrifugation, dried and weighed, and the content of insoluble polymer is calculated as the insoluble polymer characteristic. The peak viscosity of the gelatinized modified material during the gelatinization process is measured as the gelatinization modification characteristic; The degree of conditioning completion is determined based on the content of the insoluble polymer and the peak viscosity. If the conditioner is deemed unqualified, the conditioner treatment process for the initial tack mixture will be adjusted. The process adjustments include one or more of the following: extending the conditioning time, increasing the conditioning temperature, and increasing the amount of steam added. After the conditioning completion is deemed qualified, granulation is performed using a preset granulation density to obtain the pre-formed granules.

[0011] Further, the surface hardness of the tempered granules is obtained, and the measured surface hardness is compared with a preset hardness range;

[0012] The cooling temperature in the cooling process is determined based on the surface hardness, so that a temperature difference buffer layer is formed on the surface of the granular material during the one-pass embrittlement treatment.

[0013] In addition, the acidified milk pellets for calves also contain compound acidifiers, functional additives, and mixed additives, including: The composite acidifying agent is one or more of citric acid, sodium butyrate, and potassium diformate; The functional additive is one or more of grape seed extract, brewer's yeast, and yeast cell wall. The mixed additives are one or more of the following: vitamin A, vitamin D3, vitamin E, vitamin B1, vitamin B2, vitamin B12, nicotinamide, copper methionine, manganese methionine, zinc methionine, manganese sulfate monohydrate, cobalt chloride, sodium selenite, yeast selenium, stone powder, and rice husk powder.

[0014] Furthermore, the composite acidifying agent is composed of citric acid, sodium butyrate and potassium diformate in a mass ratio of 1:(1.3-2.9):(4.5-7.8).

[0015] Furthermore, the formulation of the acidified milk pelleted feed for calves comprises the following raw materials: Based on a total of 1000 copies, Corn 385–435 parts, soybean hulls 58–77 parts, molasses 19–29 parts, wheat bran 48–67 parts, wheat middlings 38–48 parts, soybean meal 250–270 parts, fermented soybean meal 48–58 parts, milk powder 38–67 parts, whey protein powder 10–19 parts, citric acid 0.9–1.3 parts, sodium butyrate 1.8–2.6 parts, potassium diformate 5.9–7.0 parts, grape seed extract 1.0–2.0 parts, brewer's yeast 2.0–4.0 parts, yeast cell wall 4.0–6.0 parts, mixed additives 8–10 parts.

[0016] Furthermore, the pore size of the acidified milk pellets for calves is 4 mm, the particle diameter is 1.5-2 mm, the surface hardness is 90-120 N, the core hardness is 40-70 N, and the pulverization rate is ≤5%.

[0017] Compared with the prior art, the beneficial effects of the present invention are that by establishing the correspondence between moisture content and target gelatinization degree in advance, and adjusting the conditioning time, temperature and steam addition amount according to real-time gelatinization degree feedback, the present invention achieves precise control of the gelatinization process, effectively solves the problem of insufficient or excessive gelatinization caused by batch fluctuations in the moisture content of raw materials, and ensures the batch stability of the granular material conditioning quality.

[0018] Furthermore, this invention employs a dual criterion of insoluble polymer content and peak viscosity to jointly determine the degree of conditioning completion, comprehensively evaluating the conditioning effect from two dimensions: the degree of chemical crosslinking and physical bonding characteristics. When the indicators fail to meet the requirements, process adjustments such as extending the conditioning time, increasing the conditioning temperature, or increasing the amount of steam added are made to ensure that the material reaches a qualified state before granulation. This dual criterion is more sensitive and reliable than a single gelatinization degree indicator, effectively avoiding the problems of loose particle structure and high pulverization rate caused by insufficient conditioning. The pulverization rate of the finished product can be stably controlled below 5%.

[0019] Furthermore, this invention flexibly adjusts the pre-cooling temperature of the one-pass embrittlement treatment based on the surface hardness of the conditioned granules: when the surface hardness is too low, the pre-cooling temperature is increased to reduce the temperature difference and prevent excessive evaporation of surface moisture leading to cracking; when the surface hardness is too high, the pre-cooling temperature is decreased to moderately increase the temperature difference and promote surface softening. This control mechanism ensures that a uniform and dense hardened shell layer is formed on the surface of the granules after the one-pass embrittlement treatment, and the hardness of the finished product is stable in the range of 90–120 N.

[0020] Furthermore, the one-pass embrittlement treatment of this invention involves instantaneous contact between a high-temperature airflow (120–160°C) and the pellets for 10–30 seconds. This causes rapid evaporation of surface moisture, forming a dense shell that effectively blocks heat conduction, preventing high-temperature heat from penetrating deep into the pellets and thus protecting heat-sensitive nutrients such as whey protein and vitamins from high-temperature denaturation. Compared to conventional long-term high-temperature drying processes, the method of this invention significantly improves the protein solubility and vitamin retention rate within the pellets, effectively enhancing the digestibility and absorption rate for calves.

[0021] Furthermore, this invention divides the drying process into two stages: the first stage is conditioning and drying, which mainly completes the dehydration of the main granular material; the second stage is a one-time embrittlement treatment, which only targets the surface of the granules with instantaneous high temperature to form a shell. The two stages have clear functions and do not interfere with each other. While ensuring that the overall moisture content of the granules meets the standard, it also takes into account the dual requirements of surface hardness and internal nutrient protection. The overall energy consumption of the process is reduced compared with the traditional one-time high-temperature drying process, and the production efficiency is improved.

[0022] Furthermore, the acidified milk pellet formula of this invention is scientifically sound and reasonable. Through the synergistic combination of milk-based feed, plant protein source, energy feed, compound acidifier, functional additives, and mixed additives, it meets the nutritional needs of calves in their early growth and development. The compound acidifier is preferably a mixture of citric acid, sodium butyrate, and potassium diformate in a mass ratio of 1:(1.3–2.9):(4.5–7.8), which can effectively reduce the pH value of the gastrointestinal tract, inhibit the growth of harmful bacteria, and promote the colonization of beneficial bacteria. The grape seed extract, brewer's yeast, and yeast cell wall in the functional additives work synergistically to exert antioxidant, immune-enhancing, and intestinal conditioning functions, significantly reducing weaning stress and diarrhea rates in calves. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation method of acidified milk pellets for beef calves according to the present invention; Figure 2 This is a schematic diagram of the main components of the acidified milk pellet feed for beef calves of the present invention; Figure 3 A flowchart for determining the conditioning time of acidified milk pellet feed for beef calves according to the present invention; Figure 4 This is a flowchart for determining the target gelatinization degree of the acidified milk pellet feed for beef calves according to the present invention. Detailed Implementation

[0024] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0025] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0026] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0027] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] The feeding and management of beef calves is a crucial aspect of the beef cattle industry, as their growth and development during the calf stage directly impacts their adult production performance and economic benefits. In calf farming practice, supplementing calves with acidified milk pellets in the early stages helps promote rumen development and alleviate weaning stress.

[0029] The following problems are common in the existing technology: Insufficient conditioning and gelatinization during the preparation of granules can easily lead to high granule pulverization rate and poor water resistance. At the same time, in order to make gelatinization as complete as possible, the gelatinization time is usually extended and the temperature is increased. However, prolonged high-temperature treatment can easily denature and deactivate heat-sensitive nutrients such as whey protein and vitamins in the raw materials. Furthermore, plant proteins and starches in the raw materials are prone to excessive cross-linking during conditioning, forming insoluble polymers. This reduces the utilization efficiency of the conditioned granules and degrades the conditioning effect of the granules.

