Pure Collagen Milk Powder and Preparation Method Thereof

Abstract

The invention relates to the technical field of collagen food. The pure collagen milk powder is prepared by concentrating and drying pure collagen milk, and the pure collagen milk is composed of the following raw materials in parts by weight: 10-80 parts of a pure collagen solution, 0.1-1 part of an emulsion stabilizer, 0.25-5 parts of white granulated sugar, 0.15-3 parts of salt, 0.01-0.5 part of a food flavor, and 20-90 parts of drinking water, wherein the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

Claims

1. A pure collagen milk powder, prepared by concentrating and drying pure collagen milk, wherein the pure collagen milk is composed of the following raw materials in parts by weight: TABLE-US-00002 pure collagen milk solution 10-80 parts emulsion stabilizer 0.1-1 part white granulated sugar 0.25-5 parts salt 0.15-3 parts food flavor 0.01-0.5 part drinking water 20-90 parts the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

2. The pure collagen milk powder according to claim 1, wherein a preparation method of the pure collagen solution comprises the following steps: a. pretreatment: washing 40-60 parts of animal skin, mechanically degreasing, cutting into strips, treating with alkali, rinsing for the first time, biologically degreasing and rinsing for the second time; b. boiling: placing the animal skin, degreased and rinsed in the step a, in water, heating to 90-100 C., and boiling for 5-10 minutes; c. mixing: heating 40-60 parts of drinking water to 40-55 C., adding 0.1-1.2 parts of a complex enzyme, and stirring to be uniform to obtain an enzyme solution; mincing the animal skin boiled in the step b, and placing into the enzyme solution, stirring to be uniform to obtain a mixture, wherein the complex enzyme is a mixture consisting of collagenase, pepsin, trypsin and flavourzyme; d. grinding: grinding the mixture obtained in the step c to obtain an animal skin collagen slurry; e. enzymatic hydrolysis: heating the animal skin collagen slurry obtained in the step d to 38-50 C., stirring and reacting for 3-5 hours to obtain an enzymatic hydrolyzate; and f. enzyme deactivation: heating the enzymatic hydrolysate obtained in the step e to 85-95 C., and carrying out enzyme deactivation for 10-20 minutes to obtain a pure collagen solution containing small molecule short-chain peptides.

3. The pure collagen milk powder according to claim 2, wherein the step a specifically comprises the following steps: a1. washing: putting 40-60 parts of fresh animal skin reaching the quarantine standard and having no drug residue into a stainless steel tank, unfreezing with drinking water, and washing; a2. mechanical degreasing: depilating, by an animal skin depilator, the animal skin washed in the step a1, and then degreasing the depilated animal skin by a degreasing machine; a3. cutting into strips: cutting the animal skin, degreased in the step a2, into animal skin strips having a width of 1-3 cm by using an animal skin cutting machine; a4. alkali treatment: putting the animal skin, cut into strips in the step a3, into a double mixing mixer, adding sodium carbonate with a mass fraction of 0.3%-0.7% for alkali treatment, stirring and mixing for 3-7 minutes; a5. primary rinsing: rinsing the animal skin, subjected to the alkali treatment in the step a4, with drinking water for 3-7 minutes, and then pouring the rinsing water out, and rinsing with drinking water again, and repeating the rinsing operation three times until the animal skin has no unpleasant odor or residual alkali odor; a7. secondary rinsing: rinsing the animal skin, subjected to the biological degreasing in step a6, with 38-55 C. hot water. the step b specifically comprises: putting into a stainless steel hanging basket the animal skin degreased and rinsed in the step a, and using a rail crane to put the stainless steel hanging basket with the animal skin into a jacketed kettle containing drinking water, and heating to 90-100 C., boiling for 5-10 minutes until the animal skin is cooked medium well, wherein the stainless steel hanging basket is lifted twice during the boiling; the step c specifically comprises: heating the above-mentioned parts by weight of drinking water to 40-55 C., adding the above-mentioned parts by weight of the complex enzyme, putting into a barrel with a mixer and stirring to be uniform, thus obtaining an enzyme solution; lifting the stainless steel hanging basket with animal skin in the step b from the jacketed kettle, conveying to the top of a meat mincer by the rail crane, opening the bottom of the stainless steel hanging basket to charge the animal skin into a hopper of the meat mincer, and mincing the animal skin with a perforated plate with a diameter of 0.3-0.5 cm to obtain animal skin granules; and allowing the minced animal skin granules to directly drop into the barrel with a mixer, and stirring to be uniform to obtain a mixture; the step d specifically comprises: putting the mixture obtained in the step c into a colloid mill with a fineness of 80 meshes for the first grinding, and then carrying out second grinding by using a colloid mill having a fineness of 200 meshes to obtain an animal skin collagen slurry under enzymatic hydrolysis.

4. The pure collagen milk powder according to claim 1, wherein each part of the emulsion stabilizer comprises the following raw materials in parts by weight: TABLE-US-00003 monoglyceride 2-5 parts sucrose ester 3-7 parts propylene glycol alginate 3-5 parts xanthan gum 2-7 parts guar gum 2-9 parts d-isoascorbate 0.5-0.8 parts trisodium phosphate 0.1-0.5 part

5. The pure collagen milk powder according to claim 1, wherein a preparation method of the pure collagen solution comprises the following steps: A. pretreatment of a pure collagen solution: carrying out testing, weighing, solution collection, degassing, filtering and cooling on the pure collagen solution; B. sterilization of the pure collagen solution: pasteurizing and cooling the pretreated pure collagen solution; C. material mixing for pure collagen milk: preheating the pasteurized and cooled pure collagen solution, adding remaining raw materials according to the weight ratio, and mixing; and D. sterilization of the pure collagen milk: carrying out UHT sterilization on the mixed pure collagen milk and then cooling.

6. The pure collagen milk powder according to claim 5, wherein the step A specifically comprises the following steps: A1. detection: detecting and standardizing the drug residue, fat content, solid content, collagen content and collagen molecular weight of the pure collagen solution respectively; A2. weighing: weighing the qualified pure collagen solution with a weighing scale A3. solution collection: collecting the weighed pure collagen solution through a pipeline; A4. degassing: degassing the pure collagen solution in the pipeline during the process of solution collection; A5. filtering: filtering the pure collagen solution in the pipeline during the process of the solution collection; A6. cooling: cooling the pure collagen solution after solution collection to 1-6 C.; and A7. storage: temporarily storing the cooled pure collagen solution in a milk bin for less than 12 hours; the step B specifically comprises the following steps: B1. preheating: preheating the pretreated pure collagen solution to 50-55 C.; B2. cleaning: remove impurities from the preheated pure collagen solution; B3. flashing: heating the cleaned pure collagen solution to 65-70 C. for flashing; B4. pasteurization: holding the temperature of the flashed pure collagen solution at 80-90 C. for 10-20 seconds for pasteurization; B5. cooling: cooling the pasteurized pure collagen solution to 6 C. or below; and B6. storage: storing the cooled pure collagen solution at a temperature of 1-6 C.; the step C specifically comprises the following steps: C1. preheating: opening a pure collagen solution pipeline, and preheating a part of the above-mentioned parts by weight of the pure collagen solution to 55-60 C.; C2. mixing: uniformly adding the above parts by weight of the emulsion stabilizer, the white granulated sugar, the salt, the food flavor and the drinking water to the preheated pure collagen solution through a feeder to obtain a mixture; C3. heat preservation: carrying out heat preservation on the mixture for 10-20 minutes through a heat preservation tube. C4. filtering: after heat preservation, filtering the mixture through a double filter; C5. homogenizing: homogenizing the filtered mixture under a pressure of 170-190 bar; C6. mixing: when the homogenized mixture passes through a four-way valve, starting a pure collagen solution blending line, mixing the mixture with another part of the pure collagen solution, and then entering a semi-finished product tank, and controlling the ratio of the mixture to the other part of the pure collagen solution to 1:4-6, stirring for 10-20 minutes, sampling and detecting to obtain pure collagen milk; C7. cooling: cooling the mixed pure collagen milk to 6 C. or below; and C8. storage: storing the cooled pure collagen milk for less than 8 hours at a temperature of less than 10 C.; the step D specifically comprises the following steps: D1. preheating: preheating the mixed pure collagen milk to 50-55 C.; D2. degassing: degassing the preheated pure collagen milk; D3. homogenizing: homogenizing the degassed pure collagen milk under a pressure of 190-210 bar at a temperature of 70-75 C.; D4. UHT sterilization: holding the temperature of the homogenized pure collagen milk at 136-142 C. for 3-5 seconds for UHT sterilization; and D5. storage: storing the sterilized pure collagen milk in a sterile tank for less than 48 hours at a temperature of less than 30 C.

