Goat yogurt as well as preparation method therefor and uses thereof

Abstract

A goat yogurt as well as a preparation method therefor and the uses thereof. The goat yogurt comprises fatty acid, the fatty acid comprising saturated fatty acid and unsaturated fatty acid, and a mass ratio of the saturated fatty acid to the unsaturated fatty acid is (55-60): (40-45). The preparation method for the goat yogurt comprises the following steps: performing homogenization-static ultrahigh pressure treatment on goat milk; placing the goat milk subjected to the homogenization-static ultrahigh pressure treatment on a shaking incubator for enzymolysis; performing water bath treatment on the goat milk subjected to enzymolysis; and performing fermentation on the goat milk subjected to the water bath treatment so as to obtain the goat yogurt. The homogenizing-static ultrahigh-pressure treatment process comprises three-stage pressure treatment; in a first-stage pressure treatment process, the pressure is 220 bar-240 bar; in a second-stage pressure treatment process, the pressure is 40 bar-60 bar; and in a third-stage pressure treatment process, the pressure is 200 MPa-300 MPa. A mass ratio of rumenic acid to linoleic acid to vaccenic acid in the unsaturated fatty acid is (7-9): (4-5): (58-65), and the vaccenic acid is t11-C18:1. The obtained goat yogurt can assist in reducing blood sugar.

Description

Sheep yogurt and its preparation method and application Technical Field

[0001] The invention relates to goat yogurt and a preparation method and application thereof. Background Art

[0002] Saturated fatty acids (SFA) increase low-density lipoprotein cholesterol (LDL-C) and are a significant risk factor for cardiovascular disease (CVD). Certain long-chain saturated fatty acids, such as C16:0 and C18:0 fatty acids, exhibit proinflammatory effects in humans, and low-level systemic inflammation is an independent risk factor for CVD and type 2 diabetes (T2D). Currently, dietary recommendations for reducing CVD risk primarily focus on reducing saturated fatty acid (SFA) intake, with recommendations to replace SFA with monounsaturated and polyunsaturated fatty acids. However, different SFAs have distinct biological functions: some short-chain and medium-chain saturated fatty acids have beneficial effects on CVD and type 2 diabetes (T2D). Therefore, the intake of all saturated fatty acids (SFA) should not be avoided.

[0003] Some bioactive lipids can cause signal transduction and biological effects by binding to specific receptors, and changes in the levels of these lipids can lead to physiological and pathological consequences, so they are considered bioactive lipids. Typical bioactive fatty acids, such as rumenic acid (c9,t11-CLA) and vacuum acid (t11-C18:1), can improve insulin resistance by activating PPAR-c.

[0004] Existing studies have reported that the risk of T2D is negatively correlated with linoleic acid (LA) biomarkers in a dose-dependent manner. This negative correlation is attributed to better glycemic control and insulin sensitivity in individuals who consume LA, leading to a lower risk of T2D. Therefore, reducing the content of saturated fatty acids in the diet and increasing the content of unsaturated fatty acids, especially rumenic acid, vacuolar acid, and linoleic acid, is beneficial for reducing the risk of chronic diseases such as CVD and T2D.

[0005] Consumers are increasingly interested in goat milk and its products, driven by its unique nutritional value and positive health effects. The lipids in goat milk are a high-quality source of lipids for human consumption, exhibiting biological activities such as anti-inflammatory and anti-thrombotic properties. While lipase activity is high in goat yogurt, triglycerides in the milk are not hydrolyzed because the milk fat globule membrane blocks contact between lipase and triglycerides. Therefore, the present application provides goat yogurt, its preparation method, and its application. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a goat yogurt and a preparation method and application thereof, which can obtain goat yogurt with low saturated fatty acid content and high unsaturated fatty acid content.

[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0008] In one aspect, the present invention provides a goat yogurt, characterized in that the goat yogurt comprises fatty acids;

[0009] The fatty acids include saturated fatty acids and unsaturated fatty acids;

[0010] The mass ratio of the saturated fatty acid to the unsaturated fatty acid is (55-60): (40-45).

[0011] Furthermore, the concentration of fatty acids in the goat yogurt is 2-3 wt%.

[0012] Furthermore, the unsaturated fatty acids include monounsaturated fatty acids and polyunsaturated fatty acids;

[0013] The mass ratio of the monounsaturated fatty acid to the polyunsaturated fatty acid is (34-37): (5-11).

[0014] Furthermore, the mass ratio of rumen acid, linoleic acid and vacuum acid in the unsaturated fatty acids is (7-9): (4-5): (58-65).

[0015] Furthermore, the contents of rumenic acid, linoleic acid and vacuum acid in the unsaturated fatty acids are 0.07-0.09 mg / mL, 0.04-0.05 mg / mL and 0.58-0.65 mg / mL, respectively.

[0016] In another aspect, the present invention provides a method for preparing goat yogurt, wherein the method for preparing goat yogurt prepares the goat yogurt described above.