[0030] Please see Figure 1 The diagram shows a flowchart of the preparation method of the acidified milk pellet feed for beef calves according to the present invention. The preparation method of the acidified milk pellet feed for beef calves according to an embodiment of the present invention includes the following steps: S1. Prepare the first component raw material, the second component raw material and the third component raw material according to the preset ratio, and mix them evenly in sequence to obtain the initial viscous mixture; S2, obtain the moisture content of the initial viscous mixture to determine the target degree of gelatinization in the conditioning process; S3, Based on the target degree of gelatinization, determine the conditioning time for the conditioning process, and condition the initially viscous mixture to obtain the gelatinized modified material; S4. Conduct an insoluble test on the gelatinized modified material to obtain insoluble polymerization characteristics, determine gelatinization modification characteristics, and determine the degree of conditioning completion based on the insoluble polymerization characteristics and gelatinization modification characteristics in order to adjust the granulation density and granulate to form pre-formed granules. S5, obtain the porosity and moisture content of the pre-made granules, determine the drying correction temperature in combination with the degree of conditioning completion, and perform the first stage of conditioning and drying on the pre-made granules to obtain the conditioned granules; S6. Obtain the surface hardness of the conditioned pellets to determine the pre-cooling temperature for the one-pass embrittlement treatment. After cooling the conditioned pellets, perform a high-temperature one-pass embrittlement treatment to obtain acidified milk pellets for beef calves.

[0031] This invention ensures uniform dispersion of each component and full embedding of fine powder into the gaps between coarse particles by grading and pulverizing three types of raw materials according to different fineness levels and mixing them in a coarse-to-fine order, laying the foundation for subsequent uniform gelatinization. Furthermore, by establishing a pre-established correspondence between moisture content and target gelatinization degree and using the achievement of the pulverization rate target to reversely establish the target value, the fluctuation of raw material moisture content is transformed into a quantifiable conditioning target. This target gelatinization degree is used to perform the first gelatinization of the raw materials to obtain the initially gelatinized material that is not fully gelatinized. This provides a process margin for further gelatinization and conditioning of the granular material in the subsequent drying process, avoiding the irreversible loss of insoluble polymers caused by excessive cross-linking due to complete gelatinization in a single process. Furthermore, during the first stage of raw material gelatinization conditioning, the degree of gelatinization is monitored online in real time and compared with the target value. The conditioning time, temperature, and steam addition are dynamically adjusted. Through the starch gelatinization mechanism and protein denaturation mechanism, the degree of gelatinization is precisely within the allowable deviation range, avoiding insufficient or excessive conditioning. At the same time, by actively setting the target degree of gelatinization for incomplete gelatinization, the process parameters during conditioning can avoid the formation of insoluble aggregates in the pellets, improving the digestibility of the pellets for calves. After obtaining the gelatinized and modified material, the degree of conditioning completion is determined by introducing two indicators: insoluble polymer content and gelatinization and denaturation characteristics. The conditioning effect is comprehensively evaluated from two dimensions: the degree of chemical crosslinking and physical bonding characteristics. This overcomes the deficiency that a single gelatinization degree indicator cannot reflect undesirable crosslinking side reactions. Based on the determination results, the pellet density is precisely controlled to ensure that the pre-formed pellets after the pellet density adjustment are completely gelatinized in the subsequent first stage of conditioning and drying. Furthermore, during the first stage of conditioning and drying, the porosity and moisture content of the pre-formed granules are measured and the conditioning completion rate is combined to determine the drying correction temperature. The granule structure characteristics and conditioning history are incorporated into the drying parameter decision-making process to achieve gentle dehydration while further gelatinizing and conditioning the raw materials that were not fully gelatinized during the conditioning process, resulting in fully gelatinized granules. Subsequently, the pre-cooling temperature is dynamically determined by detecting the surface hardness of the conditioned granules to adjust the temperature difference between the granule surface and the high-temperature airflow, ensuring the formation of a uniform and dense surface hardened shell during the one-pass embrittlement process. At the same time, it effectively blocks heat conduction, protects the conditioned granules from over-gelatinization, and prevents heat-sensitive nutrients such as internal proteins from high-temperature denaturation.

[0032] This invention avoids the reduced utilization rate of raw material nutrients due to protein denaturation by conditioning the pellets in two stages and controlling the core temperature of the pellets through pre-cooling. It achieves a surface hardness of 90-120N to resist external impact and a pulverization rate of ≤5%, and a core hardness of 40-70N. It can also maximize the retention of the nutritional activity of the pellets and make them easy to digest. It takes into account the mechanical stability and nutritional quality of the pellets, and significantly improves the product quality and feed value of calf acidified milk pellets.

[0033] Please see Figure 2 The diagram shown is a schematic representation of the main components of the acidified milk pellet feed for beef calves of the present invention.

[0034] In this embodiment, S1, the first component raw material, the second component raw material and the third component raw material are prepared according to a preset ratio, and are mixed evenly in sequence to obtain an initial viscous mixture; Specifically, the first component raw material is a dairy-based material, including one or more of milk powder or whey protein powder, with a particle size of 60-80 mesh and a passing rate of ≥95% through a standard sieve. The second component raw material is a plant protein source, including one or more types of soybean meal or fermented soybean meal, with a particle size of ≥90% passing through a 40-60 mesh standard sieve. The third component is an energy feed, including one or more of corn, soybean hulls, molasses, wheat bran, and wheat middlings, with a particle size of ≥85% passing through a 30-40 mesh standard sieve.

[0035] Specifically, the first component raw material, the second component raw material, and the third component raw material are prepared according to the preset ratio, and the three are mixed evenly in sequence to obtain the initial viscous mixture.

[0036] The specific types, particle size requirements, and mixing order of each component raw material are as follows: First component raw materials: The first component consists of one or more of milk powder and whey protein powder. This first component provides calves with milk protein, lactose, and various active immune factors, and is the most digestible and palatable protein source among acidified milk pellets. To ensure uniform dispersion of the first component during subsequent mixing and sufficient contact with the plant protein source and energy feed, its fineness must be controlled: the milk powder and / or whey protein powder should be pre-crushed to ensure that 95% or more of it passes through a 60-80 mesh standard sieve.

[0037] Second component raw materials: The second component is a plant protein source, selected from one or more of soybean meal and fermented soybean meal. Soybean meal and fermented soybean meal provide high-quality plant-based protein, while fermented soybean meal also contains beneficial microbial metabolites that help promote gut health in calves. The soybean meal and / or fermented soybean meal are pre-ground to a passing rate of ≥90% through a 40-60 mesh standard sieve. This fineness range ensures uniform distribution of plant protein in the mixture while avoiding excessive water absorption and clumping during subsequent conditioning due to over-grinding, which would affect the uniformity of gelatinization.

[0038] Third component raw materials: The third component consists of one or more of the following: corn, soybean hulls, molasses, wheat bran, and wheat middlings. Corn is the primary energy source, providing starch; soybean hulls and wheat bran provide digestible fiber, promoting rumen development; molasses provides soluble sugars and acts as a natural binder; wheat middlings combine starch and fiber, aiding in shaping. The corn, soybean hulls, wheat bran, and wheat middlings are separately pulverized to a passing rate of ≥85% through a 30-40 mesh standard sieve. This particle size range allows for sufficient absorption of steam moisture during conditioning, resulting in moderate expansion of starch granules, which is beneficial for subsequent gelatinization. Simultaneously, it retains some coarse particle structure, increasing the chewiness of the pellets and meeting the feeding characteristics of calves.

[0039] In this embodiment, the dry powder materials of the third component (excluding molasses), such as corn, soybean hulls, wheat bran, and wheat middlings, are first added to a twin-shaft paddle mixer or ribbon mixer. The mixer is started and premixed for 120-180 seconds to ensure that the components of the energy feed are initially and evenly mixed. Next, while the mixer is running continuously, the second component material, soybean meal and / or fermented soybean meal, is added evenly, and mixing continues for 90-120 seconds to ensure that the plant protein source and energy feed are thoroughly mixed. Since the fineness of the second component material is 40-60 mesh, which is higher than that of the third component material (30-40 mesh), adding the finer material later helps the fine powder to embed into the gaps between the coarse particles, improving the overall mixing uniformity. Finally, while the mixer is running continuously, the first component material, milk powder and / or whey protein powder, is added evenly, and mixing continues for 60-90 seconds. The fineness of the first component raw material is up to 60-80 mesh. Adding it last can prevent fine powder from being lost due to electrostatic adsorption or airflow disturbance. At the same time, the mixed materials are used as a carrier to ensure that the milk source base material is evenly attached to the surface and gaps of the particles.

