Non-exogenous lactoferrin-added yoghourt and production method thereof

Abstract

The invention provides non-exogenous yoghurt added with lactoferrin and a production method of the non-exogenous yoghurt. The production method comprises the following steps: (1) carrying out sterilization treatment on raw milk and then fermenting, wherein the sterilization treatment does not influence the activity of lactoferrin; (2) extracting lactoferrin from the fermented raw milk obtained in the step (1) to obtain lactoferrin and yoghourt after lactoferrin extraction; (3) carrying out sterilization treatment on the lactoferrin obtained in the step (2); (4) performing sterilization treatment on the yoghurt from which the lactoferrin is extracted in the step (2); and (5) adding the sterilized lactoferrin obtained in the step (3) into the sterilized yoghurt obtained in the step (4) and subjected to lactoferrin extraction to obtain the non-exogenous yoghurt added with the lactoferrin. According to the production method, lactoferrin extraction is carried out on whey, impurities are few, the purity is high, and when the lactoferrin is subjected to membrane filtration sterilization process treatment, the loading capacity is high, and the sterilization cost is low.

Description

Technical Field

[0001] The invention belongs to the field of dairy products, and in particular relates to a method for producing yogurt with non-exogenously added lactoferrin. Background Art

[0002] Lactoferrin (LF) is an important non-heme iron-binding glycoprotein in milk and a monomeric glycoprotein with bactericidal activity in neutrophil granules. Its molecular weight is 80kDa and it is mainly expressed and secreted by mammary epithelial cells. Sorensen et al. obtained a red protein when separating whey protein, and Polis et al. also obtained partially purified red protein when separating Lp. After Groves obtained a pure red substance by chromatography, he confirmed that this red substance was a glycoprotein bound to iron, which was called lactoferrin. Lactoferrin not only participates in the transport of iron, but also has powerful biological functions such as broad-spectrum antibacterial, antioxidant, anti-cancer, and immune system regulation. It is considered to be a new type of antibacterial and anti-cancer drug and a food additive with great development potential.

[0003] First of all, although lactoferrin is widely distributed in mammalian milk, the content in raw cow's milk is 0.0128-0.0159%. Scientific research has confirmed that raw milk is a high-risk food because harmful bacteria are not killed. If young children, the elderly and infirm, pregnant women and people with immune system problems drink raw milk, their condition may be aggravated, so raw milk needs to be heated and sterilized before consumption. However, when heating and sterilizing raw milk, lactoferrin will lose its original activity after being heated, and the inactivated lactoferrin has no effect or function on the human body.

[0004] Although the prior art production and processing methods can produce and process liquid dairy products rich in lactoferrin, the prior art production methods are all: first sterilize the liquid milk liquid, and then add the sterile lactoferrin to the sterilized sterile liquid by aseptic online addition, such as patent Nos. 200810094034.6 and 201110083557.2 for the production method of liquid milk, patent No. 201010609066.2 for the production method of lactic acid bacteria beverage, and patent No. 201310471392.5 for the production method of yogurt, although all of them can obtain liquid dairy products containing lactoferrin, the above-mentioned preparation methods all have the following problems: first sterilize the cow's milk containing active lactoferrin, and then add the active lactoferrin to the sterilized (lactoferrin inactivated) cow's milk by adding lactoferrin. Secondly, the production method of 201911198960.2 is to first extract lactoferrin from raw milk before sterilization, then sterilize the lactoferrin, and then add the sterilized lactoferrin to the sterilized milk to obtain a liquid milk production method without exogenous lactoferrin addition. However, for various reasons, there is no production method of lactoferrin-containing yogurt without exogenous lactoferrin addition in the prior art.

[0005] The above production method has the following problems:

[0006] 1. First, the milk is sterilized with a high intensity of heat, which causes the active lactoferrin contained in the milk to be inactivated by heat, and then the production process of additional active lactoferrin is added, which is a huge waste and also a major drawback of the existing production process;

[0007] 2. Even if lactoferrin is extracted from the milk before sterilization, and then the extracted lactoferrin is subjected to non-thermal sterilization treatment, and the milk after lactoferrin extraction is subjected to thermal sterilization treatment, and then the sterilized lactoferrin is added to the sterilized milk under aseptic conditions. However, the lactoferrin extracted from the milk inevitably contains a certain amount of foreign proteins. In the process of membrane filtration sterilization of lactoferrin containing foreign proteins, the filtration load of lactoferrin is small due to the presence of foreign proteins, resulting in the disadvantage of high filtration cost. Summary of the invention

[0008] In order to solve the above problems, the purpose of the present invention is to provide a yogurt without exogenous lactoferrin addition and a production method thereof. The production method extracts lactoferrin from whey with less impurities and high purity. When the lactoferrin is subjected to membrane filtration sterilization process, the loading capacity is high and the sterilization cost is low.