[0017] Furthermore, the preparation method comprises the following steps:

[0018] The goat milk is homogenized and subjected to static ultra-high pressure treatment;

[0019] The goat milk treated by homogenization and static ultrahigh pressure is placed on a shaker for enzymatic hydrolysis;

[0020] The enzymatically hydrolyzed goat milk is subjected to water bath treatment;

[0021] The goat milk after water bath is fermented to obtain goat yogurt.

[0022] Furthermore, during the homogenization-static ultrahigh pressure treatment process, the ultrahigh pressure pressure is 200MPA to 300MPA.

[0023] Furthermore, the homogenization-static ultrahigh pressure treatment process includes three stages of pressure treatment;

[0024] During the first pressure treatment, the pressure is 220bar-240bar;

[0025] During the second pressure treatment process, the pressure is 40bar-60bar;

[0026] During the third pressure treatment process, the pressure is 200MPA to 300MPA.

[0027] Furthermore, the enzymatic hydrolysis conditions are as follows:

[0028] The enzymatic hydrolysis temperature is 37-42° C., the enzymatic hydrolysis time is 15-20 min, and the shaking speed is 400 rpm.

[0029] Furthermore, the water bath conditions are as follows:

[0030] The water bath time is 10 min and the water bath temperature is 100°C.

[0031] Furthermore, the fermentation conditions are as follows:

[0032] The gram weight volume ratio of the starter to goat milk is 0.050-0.060 g / L, the fermentation temperature is 40-45° C., and the fermentation time is 4-5 hours.

[0033] Furthermore, the fermentation agent includes Streptococcus thermophilus and Lactobacillus germanicus;

[0034] The quantity ratio of the thermophilic streptococcus to the German lactobacillus bulgaricus is 1:1.

[0035] In another aspect, the present invention provides the use of goat yogurt in the preparation of a medicament for preventing and treating cardiovascular diseases and type 2 diabetes;

[0036] The goat yogurt is the goat yogurt mentioned above or the goat yogurt prepared by the method for preparing goat yogurt mentioned above.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] After the goat milk is treated with homogenization-static ultra-high pressure, the milk fat globule membrane is destroyed, and the triglycerides in the milk fat globules are evenly released in the goat milk, which can not only kill bacteria and release endogenous lipase in microorganisms, but also prevent the lipase from being completely inactivated.

[0039] The homogenization-static ultra-high pressure treatment process causes goat milk to undergo three pressure treatments, causing the milk fat globules to be destroyed and reduced in size during the first pressure treatment process, dispersed by pressure during the second pressure treatment process, and destroyed to a greater extent during the third pressure treatment process, resulting in a fat globule healing window period so that lipase can contact triglycerides for enzymatic hydrolysis.

[0040] By utilizing the specificity of lipase, the lipase can split triglycerides containing saturated fatty acid acyl chains of C18:0 and C16:0 into free fatty acids, and the free fatty acids are absorbed by thermophilic Streptococcus and Bulgarian Lactobacillus to produce unsaturated fatty acids, thereby obtaining goat yogurt with low saturated fatty acid content and high unsaturated fatty acid content. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 is a bar graph showing lipase activity in goat milk after homogenization-static ultrahigh pressure treatment according to the present invention;

[0042] FIG2 is a bar graph showing the free fatty acid content of goat milk after enzymatic hydrolysis according to the present invention;

[0043] FIG3 is a schematic diagram of the enzymatic hydrolysis of 18 triglycerides in goat milk according to the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0045] The present application introduces a goat yogurt, which includes fatty acids;

[0046] The fatty acids include saturated fatty acids and unsaturated fatty acids;

[0047] The mass ratio of the saturated fatty acid to the unsaturated fatty acid is (55-60): (40-45).

[0048] In some preferred embodiments, the concentration of fatty acids in the goat yogurt is 2-3 wt%.

[0049] In some preferred embodiments, the unsaturated fatty acids include monounsaturated fatty acids and polyunsaturated fatty acids;

[0050] The mass ratio of the monounsaturated fatty acid to the polyunsaturated fatty acid is (34-37): (5-11).

[0051] In some preferred embodiments, each 100 g of yogurt contains 2.089 g of total fatty acids.

[0052] In some preferred embodiments, the content of saturated fatty acids in the total fatty acids accounts for 55.25-58.14 wt%, and the content of unsaturated fatty acids accounts for 41.86-44.75 wt%.

[0053] In some preferred embodiments, the content of monounsaturated fatty acids in the unsaturated fatty acids is 34.85-36.09 wt%, and the content of polyunsaturated fatty acids is 5.71-10.06 wt%.

[0054] In some preferred embodiments, the mass ratio of rumenic acid, linoleic acid and vacuum acid in the unsaturated fatty acids is (7-9): (4-5): (58-65).