[0040] In some embodiments, if the formula contains liquid molasses, the molasses preheated to 40-50°C is sprayed into the mixer in an atomized form through a spraying device. The mixer is kept running during the spraying process, and after spraying, the mixture is continued for 120-180 seconds to make the molasses evenly coat the surface of the mixture and form a slightly viscous mixture.

[0041] In some embodiments, if solid molasses powder is used, it is added together with the third component raw material. After mixing, samples are taken to test the mixing uniformity, requiring a coefficient of variation (CV) value of less than or equal to 5%. A qualified initial viscous mixture has a uniform powder appearance, consistent color, clumps when squeezed by hand, and crumbles easily upon light pressure, without obvious agglomeration or particle gradation. At this point, the preparation of the initial viscous mixture is complete, and it can proceed to the subsequent conditioning process.

[0042] In this embodiment, S2, the moisture content of the initial viscous mixture is obtained to determine the target degree of gelatinization in the conditioning process.

[0043] Specifically, the initial viscous mixture obtained from S1 is sampled, and its moisture content is determined using a halogen moisture analyzer or a constant temperature oven method. The determination conditions for the halogen moisture analyzer are as follows: weigh 3-5g of sample, heat to 105℃, heat to constant weight, and the instrument automatically calculates and displays the moisture content.

[0044] In this embodiment, the target gelatinization degree is determined based on the moisture content of the initial viscous mixture. It limits the maximum degree of gelatinization the initial viscous mixture can achieve during the conditioning process. The target gelatinization degree of the initial viscous mixture is lower than the final gelatinization degree of the conditioned granules, i.e., lower than the ideal complete gelatinization degree of the conditioned granules. Moisture content is positively correlated with the target gelatinization degree; the higher the moisture content of the initial viscous mixture, the higher the ideal gelatinization degree that the material can achieve under the same conditioning conditions, and therefore the corresponding target gelatinization degree is also higher. Preferably, the target gelatinization degree is set between 60% and 80% of the ideal gelatinization degree determined by the moisture content of the initial viscous mixture. This ensures that the initial viscous mixture becomes a gelatinized modified material that is not completely gelatinized after conditioning, providing a process margin for subsequent thermal processing and avoiding excessive gelatinization.

[0045] In this embodiment, initial tack mixture samples with different moisture content gradients are prepared. Under the same formulation system, several batches of initial tack mixture samples with gradient moisture content are prepared by adjusting the amount of water added during the mixing process or the moisture content of the raw materials themselves. The moisture content gradient can be set to 10%–20%, with each step consisting of 1–2 percentage points. At least three parallel samples are prepared for each moisture content level. The prepared samples are sealed and left to stand for 2 hours to allow the moisture to fully and evenly penetrate the material.

[0046] The samples with different moisture contents were subjected to conditioning treatment under the same conditions. The maximum temperature for the conditioning process was determined based on the starch gelatinization and protein denaturation mechanisms. During conditioning, process parameters must be strictly controlled according to the temperature windows for starch gelatinization and protein denaturation. Regarding starch gelatinization, starch granules undergo ordered structural disruption under the combined effects of moisture and heat: when the material temperature rises to the gelatinization initiation temperature range of 60–65°C, starch granules begin to absorb a large amount of water and swell, intermolecular hydrogen bonds gradually break, and the crystalline structure tends to disintegrate; when the temperature rises to the optimal gelatinization temperature range of 65–70°C, amylopectin fully swells and forms a gel network. For every 10 percentage point increase in the degree of gelatinization, starch digestibility increases by approximately 5 percentage points. Regarding protein denaturation, milk protein and soy protein undergo moderate thermal denaturation in the 60–70°C range, disulfide bond rearrangement, spatial structure unfolding, and surface hydrophobicity increasing, which is beneficial for exposing protease binding sites and improving protein digestibility. When the temperature exceeds 75°C, both starch and protein will react excessively, forming insoluble aggregates, leading to a decrease in digestibility. In addition, the stirring operation during the conditioning process will cause the material temperature to gradually rise due to heat generated by mechanical friction and continuous steam contact. Therefore, even if the initial conditioning temperature is set below 75°C, the actual temperature of the material may accumulate and exceed the safety limit as the conditioning time is extended.

[0047] In this embodiment, the temperature parameter in the conditioning conditions must be strictly controlled within the safe window of 60-70℃, and the conditioning time must be considered in conjunction with the temperature to ensure that the highest temperature of the material does not exceed 70℃ throughout the entire conditioning process. In this embodiment, the conditioning temperature is set to 65℃, the conditioning time is set to 180 seconds, and the steam addition amount is set to 8% of the material mass. Monitoring showed that the highest temperature of the material under these conditions did not exceed 70℃. After each sample was conditioned, it was taken for cooling, the degree of gelatinization was measured, and the pulverization rate of the corresponding sample after being prepared into granules was detected.

[0048] Specifically, the target gelatinization degree at a specific moisture content is determined based on the ideal complete gelatinization degree corresponding to the compliant sample whose powdering rate meets the process requirements. The higher the ideal complete gelatinization degree, the higher the target gelatinization degree can be set. Furthermore, the target gelatinization degree is set to be lower than the ideal complete gelatinization degree during the conditioning stage to ensure that process margins are left for further gelatinization reactions in subsequent processes. This avoids excessive gelatinization in the subsequent stages, which could lead to the formation of insoluble products due to complete gelatinization or excessive gelatinization during the complete conditioning stage. The target gelatinization degree is set to 60%~80% of the ideal complete gelatinization degree, preferably 70%. Each moisture content and its corresponding ideal complete gelatinization degree are recorded to form a moisture content to ideal complete gelatinization degree correspondence table. This correspondence table essentially embeds the balance constraints of gelatinization and denaturation, as well as the safety limits of stirring temperature rise.

[0049] If the target degree of gelatinization is set higher than 80% of the ideal degree of complete gelatinization, the cumulative temperature rise caused by the high-temperature process in the subsequent drying and one-pass embrittlement process is very likely to cause the material temperature to exceed the safe upper limit of 75°C, resulting in the formation of insoluble aggregates. If the target gelatinization degree is set below 60% of the ideal complete gelatinization degree, the gelatinization conditions will be lost as the moisture content decreases during the subsequent drying and one-pass embrittlement process, which will easily lead to insufficient starch gelatinization and a particle powdering rate exceeding 5%.

[0050] In this embodiment, the conditioning time required during the conditioning process is determined based on the target degree of gelatinization, and this time is used to ensure that the material temperature does not exceed 70°C.

[0051] As an explanation, the above-mentioned moisture content-ideal degree of complete gelatinization correspondence table can be established through different experimental design methods. For example, statistical regression can be performed on natural batches of raw materials with different moisture contents to replace manual gradient preparation, or online detection of moisture content using near-infrared spectroscopy can replace offline sampling and determination. As long as an accurate mapping from moisture content to ideal degree of complete gelatinization can be achieved, and temperature safety constraints are embedded in the mapping relationship, it can be regarded as an equivalent implementation method of this step.

[0052] In this embodiment, S3, the conditioning time of the conditioning process is determined based on the target degree of gelatinization, and the initial viscous mixture is conditioned to obtain a gelatinized modified material.

[0053] Specifically, after determining the target gelatinization degree in step S2, this step uses feedback control of the conditioning process to find the actual conditioning time required to achieve the target gelatinization degree, and conditions the initially viscous mixture to obtain the gelatinized modified material.