7. The preparation method of a pure collagen milk powder according to claim 1, comprising the following steps: (1) vacuum concentration of pure collagen milk: concentrating pure collagen milk in vacuum, wherein the obtained pure collagen milk has a solid content of 48%-50%; (2) first-stage drying of the pure collagen milk: spray-drying the pure collagen milk concentrated in vacuum, wherein the obtained pure collagen milk powder has a moisture of 7%-8%; (3) second-stage drying of the pure collagen milk powder: fluidized bed drying and cooling the pure collagen milk powder subjected to the first-stage drying, wherein the obtained pure collagen milk powder has a moisture of 3%-5%; (4) post-treatment: discharging, sieving and drying the pure collagen milk powder; and (5) carrying out inspection and packaging.

8. The preparation method of a pure collagen milk powder according to claim 7, wherein the step (1) specifically comprises the following steps: (1.1) equipment preparation: during the operation of equipment, controlling the steam supply pressure to 1.0-1.2 MPa, and controlling the pressure of a hot-pressure pump to 0.4-0.6 MPa; (1.2) production control: carrying out vacuum concentration by using a three-effect downstream falling film evaporator, wherein first-effect vacuum concentration is carried under the following conditions: heating temperature of 70-83 C., separation chamber temperature of 63-75 C., heater vacuum degree of 0.035-0.050 MPa, and separation chamber vacuum degree of 0.045-0.068 MPa; second-effect vacuum concentration is carried under the following conditions: heating temperature of 60-75 C., separation chamber temperature of 55-65 C., heater vacuum degree of 0.045-0.060 MPa, and separation chamber vacuum degree of 0.060-0.075 MPa; second-effect vacuum concentration is carried under the following conditions: heating temperature of 55-68 C., separation chamber temperature of 45-55 C., heater vacuum degree of 0.055-0.070 MPa, separation chamber vacuum degree of 0.078-0.085 MPa, condenser vacuum degree of 0.078-0.085 MPa; (1.3) Detection: the pure collagen milk obtained after vacuum concentration has a milk solid content of 48%-50% and a milk concentration of 12-25B.

9. The preparation method of a pure collagen milk powder according to claim 7, wherein the step (2) specifically comprises the following steps: (2.1) disinfection of equipment: injecting hot water into the balancing tank before power-on, cleaning a high-pressure pump, a circulation pipeline and the balancing tank, holding the temperature of hot water at 90-100 C., and disinfecting for 10-20 minutes; (2.2) equipment preparation: When a spray drying tower is powered on, powering on an induced draft fan, an air blower, a fluidized bed fan, a Roots blower, a powder conveyor, and a powder blowing valve sequentially, and then adjusting an air valve of the induced draft fan to form a negative pressure state in the drying tower, and when the negative pressure is 60 Pa to 20 Pa, closing an air valve of the fluidized bed fan to the minimum state; (2.3) spray drying: after the pure collagen milk concentrated in vacuum enters the balancing tank, when detecting that the concentration of concentrated milk is 12-25 B and the temperature is 40-55 C., starting to feed materials, gradually increasing the pressure of the high-pressure pump and controlling the pressure of the high-pressure pump to 5-18 MPa, further controlling an inlet air temperature to 165-195 C., controlling an exhaust air temperature to 75-90 C., and controlling the pressure of the Roots blower to 0.01-0.02 MPa; (2.4) detection: the pure collagen milk powder obtained after spray drying has a moisture of 7%-8%.

10. The preparation method of a pure collagen milk powder according to claim 7, wherein The step D specifically includes the following steps: (3.1) pressure balance: when the pure collagen milk powder falls into the fluidized bed, adjusting the pressure in the fluidized bed by adjusting an air inlet volume and an exhaust air volume of the fluidized bed, so that the pressure in the fluidized bed keeps balance with the pressure in the drying tower; (3.2) hot air drying: adjusting the inlet air temperatures of stages I, II and III of the fluidized bed to 60-70 C., 40-60 C., and 25 C., respectively; and (3.3) detection: after drying and cooling by using the fluidized bed, the obtained pure collagen milk powder has a moisture of 3%-5%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0134] For understanding of those skilled in the art, the invention will be further described in conjunction with embodiments, and the embodiments mentioned are not intended to limit the invention.

Embodiment 1

[0135] A pure collagen milk powder prepared by concentrating and drying pure collagen milk, the pure collagen milk being composed of the following raw materials in parts by weight: 10 parts of a pure collagen solution, 0.1 part of an emulsion stabilizer, 0.25 parts of white granulated sugar, 0.15 parts of salt, 0.01 part of a food flavor, and 20 parts of drinking water, wherein the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

[0136] The preparation method of a pure collagen solution comprises the following steps:

[0137] a. pretreatment: washing 40 parts of pigskin, mechanically degreasing, cutting into strips, treating with alkali, rinsing for the first time, biologically degreasing and rinsing for the second time;

[0138] a1. washing: putting 40 parts of fresh pigskin reaching the quarantine standard and having no drug residue into a stainless steel tank, unfreezing with drinking water, and washing;

[0139] a2. mechanical degreasing: depilating, by a pigskin depilator, the pigskin washed in the step a1, and then degreasing the depilated pigskin by a degreasing machine;

[0140] a3. cutting into strips: cutting the pigskin, degreased in the step a2, into pigskin strips having a width of 1 cm by using a pigskin cutting machine;

[0141] a4. alkali treatment: putting the pigskin, cut into strips in the step a3, into a double mixing mixer, adding sodium carbonate with a mass fraction of 0.3% for alkali treatment, stirring and mixing for 3 minutes;

[0142] a5. primary rinsing: rinsing the pigskin, subjected to the alkali treatment in the step a4, with drinking water for 3 minutes, and then pouring the rinsing water out, and rinsing with drinking water again, and repeating the rinsing operation three times until the pigskin has no unpleasant odor or residual alkali odor;

[0143] a6. biological degreasing: degreasing the pigskin, rinsed in the step a5, in 38 C. hot water containing 0.1% by weight of lipase for 3 hours; and

[0144] a7. secondary rinsing: rinsing the pigskin, subjected to the biological degreasing in step a6, with 38 C. hot water.

[0145] b. boiling: putting into a stainless steel hanging basket the pigskin degreased and rinsed in the step a, and using a rail crane to put the stainless steel hanging basket with the the pigskin into a jacketed kettle containing drinking water, and heating to 90 C., boiling for 10 minutes until the pigskin is cooked medium well, wherein the stainless steel hanging basket is lifted twice during the boiling;

[0146] c. mixing: heating 40 parts of drinking water to 40 C., adding 0.1 part of a complex enzyme, putting into a barrel with a mixer, stirring to be uniform, thus obtaining an enzyme solution; lifting the stainless steel hanging basket with the pigskin in the step b from the jacketed kettle, conveying to the top of a meat mincer by the rail crane, opening the bottom of the stainless steel hanging basket to charge the pigskin into a hopper of the meat mincer, and mincing the pigskin with a perforated plate with a diameter of 0.3 cm to obtain pigskin granules; and allowing the minced pigskin granules to directly drop into the barrel with a mixer, and stirring to be uniform to obtain a mixture, wherein the complex enzyme is a mixture consisting of collagenase, pepsin, trypsin and flavour protease in a weight ratio of 0.5:1:0.8:1.5;

[0147] d. putting the mixture obtained in the step c into a colloid mill with a fineness of 80 meshes for the first grinding, and then carrying out second grinding by using a colloid mill having a fineness of 200 meshes to obtain a pigskin collagen slurry under enzymatic hydrolysis;

[0148] e. enzymatic hydrolysis: heating the pigskin collagen slurry obtained in the step d to 40 C., stirring and reacting for 5 hours to obtain an enzymatic hydrolyzate; and

[0149] f. enzyme deactivation: heating the enzymatic hydrolysate obtained in the step e to 85 C., and carrying out enzyme deactivation for 20 minutes to obtain a pure collagen solution containing small molecule short-chain peptides having a molecular weight of 1000-4000 Daltons.

[0150] Each part of the emulsion stabilizer comprises the following raw materials in parts by weight: 2 parts of monoglyceride, 3 parts of sucrose ester, 3 parts of propylene glycol alginate, 2 parts of xanthan gum, 2 parts of guar gum, 0.5 part of d-isoascorbate, and 0.1 part of trisodium phosphate.