[0055] In some preferred embodiments, the contents of rumenic acid, linoleic acid and vacuolar acid in the unsaturated fatty acids are 0.07-0.09 mg / mL, 0.04-0.05 mg / mL and 0.58-0.65 mg / mL, respectively.

[0056] This application introduces a method for preparing the above-mentioned goat yogurt.

[0057] The preparation method of goat yogurt of the present application comprises the following steps:

[0058] S1 homogenizes goat milk and performs static ultra-high pressure treatment.

[0059] In some preferred embodiments, the goat milk is subjected to homogenization-static ultrahigh pressure treatment for 60 seconds.

[0060] In some preferred embodiments, during the homogenization-static ultra-high pressure treatment process, the ultra-high pressure pressure is 200MPA~300MPA, the sterilization intensity reaches 99.99%, the endogenous lipase of the microorganism is released, and the biological function of the lipase is not affected under the process intensity of 200MPA~300MPA. The lipase activity in goat milk is optimal, and the enzyme activity is 1683-1732U / L.

[0061] In some preferred embodiments, the homogenization-static ultrahigh pressure treatment process includes three stages of pressure treatment:

[0062] During the first pressure treatment process, the pressure is 220bar-240bar; during the second pressure treatment process, the pressure is 40bar-60bar; during the third pressure treatment process, the pressure is 200MPA~300MPA.

[0063] Lipase activity is high in goat yogurt, but triglycerides in goat milk are not hydrolyzed because the milk fat globule membrane blocks lipase from contacting triglycerides. The three-stage cascade pressure treatment process evenly distributes the milk fat globules throughout the goat milk system. The milk fat globule membranes are then broken down, releasing triglycerides from the milk fat globules and distributing them evenly throughout the milk, allowing lipase to directly contact triglycerides.

[0064] S2 places the goat milk after homogenization-static ultra-high pressure treatment on a shaker for enzymatic hydrolysis. The shaker increases the chance of lipase contacting triglycerides, causing triglycerides to be hydrolyzed to produce 450-600 mg / 100 g of free fatty acids. At this time, the rancid smell produced by the free fatty acids is acceptable.

[0065] In some preferred embodiments, the lipase specifically hydrolyzes 18 triglycerides with fatty acyl chains of the C16:0 or C18 family in goat milk: TG (16:0 / 4:0 / 17:0), TG (16:0 / 6:0 / 18:1), TG (16:0 / 6:0 / 18:1), TG (4:0 / 14:0 / 16:0), TG (16:0 / 8:0 / 10:0), TG (16:0 / 6:0 / 14:0), TG (18:4 / 10:0 / 16:0), TG (16:0 / 10:0 / 18:1). 8:3), TG(16:0 / 14:0 / 18:1), TG(18:0 / 16:0 / 16:0), TG(18:0 / 16:0 / 21:0), TG(18:0 / 16:0 / 22:0)TG(18:0 / 18:0 / 18 :0), TG(4:0 / 15:0 / 18:1), TG(10:0 / 18:1 / 18:2), TG(18:1 / 14:0 / 18:1), TG(6:0 / 10:0 / 18:2) and TG(4:0 / 14:0 / 18:1).

[0066] In some preferred embodiments, the enzymatic hydrolysis conditions are as follows:

[0067] The enzymatic hydrolysis temperature is 37-42° C., the enzymatic hydrolysis time is 15-20 min, and the shaking speed is 400 rpm.

[0068] In some preferred embodiments, the water bath conditions are as follows:

[0069] The water bath time is 10 min and the water bath temperature is 100°C.

[0070] S3 treats the enzymatically hydrolyzed goat milk in a water bath to inactivate the lipase in the goat milk and stop the enzymatic hydrolysis.

[0071] S4 ferments the goat milk after the water bath to obtain goat yogurt.

[0072] In some preferred embodiments, during the fermentation process, free fatty acids in goat milk are absorbed and utilized by fermentation bacteria, thereby reducing the contents of C18:0, C18:1 and C16:0 and increasing the contents of rumenic acid, linoleic acid and vacuum acid.

[0073] In some preferred embodiments, the fermentation conditions are as follows:

[0074] The gram weight volume ratio of the starter to goat milk is 0.050-0.060 g / L, the fermentation temperature is 40-45° C., and the fermentation time is 4-5 hours.

[0075] In some preferred embodiments, the fermentation conditions are as follows:

[0076] The gram-weight-volume ratio of the starter culture to goat milk is 0.056 g / L, the fermentation temperature is 42° C., and the fermentation time is 4.5 h.

[0077] In some preferred embodiments, the fermentation agent includes Streptococcus thermophilus and Lactobacillus bulgaricus;

[0078] The quantity ratio of the thermophilic streptococcus to the German lactobacillus bulgaricus is 1:1.

[0079] In some preferred embodiments, the starter culture is MY105 starter culture.

[0080] Those skilled in the art can apply the above-mentioned goat yogurt or the goat yogurt prepared by the above-mentioned method for preparing goat yogurt to prepare medicines for preventing and treating cardiovascular diseases and type 2 diabetes.