[0054] In this embodiment, based on the target degree of gelatinization, the actual conditioning time required to achieve the target degree of gelatinization is determined through feedback control of the conditioning process. The initially viscous mixture is then conditioned to obtain a gelatinized modified material. Throughout the process, the material temperature must be strictly monitored to ensure it never exceeds 70°C to prevent the formation of insoluble aggregates.

[0055] Specifically, the initial parameters for conditioning are set based on the formula characteristics, ambient temperature and humidity, and equipment specifications. In this embodiment, the values ​​range as follows: Initial conditioning time: 120-180 seconds. The residence time of the material in the conditioner is controlled by adjusting the spindle speed of the conditioner and the opening of the discharge gate. Initial conditioning temperature: 60~70℃, which is achieved by adjusting the steam intake and jacket heating temperature. The upper limit of the initial temperature is set at 65℃, with a safety margin to cope with the temperature rise during stirring. Initial steam addition: 6% to 10% of the initial viscous mixture mass, steam pressure controlled at 0.3 to 0.5 MPa, steam should be dry saturated steam, sprayed in after removing condensate through a steam-water separator.

[0056] Start the conditioner and, after the cylinder has preheated to the set temperature, begin feeding and simultaneously introduce steam to propel the initially viscous mixture through the conditioner while it is being stirred. The continuous tumbling of the stirring blades within the conditioner generates mechanical frictional heat, and the continuous contact between the material and steam also causes the temperature to gradually accumulate and rise. Therefore, a temperature sensor is installed at the conditioner outlet or in the middle of the cylinder to monitor the material temperature in real time, ensuring that the material temperature does not exceed 75°C at any time.

[0057] After the conditioning process begins, take samples at the conditioner outlet every 30–60 seconds, spread the samples thinly, and cool them to room temperature (25°C) to terminate the gelatinization process. After cooling, take an appropriate amount of sample and test its gelatinization degree according to NY / T 4125-2022 "Determination of Starch Gelatinization Degree in Feed", which is the real-time gelatinization degree. Record the material temperature at the time of sampling.

[0058] The measured real-time degree of gelatinization is compared with the target degree of gelatinization determined in step S2, and the conditioning process parameters are dynamically adjusted based on the comparison results.

[0059] In this embodiment, when the real-time gelatinization degree is lower than the target gelatinization degree, and the difference between the two is less than or equal to 3 percentage points, the preferred adjustment method is to extend the conditioning time. Based on the original conditioning time, each extension should be 15-30 seconds, which can be achieved by reducing the main shaft speed of the conditioner or decreasing the opening of the discharge gate. While extending the time, temperature changes must be monitored. If the temperature is already close to 70°C, the time should not be extended further; instead, the amount of steam added should be increased or the temperature slightly raised, but the temperature increase must ensure that it does not exceed 70°C.

[0060] When the real-time gelatinization degree is lower than the target gelatinization degree, and the difference between the two is greater than 3 percentage points, it indicates that the conditioning intensity is significantly insufficient. It is advisable to take two or three adjustment methods at the same time: on the basis of extending the conditioning time, simultaneously increase the conditioning temperature by 3-5℃ each time and / or increase the amount of steam added by 1%-2% of the material mass each time. When the temperature reaches the upper limit of 70℃ and the gelatinization degree still does not meet the standard, it is necessary to check whether the moisture content of the raw materials or the formula is abnormal, and take other auxiliary measures, such as adjusting the fineness of the raw materials, rather than further increasing the temperature.

[0061] If the real-time gelatinization degree has reached or exceeded the upper limit of the allowable deviation of the target gelatinization degree, it indicates that the conditioning may be overdone. In this case, the conditioning time should be shortened or the conditioning temperature should be reduced to avoid over-gelatinization of the material and reduce the risk of insoluble aggregate formation.

[0062] When the real-time gelatinization degree first reaches the allowable deviation range of the target gelatinization degree and the temperature record confirms safety, record the total processing time from the start of conditioning to this point. This time is the optimal conditioning time for this batch of initial viscous mixture under the conditions of this moisture content and equipment. This conditioning time is recorded and archived as a process parameter. Subsequent batches with the same formula and the same moisture content range can directly use this conditioning time for conditioning without repeated testing and adjustment, but routine temperature monitoring is still necessary to prevent abnormalities.

[0063] After conditioning, the material is discharged from the outlet of the conditioner. At this point, the material has changed from the initial powder to a gelatinized modified material with significant viscoelasticity and a darker color.

[0064] In this embodiment, step S4 involves conducting an insoluble test on the gelatinized modified material to obtain insoluble polymerization characteristics; simultaneously, the gelatinization modification characteristics are measured; based on the insoluble polymerization characteristics and gelatinization modification characteristics, the conditioning completion degree is determined, and the granulation density is adjusted accordingly to granulate and form pre-formed granules. Please see Figure 4 The flowchart shown is a process for determining the target gelatinization degree of the acidified milk pellet feed for beef calves according to the present invention.

[0065] Specifically, the insoluble polymer content is expressed as a percentage of the dry weight of the insoluble matter to the sample mass. This is calculated by dividing the dried mass of the insoluble matter by the mass of the sample. This insoluble polymer content represents the insoluble polymerization characteristic, reflecting the proportion of insoluble polymers formed during the conditioning process due to excessive cross-linking. A higher content indicates more severe undesired cross-linking and poorer conditioning quality.

[0066] In this embodiment, the insoluble polymerization characteristics are obtained based on the insolubility test, specifically including: Take approximately 50g of the gelatinized modified material obtained from S3, reduce it to a quartered sample, rapidly cool it to room temperature, and seal it for later testing. Weigh 10g of the sample into a 250mL beaker and add 150mL of warm water (40-60℃). The temperature should not be too high to avoid further starch gelatinization interfering with the test results; the temperature should also not be too low to ensure the complete dissolution of soluble components. Stir thoroughly with a glass rod for 3-5 minutes to completely dissolve and disperse the soluble components in the sample, forming a uniform suspension. Transfer the suspension to a centrifuge tube and centrifuge at 3000-4000 rpm for 10-15 minutes. After centrifugation, discard the supernatant and retain the bottom precipitate. Add 100mL of warm water (40-60℃) to the precipitate again, stir thoroughly, wash, and centrifuge again. Repeat this washing and centrifugation operation 2-3 times until the supernatant is clear and transparent, ensuring that the soluble components have been fully eluted. Transfer the resulting insoluble precipitate to a pre-weighed weighing bottle or evaporating dish, and dry it in a constant-temperature drying oven at 105℃±2℃ for 4–6 hours until constant weight. After drying, remove the precipitate and cool it to room temperature in a desiccator, then weigh the dry weight of the insoluble precipitate.

[0067] In this embodiment, the gelatinization and denaturation characteristics, determined based on peak viscosity, are used to characterize the degree of water absorption, swelling, and disintegration of starch granules during gelatinization. These characteristics are directly related to the filling performance of the material in the die cavity and the quality of granule formation. The results are measured using a rapid viscosity analyzer.

[0068] Specifically, the gelatinized modified material obtained from S3 is pulverized and passed through a 60-mesh standard sieve. The material passing through the sieve is weighed as the sample to be tested. A certain amount of sample is weighed, specifically 3.0–4.0 g of dry equivalent, and added to a special aluminum can containing 25 mL of distilled water. The sample is thoroughly stirred with a rotary paddle to ensure uniform dispersion. The aluminum can is placed in a rapid viscosity analyzer, and the instrument automatically records the viscosity change curve throughout the process. The highest viscosity value observed during the heating stage is taken as the peak viscosity, expressed in centipoises (cP).

[0069] In this embodiment, the conditioning completion degree is determined based on the insoluble characteristics and the gelatinization denaturation characteristics. The measured insoluble polymer content and the measured peak viscosity are compared with preset thresholds to determine whether the conditioning completion degree is qualified.

