Sucrose-free fermented milk and preparation method thereof

Abstract

The invention relates to the technical field of food processing, and discloses a sucrose-free fermented milk and a preparation method thereof. The fermented milk comprises the following components by mass ratio: 8-15 parts of whole milk powder, 1.01-5.03 parts of a sweetener, 0.81-2.02 parts of a stabilizer, 0.002-0.020 parts of a starter, and the balance is ultrapure water. The fermented milk has an ACE inhibitory activity of up to 95.7-99.7%, can effectively reduce the blood pressure of hypertensive consumers, and still has the effect of reducing blood pressure after the hypertensive consumers stop consuming the fermented milk for 4 weeks. The fermented milk does not add sucrose, can be stored at room temperature, does not need to be refrigerated, and has a shelf life of 150-180 days at room temperature, so it can be eaten by people who have high blood pressure and need to limit sugar intake and do not like cold food. The preparation method of the fermented milk is simple in process, low in cost, short in fermentation time, and easy to industrialize.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a sucrose-free fermented milk and a preparation method thereof. Background Art

[0002] Hypertension is a serious disease characterized by high blood pressure, which significantly increases the risk of heart, brain, kidney and other diseases. Hypertension is increasing year by year around the world and has been listed as the number one risk factor for human health by the World Health Organization. Therefore, preventing and controlling high blood pressure has become an important issue facing mankind.

[0003] Human blood pressure is regulated by many factors, among which the renin-angiotensin system (RAS) and kallikrein-kinin system (KKS) are two important mechanisms of blood pressure regulation. In the RAS system, angiotensin converting enzyme (ACE) converts inactive angiotensin I (Ang I) into a potent vasoconstrictor angiotensin II (Ang II), which leads to increased blood pressure. In the KKS system, ACE inhibits the decomposition of bradykinin, a hypotensive substance, thereby inhibiting the KKS system, which also leads to increased blood pressure. Therefore, ACE has become an ideal target for the treatment of hypertension, and its inhibitors have developed a large class of drugs for the treatment of hypertension. However, studies have shown that some patients will experience adverse reactions such as coughing, dizziness, fatigue, angioedema, and increased potassium levels after taking synthetic ACE inhibitors, and long-term use will have toxic side effects on various organs of the human body.

[0004] Food-derived ACE inhibitory peptides have the advantages of low cost and no side effects, and are ideal blood pressure-lowering ingredients. Some reports have disclosed technologies that use cow's milk as a base to produce ACE inhibitory peptides, which then have the effect of lowering blood pressure. However, these reports all have some shortcomings: 1. Low ACE inhibitory activity, such as "a fermented milk product" disclosed in announcement number CN 105613731B, the ACE inhibition rate of the fermented milk product is 27.89-45.15%, and "Lactobacillus helveticus H11 and its application" disclosed in application number CN 109517763A, the ACE inhibition rate of the brown active lactic acid bacteria beverage is 60-70%; 2. There is a lack of direct verification of the actual blood pressure-lowering effect of fermented milk on the human body. For example, the "production method of yogurt with auxiliary blood pressure lowering and liver protection function" disclosed in application number CN 107173438A only discloses indirect data such as rat systolic blood pressure; the yogurt in the "yak yogurt with blood pressure lowering function and its preparation method" disclosed in application number CN 114365765A only discloses indirect data such as rat systolic blood pressure, diastolic blood pressure, pressure difference and rat angiotensinogen (AGT) content, ACE content and Ang II content, but no direct data such as changes in human blood pressure. 3. There is only a blood pressure lowering effect during consumption, but no verification of the blood pressure lowering ability after stopping consumption. For example, the yogurt in the "high calcium and low sugar yogurt with blood pressure lowering function and its preparation method" disclosed in application number CN 110623068A can reduce the average systolic blood pressure of the human body by 10.82 mmHg and the average diastolic blood pressure by 5.54 mmHg after continuous consumption for 6 weeks, but there is no blood pressure data after stopping consumption. 4. Contains sucrose. Since people with hypertension often have high blood sugar, they often need to limit sugar intake. For example, the technologies disclosed in announcement number CN 105613731B, application number CN 114365765A, and application number CN110623068A do not circumvent the use of sucrose, which will bring additional burden to consumers. 5. Short shelf life. Yogurt with a long shelf life is easy to store and does not require refrigeration, which is convenient for consumers to eat. For example, the technical solutions disclosed in publication number CN 105613731B, application number CN 114365765A, and application publication number CN 110623068A do not explain the shelf life, and there is no ACE inhibitory activity data during the shelf life. 6. The process for producing ACE inhibitory peptides is complicated and costly. There are two main methods for producing food-borne ACE inhibitory peptides: enzymatic hydrolysis and fermentation. For example, the technical solutions disclosed in application number CN 107173438A, publication number CN 105613731B, etc. all use enzymatic hydrolysis to produce ACE inhibitory peptides. However, the enzymatic hydrolysis method requires separate enzymatic hydrolysis and enzyme inactivation processes, requires a more precise heating and cooling process, has high requirements for equipment, and consumes a lot of energy.In addition, the "Application of Lactobacillus helveticus in the preparation of fermented products for lowering blood pressure" disclosed in application number CN 114680337A (for) adopts a fermentation method to produce ACE inhibitory peptides, but the fermentation time must be at least 10 hours to produce more than 90% ACE inhibitory activity. The actual fermentation time is relatively long and the production cost is relatively high. Summary of the invention