[0009] In order to achieve the above object, the present invention provides a method for producing yogurt without exogenous lactoferrin addition, which comprises the following steps:

[0010] (1) sterilizing the raw milk and then fermenting it, wherein the sterilization does not affect the activity of lactoferrin;

[0011] (2) extracting lactoferrin from the fermented raw milk obtained in step (1) to obtain lactoferrin and yogurt from which the lactoferrin is extracted;

[0012] (3) sterilizing the lactoferrin obtained in step (2);

[0013] (4) sterilizing the yogurt from which lactoferrin is extracted obtained in step (2);

[0014] (5) adding the sterilized lactoferrin obtained in step (3) to the sterilized yogurt from which lactoferrin has been extracted obtained in step (4) to obtain the yogurt to which lactoferrin is not added exogenously.

[0015] According to a specific embodiment of the present invention, preferably, step (1) comprises the following steps:

[0016] (a) Purifying milk: subjecting the raw milk to a centrifugal purification process to obtain raw milk after centrifugal purification;

[0017] (b) separation: centrifuging the purified raw milk to separate the cream from the skimmed milk;

[0018] (c) Skim milk prefiltration: Prefiltration removes larger particles in skim milk;

[0019] (d) Skim milk degerming filtration: The pre-filtered skim milk is degerming to remove most of the microorganisms in the skim milk and reduce the bacterial content in the skim milk;

[0020] (e) Sterilization of skim milk: The skim milk after the sterilization treatment is sterilized at 69-71°C for 13-15 seconds to kill the bacteria in the skim milk that may affect the fermentation, so as to prevent the fermented milk from deteriorating due to the high content of bacteria during the fermentation process;

[0021] (f) Cream sterilization: The cream is sterilized at 136-137° C. for 4-6 seconds (ultra-high temperature sterilization), and then cooled to 69-71° C. to obtain sterile cream;

[0022] (g) Online mixing: the sterilized skim milk and the sterilized cooled cream are mixed online;

[0023] (h) Homogenization: homogenizing the mixed skim milk and cream to refine the fat globules in the materials;

[0024] (i) Cooling: more preferably, cooling to 40-43° C.; lowering the homogenized milk to the fermentation temperature is conducive to the proliferation of bacteria until the fermentation is completed;

[0025] (j) fermentation: adding a fermentation agent, more preferably, standing and fermenting for 6-8 hours;

[0026] (k) Demulsification: breaking the fermented yogurt to increase the fluidity of the yogurt, which is beneficial for pumping the yogurt.

[0027] According to a specific embodiment of the present invention, preferably, step (2) comprises the following steps:

[0028] (a) whey separation: the fermented raw milk is subjected to whey separation to obtain whey and whey-free yogurt respectively;

[0029] (b) Lactoferrin extraction: Lactoferrin is extracted from whey to obtain lactoferrin.

[0030] According to a specific embodiment of the present invention, preferably, step (3) comprises the following steps: the lactoferrin obtained in step (2) is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.2-0.45 μm.

[0031] According to a specific embodiment of the present invention, preferably, step (4) comprises the following steps:

[0032] (a) yogurt sterilization: the yogurt after lactoferrin extraction is sterilized at 70-75° C. for 25-30 seconds to obtain sterilized yogurt; this operation inactivates the fermentation bacteria in the yogurt. Due to the inactivation of the bacteria, the yogurt will not continue to ferment and produce acid during the shelf life due to the fermentation bacteria contained therein, which will affect the taste of the final product and cause it to deteriorate;

[0033] (b) Cooling: The sterilized yogurt is cooled to 25-30°C.

[0034] According to a specific embodiment of the present invention, preferably, step (5) comprises the following steps:

[0035] (a) Sterile lactoferrin backfilling: adding the sterilized lactoferrin obtained in step (3) online to the sterilized yogurt from which lactoferrin has been extracted in step (4) to obtain a yogurt material containing lactoferrin;

[0036] (b) Filling: Filling is performed by aseptic filling to obtain the yogurt without exogenous lactoferrin addition.

[0037] According to a specific embodiment of the present invention, preferably, the skim milk pre-filtration is performed using a filter with a pore size of 20-60 μm.

[0038] According to a specific embodiment of the present invention, preferably, the skim milk sterilization filtration is performed using a filter with a pore size of 0.8-1.4 μm.

[0039] According to a specific embodiment of the present invention, preferably, the homogenization temperature is 68-71° C., and the homogenization pressure is 180-250 bar.