[0070] The preset threshold is determined by preliminary experiments and incorporated into the process specifications. In this embodiment, it is set as follows: Preset threshold for insoluble matter content: 4.0%; Preset lower limit of peak viscosity: 1500 cP; Specifically, when the insoluble polymer content is less than a preset threshold and the peak viscosity is greater than or equal to a preset lower limit, the conditioning completion is deemed satisfactory. This indicates that the starch gelatinization of the material was sufficient during the conditioning process, the binding performance was good, and no insoluble cross-linking side reactions occurred, making the material suitable for granulation.

[0071] If the insoluble polymer content is greater than or equal to a preset threshold, or the peak viscosity is less than a preset lower limit, and either of these conditions is not met, the conditioning completion is deemed unqualified. This indicates that the material may have excessive cross-linking leading to high insoluble content, or insufficient gelatinization leading to low viscosity, making direct granulation unsuitable.

[0072] Specifically, when the conditioning completion is deemed unqualified, the conditioning process of the initial tack mixture needs to be adjusted until both the insoluble polymer content and peak viscosity meet the requirements.

[0073] Specifically, process adjustments include one or more of the following methods: Extend the conditioning time: Based on the conditioning time recorded in step S3, extend it by 15 to 30 seconds each time to allow the starch granules more time to absorb water, swell and disintegrate, improve the degree of gelatinization, and thus increase the peak viscosity. Increase the conditioning temperature: Increase it by 1-2℃ each time to accelerate the starch gelatinization reaction rate, promote the full disintegration of starch granules, and increase peak viscosity; Increase the amount of steam added: each time increase the amount of material by 1% to 2% of the mass to provide more moisture to participate in the gelatinization reaction and improve the overall adhesion of the material.

[0074] After the above adjustments are made, the conditioning process is repeated, and the insolubility test and peak viscosity measurement are repeated until both indicators are qualified, at which point the conditioning completion is deemed qualified.

[0075] Specifically, in step S4, after the conditioning completion is determined to be qualified, the granulation density is adjusted, and granulation is carried out using the adjusted granulation density to obtain pre-formed granules.

[0076] In this embodiment, the granulation density is determined based on the degree of conditioning completion, so that the prepared pre-granulated material is fully gelatinized in the first stage of conditioning and drying. The higher the degree of conditioning completion, the higher the granulation density can be set, and the lower the degree of conditioning completion, the lower the granulation density. By adjusting the granulation density, the core material after granulation can utilize the moisture in the drying process of the granule core to promote the degree of gelatinization. The granulation equipment selected is a ring die granulator with a ring die aperture of 4mm. Preferably, the granulation density is achieved by adjusting the compression ratio. That is, the higher the granulation density, the higher the compression ratio, and the denser the compressed granules. The compression ratio is selected in the range of 1:5 to 1:8 based on the characteristics of the formulation.

[0077] In this embodiment, step S5 involves obtaining the porosity and moisture content of the pre-formed granules, determining the drying correction temperature based on the degree of conditioning completion, and performing a first-stage conditioning and drying process on the pre-formed granules to obtain the conditioned granules. Understandably, the pre-formed granules obtained in S4 already possess preliminary particle morphology and strength, but their internal moisture content is high and the particle structure is not yet dense enough. A first-stage conditioning and drying process is needed to reduce the main moisture content to a suitable range, preparing for subsequent surface embrittlement treatment. This step precisely determines the drying correction temperature by measuring the porosity and moisture content of the pre-formed granules and combining this with the conditioning completion information determined in S4, ensuring that the drying process is both efficient and does not damage the internal structure of the particles.

[0078] Specifically, the drying correction temperature is determined based on the porosity and moisture content of the pre-formed granules. The pre-formed granules prepared in S4 are cooled to room temperature, and their porosity is determined using the medium saturation method.

[0079] Specifically, weigh 20g of pre-made granules and place them in an impregnation container of known volume. Pour in anhydrous ethanol or paraffin oil as the saturating medium and record its density. Place the container in a vacuum desiccator, evacuate to -0.09MPa and maintain this vacuum for 30 minutes to allow the medium to fully penetrate the pores of the granules. After restoring to normal pressure, remove the granules, gently absorb excess medium from the surface with filter paper, and quickly weigh the saturated granules.

[0080] The total volume of the pores inside a particle is equal to the mass of the medium entering the pores of the particle divided by the density of that medium. The resulting value is the volume occupied by the pores inside the particle.

[0081] Take another set of unimpregnated precast granules and determine their apparent volume using the sand displacement method or graduated cylinder method. This apparent volume is the volume of the granules displaced by the medium, including internal pores but excluding interparticle voids. The specific procedure is as follows: put a known mass of granules into a graduated cylinder containing a fixed amount of fine sand or water, and directly read the apparent volume of the granules from the volume increment.

[0082] Porosity is defined as the percentage of the total volume of pores inside a particle to the apparent volume of the particle, that is, the total volume of pores inside the particle divided by the apparent volume of the particle.

[0083] Determination of moisture content in precast granules. Take approximately 5g of precast granule sample and heat it to constant weight at 105℃ using a halogen moisture analyzer. The instrument will automatically display the moisture content.

[0084] The conditioning completion degree is determined based on step S4. In S4, after the conditioning completion degree is deemed acceptable based on the insoluble polymer content and peak viscosity, granulation is performed to obtain pre-formed granules. Therefore, the materials entering the drying process are all materials with acceptable conditioning completion degree. The specific index values ​​measured in S4 are extracted to construct the conditioning completion degree G.

[0085] It is understandable that two fundamentally different physicochemical changes occur simultaneously during conditioning: starch gelatinization and excessive protein cross-linking. The degree of gelatinization only reflects the extent of starch gelatinization and cannot characterize the degree of side reactions such as protein cross-linking. If only the degree of gelatinization is used as a criterion, a situation may arise where the degree of gelatinization meets the standard, but excessive insoluble polymers have already been generated, leading to a decrease in the digestibility of the pelleted material. This invention introduces insoluble content as a characteristic quantity of insoluble matter content, complementing the peak viscosity characteristic quantity, and quantitatively reflects the gelatinization progress and the degree of side reactions of the initially viscous mixture during the conditioning stage.

[0086] Specifically, the conditioning completion rate is determined based on the insoluble polymer content and peak viscosity, and is used to quantify the degree of side reaction suppression during the conditioning stage. The higher the actual measured peak viscosity, and the closer it is to the preset lower limit of peak viscosity, the higher the conditioning completion rate. The lower the actual measured insoluble polymer content, and the lower it is than the preset insoluble content threshold, the higher the conditioning completion rate. A higher conditioning completion rate indicates a more ideal conditioning outcome and better suppression of side reactions during conditioning; conversely, a lower conditioning completion rate indicates a worse conditioning outcome and poorer suppression of side reactions during conditioning. In a preferred embodiment, the preset insoluble content threshold is divided by the actual measured insoluble polymer content to obtain a first ratio; the actual measured peak viscosity is divided by the preset lower limit of peak viscosity to obtain a second ratio; and the two ratios are added together to obtain the conditioning completion rate index. In this embodiment, the lower limit of peak viscosity is determined based on the minimum peak viscosity corresponding to the target gelatinization degree in the experiment. The insoluble matter content threshold is determined based on the insoluble matter content corresponding to the target gelatinization degree in the experiment.

[0087] When G > 1, it indicates that the conditioning and tempering process is more ideal; when G = 1, it indicates that the two indicators are exactly at the threshold; when G < 1, it indicates that the process is unqualified, but this situation has been intercepted and will not proceed to drying.

[0088] In this embodiment, the drying correction temperature is determined based on the particle porosity, moisture content, and conditioning completion degree G value. The drying correction temperature is determined using a pre-established lookup table.

[0089] Specifically, the process of establishing the reference table is as follows: Under the same formulation and equipment conditions, three factors—porosity, moisture content, and G-value—are designed for multi-level orthogonal experiments. Drying is carried out at different drying temperatures. The particle pulverization rate, surface crack rate, and internal protein solubility retention rate after drying are used as comprehensive evaluation indicators to select the optimal drying temperature corresponding to different combinations of porosity, moisture content, and G-value as the drying correction temperature. These correspondences are compiled into a database or reference table and input into the control system. The drying correction temperature range is 60℃~70℃.