[0151] The preparation method of a pure collagen milk comprises the following steps:

[0152] A. pretreatment of a pure collagen solution: carrying out testing, weighing, solution collection, degassing, filtering and cooling on the pure collagen solution;

[0153] A1. detection: detecting and standardizing the drug residue, fat content, solid content, collagen content and collagen molecular weight of the pure collagen solution respectively;

[0154] A2. weighing: weighing the qualified pure collagen solution with a weighing scale;

[0155] A3. solution collection: collecting the weighed pure collagen solution through a pipeline;

[0156] A4. degassing: degassing the pure collagen solution in the pipeline during the process of solution collection;

[0157] A5. filtering: filtering the pure collagen solution in the pipeline during the process of the solution collection;

[0158] A6. cooling: cooling the pure collagen solution after solution collection to 1 C.; and

[0159] A7. storage: temporarily storing the cooled pure collagen solution in a milk bin for less than 12 hours;

[0160] B. sterilization of the pure collagen solution: pasteurizing and cooling the pretreated pure collagen solution;

[0161] B1. preheating: preheating the pretreated pure collagen solution to 50 C.;

[0162] B2. cleaning: remove impurities from the preheated pure collagen solution;

[0163] B3. flashing: heating the cleaned pure collagen solution to 65 C. for flashing;

[0164] B4. pasteurization: holding the temperature of the flashed pure collagen solution at 80 C. for 20 seconds for pasteurization;

[0165] B5. cooling: cooling the pasteurized pure collagen solution to 6 C. or below; and

[0166] B6. storage: storing the cooled pure collagen solution at a temperature of 1 C.;

[0167] C. material mixing for pure collagen milk: preheating the pasteurized and cooled pure collagen solution, adding remaining raw materials according to the weight ratio, and mixing; and

[0168] C1. preheating: opening a pure collagen solution pipeline, and preheating a part of the above-mentioned parts by weight of the pure collagen solution to 55 C.;

[0169] C2. mixing: uniformly adding the above parts by weight of the emulsion stabilizer, the white granulated sugar, the salt, the food flavor and the drinking water to the preheated pure collagen solution through a feeder to obtain a mixture;

[0170] C3. heat preservation: carrying out heat preservation on the mixture for 10 minutes through a heat preservation tube.

[0171] C4. filtering: after heat preservation, filtering the mixture through a double filter;

[0172] C5. homogenizing: homogenizing the filtered mixture under a pressure of 170 bar;

[0173] C6. mixing: when the homogenized mixture passes through a four-way valve, is starting a pure collagen solution blending line, mixing the mixture with another part of the pure collagen solution, and then entering a semi-finished product tank, and controlling the ratio of the mixture to the other part of the pure collagen solution to 1:4, stirring for 10 minutes, sampling and detecting to obtain pure collagen milk;

[0174] C7. cooling: cooling the mixed pure collagen milk to 6 C. or below; and

[0175] C8. storage: storing the cooled pure collagen milk for less than 8 hours at a temperature of less than 10 C.;

[0176] D. sterilization of the pure collagen milk: carrying out UHT sterilization on the mixed pure collagen milk and then cooling.

[0177] D1. preheating: preheating the mixed pure collagen milk to 50 C.;

[0178] D2. degassing: degassing the preheated pure collagen milk;

[0179] D3. homogenizing: homogenizing the degassed pure collagen milk under a pressure of 190 bar at a temperature of 70 C.;

[0180] D4. UHT sterilization: holding the temperature of the homogenized pure collagen milk at 136 C. for 5 seconds for UHT sterilization; and

[0181] D5. storage: storing the sterilized pure collagen milk in a sterile tank for less than 48 hours at a temperature of less than 30 C.

[0182] A preparation method of a pure collagen milk powder, comprising the following steps:

[0183] (1) vacuum concentration of pure collagen milk: concentrating pure collagen milk in vacuum, wherein the obtained pure collagen milk has a solid content of 48%;

[0184] (1.1) equipment preparation: during the operation of equipment, controlling the steam supply pressure to 1.0 MPa, and controlling the pressure of a hot-pressure pump to 0.4 MPa;

[0185] (1.2) production control: carrying out vacuum concentration by using a three-effect downstream falling film evaporator, wherein

[0186] first-effect vacuum concentration is carried under the following conditions: heating temperature of 70 C., separation chamber temperature of 63 C., heater vacuum degree of 0.035 MPa, and separation chamber vacuum degree of 0.045 MPa;

[0187] second-effect vacuum concentration is carried under the following conditions: heating temperature of 60 C., separation chamber temperature of 55 C., heater vacuum degree of 0.045 MPa, and separation chamber vacuum degree of 0.060 MPa;

[0188] third-effect vacuum concentration is carried under the following conditions: heating temperature of 55 C., separation chamber temperature of 45 C., heater vacuum degree of 0.055 MPa, separation chamber vacuum degree of 0.078 MPa, condenser vacuum degree of 0.078 MPa; and

[0189] (1.3) Detection: the pure collagen milk obtained after vacuum concentration has a milk solid content of 48% and a milk concentration of 1213e.

[0190] (2) first-stage drying of the pure collagen milk: spray-drying the pure collagen milk concentrated in vacuum, wherein the obtained pure collagen milk powder has a moisture of 7%;

[0191] (2.1) disinfection of equipment: injecting hot water into the balancing tank before power-on, cleaning a high-pressure pump, a circulation pipeline and the balancing tank, holding the temperature of hot water at 90 C., and disinfecting for 10 minutes;

[0192] (2.2) equipment preparation: When a spray drying tower is powered on, powering on an induced draft fan, an air blower, a fluidized bed fan, a Roots blower, a powder conveyor, and a powder blowing valve sequentially, and then adjusting an air valve of the induced draft fan to form a negative pressure state in the drying tower, and when the negative pressure is 60 Pa, closing an air valve of the fluidized bed fan to the minimum state;

[0193] (2.3) spray drying: after the pure collagen milk concentrated in vacuum enters the balancing tank, when detecting that the concentration of concentrated milk is 12 Be and the temperature is 40 C., starting to feed materials, gradually increasing the pressure of the high-pressure pump and controlling the pressure of the high-pressure pump to 5 MPa, further controlling an inlet air temperature to 165 C., controlling an exhaust air temperature to 75 C., and controlling the pressure of the Roots blower to 0.01 MPa;

[0194] (2.4) detection: the pure collagen milk powder obtained after spray drying has a moisture of 7%.

[0195] (3) second-stage drying of the pure collagen milk powder: fluidized bed drying and cooling the pure collagen milk powder subjected to the first-stage drying, wherein the obtained pure collagen milk powder has a moisture of 3%;

[0196] (3.1) pressure balance: when the pure collagen milk powder falls into the fluidized bed, adjusting the pressure in the fluidized bed by adjusting an air inlet volume and an exhaust air volume of the fluidized bed, so that the pressure in the fluidized bed keeps balance with the pressure in the drying tower;

[0197] (3.2) hot air drying: adjusting the inlet air temperatures of stages I, II and III of the fluidized bed to 60 C., 40 C., 20 C., respectively; and

[0198] (3.3) detection: after drying and cooling by using the fluidized bed, the obtained pure collagen milk powder has a moisture of 3%.

[0199] (4) post-treatment: discharging, sieving and drying the pure collagen milk powder; and

[0200] (5) carrying out inspection and packaging.

Embodiment 2

[0201] A pure collagen milk powder prepared by concentrating and drying pure collagen milk, the pure collagen milk being composed of the following raw materials in parts by weight: 300 parts of a pure collagen solution, 0.3 part of an emulsion stabilizer, 2 parts of white granulated sugar, 1 parts of salt, 0.1 part of a food flavor, and 40 parts of drinking water, wherein the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

[0202] The preparation method of a pure collagen solution comprises the following steps:

[0203] a. pretreatment: washing 45 parts of pigskin, mechanically degreasing, cutting into strips, treating with alkali, rinsing for the first time, biologically degreasing and rinsing for the second time;

[0204] a1. washing: putting 45 parts of fresh cowhide reaching the quarantine standard and having no drug residue into a stainless steel tank, unfreezing with drinking water, and washing;

[0205] a2. mechanical degreasing: depilating, by a cowhide depilator, the cowhide washed in the step a1, and then degreasing the depilated cowhide by a degreasing machine;

[0206] a3. cutting into strips: cutting the cowhide, degreased in the step a2, into cowhide strips having a width of 1.5 cm by using a cowhide cutting machine;

[0207] a4. alkali treatment: putting the cowhide, cut into strips in the step a3, into a double mixing mixer, adding sodium carbonate with a mass fraction of 0.4% for alkali treatment, stirring and mixing for 4 minutes;

[0208] a5. primary rinsing: rinsing the cowhide, subjected to the alkali treatment in the step a4, with drinking water for 4 minutes, and then pouring the rinsing water out, and rinsing with drinking water again, and repeating the rinsing operation three times until the cowhide has no unpleasant odor or residual alkali odor;

[0209] a6. biological degreasing: degreasing the cowhide, rinsed in the step a5, in 42 C. hot water containing 0.2% by weight of lipase for 3.5 hours; and

[0210] a7. secondary rinsing: rinsing the cowhide, subjected to the biological degreasing in step a6, with 42 C. hot water.