[0005] In order to overcome the problems in the prior art of low ACE inhibitory activity of traditional blood pressure lowering fermented milk, insufficient data on human blood pressure lowering effects, no blood pressure data after stopping consumption, high sucrose content, short shelf life and complex production process, the present application provides a sucrose-free fermented milk and a preparation method thereof. The fermented milk has high ACE inhibitory activity and high stability, and still has a blood pressure lowering effect for a period of time after stopping use, does not contain sucrose, and has a long shelf life. The preparation method of the fermented milk has the characteristics of simple process, low cost, short fermentation time and easy industrial production.

[0006] The specific technical scheme of the present invention is:

[0007] A sucrose-free fermented milk, comprising the following components by weight:

[0008] 8~15 portions of whole milk powder,

[0009] Sweetener 1.01~5.03 parts,

[0010] Stabilizer 0.81~2.02 parts,

[0011] 0.002~0.020 parts of leavening agent,

[0012] Ultrapure water balance;

[0013] The fermentation agent comprises thermophilic streptococcus WHH1590 freeze-dried powder, Lactobacillus delbrueckii subspecies bulgaricus WHH699 freeze-dried powder and Lactobacillus helveticus WHH2580 freeze-dried powder in a mass ratio of 90-100:15-25:1, and the number of viable bacteria in the fermentation agent is 1×10 7 ~5×10 10 CFU / g.

[0014] The present application provides a sucrose-free fermented milk, which is made by fermenting whole milk powder with a starter and mixing it with a stabilizer and a sweetener. The ACE inhibitory activity of the fermented milk can reach 95.7-99.7%, which can effectively reduce the blood pressure of hypertensive consumers, and at the same time, the hypertensive consumers still have the effect of reducing blood pressure after the fourth week of stopping consuming the fermented milk. The fermented milk does not add sucrose, and can be consumed by people with high blood pressure who need to limit sugar intake and do not like cold food. It has the advantages of high acceptability, high safety, and no side effects, and has important efficacy value and social value.

[0015] The starter culture is a composite starter culture composed of thermophilic Streptococcus WHH1590 freeze-dried powder, Lactobacillus delbrueckii subspecies bulgaricus WHH699 freeze-dried powder and Lactobacillus helveticus WHH2580 freeze-dried powder. The thermophilic Streptococcus WHH1590 was screened by the inventor from fermented foods in the Tibet Autonomous Region and was deposited in the General Microbiology Center of the China Microbiological Culture Collection Administration on July 27, 2022. Its deposit number is CGMCC No.25413, and the microbial classification is named Streptococcus thermophilus Streptococcus thermophilus Lactobacillus delbrueckii subspecies bulgaricus WHH699 was screened by the inventor from yak yogurt samples collected from rural Xining City, Qinghai Province, my country. It was deposited in the General Microbiology Center of China Microbiological Culture Collection Administration on July 27, 2022. Its deposit number is CGMCC No.25414, and the microbial classification is named Lactobacillus delbrueckii subspecies bulgaricus Lactobacillus delbrueckii subsp.bulgaricus Lactobacillus helveticus WHH2580 was screened by the inventor from yogurt samples collected from Narat Hongshangou in Xinjiang, my country. It was deposited in the General Microbiological Center of China Microbiological Culture Collection Committee on October 23, 2019. Its deposit number is: CGMCC No. 18730. The microbial classification is named Lactobacillus helveticus Lactobacillus helveticus The above-mentioned fermentation agent has a synergistic fermentation effect, which can significantly increase the yield of ACE inhibitory peptides in the fermentation product. At the same time, the fermentation conditions of the fermentation agent are simple and the cycle is short, and it has extremely high application value when used.