[0090] The first stage of conditioning and drying is determined based on the parameters of the dryer. The pre-formed granules obtained in S4 are fed into a fluidized bed dryer or a multi-layer belt dryer by a belt conveyor for the first stage of conditioning and drying. The dryer inlet air temperature is set to the drying correction temperature determined above, and the outlet air temperature is usually 15-25°C lower than the inlet air temperature. The bed thickness is controlled at 30-50 mm, and the material residence time is set according to the target moisture content reduction; in this embodiment, it is set to 5-15 minutes.

[0091] In this embodiment, the measured porosity, moisture content, and G value are input, and the control system automatically retrieves the corresponding drying correction temperature from the lookup table.

[0092] During the drying process, hot air passes evenly through the granular material layer. Moisture inside the granules migrates to the surface as steam, undergoing further gelatinization during this migration. The steam overflowing from the granules is carried away by the hot air, causing a slight shrinkage in granule volume, a decrease in porosity, and a denser structure. The drying endpoint is determined by an online moisture meter at the outlet: when the moisture content of the granules drops to 12%–14%, the conditioning drying endpoint is reached. At this point, the granules possess a certain surface hardness and overall strength, and are thus treated as conditioned granules. After discharge, fine powder is removed by a vibrating screen, and the finished conditioned granules proceed to the next process, S6, for surface embrittlement treatment.

[0093] In this embodiment, step S6 involves obtaining the surface hardness of the conditioned pellets to determine the pre-cooling temperature for the one-pass embrittlement treatment. After cooling the conditioned pellets, a high-temperature one-pass embrittlement treatment is performed to obtain acidified milk pellets for beef calves.

[0094] The S5 conditioned pellets have completed the first stage of conditioning and drying, with the main moisture content reduced to 12%–14%. However, a dense protective shell has not yet formed on the surface of the pellets. If prolonged high-temperature drying is carried out directly, the heat will penetrate deep into the pellets, easily causing heat-sensitive nutrients such as whey protein and vitamins to denature and become inactive.

[0095] Specifically, this step dynamically determines the pre-cooling temperature by detecting the surface hardness of the particles, and then performs a high-temperature one-time embrittlement treatment, which instantly forms a dense hardened shell on the particle surface, protecting the internal nutrients while giving the particles ideal surface hardness and water resistance.

[0096] In this embodiment, the surface hardness of the conditioned granules is determined based on hardness testing. The conditioned granules prepared in step S5 are cooled to room temperature, and 20-30 intact granules are randomly selected. The surface hardness of each granule is measured using a particle hardness tester. The particle hardness tester is either spring-loaded or digitally displayed, with a flat indenter probe whose diameter is larger than the particle size to ensure uniform stress distribution across the granules during pressurization.

[0097] During testing, the particles are placed on the stage of the hardness tester, and the pressure handle is rotated at a constant speed or the automatic loading program is started. The loading speed is controlled between 10 and 20 N / s. The maximum force value at the moment the particle is crushed is recorded, and the unit is Newton (N). After testing each particle, the average value is taken as the surface hardness value of the batch of conditioned and tempered granules.

[0098] In this embodiment, the pre-cooling temperature is determined by comparing the measured surface hardness of the conditioned granules with a preset hardness range. The preset hardness range is a target value range pre-set according to the quality requirements of the finished granules; in this embodiment, the hardness of the granules is taken as 90–120 N.

[0099] Specifically, based on the comparison results, the pre-cooling temperature before the one-pass embrittlement treatment is determined according to the following rules: When the surface hardness is within the preset hardness range, specifically between 90 and 120 N, it indicates that the surface of the granules is of moderate hardness and the density of the granule structure is suitable. A first pre-cooling temperature is then used to cool the conditioned granules. This first pre-cooling temperature is determined based on the temperature rise during heat exchange between the granule surface and core in the catalytic process of the one-pass embrittlement treatment. This ensures that the core temperature of the granules remains below the temperature of gelatinization and denaturation after the one-pass embrittlement treatment, allowing a suitable temperature difference buffer layer to form on the granule surface during subsequent one-pass embrittlement treatments. This ensures that surface moisture evaporates rapidly in the high-temperature airflow to form a dense shell, while preventing surface thermal shock cracking due to excessive temperature difference, and maintaining conditions where the core of the granules does not undergo high-temperature denaturation. Preferably, the first pre-cooling temperature is generally set to 40–50°C.

[0100] When the surface hardness is below the lower limit of the preset hardness range, and the measured surface hardness is less than 90 N, it indicates that the surface of the granules is relatively soft, the particle structure is relatively loose, and the surface moisture content may be too high. In this case, directly performing high-temperature embrittlement treatment at a higher temperature requires an increased time for the evaporation of surface moisture to achieve the same surface hardness requirement. This prolonged heat exchange time results in more heat being exchanged to the core of the granules. If the core temperature is too high, it will exceed 70°C after heat exchange, causing denaturation and inactivation of heat-sensitive nutrients such as proteins. Therefore, when the surface hardness is below the lower limit of the preset hardness range, the pre-cooling temperature needs to be lowered to a second pre-cooling temperature. The second pre-cooling temperature is lower than the first pre-cooling temperature and is set between 25°C and 40°C. By lowering the pre-cooling temperature, the temperature rise of heat exchange between the granule surface and the core is controlled, preventing the impact of high-temperature heat on the core from causing protein denaturation. This isolates the denaturation range to the particle surface, protecting the internal nutrients.

[0101] When the surface hardness exceeds the upper limit of the preset hardness range, a measured surface hardness greater than 120 N indicates that the granule surface is relatively hard and dense. The evaporation time required for surface moisture needs to be reduced to achieve the same surface hardness requirement. This shortens the heat exchange time, resulting in less heat being transferred to the granule core. If the core can be heated to a higher temperature, the core temperature after heat exchange should not exceed 70°C. Therefore, when the surface hardness exceeds the upper limit of the preset hardness range, the pre-cooling temperature is increased to the third pre-cooling temperature. The third pre-cooling temperature is higher than the first pre-cooling temperature and is set at 50°C–60°C. By increasing the pre-cooling temperature, while meeting the requirements for forming a uniform and complete protective shell and controlling protein denaturation in the subsequent one-pass embrittlement treatment, cooling efficiency can be improved, thus increasing the granule preparation efficiency.

[0102] In this embodiment, after determining the pre-cooling temperature, the conditioned granules are cooled. A counter-current cooler is selected as the cooling equipment. By adjusting the inlet air temperature and air volume, the core temperature of the granules is reduced to the determined pre-cooling temperature.

[0103] In this embodiment, a high-temperature one-pass embrittlement treatment is used to convey the conditioned granules cooled to the pre-cooled temperature into a high-temperature drying device for high-temperature drying.

[0104] Specifically, in the high-temperature one-pass embrittlement treatment, the surface of the granules comes into instantaneous contact with the high-temperature airflow, causing surface moisture to evaporate rapidly. The surface starch and protein undergo a momentary gelatinization-solidification reaction under short-term high temperature, forming a uniformly thick and dense hardened shell. Pre-cooling creates a temperature buffer layer between the granule surface and the core, slowing heat transfer to the granule interior and effectively protecting heat-sensitive nutrients such as proteins and vitamins from high-temperature denaturation. Because the high-temperature one-pass embrittlement treatment is extremely short, lasting only 10–30 seconds, the heat is mainly concentrated in the shallow 0.3–0.5 mm layer of the granule surface. The internal temperature rise is minimal, ensuring that the core temperature does not exceed 60°C after treatment, far below the temperature threshold for whey protein denaturation and vitamin decomposition, thus maintaining the stability of the core proteins.

[0105] In this embodiment, after the one-pass embrittlement treatment is completed, the pellets are discharged from the discharge port of the processing chamber and rapidly cooled to room temperature by room temperature cold air to obtain the finished product of acidified milk pellets for beef calves.