[0040] According to a specific embodiment of the present invention, preferably, the demulsification is performed at a rotation speed of 70-90 rpm for 10-15 min.

[0041] According to a specific embodiment of the present invention, preferably, the whey separation is performed using a whey separator or a membrane filtration method.

[0042] According to a specific embodiment of the present invention, preferably, the lactoferrin extraction is performed by chromatography.

[0043] According to a specific embodiment of the present invention, the above production method comprises the following specific steps:

[0044] (1) Milk purification: The raw milk is centrifuged and purified by a milk purifier;

[0045] (2) Separation: Centrifuge the purified raw milk to separate the cream from the skimmed milk;

[0046] (3) Skim milk prefiltration: Use a 20-60 μm pore size filter to prefilter the skim milk to remove larger particles in the skim milk;

[0047] (4) Skim milk sterilization filtration: The pre-filtered skim milk is sterilized and filtered using a 0.8-1.4 μm pore size filter to remove most of the microorganisms in the skim milk;

[0048] (5) Sterilization of skim milk: The skim milk after the sterilization treatment is sterilized at 69-71°C for 13-15 seconds;

[0049] (6) Cream sterilization: The cream is sterilized at 136-137°C for 4-6 seconds and then cooled to 69-71°C;

[0050] (7) Online mixing: the sterilized skim milk and the sterilized cooled cream are mixed online;

[0051] (8) Homogenization: homogenize the mixed skim milk and cream at a homogenization temperature of 68-71° C. and a homogenization pressure of 180-250 bar;

[0052] (9) Cooling: Cooling the homogenized material to the fermentation temperature, which is 40-43° C. for subsequent fermentation;

[0053] (10) Fermentation: Add a fermentation agent to the homogenized material cooled to 40-43° C. and allow to ferment for 6-8 hours;

[0054] (11) Demulsification: After fermentation, the yogurt is stirred to demulsify, and stirred at 70-90 rpm for 10-15 min;

[0055] (12) whey separation: performing whey separation on the yogurt after stirring and demulsification to obtain whey and whey-free yogurt respectively (whey separation can be performed by a whey separator or a membrane filtration method);

[0056] (13) Lactoferrin extraction: extracting lactoferrin from whey using chromatography equipment to obtain lactoferrin;

[0057] (14) Yogurt sterilization: sterilizing the whey-free yogurt material at 70-75° C. for 25-30 seconds to obtain sterilized yogurt;

[0058] (15) Cooling: Cooling the sterilized yogurt to 25-30° C.

[0059] (16) Sterilization of lactoferrin: The lactoferrin extracted from whey is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.1-0.4 μm to obtain sterile lactoferrin;

[0060] (17) Sterile lactoferrin backfilling: adding sterile lactoferrin online to the sterilized and cooled yogurt to obtain a yogurt material containing lactoferrin;

[0061] (18) Filling: The yogurt material containing lactoferrin is filled by aseptic filling, and finally the yogurt product without exogenous lactoferrin addition is obtained.

[0062] The present invention also provides yogurt without exogenous lactoferrin added prepared by the production method.

[0063] The production method of the present invention can produce a yogurt product containing active lactoferrin, and the lactoferrin contained in the yogurt product is not exogenously added lactoferrin. The difference from the traditional process of producing a yogurt product containing active lactoferrin is that the production method of the present invention first extracts lactoferrin contained in fermented cow's milk whey, then obtains sterile lactoferrin through a sterilization process and backfills it into the sterilized yogurt, so that the lactoferrin contained in the cow's milk itself can be effectively utilized, instead of the inappropriate and wasteful production method of first sterilizing the cow's milk containing active lactoferrin to inactivate the activity of lactoferrin in the cow's milk and then adding sterile lactoferrin exogenously.

[0064] The advantages and significant effects of the present invention are:

[0065] 1. The present invention solves the drawbacks of the current production method of liquid dairy products containing active lactoferrin ingredients: first sterilizing the milk to inactivate the active lactoferrin in the milk, and then adding the active lactoferrin, which is a wasteful and uneconomical production and processing method;

[0066] 2. When extracting lactoferrin, the present invention extracts lactoferrin from whey instead of extracting lactoferrin from skim milk according to the traditional process. Furthermore, compared with lactoferrin extracted from skim milk by the traditional process, the lactoferrin extracted by the present invention has less impurities and higher purity. When the lactoferrin is subjected to membrane filtration sterilization process, the loading capacity is higher and the sterilization cost is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a flow chart of the production method of yogurt without exogenous lactoferrin addition of the present invention;