[0211] b. boiling: putting into a stainless steel hanging basket the pigskin degreased and rinsed in the step a, and using a rail crane to put the stainless steel hanging basket with the the pigskin into a jacketed kettle containing drinking water, and heating to 92 C., boiling for 8 minutes until the pigskin is cooked medium well, wherein the stainless steel hanging basket is lifted twice during the boiling;

[0212] c. mixing: heating 45 parts of drinking water to 45 C., adding 0.6 part of a complex enzyme, putting into a barrel with a mixer, stirring to be uniform, thus obtaining an enzyme solution; lifting the stainless steel hanging basket with the pigskin in the step b from the jacketed kettle, conveying to the top of a meat mincer by the rail crane, opening the bottom of the stainless steel hanging basket to charge the pigskin into a hopper of the meat mincer, and mincing the pigskin with a perforated plate with a diameter of 0.35 cm to obtain pigskin granules; and allowing the minced pigskin granules to directly drop into the barrel with a mixer, and stirring to be uniform to obtain a mixture, wherein the complex enzyme is a mixture consisting of collagenase, pepsin, trypsin and flavour protease in a weight ratio of 0.8:1:0.9:1.8;

[0213] d. putting the mixture obtained in the step c into a colloid mill with a fineness of 80 meshes for the first grinding, and then carrying out second grinding by using a colloid mill having a fineness of 200 meshes to obtain a pigskin collagen slurry under enzymatic hydrolysis;

[0214] e. enzymatic hydrolysis: heating the pigskin collagen slurry obtained in the step d to 42 C., stirring and reacting for 4.5 hours to obtain an enzymatic hydrolyzate; and

[0215] f. enzyme deactivation: heating the enzymatic hydrolysate obtained in the step e to 88 C., and carrying out enzyme deactivation for 18 minutes to obtain a pure collagen solution containing small molecule short-chain peptides having a molecular weight of 1000-4000 Daltons.

[0216] Each part of the emulsion stabilizer comprises the following raw materials in parts by weight: 6 parts of monoglyceride, 7 parts of sucrose ester, 3.5 parts of propylene glycol alginate, 3 parts of xanthan gum, 4 parts of guar gum, 0.6 part of d-isoascorbate, and 0.2 part of trisodium phosphate.

[0217] The preparation method of a pure collagen milk comprises the following steps:

[0218] A. pretreatment of a pure collagen solution: carrying out testing, weighing, solution collection, degassing, filtering and cooling on the pure collagen solution;

[0219] A1. detection: detecting and standardizing the drug residue, fat content, solid content, collagen content and collagen molecular weight of the pure collagen solution respectively;

[0220] A2. weighing: weighing the qualified pure collagen solution with a weighing scale

[0221] A3. solution collection: collecting the weighed pure collagen solution through a pipeline;

[0222] A4. degassing: degassing the pure collagen solution in the pipeline during the process of solution collection;

[0223] A5. filtering: filtering the pure collagen solution in the pipeline during the process of the solution collection;

[0224] A6. cooling: cooling the pure collagen solution after solution collection to 2 C.; and

[0225] A7. storage: temporarily storing the cooled pure collagen solution in a milk bin for less than 12 hours;

[0226] B. sterilization of the pure collagen solution: pasteurizing and cooling the pretreated pure collagen solution;

[0227] B1. preheating: preheating the pretreated pure collagen solution to 51 C.;

[0228] B2. cleaning: remove impurities from the preheated pure collagen solution;

[0229] B3. flashing: heating the cleaned pure collagen solution to 66 C. for flashing;

[0230] B4. pasteurization: holding the temperature of the flashed pure collagen solution at 82 C. for 18 seconds for pasteurization;

[0231] B5. cooling: cooling the pasteurized pure collagen solution to 6 C. or below; and

[0232] B6. storage: storing the cooled pure collagen solution at a temperature of 2 C.;

[0233] C. material mixing for pure collagen milk: preheating the pasteurized and cooled pure collagen solution, adding remaining raw materials according to the weight ratio, and mixing; and

[0234] C1. preheating: opening a pure collagen solution pipeline, and preheating a part of the above-mentioned parts by weight of the pure collagen solution to 56 C.;

[0235] C2. mixing: uniformly adding the above parts by weight of the emulsion stabilizer, the white granulated sugar, the salt, the food flavor and the drinking water to the preheated pure collagen solution through a feeder to obtain a mixture;

[0236] C3. heat preservation: carrying out heat preservation on the mixture for 12 minutes through a heat preservation tube.

[0237] C4. filtering: after heat preservation, filtering the mixture through a double filter;

[0238] C5. homogenizing: homogenizing the filtered mixture under a pressure of 175 bar;

[0239] C6. mixing: when the homogenized mixture passes through a four-way valve, starting a pure collagen solution blending line, mixing the mixture with another part of the pure collagen solution, and then entering a semi-finished product tank, and controlling the ratio of the mixture to the other part of the pure collagen solution to 1:4.5, stirring for 12 minutes, sampling and detecting to obtain pure collagen milk;

[0240] C7. cooling: cooling the mixed pure collagen milk to 6 C. or below; and

[0241] C8. storage: storing the cooled pure collagen milk for less than 8 hours at a temperature of less than 10 C.;

[0242] D. sterilization of the pure collagen milk: carrying out UHT sterilization on the mixed pure collagen milk and then cooling.

[0243] D1. preheating: preheating the mixed pure collagen milk to 51 C.;

[0244] D2. degassing: degassing the preheated pure collagen milk;

[0245] D3. homogenizing: homogenizing the degassed pure collagen milk under a pressure of 195 bar at a temperature of 71 C.;

[0246] D4. UHT sterilization: holding the temperature of the homogenized pure collagen milk at 138 C. for 4.5 seconds for UHT sterilization; and

[0247] D5. storage: storing the sterilized pure collagen milk in a sterile tank for less than 48 hours at a temperature of less than 30 C.

[0248] A preparation method of a pure collagen milk powder, comprising the following steps:

[0249] (1) vacuum concentration of pure collagen milk: concentrating pure collagen milk in vacuum, wherein the obtained pure collagen milk has a solid content of 48.5%;

[0250] (1.1) equipment preparation: during the operation of equipment, controlling the steam supply pressure to 1.1 MPa, and controlling the pressure of a hot-pressure pump to 0.5 MPa;

[0251] (1.2) production control: carrying out vacuum concentration by using a three-effect downstream falling film evaporator, wherein

[0252] first-effect vacuum concentration is carried under the following conditions: heating temperature of 74 C., separation chamber temperature of 66 C., heater vacuum degree of 0.038 MPa, and separation chamber vacuum degree of 0.050 MPa;

[0253] second-effect vacuum concentration is carried under the following conditions: heating temperature of 64 C., separation chamber temperature of 58 C., heater vacuum degree of 0.048 MPa, and separation chamber vacuum degree of 0.064 MPa;

[0254] third-effect vacuum concentration is carried under the following conditions: heating temperature of 58 C., separation chamber temperature of 48 C., heater vacuum degree of 0.080 MPa, separation chamber vacuum degree of 0.078-0.085 MPa, condenser vacuum degree of 0.080 MPa; and

[0255] (1.3) Detection: the pure collagen milk obtained after vacuum concentration has a milk solid content of 48.5% and a milk concentration of 15B.

[0256] (2) first-stage drying of the pure collagen milk: spray-drying the pure collagen milk concentrated in vacuum, wherein the obtained pure collagen milk powder has a moisture of 7.5%;

[0257] (2.1) disinfection of equipment: injecting hot water into the balancing tank before power-on, cleaning a high-pressure pump, a circulation pipeline and the balancing tank, holding the temperature of hot water at 92 C., and disinfecting for 12 minutes;

[0258] (2.2) equipment preparation: When a spray drying tower is powered on, powering on an induced draft fan, an air blower, a fluidized bed fan, a Roots blower, a powder conveyor, and a powder blowing valve sequentially, and then adjusting an air valve of the induced draft fan to form a negative pressure state in the drying tower, and when the negative pressure is 50 Pa, closing an air valve of the fluidized bed fan to the minimum state;

[0259] (2.3) spray drying: after the pure collagen milk concentrated in vacuum enters the balancing tank, when detecting that the concentration of concentrated milk is 15 Be and the temperature is 44 C., starting to feed materials, gradually increasing the pressure of the high-pressure pump and controlling the pressure of the high-pressure pump to 8 MPa, further controlling an inlet air temperature to 175 C., controlling an exhaust air temperature to 78 C., and controlling the pressure of the Roots blower to 0.02 MPa;

[0260] (2.4) detection: the pure collagen milk powder obtained after spray drying has a moisture of 7.5%.

[0261] (3) second-stage drying of the pure collagen milk powder: fluidized bed drying and cooling the pure collagen milk powder subjected to the first-stage drying, wherein the obtained pure collagen milk powder has a moisture of 3.5%;

[0262] (3.1) pressure balance: when the pure collagen milk powder falls into the fluidized bed, adjusting the pressure in the fluidized bed by adjusting an air inlet volume and an exhaust air volume of the fluidized bed, so that the pressure in the fluidized bed keeps balance with the pressure in the drying tower;

[0263] (3.2) hot air drying: adjusting the inlet air temperatures of stages I, II and III of the fluidized bed to 60 C., 42 C., 21 C., respectively; and

[0264] (3.3) detection: after drying and cooling by using the fluidized bed, the obtained pure collagen milk powder has a moisture of 3.5%.

[0265] (4) post-treatment: discharging, sieving and drying the pure collagen milk powder; and

[0266] (5) carrying out inspection and packaging.