[0106] The finished product meets the following inspection standards: pore size of 4mm, particle length of 1.5-2mm, hardness of 90-120N, and pulverization rate of ≤5%. After passing inspection, it is weighed, packaged, and stored in the warehouse.

[0107] In any of the above embodiments S1 to S6, the acidified milk pellets for calves also contain a compound acidifier. The compound acidifier is composed of citric acid, sodium butyrate and potassium diformate, with a mass ratio of 1:(1.3 to 2.9):(4.5 to 7.8).

[0108] A compound of citric acid, sodium butyrate, and potassium diformate in a mass ratio of 1:(1.3–2.9):(4.5–7.8) achieves a synergistic effect of rapid acidification, sustained antibacterial activity, and intestinal nutrition. Citric acid provides immediate acidification, sodium butyrate provides intestinal nutrition and repair, and potassium diformate provides end-to-end antibacterial protection. Insufficient or excessive proportions of these three components will disrupt this synergistic effect. If the amount of citric acid is too low, the acidification rate will be insufficient, and the gastric pH will not quickly drop to the appropriate range, affecting protein digestion. If the amount of sodium butyrate is too low, the intestinal development promotion effect will be insignificant. If the amount of potassium diformate is too low, the antibacterial spectrum and duration of action will be insufficient. Conversely, excessive use of any component not only increases costs but may also negatively impact calf feed intake due to over-acidification.

[0109] In any of the above embodiments, the formulation of acidified milk pellets for beef calves comprises the following raw materials: Corn 385–435 parts, soybean hulls 58–77 parts, molasses 19–29 parts, wheat bran 48–67 parts, wheat middlings 38–48 parts, soybean meal 250–270 parts, fermented soybean meal 48–58 parts, milk powder 38–67 parts, whey protein powder 10–19 parts, citric acid 0.9–1.3 parts, sodium butyrate 1.8–2.6 parts, potassium diformate 5.9–7.0 parts, grape seed extract 1.0–2.0 parts, brewer's yeast 2.0–4.0 parts, yeast cell wall 4.0–6.0 parts, mixed additives 8–10 parts.

[0110] After the above raw materials are classified and crushed to the corresponding particle size requirements according to the method described in S1, they are weighed according to the formula and put into the mixer in sequence and mixed evenly to obtain the initial viscous mixture, which then enters the subsequent preparation process S2 to S6 to finally obtain the finished product of acidified milk pellets for beef calves.

[0111] Example: This embodiment provides a method for preparing acidified milk pellets for beef calves using a preferred formula and complete process.

[0112] The formula, based on a total of 1000 parts, includes: 410 parts corn, 68 parts soybean hulls, 24 parts molasses, 58 parts wheat bran, 43 parts wheat middlings, 260 parts soybean meal, 53 parts fermented soybean meal, 53 parts milk powder, 15 parts whey protein powder, 1.1 parts citric acid, 2.2 parts sodium butyrate, 6.5 parts potassium diformate, 1.5 parts grape seed extract, 3.0 parts brewer's yeast, 5.0 parts yeast cell wall, and 9 parts mixed additives. The mixed additives consist of vitamins A, D3, E, B1, B2, and B6. 12 It is a compound of nicotinamide, copper methionine, manganese methionine, zinc methionine, manganese sulfate monohydrate, cobalt chloride, sodium selenite, yeast selenium, limestone powder, and rice husk powder in the conventional amounts required for calf nutrition.

[0113] Preparation process: S1. Corn, soybean hulls, wheat bran, and wheat middlings are ground to a mesh size of 30-40 with a passing rate of ≥85%; soybean meal and fermented soybean meal are ground to a mesh size of 40-60 with a passing rate of ≥90%; milk powder and whey protein powder are ground to a mesh size of 60-80 with a passing rate of ≥95%. After weighing according to the formula, the third component (excluding molasses) is first added to a twin-shaft paddle mixer and premixed for 150 seconds, then the second component is added and mixed for 100 seconds, then the first component is added and mixed for 80 seconds. Finally, preheated liquid molasses (45°C) is sprayed in in atomized form and mixed for another 150 seconds to obtain a preliminary viscous mixture. Its moisture content was measured to be 14.0%.

[0114] S2, according to the pre-established table of correspondence between moisture content and ideal gelatinization degree, the ideal gelatinization degree corresponding to a moisture content of 14.0% is 82%, which is the gelatinization degree that can be achieved when the particle pulverization rate is ≤5% under the conditions of a conditioning temperature of 65℃, a duration of 180s, and a steam addition of 8%. To ensure that the initially viscous mixture obtains a gelatinized modified material that is not completely gelatinized after conditioning treatment, and to reserve sufficient process margin for the secondary gelatinization in the subsequent first stage of conditioning and drying in S5, and to avoid irreversible loss caused by excessive cross-linking and the formation of insoluble polymers due to continuous heating during the drying stage in S5 after the single complete gelatinization in S3, this embodiment sets the target gelatinization degree to between 60% and 80% of the ideal gelatinization degree, specifically taking 70%, i.e., 82% × 70% ≈ 57%. This setting ensures that the target gelatinization degree of the initial viscous mixture is lower than the final gelatinization degree of the conditioned granules, that is, lower than the ideal complete gelatinization degree of the conditioned granules. At the end of S3 conditioning, the material is in a state that is not completely gelatinized. The remaining ungelatinized starch will be gradually gelatinized in the S5 drying stage, achieving the process goal of two-stage gelatinization.

[0115] S3, initial conditioning temperature set at 65℃, steam addition at 8%, initial duration 180s. Monitoring at various time points: at 60s, material temperature 62℃, gelatinization degree 63%; at 120s, temperature 64℃, gelatinization degree 71%; at 180s, temperature 66℃, gelatinization degree 76.5%. The real-time gelatinization degree differed from the target value by 5.5 percentage points (>3 percentage points), and the current temperature of 66℃ still had a margin from the 70℃ upper limit. The conditioning time was extended to 240s, while the conditioning temperature remained unchanged at 65℃. Continuing to run for 240s, the material temperature reached 67℃, and the gelatinization degree was 82.3%, falling within the allowable range of 82%±2% (80%~84%). The highest temperature throughout the process was 67℃, not exceeding the 70℃ safety upper limit. The optimal conditioning time of 240s was recorded, yielding the initially gelatinized material.

[0116] S4. Take the initial gelatinized material for insolubility testing and peak viscosity measurement. The insoluble polymer content is 2.5% (preset threshold 4.0%), and the peak viscosity is 1780 cP (preset lower limit 1500 cP). Both indicators are qualified, and the conditioning completion is judged to be qualified. Calculate the conditioning completion index G: The characteristic quantity of insoluble content is taken as the preset threshold divided by the actual value, i.e., 4.0% / 2.5% = 1.60, multiplied by the first weighting coefficient 0.5, resulting in 0.80; the characteristic quantity of peak viscosity is taken as the actual value divided by the lower limit, i.e., 1780 / 1500≈1.19, multiplied by the second weighting coefficient 0.5, resulting in 0.59; add the two, G = 0.80 + 0.59 = 1.39. G > 1, indicating that the conditioning completion is relatively ideal. Granulation is carried out using the preset granulation density, with a compression ratio set to 1:7, a ring die aperture of 4 mm, and a particle length of 1.8 mm, to obtain pre-formed granules.