[0068] Figure 2 The process flow chart of yogurt production with traditional exogenous lactoferrin added;

[0069] Figure 3 This is a production process flow chart of milk without exogenous lactoferrin addition. DETAILED DESCRIPTION

[0070] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0071] Example 1

[0072] This embodiment provides a yogurt without exogenous lactoferrin addition, and the preparation process is as follows: Figure 1 As shown, it is prepared by the following steps:

[0073] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0074] (2) separating the purified raw milk to obtain skimmed milk and cream;

[0075] (3) pre-filtering the skim milk using a 60 μm pore size filter to remove larger particulate matter in the skim milk;

[0076] (4) The pre-filtered skim milk is subjected to sterilization filtration using a 1.4 μm pore size filter to remove most of the microorganisms in the skim milk, thereby reducing the total bacterial count in the skim milk;

[0077] (5) sterilizing the skimmed milk after the sterilization treatment at 71° C. for 13 seconds;

[0078] (6) sterilizing the cream at 137° C. for 4 seconds and cooling the cream to 71° C. after sterilization;

[0079] (7) mixing the sterilized skim milk and the sterilized cream cooled to 71° C. in-line;

[0080] (8) Homogenize the mixed skim milk and cream at a homogenization temperature of 71°C and a homogenization pressure of 200 bar.

[0081] (9) cooling the homogenized material to the fermentation temperature, which is 43° C., for subsequent fermentation;

[0082] (10) adding fermentation agent (Lactobacillus bulgaricus and Streptococcus thermophilus) to the homogenized material cooled to 43° C. and allowing to ferment for 8 hours;

[0083] (11) After the fermentation is completed, the yogurt is stirred and demulsified, and the demulsification condition is 90 rpm for 10 min;

[0084] (12) performing whey separation on the yogurt after stirring and demulsifying to obtain whey and whey-free yogurt respectively (whey separation can be performed by a whey separator or a membrane filtration method);

[0085] (13) extracting lactoferrin from whey using a chromatography device to obtain lactoferrin; (cation chromatography column)

[0086] (14) sterilizing the whey-free yogurt material at 71° C. for 25 seconds to obtain sterilized yogurt;

[0087] (15) Cooling the sterilized yogurt to 30° C.

[0088] (16) The lactoferrin extracted from the whey is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.2 μm to obtain sterile lactoferrin;

[0089] (17) adding sterile lactoferrin online to the sterilized and cooled yogurt to obtain a yogurt material containing lactoferrin;

[0090] (18) The yogurt material containing lactoferrin is filled in an aseptic filling manner to finally obtain the yogurt product without exogenous lactoferrin addition.

[0091] Example 2

[0092] This embodiment provides a yogurt without exogenous lactoferrin addition, which is prepared by the following steps:

[0093] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0094] (2) separating the purified raw milk to obtain skimmed milk and cream;

[0095] (3) pre-filtering the skim milk using a 20 μm pore size filter to remove larger particulate matter in the skim milk;

[0096] (4) The pre-filtered skim milk is subjected to sterilization filtration using a 1.0 μm pore size filter to remove most of the microorganisms in the skim milk, thereby reducing the total bacterial count in the skim milk;

[0097] (5) sterilizing the skimmed milk after the sterilization treatment at 69° C. for 15 seconds;

[0098] (6) sterilizing the cream at 136° C. for 5 seconds and cooling the cream to 69° C. after sterilization;

[0099] (7) mixing the sterilized skim milk and the sterilized cream cooled to 69° C. in-line;

[0100] (8) homogenizing the mixed skim milk and cream at a homogenization temperature of 69° C. and a homogenization pressure of 180 bar;

[0101] (9) Cooling the homogenized material to the fermentation temperature, which is 42° C., for subsequent fermentation;

[0102] (10) adding a fermentation agent to the homogenized material cooled to 42° C. and allowing it to ferment for 7 hours;

[0103] (11) After the fermentation is completed, the yogurt is stirred and demulsified, and the demulsification condition is 12 min at 80 rpm;

[0104] (12) performing whey separation on the yogurt after stirring and demulsifying to obtain whey and whey-free yogurt, respectively. (Whey separation can be performed by a whey separator or a membrane filtration method);

[0105] (13) extracting lactoferrin from whey using a chromatography device to obtain lactoferrin;

[0106] (14) sterilizing the whey-free yogurt material at 72° C. for 25 seconds to obtain sterilized yogurt;

[0107] (15) Cooling the sterilized yogurt to 27° C.