[0016] Preferably, the sweetener is selected from one or more of acesulfame potassium, aspartame and xylitol.

[0017] Preferably, the stabilizer is selected from one or more of sodium carboxymethyl cellulose, gellan gum and hydroxypropyl distarch phosphate.

[0018] A method for preparing sucrose-free fermented milk comprises the following steps:

[0019] (1) Milk liquid preparation: whole milk powder is placed in preheated ultrapure water and subjected to heating, shearing, static hydration, homogenization and sterilization to prepare a fermentation base;

[0020] (2) Inoculation and fermentation: inoculating the starter into the fermentation base prepared in step (1), stirring evenly, and allowing to stand for fermentation to form a yogurt base;

[0021] (3) Preparation of glue solution: adding stabilizer and sweetener into preheated ultrapure water and shearing and cooling to prepare glue solution;

[0022] (4) Preparation of fermented milk: The yogurt base prepared in step (2) is stirred and demulsified to prepare a demulsified yogurt base, and the gelatin solution prepared in step (3) is injected into the demulsified yogurt base and the mixture is homogenized twice, filled and sterilized in sequence to prepare sucrose-free fermented milk.

[0023] The present application also provides a method for preparing sucrose-free fermented milk, which is prepared by pretreating, homogenizing, sterilizing, fermenting, re-sterilizing and hot filling the raw materials. The above process enables the prepared sucrose-free fermented milk to be stored at room temperature without refrigeration, and the shelf life at room temperature can reach 150 to 190 days. At the same time, the effective ingredients are retained to the maximum extent without being destroyed during the processing, thereby ensuring the functionality of the product.

[0024] Preferably, the temperature of the preheated ultrapure water in step (1) is 45-60° C., and the shearing conditions include: a shear rate of 3000-4000 rpm / min, a shearing time of 10-15 min, and a standing hydration time of 15-20 min.

[0025] Preferably, the homogenization conditions in step (1) include: a primary homogenization pressure of 20 MPa, a secondary homogenization pressure of 5 MPa, and a homogenization temperature of 60-65°C; the sterilization conditions include: a sterilization temperature of 90-96°C, a time of 5-10 min, and a cooling temperature of 41-43°C.

[0026] Preferably, the static fermentation conditions in step (2) include: fermentation temperature 40-42° C., and fermentation time 6-8 h.

[0027] Preferably, the temperature of the preheated ultrapure water in step (3) is 50-60° C., and the shearing conditions include: a shear rate of 3000-4000 rpm / min, and a shearing time of 15-20 min.

[0028] Preferably, the conditions for the secondary homogenization in step (4) include: a primary homogenization pressure of 20 MPa, a secondary homogenization pressure of 5 MPa, and a homogenization temperature of 60-65°C.

[0029] Preferably, the sterilization conditions in step (4) include: temperature 85-87°C, time 15-18 min.

[0030] Compared with the prior art, this application has the following technical effects:

[0031] (1) The ACE inhibitory activity of the sucrose-free fermented milk of the present application can reach 95.7-99.7%, which can effectively lower the blood pressure of hypertensive consumers. At the same time, it still has the effect of lowering blood pressure after the hypertensive consumers stop consuming the fermented milk for 4 weeks;

[0032] (2) The sucrose-free fermented milk of the present application does not contain sucrose and can be stored at room temperature without refrigeration. The shelf life at room temperature can reach 150 to 190 days, and can be consumed by people with high blood pressure who need to limit sugar intake and who do not like cold food.