Embodiment 3

[0267] A pure collagen milk powder prepared by concentrating and drying pure collagen milk, the pure collagen milk being composed of the following raw materials in parts by weight: 45 parts of a pure collagen solution, 0.5 part of an emulsion stabilizer, 3 parts of white granulated sugar, 2 parts of salt, 0.2 part of a food flavor, and 55 parts of drinking water, wherein the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

[0268] The preparation method of a pure collagen solution comprises the following steps:

[0269] a. pretreatment: washing 50 parts of sheepskin, mechanically degreasing, cutting into strips, treating with alkali, rinsing for the first time, biologically degreasing and rinsing for the second time;

[0270] a1. washing: putting 50 parts of fresh sheepskin reaching the quarantine standard and having no drug residue into a stainless steel tank, unfreezing with drinking water, and washing;

[0271] a2. mechanical degreasing: depilating, by a sheepskin depilator, the sheepskin washed in the step a1, and then degreasing the depilated sheepskin by a degreasing machine;

[0272] a3. cutting into strips: cutting the sheepskin, degreased in the step a2, into sheepskin strips having a width of 2 cm by using a sheepskin cutting machine;

[0273] a4. alkali treatment: putting the sheepskin, cut into strips in the step a3, into a double mixing mixer, adding sodium carbonate with a mass fraction of 0.5% for alkali treatment, stirring and mixing for 5 minutes;

[0274] a5. primary rinsing: rinsing the sheepskin, subjected to the alkali treatment in the step a4, with drinking water for 5 minutes, and then pouring the rinsing water out, and rinsing with drinking water again, and repeating the rinsing operation three times until the sheepskin has no unpleasant odor or residual alkali odor;

[0275] a6. biological degreasing: degreasing the sheepskin, rinsed in the step a5, in 45 C. hot water containing 0.3% by weight of lipase for 4 hours; and

[0276] a7. secondary rinsing: rinsing the sheepskin, subjected to the biological degreasing in step a6, with 48 C. hot water.

[0277] b. boiling: putting into a stainless steel hanging basket the pigskin degreased and rinsed in the step a, and using a rail crane to put the stainless steel hanging basket with the the pigskin into a jacketed kettle containing drinking water, and heating to 95 C., boiling for 7 minutes until the pigskin is cooked medium well, wherein the stainless steel hanging basket is lifted twice during the boiling;

[0278] c. mixing: heating 50 parts of drinking water to 48 C., adding 0.8 part of a complex enzyme, putting into a barrel with a mixer, stirring to be uniform, thus obtaining an enzyme solution; lifting the stainless steel hanging basket with the pigskin in the step b from the jacketed kettle, conveying to the top of a meat mincer by the rail crane, opening the bottom of the stainless steel hanging basket to charge the pigskin into a hopper of the meat mincer, and mincing the pigskin with a perforated plate with a diameter of 0.4 cm to obtain pigskin granules; and allowing the minced pigskin granules to directly drop into the barrel with a mixer, and stirring to be uniform to obtain a mixture, wherein the complex enzyme is a mixture consisting of collagenase, pepsin, trypsin and flavour protease in a weight ratio of 1:1:1:2;

[0279] d. putting the mixture obtained in the step c into a colloid mill with a fineness of 80 meshes for the first grinding, and then carrying out second grinding by using a colloid mill having a fineness of 200 meshes to obtain a pigskin collagen slurry under enzymatic hydrolysis;

[0280] e. enzymatic hydrolysis: heating the pigskin collagen slurry obtained in the step d to 45 C., stirring and reacting for 4 hours to obtain an enzymatic hydrolyzate; and

[0281] f. enzyme deactivation: heating the enzymatic hydrolysate obtained in the step e to 90 C., and carrying out enzyme deactivation for 15 minutes to obtain a pure collagen solution containing small molecule short-chain peptides having a molecular weight of 1000-4000 Daltons.

[0282] Each part of the emulsion stabilizer comprises the following raw materials in parts by weight: 3.5 parts of monoglyceride, 5 parts of sucrose ester, 4 parts of propylene glycol alginate, 4.5 parts of xanthan gum, 5.5 parts of guar gum, 0.65 part of d-isoascorbate, and 0.3 part of trisodium phosphate.

[0283] The preparation method of a pure collagen milk comprises the following steps:

[0284] A. pretreatment of a pure collagen solution: carrying out testing, weighing, solution collection, degassing, filtering and cooling on the pure collagen solution;

[0285] A1. detection: detecting and standardizing the drug residue, fat content, solid content, collagen content and collagen molecular weight of the pure collagen solution respectively;

[0286] A2. weighing: weighing the qualified pure collagen solution with a weighing scale

[0287] A3. solution collection: collecting the weighed pure collagen solution through a pipeline;

[0288] A4. degassing: degassing the pure collagen solution in the pipeline during the process of solution collection;

[0289] A5. filtering: filtering the pure collagen solution in the pipeline during the process of the solution collection;

[0290] A6. cooling: cooling the pure collagen solution after solution collection to 3 C.; and

[0291] A7. storage: temporarily storing the cooled pure collagen solution in a milk bin for less than 12 hours;

[0292] B. sterilization of the pure collagen solution: pasteurizing and cooling the pretreated pure collagen solution;

[0293] B1. preheating: preheating the pretreated pure collagen solution to 52 C.;

[0294] B2. cleaning: remove impurities from the preheated pure collagen solution;

[0295] B3. flashing: heating the cleaned pure collagen solution to 68 C. for flashing;

[0296] B4. pasteurization: holding the temperature of the flashed pure collagen solution at 85 C. for 15 seconds for pasteurization;

[0297] B5. cooling: cooling the pasteurized pure collagen solution to 6 C. or below; and

[0298] B6. storage: storing the cooled pure collagen solution at a temperature of 3 C.;

[0299] C. material mixing for pure collagen milk: preheating the pasteurized and cooled pure collagen solution, adding remaining raw materials according to the weight ratio, and mixing; and

[0300] C1. preheating: opening a pure collagen solution pipeline, and preheating a part of the above-mentioned parts by weight of the pure collagen solution to 57 C.;

[0301] C2. mixing: uniformly adding the above parts by weight of the emulsion stabilizer, the white granulated sugar, the salt, the food flavor and the drinking water to the preheated pure collagen solution through a feeder to obtain a mixture;

[0302] C3. heat preservation: carrying out heat preservation on the mixture for 15 minutes through a heat preservation tube.

[0303] C4. filtering: after heat preservation, filtering the mixture through a double filter;

[0304] C5. homogenizing: homogenizing the filtered mixture under a pressure of 180 bar;

[0305] C6. mixing: when the homogenized mixture passes through a four-way valve, starting a pure collagen solution blending line, mixing the mixture with another part of the pure collagen solution, and then entering a semi-finished product tank, and controlling the ratio of the mixture to the other part of the pure collagen solution to 1:5, stirring for 15 minutes, sampling and detecting to obtain pure collagen milk;

[0306] C7. cooling: cooling the mixed pure collagen milk to 6 C. or below; and

[0307] C8. storage: storing the cooled pure collagen milk for less than 8 hours at a temperature of less than 10 C.;

[0308] D. sterilization of the pure collagen milk: carrying out UHT sterilization on the mixed pure collagen milk and then cooling.

[0309] D1. preheating: preheating the mixed pure collagen milk to 52 C.;

[0310] D2. degassing: degassing the preheated pure collagen milk;

[0311] D3. homogenizing: homogenizing the degassed pure collagen milk under a pressure of 200 bar at a temperature of 72 C.;

[0312] D4. UHT sterilization: holding the temperature of the homogenized pure collagen milk at 139 C. for 4 seconds for UHT sterilization; and

[0313] D5. storage: storing the sterilized pure collagen milk in a sterile tank for less than 48 hours at a temperature of less than 30 C.

[0314] A preparation method of a pure collagen milk powder, comprising the following steps:

[0315] (1) vacuum concentration of pure collagen milk: concentrating pure collagen milk in vacuum, wherein the obtained pure collagen milk has a solid content of 49%;

[0316] (1.1) equipment preparation: during the operation of equipment, controlling the steam supply pressure to 1.1 MPa, and controlling the pressure of a hot-pressure pump to 0.5 MPa;

[0317] (1.2) production control: carrying out vacuum concentration by using a three-effect downstream falling film evaporator, wherein

[0318] first-effect vacuum concentration is carried under the following conditions: heating temperature of 78 C., separation chamber temperature of 68 C., heater vacuum degree of 0.042 MPa, and separation chamber vacuum degree of 0.052 MPa;

[0319] second-effect vacuum concentration is carried under the following conditions: heating temperature of 68 C., separation chamber temperature of 60 C., heater vacuum degree of 0.052 MPa, and separation chamber vacuum degree of 0.068 MPa;

[0320] third-effect vacuum concentration is carried under the following conditions: heating temperature of 62 C., separation chamber temperature of 50 C., heater vacuum degree of 0.062 MPa, separation chamber vacuum degree of 0.082 MPa, condenser vacuum degree of 0.082 MPa; and

[0321] (1.3) Detection: the pure collagen milk obtained after vacuum concentration has a milk solid content of 49% and a milk concentration of 18B.