[0081] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0082] Example 1

[0083] This embodiment provides a method for preparing goat yogurt with a low saturated fatty acid (SFA) content and a high unsaturated fatty acid (UFA) content.

[0084] The preparation method of this embodiment comprises the following steps:

[0085] S1 homogenizes goat milk and performs static ultra-high pressure treatment.

[0086] When used, homogenization-static ultra-high pressure is a three-stage pressure treatment of 230bar-50bar-250MPA in series.

[0087] S2 places the goat milk treated with homogenization-static ultrahigh pressure on a shaker for enzymatic hydrolysis.

[0088] When used, the goat milk was placed on a shaker at 40°C and enzymatically hydrolyzed at 400 rpm for 20 minutes.

[0089] S3 treats the enzymatically hydrolyzed goat milk in a water bath.

[0090] When using, place the goat milk in a 100℃ water bath for 10 minutes, then cool it to 45℃ and prepare for inoculation on a sterile operating table.

[0091] S4 ferments the goat milk after the water bath to obtain goat yogurt.

[0092] When used, the MY105 starter culture is added to goat milk at an inoculation rate of 56 mg / L. The inoculated goat milk is kept at a constant temperature of 42° C. and fermented for 4.5 hours to obtain goat yogurt.

[0093] The content of fatty acids in the goat yogurt of this embodiment is 20.89 mg / mL.

[0094] The percentage content of saturated fatty acids in the fatty acids is 57.54 wt %, and the percentage content of unsaturated fatty acids is 42.46 wt %.

[0095] The percentage content of monounsaturated fatty acids in the unsaturated fatty acids is 35.9 wt %, and the percentage content of polyunsaturated fatty acids is 6.56 wt %.

[0096] In actual application, the contents of rumen acid, linoleic acid and vacuum acid in the unsaturated fatty acids are 0.08 mg / mL, 0.04 mg / mL and 0.61 mg / mL respectively.

[0097] Example 2

[0098] This embodiment provides a method for preparing goat yogurt with a low saturated fatty acid (SFA) content and a high unsaturated fatty acid (UFA) content.

[0099] The difference between the preparation method of this embodiment and that of Example 1 is:

[0100] Homogenization-static ultra-high pressure is a three-stage pressure treatment with 220bar-40bar-200MPA connected in series.

[0101] The content of fatty acids in the goat yogurt of this embodiment is 20.95 mg / mL.

[0102] The percentage content of saturated fatty acids in the fatty acids is 60 wt %, and the percentage content of unsaturated fatty acids is 40 wt %.

[0103] The percentage content of monounsaturated fatty acids in the unsaturated fatty acids is 34 wt %, and the percentage content of polyunsaturated fatty acids is 6 wt %.

[0104] In actual application, the contents of rumenic acid, linoleic acid and vacuum acid in the unsaturated fatty acids are 0.07 mg / mL, 0.04 mg / mL and 0.58 mg / mL respectively.

[0105] Example 3

[0106] This embodiment provides a method for preparing goat yogurt with a low saturated fatty acid (SFA) content and a high unsaturated fatty acid (UFA) content.

[0107] The difference between the preparation method of this embodiment and that of Example 1 is:

[0108] (1) Homogenization-static ultra-high pressure is a three-stage pressure treatment with 240bar-60bar-300MPA in series.

[0109] (2) Place the goat milk on a shaker at 40°C and enzymatically hydrolyze at 400 rpm for 15 min.

[0110] The content of fatty acids in the goat yogurt of this embodiment is 20.72 mg / mL.

[0111] The percentage content of saturated fatty acids in the fatty acids is 55 wt %, and the percentage content of unsaturated fatty acids is 45 wt %.

[0112] The percentage content of monounsaturated fatty acids in the unsaturated fatty acids is 37 wt %, and the percentage content of polyunsaturated fatty acids is 8 wt %.

[0113] In actual application, the contents of rumenic acid, linoleic acid and vacuum acid in the unsaturated fatty acids are 0.09 mg / mL, 0.05 mg / mL and 0.65 mg / mL respectively.

[0114] Example 4

[0115] Based on Example 1, this example analyzes the effect of the pressure of homogenization-static ultrahigh pressure on the lipase activity and the sterilization effect.

[0116] The lipase activity of this embodiment was determined using an ELISA kit, a double-antibody one-step sandwich enzyme-linked immunosorbent assay (ELISA): the sample, standard, and HRP-labeled detection antibody were added sequentially to the coated microwells pre-coated with lipase antibodies, incubated, and thoroughly washed. The color was developed using the substrate TMB, which was converted to blue under the catalysis of peroxidase and to a final yellow under the action of acid. The depth of the color was positively correlated with the lipase activity in the sample. The absorbance (OD value) was measured at a wavelength of 450 nm using a microplate reader to calculate the sample activity.