[0108] (16) The lactoferrin extracted from the whey is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.4 μm to obtain sterile lactoferrin;

[0109] (17) adding sterile lactoferrin online to the sterilized and cooled yogurt to obtain a yogurt material containing lactoferrin;

[0110] (18) The yogurt material containing lactoferrin is filled in an aseptic filling manner to finally obtain the yogurt product without exogenous lactoferrin addition.

[0111] Example 3

[0112] This embodiment provides a yogurt without exogenous lactoferrin addition, which is prepared by the following steps:

[0113] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0114] (2) separating the purified raw milk to obtain skimmed milk and cream;

[0115] (3) pre-filtering the skim milk using a 40 μm pore size filter to remove larger particulate matter in the skim milk;

[0116] (4) The pre-filtered skim milk is subjected to sterilization filtration using a 0.8 μm pore size filter to remove most of the microorganisms in the skim milk, thereby reducing the total bacterial count in the skim milk;

[0117] (5) sterilizing the skimmed milk after the sterilization treatment at 69° C. for 15 seconds;

[0118] (6) sterilizing the cream at 137° C. for 4 seconds and cooling the cream to 69° C. after sterilization;

[0119] (7) mixing the sterilized skim milk and the sterilized cream cooled to 69° C. in-line;

[0120] (8) homogenizing the mixed skim milk and cream at a homogenization temperature of 70° C. and a homogenization pressure of 190 bar;

[0121] (9) Cooling the homogenized material to the fermentation temperature, which is 42° C., for subsequent fermentation;

[0122] (10) adding a fermentation agent to the homogenized material cooled to 42° C. and allowing it to ferment for 7.5 hours;

[0123] (11) After the fermentation is completed, the yogurt is stirred and demulsified, and the demulsification condition is 12 min at 85 rpm;

[0124] (12) performing whey separation on the yogurt after stirring and demulsifying to obtain whey and whey-free yogurt respectively (whey separation can be performed by a whey separator or a membrane filtration method);

[0125] (13) extracting lactoferrin from whey using a chromatography device to obtain lactoferrin;

[0126] (14) sterilizing the whey-free yogurt material at 72° C. for 26 seconds to obtain sterilized yogurt;

[0127] (15) Cooling the sterilized yogurt to 28° C.

[0128] (16) The lactoferrin extracted from the whey is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.2 μm to obtain sterile lactoferrin;

[0129] (17) adding sterile lactoferrin online to the sterilized and cooled yogurt to obtain a yogurt material containing lactoferrin;

[0130] (18) The yogurt material containing lactoferrin is filled in an aseptic filling manner to finally obtain the yogurt product without exogenous lactoferrin addition.

[0131] Example 4

[0132] This embodiment provides a yogurt without exogenous lactoferrin addition, which is prepared by the following steps:

[0133] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0134] (2) separating the purified raw milk to obtain skimmed milk and cream;

[0135] (3) pre-filtering the skim milk using a 30 μm pore size filter to remove larger particulate matter in the skim milk;

[0136] (4) The pre-filtered skim milk is subjected to sterilization filtration using a 1.4 μm pore size filter to remove most of the microorganisms in the skim milk, thereby reducing the total bacterial count in the skim milk;

[0137] (5) sterilizing the skimmed milk after the sterilization treatment at 69° C. for 15 seconds;

[0138] (6) sterilizing the cream at 137° C. for 4 seconds and cooling to 70° C. after sterilization;

[0139] (7) mixing the sterilized skim milk and the sterilized cream cooled to 70° C. in-line;

[0140] (8) homogenizing the mixed skim milk and cream at a homogenization temperature of 70° C. and a homogenization pressure of 240 bar;

[0141] (9) Cooling the homogenized material to the fermentation temperature, which is 42° C., for subsequent fermentation;

[0142] (10) adding a fermentation agent to the homogenized material cooled to 42° C. and allowing it to ferment for 8 hours;

[0143] (11) After the fermentation is completed, the yogurt is stirred and demulsified, and the demulsification condition is 90 rpm for 10 min;

[0144] (12) performing whey separation on the yogurt after stirring and demulsifying to obtain whey and whey-free yogurt, respectively (whey separation can be performed by a whey separator or a membrane filtration method);

[0145] (13) extracting lactoferrin from whey using a chromatography device to obtain lactoferrin;

[0146] (14) sterilizing the whey-free yogurt material at 75° C. for 25 seconds to obtain sterilized yogurt;

[0147] (15) Cooling the sterilized yogurt to 29° C.

[0148] (16) The lactoferrin extracted from the whey is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.45 μm to obtain sterile lactoferrin;

[0149] (17) adding sterile lactoferrin online to the sterilized and cooled yogurt to obtain a yogurt material containing lactoferrin;

[0150] (18) The yogurt material containing lactoferrin is filled in an aseptic filling manner to finally obtain the yogurt product without exogenous lactoferrin addition.