[0033] (3) The preparation method of the sucrose-free fermented milk of the present application has simple process, low cost, short fermentation time and is easy for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 1 is a diagram showing the test period and age of test participants in Example 5 of the present invention.

[0035] Figure 2 4 is a graph showing changes in systolic blood pressure of some typical individuals during the test period of Example 5 of the present invention.

[0036] Figure 3 4 is a graph showing changes in diastolic blood pressure of some typical individuals during the test period of Example 5 of the present invention.

[0037] Figure 4 This is a graph showing changes in diastolic blood pressure of some normotensive individuals during the test period of Example 5 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the embodiments.

[0039] Embodiment 1:

[0040] A sucrose-free fermented milk, comprising the following components by weight:

[0041] 11 parts whole milk powder,

[0042] Sweeteners include, by weight: 0.01 part of acesulfame potassium, 0.01 part of aspartame, and 0.3 part of xylitol;

[0043] The stabilizer includes, by weight: 0.3 parts of hydroxypropyl distarch phosphate, 0.7 parts of sodium carboxymethyl cellulose, and 0.02 parts of gellan gum;

[0044] 0.02 parts of starter, the starter includes freeze-dried powder of Streptococcus thermophilus WHH1590, freeze-dried powder of Lactobacillus delbrueckii subspecies bulgaricus WHH699 and freeze-dried powder of Lactobacillus helveticus WHH2580 in a mass ratio of 90:25:1, and the number of viable bacteria in the starter is 5×10 10 CFU / g;

[0045] Ultrapure water balance;

[0046] A method for preparing sucrose-free fermented milk comprises the following steps:

[0047] (1) Milk preparation: whole milk powder was placed in preheated ultrapure water (50°C) and subjected to heating, shearing, static hydration, homogenization and sterilization to prepare a fermentation base. The amount of whole milk powder added was 300 g / L. The shearing conditions included: shear rate 3500 rpm / min, shearing time 12 min, static hydration time 18 min, homogenization conditions included: primary homogenization pressure 20 MPa, secondary homogenization pressure 5 MPa, homogenization temperature 62°C, sterilization conditions included: sterilization temperature 90°C, time 8 min, cooling temperature 42°C;

[0048] (2) Inoculation and fermentation: inoculating the starter into the fermentation base prepared in step (1), stirring evenly, and standing for fermentation and cooling for less than 15° C. to prepare a yogurt base. The standing fermentation conditions include: fermentation temperature of 41° C. and fermentation time of 7 h.

[0049] (3) Preparation of glue solution: the stabilizer and the sweetener are added to the preheated ultrapure water and the solution is prepared by shearing and cooling (cooling to below 30°C). The temperature of the preheated ultrapure water is 55°C. The shearing conditions include: shear rate of 3500 rpm / min and shear time of 18 min.

[0050] (4) Preparation of fermented milk: The yogurt base prepared in step (2) is stirred and demulsified to prepare a demulsified yogurt base, and the colloid solution prepared in step (3) is injected into the demulsified yogurt base, and the mixture is subjected to secondary homogenization, filling and sterilization in sequence to prepare sucrose-free fermented milk. The secondary homogenization conditions include: a primary homogenization pressure of 20 MPa, a secondary homogenization pressure of 5 MPa, and a homogenization temperature of 62°C. The sterilization conditions include: a temperature of 85°C and a time of 18 min.

[0051] Embodiment 2:

[0052] A sucrose-free fermented milk, comprising the following components by weight:

[0053] 8 parts whole milk powder,

[0054] Sweeteners include, by weight: 0.015 parts of acesulfame potassium, 0.015 parts of aspartame, and 1 part of xylitol;

[0055] The stabilizer includes, by weight: 0.6 parts of hydroxypropyl distarch phosphate, 1 part of sodium carboxymethyl cellulose, and 0.01 parts of gellan gum;

[0056] 0.002 parts of starter, the starter includes freeze-dried powder of Streptococcus thermophilus WHH1590, freeze-dried powder of Lactobacillus delbrueckii subspecies bulgaricus WHH699 and freeze-dried powder of Lactobacillus helveticus WHH2580 in a mass ratio of 90:15:1, and the number of viable bacteria in the starter is 5×10 10 CFU / g;