[0117] The total number of culturable microbial colonies in the goat milk sample of this example was detected by plate counting using the method of national standard GB4789.2-2016.

[0118] The preparation method of goat yogurt in this embodiment is different from that in Example 1 in that:

[0119] In order to analyze the effect of pressure on lipase activity and sterilization effect, homogenization-static ultrahigh pressure was set as one stage of pressure treatment, and goat milk samples were treated with different pressure values.

[0120] When used, the static ultrahigh pressure equipment is a 0-500MPa static ultrahigh pressure equipment, and the pressure gradient is set to 50MPa.

[0121] In practical application, the lipase activity and viable bacteria concentration in goat milk after homogenization-static ultrahigh pressure treatment were analyzed.

[0122] Referring to Figure 1 , the lipase activity in the goat milk sample was 1183 U / L.

[0123] After ultrahigh pressure treatment (UHP) at temperatures below 350 MPa, the high pressure physically destroys microorganisms in goat milk, releasing the endogenous enzyme lipase directly into the milk system. This leads to an increase in lipase activity. As shown in Figure 1, lipase activity is optimal at pressures between 200 MPa and 300 MPa, reaching 1683-1732 U / L.

[0124] After the goat milk samples were subjected to ultrahigh pressure treatment above 350 MPa, the excessive pressure caused lipase denaturation, resulting in a decrease in enzyme activity. This shows that the lipase tolerance pressure is below 350 MPa. Referring to Figure 1, the lipase activity in the goat milk samples was the lowest at pressures above 400 MPa.

[0125] As shown in Table 1, after ultrahigh pressure treatment, the number of microorganisms in the goat milk samples decreased, and the sterilization effect became better with the increase of pressure.

[0126] After ultra-high pressure treatment of more than 350MPa, the sterilization rate of microorganisms in goat milk samples can reach more than 99.999%; after ultra-high pressure treatment of 200MPa-300MPa, the sterilization rate of microorganisms in goat milk samples can reach more than 99.99%.

[0127] Table 1 Total bacterial counts in milk samples

[0128]

[0129] Example 5

[0130] Based on Example 1, this example analyzes the effect of enzymatic hydrolysis time on the free fatty acid content.

[0131] The preparation method of goat yogurt in this embodiment is different from that in Example 1 in that:

[0132] The goat milk was placed on a shaker at 40°C and enzymatically hydrolyzed at 400 rpm for 5, 10, 15, 20, 25, and 30 min, and the free fatty acid (FFA) content in the goat milk after enzymatic hydrolysis was determined.

[0133] Referring to Figure 2, as the enzymatic hydrolysis time increases, the free fatty acid content in goat milk gradually increases.

[0134] When the enzymatic hydrolysis time was 20 min, goat milk showed a slight rancid smell and lipid oxidation smell; when the enzymatic hydrolysis time was 25 min and 30 min, goat milk showed a more obvious rancid smell and lipid oxidation smell.

[0135] Referring to Figure 2, when the enzymatic hydrolysis time is greater than 20 minutes, the trend of increasing free fatty acid content in goat milk gradually decreases. It can be seen that the broken milk fat globule membranes recombine to form new small fat globules while oscillating, thereby blocking lipase from contacting triglycerides, resulting in slower efficiency in hydrolyzing triglycerides.

[0136] When the enzymatic hydrolysis time is 15-20 minutes, the free fatty acid content in goat milk is 763-877 mg / 100 g. When the enzymatic hydrolysis time is 0 minutes, 15 minutes, and 20 minutes, the free fatty acid content in goat milk can be seen. When the enzymatic hydrolysis time is 15-20 minutes, the enzymatic hydrolysis process can produce 450-600 mg / 100 g of FFA.

[0137] Example 6

[0138] Based on Example 1, this example analyzes the specificity of lipase in goat milk.

[0139] Triglycerides (SDLs) are the main lipids in goat milk, accounting for about 98% by weight of the total lipids. During the enzymatic hydrolysis process, triglycerides are broken down into diglycerides and free fatty acids, and the content of triglycerides (SDLs) in goat milk is reduced.

[0140] This example is based on non-targeted lipidomics technology. Ultra-high-performance liquid chromatography (UHPLC) coupled with Q-Exactive Orbitrap Mass Spectrometry was used to characterize the main triglyceride molecules in lipase-hydrolyzed goat milk. The specific method is based on Gao W, Yin Q, Wang X, Teng X, Jin R, Liu N, et al. UHPLC-Q-Exactive Orbitrap mass spectrometry reveals the lipidomics of bovine milk and yogurt. Food Chemistry 2022, 392: 133267.