[0151] Production process of traditional exogenously added lactoferrin yogurt (Comparative Examples 1-4)

[0152] Comparative Example 1

[0153] This comparative example provides a yogurt with exogenous lactoferrin added, the preparation process is as follows Figure 2 As shown, it is prepared by the following steps:

[0154] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0155] (2) preheating the purified raw milk to 70° C.

[0156] (3) homogenizing the preheated raw milk at a homogenization temperature of 70° C. and a homogenization pressure of 200 bar;

[0157] (4) sterilizing the homogenized raw milk at 95°C for 300 seconds;

[0158] (5) cooling the sterilized raw milk to a fermentation temperature of 40° C. for subsequent fermentation;

[0159] (6) adding a fermentation agent to the raw milk that has been homogenized and cooled to 40° C., and allowing to ferment for 7 hours;

[0160] (7) adding exogenous lactoferrin (purchased lactoferrin powder, such as American Hilma lactoferrin powder) to the fermented yogurt to obtain yogurt containing lactoferrin;

[0161] (8) Filling the yogurt containing lactoferrin to finally obtain a yogurt product containing lactoferrin.

[0162] Comparative Example 2

[0163] This comparative example provides a yogurt with exogenously added lactoferrin, which is prepared by the following steps:

[0164] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0165] (2) preheating the purified raw milk to 71° C.

[0166] (3) homogenizing the preheated raw milk at a homogenization temperature of 71° C. and a homogenization pressure of 220 bar;

[0167] (4) sterilizing the homogenized raw milk at 96°C for 300 seconds;

[0168] (5) cooling the sterilized raw milk to a fermentation temperature of 40° C. for subsequent fermentation;

[0169] (6) adding a fermentation agent to the raw milk that has been homogenized and cooled to 39° C., and allowing to ferment for 7.5 hours;

[0170] (7) adding exogenous lactoferrin to the fermented yogurt to obtain yogurt containing lactoferrin;

[0171] (8) Filling the yogurt containing lactoferrin to finally obtain a yogurt product containing lactoferrin.

[0172] Comparative Example 3

[0173] This comparative example provides a yogurt with exogenously added lactoferrin, which is prepared by the following steps:

[0174] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0175] (2) preheating the purified raw milk to 72° C.

[0176] (3) homogenizing the preheated raw milk at a homogenization temperature of 72° C. and a homogenization pressure of 210 bar;

[0177] (4) sterilizing the homogenized raw milk at 95°C for 300 seconds;

[0178] (5) cooling the sterilized raw milk to a fermentation temperature of 40° C. for subsequent fermentation;

[0179] (6) adding a fermentation agent to the raw milk that has been homogenized and cooled to 41° C., and allowing to ferment for 7.5 hours;

[0180] (7) adding exogenous lactoferrin to the fermented yogurt to obtain yogurt containing lactoferrin;

[0181] (8) Filling the yogurt containing lactoferrin to finally obtain a yogurt product containing lactoferrin.

[0182] Comparative Example 4

[0183] This comparative example provides a yogurt with exogenously added lactoferrin, which is prepared by the following steps:

[0184] (1) First, the raw milk is centrifuged through a milk purifier to remove impurities in the raw milk;

[0185] (2) preheating the purified raw milk to 73° C.

[0186] (3) homogenizing the preheated raw milk at a homogenization temperature of 73° C. and a homogenization pressure of 220 bar;

[0187] (4) sterilizing the homogenized raw milk at 96°C for 300 seconds;

[0188] (5) cooling the sterilized raw milk to a fermentation temperature of 40° C. for subsequent fermentation;

[0189] (6) adding a fermentation agent to the raw milk that has been homogenized and cooled to 40° C., and allowing to ferment for 8 hours;

[0190] (7) adding exogenous lactoferrin to the fermented yogurt to obtain yogurt containing lactoferrin;

[0191] (8) Filling the yogurt containing lactoferrin to finally obtain a yogurt product containing lactoferrin.