[0057] Ultrapure water balance;

[0058] A method for preparing sucrose-free fermented milk comprises the following steps:

[0059] (1) Milk preparation: whole milk powder was placed in preheated ultrapure water (45°C) and subjected to heating, shearing, static hydration, homogenization and sterilization to prepare a fermentation base. The shearing conditions included: shear rate of 3500 rpm / min, shearing time of 10 min, static hydration time of 20 min, homogenization conditions included: primary homogenization pressure of 20 MPa, secondary homogenization pressure of 5 MPa, homogenization temperature of 65°C, sterilization conditions included: sterilization temperature of 93°C, time of 8 min, cooling temperature of 41°C;

[0060] (2) Inoculation and fermentation: inoculating the starter into the fermentation base prepared in step (1), stirring evenly, and standing for fermentation and cooling for less than 15° C. to prepare a yogurt base. The standing fermentation conditions include: fermentation temperature of 40° C. and fermentation time of 6 h.

[0061] (3) Preparation of glue solution: stabilizer and sweetener are added to preheated ultrapure water and sheared and cooled (cooled to below 30°C) to prepare glue solution. The temperature of preheated ultrapure water is 50°C. The shearing conditions include: shear rate of 3500 rpm / min and shear time of 20 min.

[0062] (4) Preparation of fermented milk: The yogurt base prepared in step (2) is stirred and demulsified to prepare a demulsified yogurt base, and the gel solution prepared in step (3) is injected into the demulsified yogurt base and sequentially subjected to secondary homogenization, filling and sterilization to prepare sucrose-free fermented milk. The secondary homogenization conditions include: a primary homogenization pressure of 20 MPa, a secondary homogenization pressure of 5 MPa, and a homogenization temperature of 62°C. The sterilization conditions include: a temperature of 86°C and a time of 18 min.

[0063] Embodiment 3:

[0064] A sucrose-free fermented milk, comprising the following components by weight:

[0065] 15 parts whole milk powder,

[0066] Sweeteners include, by weight: 0.005 parts of acesulfame potassium, 0.005 parts of aspartame, and 5 parts of xylitol;

[0067] The stabilizer includes, by weight: 1 part of hydroxypropyl distarch phosphate, 0.5 part of sodium carboxymethyl cellulose, and 0.02 part of gellan gum;

[0068] 0.01 part of starter, the starter includes freeze-dried powder of Streptococcus thermophilus WHH1590, freeze-dried powder of Lactobacillus delbrueckii subspecies bulgaricus WHH699 and freeze-dried powder of Lactobacillus helveticus WHH2580 in a mass ratio of 100:20:1, and the number of viable bacteria in the starter is 5×10 10 CFU / g;

[0069] Ultrapure water balance;

[0070] A method for preparing sucrose-free fermented milk comprises the following steps:

[0071] (1) Milk preparation: whole milk powder was placed in preheated ultrapure water (45°C) and subjected to heating, shearing, static hydration, homogenization and sterilization to prepare a fermentation base. The amount of whole milk powder added was 300 g / L. The shearing conditions included: shear rate 3500 rpm / min, shearing time 15 min, static hydration time 15 min, homogenization conditions included: primary homogenization pressure 20 MPa, secondary homogenization pressure 5 MPa, homogenization temperature 60°C, sterilization conditions included: sterilization temperature 90°C, time 10 min, cooling temperature 43°C;

[0072] (2) Inoculation and fermentation: inoculating the starter into the fermentation base prepared in step (1), stirring evenly, and standing for fermentation and cooling for less than 15° C. to prepare a yogurt base. The conditions for standing for fermentation include: fermentation temperature of 42° C. and fermentation time of 8 h.

[0073] (3) Preparation of glue solution: The stabilizer and the sweetener are added to the preheated ultrapure water and the mixture is sheared and cooled (to below 30°C) to prepare the glue solution. The temperature of the preheated ultrapure water is 55°C. The shearing conditions include: shear rate of 3500 rpm / min and shear time of 15 min.