[0141] 100 μL of untreated goat milk and the goat milk after enzymatic hydrolysis in Example 1 were added to 200 μL of ultrapure water and mixed. 240 μL of pre-cooled methanol was added and vortexed. 800 μL of MTBE was added and vortexed. The mixture was allowed to stand at room temperature for 30 min and centrifuged at 14,000 g for 15 min at 10°C. The upper organic phase was collected and dried with nitrogen. For liquid chromatography-mass spectrometry analysis, 200 μL of isopropanol solution was added for reconstitution, vortexed, and centrifuged at 14,000 g for 15 min at 10°C. The supernatant was sampled and analyzed. The samples were analyzed for lipids using a UHPLC Nexera LC-30A ultra-high performance liquid chromatography system (SHIMADZU) coupled to a Q-Exactive Plus mass spectrometer (Thermo Scientific). Lipid separation was performed using a Waters ACQUITY UPLC CSH C18, 1.7 μm, 2.1 mm × 100 mm column. The column temperature was 45°C and the flow rate was 300 μL / min. The mobile phase compositions were A: 10 mM ammonium formate, acetonitrile in water (acetonitrile:water=6:4, v / v), and B: 10 mM ammonium formate, acetonitrile in isopropanol (acetonitrile:isopropanol=1:9, v / v). The gradient elution program was as follows: 30% B from 0 to 2 min, linear B from 30% to 100% from 2 to 25 min, and 30% B from 25 to 35 min. Electrospray ionization (ESI) detection was performed in both positive and negative ion modes. Specific parameters were as follows: Heater Temp 300°C, Sheath Gas Flow Rate 45 arb, Aux Gas Flow Rate 15 arb, Sweep Gas Flow Rate 1 arb, Capillary Temp 350°C; in positive mode, spray voltage 3.0 kV, S-Lens RF Level 50%; in negative mode, spray voltage 2.5 kV, S-Lens RF Level 60%, MS1 scan range: 250–1800 DA. Peak identification, peak extraction, and lipid identification (secondary identification) were performed using LipidSearch software (Thermo Scientific™). The main parameters are: precursor tolerance: 5ppm, product tolerance: 5ppm, product ion threshold: 5%.One-way ANOVA was used to identify significant differences in lipid molecules (P < 0.05), and supervised orthogonal partial least squares discriminant analysis (OPLS-DA) was used to perform multivariate statistical analysis on the data. This analysis was used to obtain the classification model and simultaneously extract the variables that contributed significantly to the classification. Projection, VIP)>1, and the lipid molecules with P<0.05 and VIP>1 were screened, and finally the goat milk and the goat milk treated with Example 1 were obtained in TG (16:0 / 4:0 / 17:0), TG (16:0 / 6:0 / 18:1), TG (16:0 / 6:0 / 18:1), TG (4:0 / 14:0 / 16:0), TG (16:0 / 8:0 / 10:0), TG (16:0 / 6:0 / 14:0), TG (18:4 / 10:0 / 16:0), TG (16:0 / 10:0 / 18:3 , TG(16:0 / 14:0 / 18:1), TG(18:0 / 16:0 / 16:0), TG(18:0 / 16:0 / 21:0), TG(18:0 / 16:0 / 22:0)TG(18:0 / 18:0 / 18:0), TG(4:0 / 15:0 / 18:1), TG(10:0 / 18:1 / 18:2), TG(18:1 / 14:0 / 18:1), TG(6:0 / 10:0 / 18:2) and TG(4:0 / 14:0 / 18:1) were significantly decreased, with P<0.05 and VIP>1.

[0142] The goat milk of this embodiment is goat milk. It can be seen that the lipase in goat milk has a specific cleavage rule and tends to hydrolyze triglycerides containing C16:0 fatty acyl chains and C18 family fatty acyl chains. There are 18 types of SDLs containing C16:0 fatty acyl chains and C18 family fatty acyl chains in the SDLs lipid molecules of goat milk, namely TG (16:0 / 4:0 / 17:0), TG (16:0 / 6:0 / 18:1), TG (16:0 / 6:0 / 18:1), TG (4:0 / 14:0 / 16:0), TG (16:0 / 8:0 / 10:0), TG (16:0 / 6:0 / 14:0), TG (18:4 / 10:0 / 16:0), TG (16:0 / 10:0 / 18:3), TG(16:0 / 14:0 / 18:1), TG(18:0 / 16:0 / 16:0), TG(18:0 / 16:0 / 21:0), TG(18:0 / 16:0 / 22:0)TG(18:0 / 18:0 / 18 :0), TG(4:0 / 15:0 / 18:1), TG(10:0 / 18:1 / 18:2), TG(18:1 / 14:0 / 18:1), TG(6:0 / 10:0 / 18:2) and TG(4:0 / 14:0 / 18:1).

[0143] SDLs containing C16:0 fatty acyl chains react with lipase to produce FFA (16:0) and the remaining diacylglycerol. For example, TG (16:0 / 4:0 / 17:0) produces FFA (16:0) and DG (16:0 / 4:0) after reacting with lipase. Similarly, the same is true for SDLs containing C18 fatty acyl chains of the C18 family. For example, TG (18:0 / 18:0 / 18:0) produces FFA (18:0) and DG (18:0 / 18:0) after reacting with lipase.