[0322] (2.1) disinfection of equipment: injecting hot water into the balancing tank before power-on, cleaning a high-pressure pump, a circulation pipeline and the balancing tank, holding the temperature of hot water at 95 C., and disinfecting for 15 minutes;

[0323] (2.2) equipment preparation: When a spray drying tower is powered on, powering on an induced draft fan, an air blower, a fluidized bed fan, a Roots blower, a powder conveyor, and a powder blowing valve sequentially, and then adjusting an air valve of the induced draft fan to form a negative pressure state in the drying tower, and when the negative pressure is 50 Pa, closing an air valve of the fluidized bed fan to the minimum state;

[0324] (2.3) spray drying: after the pure collagen milk concentrated in vacuum enters the balancing tank, when detecting that the concentration of concentrated milk is 18 Be and the temperature is 48 C., starting to feed materials, gradually increasing the pressure of the high-pressure pump and controlling the pressure of the high-pressure pump to 23 MPa, further controlling an inlet air temperature to 180 C., controlling an exhaust air temperature to 82 C., and controlling the pressure of the Roots blower to 0.01 MPa;

[0325] (2.4) detection: the pure collagen milk powder obtained after spray drying has a moisture of 7%.

[0326] (3) second-stage drying of the pure collagen milk powder: fluidized bed drying and cooling the pure collagen milk powder subjected to the first-stage drying, wherein the obtained pure collagen milk powder has a moisture of 4%;

[0327] (3.1) pressure balance: when the pure collagen milk powder falls into the fluidized bed, adjusting the pressure in the fluidized bed by adjusting an air inlet volume and an exhaust air volume of the fluidized bed, so that the pressure in the fluidized bed keeps balance with the pressure in the drying tower;

[0328] (3.2) hot air drying: adjusting the inlet air temperatures of stages I, II and III of the fluidized bed to 65 C., 45 C., 22 C., respectively; and

[0329] (3.3) detection: after drying and cooling by using the fluidized bed, the obtained pure collagen milk powder has a moisture of 3%-5%.

[0330] (4) post-treatment: discharging, sieving and drying the pure collagen milk powder; and

[0331] (5) carrying out inspection and packaging.

Embodiment 4

[0332] A pure collagen milk powder prepared by concentrating and drying pure collagen milk, the pure collagen milk being composed of the following raw materials in parts by weight: 60 parts of a pure collagen solution, 0.8 part of an emulsion stabilizer, 4 parts of white granulated sugar, 2.5 parts of salt, 0.4 part of a food flavor, and 70 parts of drinking water, wherein the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

[0333] The preparation method of a pure collagen solution comprises the following steps:

[0334] a. pretreatment: washing 55 parts of horseskin, mechanically degreasing, cutting into strips, treating with alkali, rinsing for the first time, biologically degreasing and rinsing for the second time;

[0335] a1. washing: putting 55 parts of fresh horseskin reaching the quarantine standard and having no drug residue into a stainless steel tank, unfreezing with drinking water, and washing;

[0336] a2. mechanical degreasing: depilating, by a horseskin depilator, the horseskin washed in the step a1, and then degreasing the depilated horseskin by a degreasing machine;

[0337] a3. cutting into strips: cutting the horseskin, degreased in the step a2, into horseskin strips having a width of 2.5 cm by using a horseskin cutting machine;

[0338] a4. alkali treatment: putting the horseskin, cut into strips in the step a3, into a double mixing mixer, adding sodium carbonate with a mass fraction of 0.6% for alkali treatment, stirring and mixing for 6 minutes;

[0339] a5. primary rinsing: rinsing the horseskin, subjected to the alkali treatment in the step a4, with drinking water for 6 minutes, and then pouring the rinsing water out, and rinsing with drinking water again, and repeating the rinsing operation three times until the horseskin has no unpleasant odor or residual alkali odor;

[0340] a6. biological degreasing: degreasing the horseskin, rinsed in the step a5, in 48 C. hot water containing 0.4% by weight of lipase for 4.5 hours; and

[0341] a7. secondary rinsing: rinsing the horseskin, subjected to the biological degreasing in step a6, with 52 C. hot water.

[0342] b. boiling: putting into a stainless steel hanging basket the pigskin degreased and rinsed in the step a, and using a rail crane to put the stainless steel hanging basket with the the pigskin into a jacketed kettle containing drinking water, and heating to 98 C., boiling for 6 minutes until the pigskin is cooked medium well, wherein the stainless steel hanging basket is lifted twice during the boiling;

[0343] c. mixing: heating 55 parts of drinking water to 50 C., adding 1.0 part of a complex enzyme, putting into a barrel with a mixer, stirring to be uniform, thus obtaining an enzyme solution; lifting the stainless steel hanging basket with the pigskin in the step b from the jacketed kettle, conveying to the top of a meat mincer by the rail crane, opening the bottom of the stainless steel hanging basket to charge the pigskin into a hopper of the meat mincer, and mincing the pigskin with a perforated plate with a diameter of 0.45 cm to obtain pigskin granules; and allowing the minced pigskin granules to directly drop into the barrel with a mixer, and stirring to be uniform to obtain a mixture, wherein the complex enzyme is a mixture consisting of collagenase, pepsin, trypsin and flavour protease in a weight ratio of 1.2:1:1:2.2;

[0344] d. putting the mixture obtained in the step c into a colloid mill with a fineness of 80 meshes for the first grinding, and then carrying out second grinding by using a colloid mill having a fineness of 200 meshes to obtain a pigskin collagen slurry under enzymatic hydrolysis;

[0345] e. enzymatic hydrolysis: heating the pigskin collagen slurry obtained in the step d to 48 C., stirring and reacting for 3.5 hours to obtain an enzymatic hydrolyzate; and

[0346] f. enzyme deactivation: heating the enzymatic hydrolysate obtained in the step e to 92 C., and carrying out enzyme deactivation for 12 minutes to obtain a pure collagen solution containing small molecule short-chain peptides having a molecular weight of 1000-4000 Daltons.

[0347] Each part of the emulsion stabilizer comprises the following raw materials in parts by weight: 4 parts of monoglyceride, 6 parts of sucrose ester, 4.5 parts of propylene glycol alginate, 6 parts of xanthan gum, 7 parts of guar gum, 0.7 part of d-isoascorbate, and 0.4 part of trisodium phosphate.

[0348] The preparation method of a pure collagen milk comprises the following steps:

[0349] A. pretreatment of a pure collagen solution: carrying out testing, weighing, solution collection, degassing, filtering and cooling on the pure collagen solution;

[0350] A1. detection: detecting and standardizing the drug residue, fat content, solid content, collagen content and collagen molecular weight of the pure collagen solution respectively;

[0351] A2. weighing: weighing the qualified pure collagen solution with a weighing scale

[0352] A3. solution collection: collecting the weighed pure collagen solution through a pipeline;

[0353] A4. degassing: degassing the pure collagen solution in the pipeline during the process of solution collection;

[0354] A5. filtering: filtering the pure collagen solution in the pipeline during the process of the solution collection;

[0355] A6. cooling: cooling the pure collagen solution after solution collection to 5 C.; and

[0356] A7. storage: temporarily storing the cooled pure collagen solution in a milk bin for less than 12 hours;

[0357] B. sterilization of the pure collagen solution: pasteurizing and cooling the pretreated pure collagen solution;

[0358] B1. preheating: preheating the pretreated pure collagen solution to 54 C.;

[0359] B2. cleaning: remove impurities from the preheated pure collagen solution;

[0360] B3. flashing: heating the cleaned pure collagen solution to 69 C. for flashing;

[0361] B4. pasteurization: holding the temperature of the flashed pure collagen solution at 88 C. for 12 seconds for pasteurization;

[0362] B5. cooling: cooling the pasteurized pure collagen solution to 6 C. or below; and

[0363] B6. storage: storing the cooled pure collagen solution at a temperature of 5 C.;

[0364] C. material mixing for pure collagen milk: preheating the pasteurized and cooled pure collagen solution, adding remaining raw materials according to the weight ratio, and mixing; and

[0365] C1. preheating: opening a pure collagen solution pipeline, and preheating a part of the above-mentioned parts by weight of the pure collagen solution to 59 C.;

[0366] C2. mixing: uniformly adding the above parts by weight of the emulsion stabilizer, the white granulated sugar, the salt, the food flavor and the drinking water to the preheated pure collagen solution through a feeder to obtain a mixture;

[0367] C3. heat preservation: carrying out heat preservation on the mixture for 18 minutes through a heat preservation tube.