[0117] S5, the porosity of the pre-formed granules was measured to be 32%, and the moisture content was 18.2%. The measured porosity (32%), moisture content (18.2%), and G-value (1.39) were input into the control system. The control system automatically retrieved the corresponding optimal drying temperature from a pre-established reference table and set it as the drying correction temperature. The reference table was established through a multi-level orthogonal experiment considering porosity, moisture content, and G-value, and was optimized using the granule pulverization rate, surface crack rate, and internal protein solubility retention rate after drying as comprehensive evaluation indicators. In this embodiment, the optimal drying temperature obtained from the table was 68℃. The pre-formed granules were fed into a fluidized bed dryer with an inlet air temperature set at 68℃, an outlet air temperature of approximately 55℃, a bed thickness of 40mm, and a material residence time of 8 minutes. During the drying process, hot air uniformly passed through the granule layer. The residual moisture inside the granules continued to participate in the starch gelatinization reaction under the action of heat. The remaining ungelatinized starch gradually underwent secondary gelatinization during the drying stage. Simultaneously, the granule moisture content decreased from 18.2% to 13.2%, reaching the conditioning and drying endpoint. After discharge, the fine powder is removed by a vibrating screen, yielding fully gelatinized conditioned granules.

[0118] S6. The surface hardness of the conditioned granules was measured to be 105N, within the preset hardness range of 90-120N. The granules were then pre-cooled at 45℃ to reduce the surface temperature to approximately 45℃. After cooling, the granules were introduced into a 150℃ high-temperature airflow for a one-time embrittlement treatment for 15 seconds. The instantaneous contact between the granule surface and the high-temperature airflow caused rapid evaporation of surface moisture, forming a dense, hardened shell. Simultaneously, the low-temperature core formed by the pre-cooling effectively blocked heat conduction, protecting internal heat-sensitive nutrients such as proteins from high-temperature denaturation. The finished product was obtained after cooling. The finished product had a pore size of 4mm, a particle length of 1.7mm, a surface hardness of 112N, a core hardness of 54N, a pulverization rate of 3.3%, and a protein solubility retention rate of 85%. All indicators met the standards.

[0119] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing acidified milk pellets for beef calves, characterized in that, include: Prepare the first component raw material, the second component raw material, and the third component raw material according to the preset ratio, and mix them evenly in sequence to obtain the initial viscous mixture; The moisture content of the initial viscous mixture is obtained to determine the target degree of gelatinization in the conditioning process; The conditioning time is determined based on the target degree of gelatinization in order to condition the initially viscous mixture and obtain the gelatinized modified material after conditioning. An insoluble test is performed on the gelatinized modified material to obtain insoluble polymerization characteristics. Based on the insoluble characteristics and gelatinization modification characteristics, the degree of conditioning completion is determined to adjust the granulation density of the granulation process in order to granulate and form pre-formed granules. The porosity and moisture content of the pre-formed granules are obtained, and the drying correction temperature is determined in combination with the degree of conditioning completion. The pre-formed granules are then subjected to a first-stage conditioning and drying process to obtain the conditioned granules. The surface hardness of the conditioned pellets is obtained to determine the pre-cooling temperature for the one-pass embrittlement treatment of the conditioned pellets. After cooling the conditioned pellets, a high-temperature one-pass embrittlement treatment is performed to obtain acidified milk pellets for beef calves.

2. The method for preparing acidified milk pellets for beef calves according to claim 1, characterized in that, The first component raw material is one or more of milk powder or whey protein powder, and the particle size of the first component raw material is greater than or equal to 95% passing through a 60-80 mesh standard sieve; The second component raw material is one or more of soybean meal or fermented soybean meal, and the particle size of the second component raw material is greater than or equal to 90% passing through a 40-60 mesh standard sieve; The third component raw material is one or more of corn, soybean hulls, molasses, wheat bran, and wheat middlings, and the particle size of the third component raw material is such that the passing rate through a 30-40 mesh standard sieve is greater than or equal to 85%.

3. The method for preparing acidified milk pellets for beef calves according to claim 1 or 2, characterized in that, The step of obtaining the moisture content of the initial viscous mixture to determine the target degree of gelatinization in the conditioning process includes: The degree of gelatinization that can be achieved by initial viscous mixtures with different moisture contents under fixed conditioning conditions is determined in advance, and the pulverization rate of each sample prepared into granules is detected. Using a powdering rate below a preset threshold as the standard condition, and based on the gelatinization degree corresponding to the standard sample, the target gelatinization degree at the corresponding moisture content is determined to establish the correspondence between moisture content and target gelatinization degree. Based on the moisture content of the material to be processed, the target degree of gelatinization for the conditioning process is determined according to the aforementioned correspondence.

4. The method for preparing acidified milk pellets for beef calves according to claim 3, characterized in that, The method of determining the conditioning time based on the target gelatinization degree to condition the initially viscous mixture includes: Set the initial duration, temperature, and steam addition amount for conditioning treatment to condition the initially viscous mixture; During the conditioning process, the conditioning parameters are adjusted based on the real-time gelatinization degree of the material, including one or more of the following methods: extending the conditioning time, increasing the conditioning temperature, and increasing the amount of steam added, until the real-time gelatinization degree reaches the allowable deviation range of the target gelatinization degree, thereby obtaining the gelatinized modified material.

5. The method for preparing acidified milk pellets for beef calves according to claim 4, characterized in that, Take the gelatinized modified material after conditioning treatment, dissolve and disperse it in warm water at 40-60℃, separate the insoluble matter by centrifugation, dry and weigh it, and calculate the insoluble polymer content as the insoluble polymer characteristic. The peak viscosity of the gelatinized modified material during the gelatinization process is measured as the gelatinization modification characteristic; The degree of conditioning completion is determined based on the content of the insoluble polymer and the peak viscosity. If the conditioner completion rate is deemed unqualified, the conditioner treatment process for the initial tack mixture will be adjusted. The process adjustments include one or more of the following: extending the conditioning time, increasing the conditioning temperature, and increasing the amount of steam added. After the conditioning completion is deemed qualified, granulation is performed using a preset granulation density to obtain the pre-formed granules.

6. The method for preparing acidified milk pellets for beef calves according to claim 5, characterized in that, The surface hardness of the conditioned granules is obtained, and the measured surface hardness is compared with a preset hardness range. The cooling temperature in the cooling process is determined based on the surface hardness, so that a temperature difference buffer layer is formed on the surface of the granular material during the one-pass embrittlement treatment.

7. The method for preparing acidified milk pellets for beef calves according to any one of claims 3-6, characterized in that, The acidified milk pellets for calves also contain compound acidifiers, functional additives, and mixed additives, including: The composite acidifying agent is one or more of citric acid, sodium butyrate, and potassium diformate; The functional additive is one or more of grape seed extract, brewer's yeast, and yeast cell wall. The mixed additives are one or more of the following: vitamin A, vitamin D3, vitamin E, vitamin B1, vitamin B2, vitamin B12, nicotinamide, copper methionine, manganese methionine, zinc methionine, manganese sulfate monohydrate, cobalt chloride, sodium selenite, yeast selenium, stone powder, and rice husk powder.

8. The method for preparing acidified milk pellets for beef calves according to claim 7, characterized in that, The composite acidifying agent is composed of citric acid, sodium butyrate and potassium diformate, in a mass ratio of 1:(1.3-2.9):(4.5-7.8).

9. The method for preparing acidified milk pellets for beef calves according to claim 8, characterized in that, The raw materials for the acidified milk pellets for beef calves consist of the following components: Based on a total of 1000 copies, Corn 385–435 parts, soybean hulls 58–77 parts, molasses 19–29 parts, wheat bran 48–67 parts, wheat middlings 38–48 parts, soybean meal 250–270 parts, fermented soybean meal 48–58 parts, milk powder 38–67 parts, whey protein powder 10–19 parts, citric acid 0.9–1.3 parts, sodium butyrate 1.8–2.6 parts, potassium diformate 5.9–7.0 parts, grape seed extract 1.0–2.0 parts, brewer's yeast 2.0–4.0 parts, yeast cell wall 4.0–6.0 parts, mixed additives 8–10 parts.

10. The method for preparing acidified milk pellets for beef calves according to claim 9, characterized in that, The acidified milk pellets for calves have a pore size of 4 mm, a particle diameter of 1.5-2 mm, a surface hardness of 90-120 N, a core hardness of 40-70 N, and a pulverization rate of ≤5%.

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