[0074] (4) Preparation of fermented milk: The yogurt base prepared in step (2) is stirred and demulsified to prepare a demulsified yogurt base, and the gelatin solution prepared in step (3) is injected into the demulsified yogurt base and sequentially subjected to secondary homogenization, filling and sterilization to prepare sucrose-free fermented milk. The secondary homogenization conditions include: a primary homogenization pressure of 20 MPa, a secondary homogenization pressure of 5 MPa, and a homogenization temperature of 60°C. The sterilization conditions include: a temperature of 87°C and a time of 15 min.

[0075] Embodiment 4:

[0076] A comparative test was conducted between commercially available fermented milk (control group 1) and the sucrose-free fermented milk prepared in Examples 1 to 3, and their ACE inhibition rate, acidity, pH, sensory evaluation and shelf life were tested respectively. The test methods involved are as follows:

[0077] ACE inhibition rate determination method:

[0078] a) Fermented milk was centrifuged at 12000r / min for 10 minutes and the supernatant was taken for later use;

[0079] b) Prepare a 5.0mmol / L solution of hip-his-leu (HHL) with 0.1mol / L borate buffer (pH8.3) containing 0.3mol / L NaCl; add 200μL of 5.0mmol / L HHL solution and 80μL of sample into a centrifuge tube, incubate at 37℃ for 5 minutes, then add 20μL of ACE solution (dissolved in distilled water, activity is 0.1U / mL), mix well, incubate at 37℃ for 30 minutes, then add 250μL of 1.0mol / L hydrochloric acid solution to terminate the reaction;

[0080] c) Determine the content of hippuric acid by HPLC and calculate the ACE inhibition rate. The calculation formula of ACE inhibition rate is:

[0081] ACE inhibition rate (%) = (BA) / (BC) × 100;

[0082] Wherein: A is the ACE inhibition rate and the absorbance of the reaction of ACE solution and HHL at the same time; B is the absorbance of the reaction of ACE and HHL without adding sample, i.e. control; C is the absorbance when neither sample nor ACE exists, i.e. blank;

[0083] Sucrose determination method: refer to GB 5009.8-2016;

[0084] pH determination method: refer to GB 5009.237-2016;

[0085] Acidity determination method: refer to GB 5009.239-2016;

[0086] Sensory requirements: refer to GB19302-2010;

[0087] Shelf life determination: Examples 1-3 refer to T / CNFIA 001-2017; Control group 1 is determined according to the product label; the test results are shown in Table 1;

[0088] Table 1 Test results

[0089]

[0090] As shown in Table 1, the fermented milk obtained in Examples 1-3 of the present invention has an ACE inhibition rate greater than 95%, which is much higher than that of commercially available samples, among which Example 3 has the highest ACE inhibition rate, which can reach 99.7%. No sucrose was detected in the fermented milk obtained in Examples 1-3 of the present invention, indicating that the present invention can truly be sucrose-free. The pH and acidity of the fermented milk obtained in Examples 1-3 of the present invention are within the normal range of fermented milk, indicating that the fermentation acidity of the product of the present invention is controllable and meets the current national standard requirements. The fermented milk obtained in Examples 1-3 of the present invention has a good sensory evaluation, and is sweet and sour, without bitterness, indicating that the fermented milk obtained in the present invention can improve the bitterness of antihypertensive peptides, and consumers are easily accepted. In addition, the fermented milk obtained in Examples 1-3 of the present invention can have a shelf life of up to 180 days, and there is no deterioration of flavor and texture during the shelf life, and the ACE inhibition rate remains high and stable, meeting the requirements of a long shelf life.

[0091] Embodiment 5:

[0092] 37 volunteers were recruited as testers, including 36 volunteers with high blood pressure and 1 volunteer with normal blood pressure. High blood pressure refers to systolic blood pressure > 130 mmHg or diastolic blood pressure > 85 mmHg. The age distribution of volunteers is as follows: 4 people aged 25-30, 8 people aged 35-40, 10 people aged 41-45, 8 people aged 46-50, and 7 people aged 51-60. The age sample data is normally distributed. See the test period and the age of the participants for details. Figure 1 ;