[0192] Existing production process of non-exogenously added lactoferrin milk (Comparative Examples 5-8)

[0193] Comparative Example 5

[0194] This comparative example provides a non-exogenously added lactoferrin yogurt, the preparation process is as follows Figure 3As shown, it is prepared by the following steps:

[0195] (1) separating the raw milk to obtain skimmed milk and cream;

[0196] (2) extracting lactoferrin from skim milk using a chromatography device, thereby obtaining lactoferrin and skim milk without lactoferrin;

[0197] (3) mixing lactoferrin-free skim milk and cream online;

[0198] (4) The lactoferrin is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.2 μm, thereby obtaining sterile lactoferrin;

[0199] (5) preheating the mixed skim milk and cream to 71° C.;

[0200] (6) Homogenize the preheated skim milk and cream at a homogenization pressure of 200 bar;

[0201] (7) subjecting the homogenized material to UHT sterilization treatment at 137°C / 4s;

[0202] (8) Cooling the sterilized material to 25°C;

[0203] (9) adding sterile lactoferrin online to the sterilized and cooled material to obtain milk containing lactoferrin;

[0204] (10) The milk containing lactoferrin is filled by aseptic filling, thereby finally obtaining a milk product containing lactoferrin.

[0205] Comparative Example 6

[0206] This comparative example provides a non-exogenously added lactoferrin yogurt, which is prepared by the following steps:

[0207] (1) separating the raw milk to obtain skimmed milk and cream;

[0208] (2) extracting lactoferrin from skim milk using a chromatography device, thereby obtaining lactoferrin and skim milk without lactoferrin;

[0209] (3) mixing lactoferrin-free skim milk and cream online;

[0210] (4) using a sterilizing membrane with a pore size of 0.3 μm to filter and sterilize the lactoferrin, thereby obtaining sterile lactoferrin;

[0211] (5) preheating the mixed skim milk and cream to 72° C.;

[0212] (6) Homogenize the preheated skim milk and cream at a homogenization pressure of 210 bar;

[0213] (7) subjecting the homogenized material to UHT sterilization treatment at 138°C / 4s;

[0214] (8) Cooling the sterilized material to 26°C;

[0215] (9) adding sterile lactoferrin online to the sterilized and cooled material to obtain milk containing lactoferrin;

[0216] (10) The milk containing lactoferrin is filled by aseptic filling, thereby finally obtaining a milk product containing lactoferrin.

[0217] Comparative Example 7

[0218] This comparative example provides a non-exogenously added lactoferrin yogurt, which is prepared by the following steps:

[0219] (1) separating the raw milk to obtain skimmed milk and cream;

[0220] (2) extracting lactoferrin from skim milk using a chromatography device, thereby obtaining lactoferrin and skim milk without lactoferrin;

[0221] (3) mixing lactoferrin-free skim milk and cream online;

[0222] (4) The lactoferrin is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.4 μm, thereby obtaining sterile lactoferrin;

[0223] (5) preheating the mixed skim milk and cream to 73° C.;

[0224] (6) Homogenizing the preheated skim milk and cream at a homogenization pressure of 220 bar;

[0225] (7) subjecting the homogenized material to UHT sterilization treatment at 139°C / 4s;

[0226] (8) Cooling the sterilized material to 27°C;

[0227] (9) adding sterile lactoferrin online to the sterilized and cooled material to obtain milk containing lactoferrin;

[0228] (10) The milk containing lactoferrin is filled by aseptic filling, thereby finally obtaining a milk product containing lactoferrin.

[0229] Comparative Example 8

[0230] This comparative example provides a non-exogenously added lactoferrin yogurt, which is prepared by the following steps:

[0231] (1) separating the raw milk to obtain skimmed milk and cream;

[0232] (2) extracting lactoferrin from skim milk using a chromatography device, thereby obtaining lactoferrin and skim milk without lactoferrin;

[0233] (3) mixing lactoferrin-free skim milk and cream online;

[0234] (4) The lactoferrin is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.2 μm, thereby obtaining sterile lactoferrin;

[0235] (5) preheating the mixed skim milk and cream to 72° C.;

[0236] (6) Homogenize the preheated skim milk and cream at a homogenization pressure of 210 bar;

[0237] (7) subjecting the homogenized material to UHT sterilization treatment at 136°C / 4s;

[0238] (8) Cooling the sterilized material to 28°C;

[0239] (9) adding sterile lactoferrin online to the sterilized and cooled material to obtain milk containing lactoferrin;

[0240] (10) The milk containing lactoferrin is filled by aseptic filling, thereby finally obtaining a milk product containing lactoferrin.

[0241] The data comparison of the filtration capacity and filtration cost of two lactoferrin sterilization membranes for extracting lactoferrin from skim milk (Comparative Examples 5-8) and extracting lactoferrin from whey (Examples 1-4) is shown in Table 1:

[0242] Table 1: Comparison of turbidity, sterilization filtration volume and cost of two lactoferrin extracted from different materials

[0243]

[0244] In Table 1, the higher the turbidity, the higher the content of insoluble suspended matter in the solution. Turbidity: refers to the degree of obstruction caused by the solution to the passage of light, which includes the scattering of light by suspended matter and the absorption of light by solute molecules. The turbidity of water is not only related to the content of suspended matter in the water, but also to their size, shape and refractive index.