[0144] Example 7

[0145] This embodiment provides a method for preparing goat yogurt.

[0146] The preparation method of this embodiment comprises the following steps:

[0147] S1 homogenizes the goat milk.

[0148] When used, the homogenization process is a two-stage pressure process with a pressure of 230 bar to 50 bar connected in series.

[0149] S2 treats the homogenized goat milk in a water bath.

[0150] When using, place the goat milk in a 100℃ water bath for 10 minutes, then cool it to 45℃ and prepare for inoculation on a sterile operating table.

[0151] S3 ferments the goat milk after the water bath to obtain goat yogurt.

[0152] When used, the MY105 starter culture is added to goat milk at an inoculation rate of 56 mg / L. The inoculated goat milk is kept at a constant temperature of 42° C. and fermented for 4.5 hours to obtain goat yogurt.

[0153] The content of fatty acids in the goat yogurt of this embodiment is 21.61 mg / mL.

[0154] The content of saturated fatty acids in the fatty acids is 63.81 wt %, and the content of unsaturated fatty acids is 36.19 wt %.

[0155] The content of monounsaturated fatty acids in the unsaturated fatty acids is 32.67 wt %, and the content of polyunsaturated fatty acids is 3.52 wt %.

[0156] In actual application, the contents of rumenic acid, linoleic acid and vacuum acid in the unsaturated fatty acids are 0 mg / mL, 0 mg / mL and 0.19 mg / mL respectively.

[0157] Example 8

[0158] Based on Example 1 and Example 7, this example is based on lipidomics technology, and gas chromatography (GC) is connected in series with a flame ionization detector (FID), i.e., GC-FID, to analyze the fatty acid content of the goat yogurt in Example 1 and Example 7. The specific method is referred to Gao W, Yin Q, Wang X, Teng X, Jin R, Liu N, et al. UHPLC-Q-Exactive Orbitrap mass spectrometry reveals the lipidomics of bovine milk and yogurt. Food Chemistry 2022, 392: 133267. literature.

[0159] The fatty acid content detection method of the present embodiment goat yogurt is as follows:

[0160] The sample was thawed at room temperature and vortexed. 1 mL of chloroform / methanol (2:1, v / v) was added to 200 μL of the sample, and the mixture was sonicated for 15 min. The mixture was centrifuged at 10,000 g for 15 min at 4°C. 2 mL of 1% sulfuric acid-methanol solution was added to the supernatant, which was then methylated in an 80°C water bath for 30 min. After drying with nitrogen, the sample was extracted with 1 mL of n-hexane and washed with 5 mL of ultrapure water. 500 μL of the supernatant was aspirated and mixed with 25 μL of methyl salicylate as an internal standard. Fatty acid methyl esters (FAMEs) were detected using an Agilent 7890B gas chromatograph-flame ionization detector (GC-FID) equipped with an SP-2560 column (100 m × 0.25 mm ID × 0.25 μm). The inlet temperature was 250°C, and the carrier gas was N2 at a flow rate of 1.0 mL / min. A programmed temperature rising method was used, with the initial temperature set at 140°C and then increased to 180°C at a rate of 8°C / min, then increased to 210°C at a rate of 4°C / min, then increased to 240°C at a rate of 15°C / min and maintained for 4.5 min, and then increased to 250°C at a rate of 5°C / min and maintained for 10 min. The injection volume was 1 μL, the split ratio was 100:1, and a split injection method was used.

[0161] Peak identification and peak extraction were performed on the test data, and the peak area was analyzed by normalization. The concentration of fatty acids in each sample was converted to the peak area of ​​methyl salicylate. The specific formula is as follows:

[0162]

[0163] Wherein, S fatty acid is the peak area of ​​fatty acid, S salicylic acid is the peak area of ​​salicylic acid, and C salicylic acid is the concentration of salicylic acid.

[0164] Referring to Table 2, a total of 26 fatty acids were detected in the goat yogurts of Examples 1 and 7.

[0165] The fatty acids with the highest content in the goat yogurt of Example 7 include C18:1n9c at 6.47 mg / mL, C16:0 at 5.79 mg / mL, and C18:0 at 4.63 mg / mL. The vacuoleic acid (t11-C18:1) content in the goat yogurt of Example 7 was 0.19 mg / mL, while the linoleic acid (LA) and rumenic acid (c9,t11-CLA) contents were both zero.

[0166] The C18:1n9c content in the goat yogurt of Example 1 was reduced to 5.86 mg / mL, the C16:0 content was reduced to 3.88 mg / mL, and the C18:0 content was reduced to 3.12 mg / mL. The vacuolar acid (t11-C18:1) content in the goat yogurt of Example 1 was increased to 0.61 mg / mL, the linoleic acid (LA) content was increased to 0.04 mg / mL, and the rumenic acid (c9,t11-CLA) content was increased to 0.08 mg / mL.