[0093] The experiment adopted a before-and-after self-control design, and the volunteers did not change their eating habits and living habits during the trial, which lasted for 8 weeks. The trial sample was the fermented milk obtained in Example 3. The trial sample was delivered to the volunteers in advance according to the amount for one week, and the start time of the trial was marked. One bottle (200 mL) was given every day, and the tasting time was not fixed every day. During the entire tasting process, the volunteers were asked about their tasting experience from time to time, and questions and doubts were answered in a timely manner; the volunteers' blood pressure was measured once a week after the initial 0 week, 1 week, 2 weeks, 3 weeks, 4 weeks of tasting, and 1 week, 2 weeks, 3 weeks, and 4 weeks of fasting. Each volunteer was measured 3 times in parallel, and the results were averaged; the differences in systolic and diastolic blood pressure between people with high blood pressure and volunteers with normal blood pressure during the tasting and fasting periods were analyzed; R software (version 4.0.3) was used to perform statistical analysis on the test results; paired t-test was used to test and analyze the data; the statistical result P < 0.05 was considered significant; without changing their own eating habits and living habits, the changes in systolic blood pressure of people with high blood pressure during the entire trial period are shown in Table 2, and the changes in systolic blood pressure of some typical individuals during the entire trial period are shown in Table 2. Figure 2 ;

[0094] Table 2 Changes in systolic blood pressure during the entire trial

[0095]

[0096] As shown in Table 2 and Figure 2 As shown in the figure, after 1 week of trial, systolic blood pressure had decreased significantly compared with the initial value (P < 0.05), and the degree of decrease increased with the number of weeks. After 2 weeks of trial, systolic blood pressure decreased significantly compared with the initial value (P < 0.001). After 1, 2, 3, and 4 weeks of trial, systolic blood pressure decreased by 3.8 mmHg, 8.4 mmHg, 13.2 mmHg, and 10.6 mmHg respectively compared with the initial value. After 4 weeks of trial, the most significant individual systolic blood pressure decreased by up to 30 mmHg compared with the initial value. Hg, has dropped to the normal blood pressure range, after stopping for 1 week, systolic blood pressure is still significantly lower than the initial value (P < 0.05), after stopping for 2 weeks, systolic blood pressure is significantly lower than the initial value (P < 0.01), after stopping for 3 and 4 weeks, systolic blood pressure is extremely significantly lower than the initial value (P < 0.001), after stopping for 1 week, 2 weeks, 3 weeks, 4 weeks, systolic blood pressure is lowered by 9.4mmHg, 8.3mmHg, 13.7mmHg, 11.0mmHg respectively compared with the initial value. This shows that the effect of lowering systolic blood pressure is still maintained within 4 weeks of stopping;

[0097] Without changing their eating and living habits, the changes in diastolic blood pressure of people with high blood pressure during the entire trial period are shown in Table 3. The changes in diastolic blood pressure of some typical individuals during the entire trial period are shown in Figure 3 ;

[0098] Table 3 Changes in diastolic blood pressure during the entire trial period

[0099]

[0100] As shown in Table 3 and Figure 3 As shown in the figure, after 1 and 2 weeks of trial, diastolic blood pressure had a downward trend compared with the initial value, but it was not statistically significant (P>0.05); after 3 and 4 weeks of trial, diastolic blood pressure had a significant decrease compared with the initial value (P<0.001). The degree of decrease increased with the number of weeks. After the recruited people tried the diet for 3 and 4 weeks, the diastolic blood pressure decreased by 6mmHg and 6.5mmHg respectively compared with the initial value; after 4 weeks of trial diet, the diastolic blood pressure of the most significant individual decreased by up to 20mmHg compared with the initial value, which has dropped to the normal blood pressure range; after stopping the diet for 1 week, the diastolic blood pressure rebounded, but it was not statistically significant compared with the initial value (P>0.05); after stopping the diet for 2 and 3 weeks, the diastolic blood pressure continued to decrease, and it was significantly lower than the initial value (P<0.01, P<0.001); after stopping the diet for four weeks, the diastolic blood pressure rebounded, but the mean was still lower than the initial value; after stopping the diet for 1, 2, 3, and 4 weeks, the diastolic blood pressure decreased by 0.8mmHg, 4.6mmHg, 7.7mmHg, and 3.7mmHg respectively compared with the initial value. This shows that the diastolic blood pressure lowering effect is still partially maintained within 3 weeks of stopping the diet;

[0101] Without changing their eating and living habits, the changes in blood pressure of people with normal blood pressure during the trial diet are shown in Figure 4 ,like Figure 4 As shown, there was no significant change in systolic and diastolic blood pressure in people with normal blood pressure after trying the diet for 4 weeks and stopping the diet for 4 weeks.