[0245] Comparison of the cost of yogurt containing lactoferrin: yogurt without exogenous lactoferrin addition and yogurt with exogenous lactoferrin addition:

[0246] In the yogurt production method of Patent 201310471392.5, the amount of exogenously added lactoferrin is 10-500 mg / L.

[0247] The lactoferrin content in cow's milk is usually around 100 mg / L. The cost of the two preparation methods can be calculated and compared based on the addition amount of 100 mg / L. The price of lactoferrin is calculated based on the usual market price of 15,000 yuan / kg.

[0248] The added amount is 100 mg / L, and the consumption per ton of yogurt is 100 g. The consumption for 10 tons of yogurt is 1 kg.

[0249] Therefore, for every 10 tons of yogurt produced, the production cost of yogurt with exogenous lactoferrin added is 15,000 yuan higher than the cost of yogurt without exogenous lactoferrin added.

[0250] According to calculations based on a factory with a daily output of 100 tons, the daily cost difference between the two production processes of exogenous addition and non-exogenous addition is 150,000 yuan / day.

Claims

1. A method for producing yogurt without exogenous lactoferrin addition, comprising the following steps: (1) sterilizing the raw milk and then fermenting it, wherein the sterilization does not affect the activity of lactoferrin; (2) extracting lactoferrin from the fermented raw milk obtained in step (1) to obtain lactoferrin and yogurt from which the lactoferrin is extracted; (3) sterilizing the lactoferrin obtained in step (2); (4) sterilizing the yogurt from which lactoferrin is extracted obtained in step (2); (5) adding the sterilized lactoferrin obtained in step (3) to the sterilized yogurt from which lactoferrin has been extracted obtained in step (4) to obtain the yogurt to which lactoferrin is not added exogenously.

2. The production method according to claim 1, wherein Step (1) comprises the following steps: (a) Milk purification: The raw milk is subjected to a centrifugal milk purification process; (b) separation: centrifuging the purified raw milk to separate the cream from the skimmed milk; (c) Skim milk prefiltration: Prefiltration removes particulate matter from skim milk; (d) skim milk sterilization filtration: the skim milk after pre-filtration is sterilized; (e) Sterilization of skim milk: sterilizing the skim milk after the sterilization treatment at 69-71° C. for 13-15 seconds; (f) Cream sterilization: The cream is sterilized at 136-137°C for 4-6 seconds and then cooled to 69-71°C; (g) Online mixing: the sterilized skim milk and the sterilized cooled cream are mixed online; (h) Homogenizing: homogenizing the mixed skim milk and cream; (i) cooling; (j) fermentation; (k) Demulsification.

3. The production method according to claim 1, wherein Step (2) comprises the following steps: (a) whey separation: the fermented raw milk is subjected to whey separation to obtain whey and whey-free yogurt respectively; (b) Lactoferrin extraction: Lactoferrin is extracted from whey to obtain lactoferrin.

4. The production method according to claim 1, wherein Step (3) comprises the following steps: The lactoferrin obtained in step (2) is sterilized by membrane filtration using a sterilization membrane with a pore size of 0.2-0.45 μm.

5. The production method according to claim 1, wherein Step (4) comprises the following steps: (a) yogurt sterilization: sterilizing the yogurt after lactoferrin extraction at 70-75° C. for 25-30 seconds to obtain sterilized yogurt; (b) Cooling: The sterilized yogurt is cooled to 25-30°C.

6. The production method according to claim 1, wherein: Step (5) comprises the following steps: (a) Sterile lactoferrin backfilling: adding the sterilized lactoferrin obtained in step (3) online to the sterilized yogurt from which lactoferrin has been extracted in step (4) to obtain a yogurt material containing lactoferrin; (b) Filling: Filling is performed by aseptic filling to obtain the yogurt without exogenous lactoferrin addition.

7. The production method according to claim 2, wherein: The skim milk pre-filtration is performed using a filter with a pore size of 20-60 μm; Preferably, the skimmed milk sterilization filtration is performed using a filter with a pore size of 0.8-1.4 μm; Preferably, the homogenization temperature is 68-71°C and the homogenization pressure is 180-250 bar; Preferably, the demulsification is performed at a rotation speed of 70-90 rpm for 10-15 min.

8. The production method according to claim 3, wherein: The whey separation is carried out by using a whey separator or a membrane filtration method.

9. The production method according to claim 3, wherein: The lactoferrin extraction is carried out by chromatography.

10. Yogurt without exogenous lactoferrin added prepared by the production method according to any one of claims 1 to 9.

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