[0368] C4. filtering: after heat preservation, filtering the mixture through a double filter;

[0369] C5. homogenizing: homogenizing the filtered mixture under a pressure of 185 bar;

[0370] C6. mixing: when the homogenized mixture passes through a four-way valve, starting a pure collagen solution blending line, mixing the mixture with another part of the pure collagen solution, and then entering a semi-finished product tank, and controlling the ratio of the mixture to the other part of the pure collagen solution to 1:5.5, stirring for 18 minutes, sampling and detecting to obtain pure collagen milk;

[0371] C7. cooling: cooling the mixed pure collagen milk to 6 C. or below; and

[0372] C8. storage: storing the cooled pure collagen milk for less than 8 hours at a temperature of less than 10 C.;

[0373] D. sterilization of the pure collagen milk: carrying out UHT sterilization on the mixed pure collagen milk and then cooling.

[0374] D1. preheating: preheating the mixed pure collagen milk to 54 C.;

[0375] D2. degassing: degassing the preheated pure collagen milk;

[0376] D3. homogenizing: homogenizing the degassed pure collagen milk under a pressure of 205 bar at a temperature of 74 C.;

[0377] D4. UHT sterilization: holding the temperature of the homogenized pure collagen milk at 140 C. for 3.5 seconds for UHT sterilization; and

[0378] D5. storage: storing the sterilized pure collagen milk in a sterile tank for less than 48 hours at a temperature of less than 30 C.

[0379] A preparation method of a pure collagen milk powder, comprising the following steps:

[0380] (1) vacuum concentration of pure collagen milk: concentrating pure collagen milk in vacuum, wherein the obtained pure collagen milk has a solid content of 49.5%;

[0381] (1.1) equipment preparation: during the operation of equipment, controlling the steam supply pressure to 1.1 MPa, and controlling the pressure of a hot-pressure pump to 0.5 MPa;

[0382] (1.2) production control: carrying out vacuum concentration by using a three-effect downstream falling film evaporator, wherein

[0383] first-effect vacuum concentration is carried under the following conditions: heating temperature of 80 C., separation chamber temperature of 72 C., heater vacuum degree of 0.046 MPa, and separation chamber vacuum degree of 0.064 MPa;

[0384] second-effect vacuum concentration is carried under the following conditions: heating temperature of 72 C., separation chamber temperature of 62 C., heater vacuum degree of 0.056 MPa, and separation chamber vacuum degree of 0.072 MPa;

[0385] third-effect vacuum concentration is carried under the following conditions: heating temperature of 64 C., separation chamber temperature of 52 C., heater vacuum degree of 0.066 MPa, separation chamber vacuum degree of 0.084 MPa, condenser vacuum degree of 0.084 MPa; and

[0386] (1.3) Detection: the pure collagen milk obtained after vacuum concentration has a milk solid content of 49.5% and a milk concentration of 2213e.

[0387] (2) first-stage drying of the pure collagen milk: spray-drying the pure collagen milk concentrated in vacuum, wherein the obtained pure collagen milk powder has a moisture of 7.5%;

[0388] (2.1) disinfection of equipment: injecting hot water into the balancing tank before power-on, cleaning a high-pressure pump, a circulation pipeline and the balancing tank, holding the temperature of hot water at 98 C., and disinfecting for 18 minutes;

[0389] (2.2) equipment preparation: When a spray drying tower is powered on, powering on an induced draft fan, an air blower, a fluidized bed fan, a Roots blower, a powder conveyor, and a powder blowing valve sequentially, and then adjusting an air valve of the induced draft fan to form a negative pressure state in the drying tower, and when the negative pressure is , closing an air valve of the fluidized bed fan to the minimum state;

[0390] (2.3) spray drying: after the pure collagen milk concentrated in vacuum enters the balancing tank, when detecting that the concentration of concentrated milk is 18 Be and the temperature is 52 C., starting to feed materials, gradually increasing the pressure of the high-pressure pump and controlling the pressure of the high-pressure pump to 24 MPa, further controlling an inlet air temperature to 185 C., controlling an exhaust air temperature to 86 C., and controlling the pressure of the Roots blower to 0.02 MPa;

[0391] (2.4) detection: the pure collagen milk powder obtained after spray drying has a moisture of 7.5%.

[0392] (3) second-stage drying of the pure collagen milk powder: fluidized bed is drying and cooling the pure collagen milk powder subjected to the first-stage drying, wherein the obtained pure collagen milk powder has a moisture of 4.5%;

[0393] (3.1) pressure balance: when the pure collagen milk powder falls into the fluidized bed, adjusting the pressure in the fluidized bed by adjusting an air inlet volume and an exhaust air volume of the fluidized bed, so that the pressure in the fluidized bed keeps balance with the pressure in the drying tower;

[0394] (3.2) hot air drying: adjusting the inlet air temperatures of stages I, II and III of the fluidized bed to 68 C., 55 C., 23 C., respectively; and

[0395] (3.3) detection: after drying and cooling by using the fluidized bed, the obtained pure collagen milk powder has a moisture of 4.5%.

[0396] (4) post-treatment: discharging, sieving and drying the pure collagen milk powder; and

[0397] (5) carrying out inspection and packaging.

Embodiment 5

[0398] A pure collagen milk powder prepared by concentrating and drying pure collagen milk, the pure collagen milk being composed of the following raw materials in parts by weight: 80 parts of a pure collagen solution, 1 part of an emulsion stabilizer, 5 parts of white granulated sugar, 3 parts of salt, 0.5 part of a food flavor, and 90 parts of drinking water, wherein the pure collagen solution is a pure collagen solution containing small molecule short-chain peptides.

[0399] The preparation method of a pure collagen solution comprises the following steps:

[0400] a. pretreatment: washing 60 parts of donkey hide, mechanically degreasing, cutting into strips, treating with alkali, rinsing for the first time, biologically degreasing and rinsing for the second time;

[0401] a1. washing: putting 60 parts of fresh donkey hide reaching the quarantine standard and having no drug residue into a stainless steel tank, unfreezing with drinking water, and washing;

[0402] a2. mechanical degreasing: depilating, by a donkey hide depilator, the donkey hide washed in the step a1, and then degreasing the depilated donkey hide by a degreasing machine;

[0403] a3. cutting into strips: cutting the donkey hide, degreased in the step a2, into cowhide strips having a width of 3 cm by using a donkey hide cutting machine;

[0404] a4. alkali treatment: putting the donkey hide, cut into strips in the step a3, into a double mixing mixer, adding sodium carbonate with a mass fraction of 0.7% for alkali treatment, stirring and mixing for 7 minutes;

[0405] a5. primary rinsing: rinsing the donkey hide, subjected to the alkali treatment in the step a4, with drinking water for 7 minutes, and then pouring the rinsing water out, and rinsing with drinking water again, and repeating the rinsing operation three times until the donkey hide has no unpleasant odor or residual alkali odor;

[0406] a6. biological degreasing: degreasing the donkey hide, rinsed in the step a5, in 50 C. hot water containing 0.5% by weight of lipase for 5 hours;

[0407] a7. secondary rinsing: rinsing the donkey hide, subjected to the biological degreasing in step a6, with 55 C. hot water.

[0408] b. boiling: putting into a stainless steel hanging basket the pigskin degreased and rinsed in the step a, and using a rail crane to put the stainless steel hanging basket with the the pigskin into a jacketed kettle containing drinking water, and heating to 100 C., boiling for 5 minutes until the pigskin is cooked medium well, wherein the stainless steel hanging basket is lifted twice during the boiling;

[0409] c. mixing: heating 60 parts of drinking water to 55 C., adding 1.2 part of a complex enzyme, putting into a barrel with a mixer, stirring to be uniform, thus obtaining an enzyme solution; lifting the stainless steel hanging basket with the pigskin in the step b from the jacketed kettle, conveying to the top of a meat mincer by the rail crane, opening the bottom of the stainless steel hanging basket to charge the pigskin into a hopper of the meat mincer, and mincing the pigskin with a perforated plate with a diameter of 0.5 cm to obtain pigskin granules; and allowing the minced pigskin granules to directly drop into the barrel with a mixer, and stirring to be uniform to obtain a mixture, wherein the complex enzyme is a mixture consisting of collagenase, pepsin, trypsin and flavour protease in a weight ratio of 1.5:1:1.2:2.5;

[0410] d. putting the mixture obtained in the step c into a colloid mill with a fineness of 80 meshes for the first grinding, and then carrying out second grinding by using a colloid mill having a fineness of 200 meshes to obtain a pigskin collagen slurry under enzymatic hydrolysis;

[0411] e. enzymatic hydrolysis: heating the pigskin collagen slurry obtained in the step d to 50 C., stirring and reacting for 3 hours to obtain an enzymatic hydrolyzate; and

[0412] f. enzyme deactivation: heating the enzymatic hydrolysate obtained in the step e to 95 C., and carrying out enzyme deactivation for 10 minutes to obtain a pure collagen solution containing small molecule short-chain peptides having a molecular weight of 1000-4000 Daltons.

[0413] Each part of the emulsion stabilizer comprises the following raw materials in parts by weight: 5 parts of monoglyceride, 7 parts of sucrose ester, 5 parts of propylene glycol alginate, 7 parts of xanthan gum, 9 parts of guar gum, 0.8 part of d-isoascorbate, and 0.5 part of trisodium phosphate.