[0167] In addition, compared with Example 7, the total saturated fatty acids in the goat yogurt of Example 1 were reduced from 63.81 wt % to 57.54 wt %, and the unsaturated fatty acids were increased from 36.19 wt % to 42.46 wt %.

[0168] Table 2 Total fatty acid content of goat yogurt in Example 1 and Example 7

[0169]

[0170]

[0171]

[0172] Example 9

[0173] Based on Example 1 and Example 7, this example analyzes the effect of goat yogurt on blood sugar in mice.

[0174] Thirty 8-week-old male db / db mice with C57BL / KS.db background were selected as type 2 diabetes mouse models (T2DM mouse models). The fasting blood glucose level of the type 2 diabetes mouse models was ≥7.0 mmol·L on different days. -1 And random blood glucose ≥11.1mmol·L -1 .

[0175] The male db / db mice of the C57BL / KS.db background in this example were purchased from Nanjing Junke Biotechnology Co., Ltd.

[0176] The T2DM mouse model was kept in an environmental temperature of 22-25°C, a humidity of 55%-70%, a 12-h light-dark cycle, ventilation, and a normal diet. The mice were randomly divided into three groups, with 10 db / dbT2DM mice in each group: a blank group, an SS7 group, and an SS1 group.

[0177] Blank group: 15g·kg -1 The T2DM mouse model was gavaged with normal saline for 6 weeks.

[0178] SS7 group: 15g·kg -1The T2DM mouse model was orally administered with the goat yogurt of Example 7 for 6 weeks.

[0179] SS1 group: 15g·kg -1 The T2DM mouse model was orally administered with the goat yogurt of Example 1 for 6 weeks.

[0180] After gavage for 6 weeks, each group of T2DM mouse models were deprived of water for more than 8 hours per week and fasted once a week, and fasting blood glucose was measured.

[0181] Referring to Table 3, after 5 weeks of gavage, there was no significant difference in the fasting blood glucose of the T2DM mouse model between the blank group and the SS7 group, but the fasting blood glucose of the T2DM mouse model in the SS1 group was significantly lower than that in the SS7 group and the blank group. It can be seen that the goat yogurt obtained in Example 1 can lower the blood glucose of mice.

[0182] Table 3 Changes of fasting blood glucose in mice in each group after intervention

[0183]

[0184] In the table, * indicates P < 0.05 compared with the SS7 group, ▲ indicates P < 0.05 compared with the blank group.

[0185] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A goat yogurt, characterized in that: The goat yogurt includes fatty acids; The fatty acids include saturated fatty acids and unsaturated fatty acids; The mass ratio of the saturated fatty acid to the unsaturated fatty acid is (55-60): (40-45); The preparation method of goat yogurt comprises the following steps: The goat milk is homogenized and subjected to static ultra-high pressure treatment; The goat milk treated by homogenization-static ultrahigh pressure is placed on a shaker for enzymatic hydrolysis; The enzymatically hydrolyzed goat milk is subjected to water bath treatment; Fermenting the goat milk after water bath to obtain goat yogurt; The homogenization-static ultrahigh pressure treatment process includes three stages of pressure treatment; During the first stage of pressure treatment, the pressure is 220bar-240bar; During the second pressure treatment, the pressure is 40bar-60bar; During the third stage of pressure treatment, the pressure is 200MPa to 300MPa; The mass ratio of rumenic acid, linoleic acid and vacuum acid in the unsaturated fatty acids is (7-9): (4-5): (58-65); The vacuum acid is t11-C18:

1.

2. The goat yogurt according to claim 1, characterized in that The concentration of fatty acids in the goat yogurt is 2-3 wt%.

3. The goat yogurt according to claim 1, characterized in that The unsaturated fatty acids include monounsaturated fatty acids and polyunsaturated fatty acids; The mass ratio of the monounsaturated fatty acid to the polyunsaturated fatty acid is (34-37):(5-11).

4. The goat yogurt according to claim 1, characterized in that The enzymatic hydrolysis conditions are as follows: The enzymatic hydrolysis temperature is 37-42°C, the enzymatic hydrolysis time is 15-20 min, and the shaking speed is 400 rpm; And / or, the water bath conditions are as follows: The water bath time is 10 min, and the water bath temperature is 100°C; And / or, the fermentation conditions are as follows: The gram-weight-volume ratio of the starter to goat milk is 0.050-0.060 g / L, the fermentation temperature is 40-45° C., and the fermentation time is 4-5 hours.

5. The goat yogurt according to claim 4, characterized in that The fermentation agent includes thermophilic streptococcus and German lactobacillus bulgaricus; The quantity ratio of the thermophilic streptococcus to the German lactobacillus bulgaricus is 1:

1.

6. Application of goat yogurt in the preparation of drugs for preventing and treating cardiovascular diseases and type 2 diabetes; The goat yogurt is the goat yogurt according to any one of claims 1 to 5.

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