[0102] In summary, the long-shelf-life sucrose-free fermented milk prepared in Example 3 has the effect of lowering diastolic and systolic blood pressure for people with high blood pressure, and can still lower systolic blood pressure within 4 weeks after stopping consumption, and can still lower diastolic blood pressure within 3 weeks after stopping consumption. Its effect has a certain long-term effect, and has a blood pressure-lowering effect in the 4th week after stopping consumption, while has no effect on the diastolic and systolic blood pressure of people with normal blood pressure.

[0103] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing sucrose-free fermented milk, characterized in that: The following steps are involved: (1) Milk preparation: 8-15 parts of whole milk powder are placed in preheated ultrapure water and heated, sheared, left to stand for hydration, homogenized, and sterilized to prepare a fermentation base; (2) Inoculation and fermentation: inoculating 0.002-0.020 parts of the starter into the fermentation base prepared in step (1), stirring evenly, and standing for fermentation to prepare a yogurt base, wherein the conditions for the standing fermentation include: a fermentation temperature of 40-42° C. and a fermentation time of 6-8 h; (3) Preparation of glue solution: 0.81-2.02 parts of stabilizer and 1.01-5.03 parts of sweetener are added to preheated ultrapure water and the mixture is sheared and cooled to prepare glue solution; (4) Preparation of fermented milk: stirring and demulsifying the yogurt base prepared in step (2) to prepare a demulsified yogurt base, injecting the gelatin solution prepared in step (3) into the demulsified yogurt base, and sequentially homogenizing, filling and sterilizing for a second time to prepare sucrose-free fermented milk; The fermentation agent comprises thermophilic streptococcus WHH1590 freeze-dried powder, Lactobacillus delbrueckii subspecies bulgaricus WHH699 freeze-dried powder and Lactobacillus helveticus WHH2580 freeze-dried powder in a mass ratio of 90-100:15-25:1, and the number of viable bacteria in the fermentation agent is 1×10 7 ~5×10 10 CFU / g.

2. The method for preparing sucrose-free fermented milk according to claim 1, characterized in that: The temperature of the preheated ultrapure water in step (1) is 45-60° C., and the shearing conditions include: a shear rate of 3000-4000 rpm, a shearing time of 10-15 min, and a standing hydration time of 15-20 min.

3. The method for preparing sucrose-free fermented milk according to claim 1, characterized in that: The homogenization conditions in step (1) include: a first-level homogenization pressure of 20 MPa, a second-level homogenization pressure of 5 MPa, and a homogenization temperature of 60-65°C. The sterilization conditions include: a sterilization temperature of 90-96°C, a time of 5-10 min, and a cooling temperature of 41-43°C.

4. The method for preparing sucrose-free fermented milk according to claim 1, characterized in that: The temperature of the preheated ultrapure water in step (3) is 50-60° C., and the shearing conditions include: a shear rate of 3000-4000 rpm and a shearing time of 15-20 min.

5. The method for preparing sucrose-free fermented milk according to claim 1, characterized in that: The conditions for the secondary homogenization in step (4) include: a primary homogenization pressure of 20 MPa, a secondary homogenization pressure of 5 MPa, and a homogenization temperature of 60-65°C.

6. The method for preparing sucrose-free fermented milk according to claim 1, characterized in that: The sterilization conditions in step (4) include: temperature 85-87°C, time 15-18 min.

7. A sucrose-free fermented milk prepared according to the preparation method according to any one of claims 1 to 6, characterized in that: Ingredients include whole milk powder, sweeteners, stabilizers, fermentation agents and ultrapure water.

8. The sucrose-free fermented milk according to claim 7, characterized in that: The sweetener is selected from one or more of acesulfame potassium, aspartame and xylitol.

9. The sucrose-free fermented milk according to claim 7, characterized in that: The stabilizer is selected from one or more of sodium carboxymethyl cellulose, gellan gum and hydroxypropyl distarch phosphate.

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