[0414] The preparation method of a pure collagen milk comprises the following steps:

[0415] A. pretreatment of a pure collagen solution: carrying out testing, weighing, solution collection, degassing, filtering and cooling on the pure collagen solution;

[0416] A1. detection: detecting and standardizing the drug residue, fat content, solid content, collagen content and collagen molecular weight of the pure collagen solution respectively;

[0417] A2. weighing: weighing the qualified pure collagen solution with a weighing scale

[0418] A3. solution collection: collecting the weighed pure collagen solution through a pipeline;

[0419] A4. degassing: degassing the pure collagen solution in the pipeline during the process of solution collection;

[0420] A5. filtering: filtering the pure collagen solution in the pipeline during the process of the solution collection;

[0421] A6. cooling: cooling the pure collagen solution after solution collection to 6 C.; and

[0422] A7. storage: temporarily storing the cooled pure collagen solution in a milk bin for less than 12 hours;

[0423] B. sterilization of the pure collagen solution: pasteurizing and cooling the pretreated pure collagen solution;

[0424] B1. preheating: preheating the pretreated pure collagen solution to 55 C.;

[0425] B2. cleaning: remove impurities from the preheated pure collagen solution;

[0426] B3. flashing: heating the cleaned pure collagen solution to 70 C. for flashing;

[0427] B4. pasteurization: holding the temperature of the flashed pure collagen solution at 90 C. for 10 seconds for pasteurization;

[0428] B5. cooling: cooling the pasteurized pure collagen solution to 6 C. or below; and

[0429] B6. storage: storing the cooled pure collagen solution at a temperature of 6 C.;

[0430] C. material mixing for pure collagen milk: preheating the pasteurized and cooled pure collagen solution, adding remaining raw materials according to the weight ratio, and mixing; and

[0431] C1. preheating: opening a pure collagen solution pipeline, and preheating a part of the above-mentioned parts by weight of the pure collagen solution to 60 C.;

[0432] C2. mixing: uniformly adding the above parts by weight of the emulsion stabilizer, the white granulated sugar, the salt, the food flavor and the drinking water to the preheated pure collagen solution through a feeder to obtain a mixture;

[0433] C3. heat preservation: carrying out heat preservation on the mixture for 20 minutes through a heat preservation tube.

[0434] C4. filtering: after heat preservation, filtering the mixture through a double filter;

[0435] C5. homogenizing: homogenizing the filtered mixture under a pressure of 190 bar;

[0436] C6. mixing: when the homogenized mixture passes through a four-way valve, starting a pure collagen solution blending line, mixing the mixture with another part of the pure collagen solution, and then entering a semi-finished product tank, and controlling the is ratio of the mixture to the other part of the pure collagen solution to 1:6, stirring for 20 minutes, sampling and detecting to obtain pure collagen milk;

[0437] C7. cooling: cooling the mixed pure collagen milk to 6 C. or below; and

[0438] C8. storage: storing the cooled pure collagen milk for less than 8 hours at a temperature of less than 10 C.;

[0439] D. sterilization of the pure collagen milk: carrying out UHT sterilization on the mixed pure collagen milk and then cooling.

[0440] D1. preheating: preheating the mixed pure collagen milk to 55 C.;

[0441] D2. degassing: degassing the preheated pure collagen milk;

[0442] D3. homogenizing: homogenizing the degassed pure collagen milk under a pressure of 210 bar at a temperature of 75 C.;

[0443] D4. UHT sterilization: holding the temperature of the homogenized pure collagen milk at 142 C. for 3 seconds for UHT sterilization; and

[0444] D5. storage: storing the sterilized pure collagen milk in a sterile tank for less than 48 hours at a temperature of less than 30 C.

[0445] A preparation method of a pure collagen milk powder, comprising the following steps:

[0446] (1) vacuum concentration of pure collagen milk: concentrating pure collagen milk in vacuum, wherein the obtained pure collagen milk has a solid content of 50%;

[0447] (1.1) equipment preparation: during the operation of equipment, controlling the steam supply pressure to 1.2 MPa, and controlling the pressure of a hot-pressure pump to 0.6 MPa;

[0448] (1.2) production control: carrying out vacuum concentration by using a three-effect downstream falling film evaporator, wherein

[0449] first-effect vacuum concentration is carried under the following conditions: heating temperature of 83 C., separation chamber temperature of 75 C., heater vacuum degree of 0.050 MPa, and separation chamber vacuum degree of 0.068 MPa;

[0450] second-effect vacuum concentration is carried under the following conditions: heating temperature of 75 C., separation chamber temperature of 65 C., heater vacuum degree of 0.060 MPa, and separation chamber vacuum degree of 0.075 MPa;

[0451] third-effect vacuum concentration is carried under the following conditions: heating temperature of 68 C., separation chamber temperature of 55 C., heater vacuum degree of 0.070 MPa, separation chamber vacuum degree of 0.078-0.085 MPa, condenser vacuum degree of 0.085 MPa; and

[0452] (1.3) Detection: the pure collagen milk obtained after vacuum concentration has a milk solid content of 48%-50% and a milk concentration of 12-2513e.

[0453] (2) first-stage drying of the pure collagen milk: spray-drying the pure collagen milk concentrated in vacuum, wherein the obtained pure collagen milk powder has a moisture of 8%;

[0454] (2.1) disinfection of equipment: injecting hot water into the balancing tank before power-on, cleaning a high-pressure pump, a circulation pipeline and the balancing tank, holding the temperature of hot water at 100 C., and disinfecting for 20 minutes;

[0455] (2.2) equipment preparation: When a spray drying tower is powered on, powering on an induced draft fan, an air blower, a fluidized bed fan, a Roots blower, a powder conveyor, and a powder blowing valve sequentially, and then adjusting an air valve of the induced draft fan to form a negative pressure state in the drying tower, and when the negative pressure is 20 Pa, closing an air valve of the fluidized bed fan to the minimum state;

[0456] (2.3) spray drying: after the pure collagen milk concentrated in vacuum enters the balancing tank, when detecting that the concentration of concentrated milk is 25 Be and the temperature is 55 C., starting to feed materials, gradually increasing the pressure of the high-pressure pump and controlling the pressure of the high-pressure pump to 18 MPa, further controlling an inlet air temperature to 195 C., controlling an exhaust air temperature to 90 C., and controlling the pressure of the Roots blower to 0.01 MPa;

[0457] (2.4) detection: the pure collagen milk powder obtained after spray drying has a moisture of 8%.

[0458] (3) second-stage drying of the pure collagen milk powder: fluidized bed drying and cooling the pure collagen milk powder subjected to the first-stage drying, wherein the obtained pure collagen milk powder has a moisture of 5%;

[0459] (3.1) pressure balance: when the pure collagen milk powder falls into the fluidized bed, adjusting the pressure in the fluidized bed by adjusting an air inlet volume and an exhaust air volume of the fluidized bed, so that the pressure in the fluidized bed keeps balance with the pressure in the drying tower;

[0460] (3.2) hot air drying: adjusting the inlet air temperatures of stages I, II and III of the fluidized bed to 70 C., 60 C., 24 C., respectively; and

[0461] (3.3) detection: after drying and cooling by using the fluidized bed, the obtained pure collagen milk powder has a moisture of 5%.

[0462] (4) post-treatment: discharging, sieving and drying the pure collagen milk powder; and

[0463] (5) carrying out inspection and packaging.

[0464] The test report of the pure collagen milk powder prepared in Embodiments 1-5 is shown in Table 1:

TABLE-US-00001 TABLE 1 National Test item standard Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Odor Minor No No No No No The content of peptides 75% 98.5% 98.8% 99.2% 99.1% 98.7% (having a molecular weight of 1000-4000 Daltons) in total proteins Absorption rate of the 85% 100% 100% 100% 100% 100% human body pH 7.0-8.0 7.4 7.5 7.5 7.5 7.4 Total number of bacteria 30000 1200 1100 1000 1050 1150 (cfu/g) Number of coliform 30 8 10 12 11 9 bacteria (MPN/100 g) Number of molds and 50 5 7 8 6 4 yeasts Pathogenic bacteria Not Negative Negative Negative Negative Negative detectable

[0465] It can be seen from the above table that the pure collagen milk powder of the invention has comprehensive nutrition and no odor, and the content of small molecule short-chain peptides having a molecular weight of 1000-4000 Daltons is over 98%; due to the small molecular weight, the pure collagen milk powder can be absorbed easily by the human body, with an absorption rate of 100%; moreover, bacteria, fungi and pathogenic bacteria are extremely low in content and the pure collagen milk powder is environmentally friendly and can be used to supplement and balance the loss of collagen in the human body.

[0466] The above-described embodiments are preferred embodiments of the invention, and the invention may also be implemented in other ways, and any obvious alternatives, made without departing from the concept of the invention, fall within the scope of the invention.