Preparation method and application of fermented laver compound beverage with high palatability and antihypertensive activity

Abstract

The invention belongs to the technical field of marine organisms and fermentation, and relates to a preparation method and application of a fermented laver compound beverage with high palatability and antihypertensive activity, and the fermented laver compound beverage comprises fermented laver juice, Chinese wolfberry juice, citric acid and white granulated sugar. The prepared compound beverage has the activity of antihypertensive peptide and better oxidation resistance, and can be used as food and health care products with certain effects. The whole texture is a water sample and is not viscous, the fishy smell of the laver is completely eliminated, the laver has sour, sweet and delicious taste and bright color, the laver can be loved by numerous consumers, development and utilization of the laver can be deeply excavated, and the laver has wide market prospects.

Description

Technical Field

[0001] The invention relates to the field of marine biology and fermentation technology, in particular to a preparation method and application of a fermented laver and wolfberry composite beverage with high palatability and high blood pressure-lowering activity. Background Art

[0002] Laver is a marine organism belonging to the red algae. It is rich in 18 kinds of amino acids, including 8 kinds of amino acids that are essential to humans, and the content is high. Among them, umami amino acids and sweet amino acids account for 1 / 2 of the total, making laver particularly delicious; the guanosine acid contained in it gives laver a special vanilla flavor; the inosinic acid and mannitol contained in it give laver a dried fish floss flavor. Laver is also very rich in vitamins. The content of vitamin A is about 67 times that of milk; the content of vitamin B is 6 times that of beef; and the content of vitamin C is equal to that of tomatoes. Laver also contains more inorganic salts such as sugars, calcium, phosphorus, and iron. The nutritional components and health value of laver make it have great application potential in the food industry. However, due to the dietary habits of Chinese people, there are not many varieties of laver products on the market, mainly laver cakes, instant laver sheets and small-packaged soups. At present, the development of laver products is not deep enough, the varieties are single, and they lack competitiveness. It is rare to develop them into high value-added products. In addition, laver has a certain fishy smell when eaten directly, which also makes it difficult to use laver directly to make beverages. The use of biological enzymatic hydrolysis to make laver products usually cannot effectively remove the fishy smell, and dextrin must be added later to remove the fishy smell. The added dextrin causes the mouthfeel to thicken, which is also difficult to use to make beverages.

[0003] Antihypertensive peptides are natural proteins that exist in organisms and have the function of lowering blood pressure. They are commonly found in foods such as beans, tea, fish and shellfish, fruits, and buckwheat flour. Currently, the most common method for obtaining antihypertensive peptides is to prepare and extract them from milk proteins using enzymatic and microbial methods. Casein is the best source of antihypertensive peptides. For example, αs1, αs2 casein, and β casein can be hydrolyzed with trypsin to obtain antihypertensive peptides with IC50 < 30μM.

[0004] When studying the mechanism of hypertension, it is essential to discuss ACE. ACE is a membrane-bound dipeptide carboxylase that plays an important role in regulating blood pressure in the renin-angiotensin system (RAS) and kallikrein-kinin system (KKS) in vivo. The commonly used in vitro activity determination method of antihypertensive peptides is to evaluate the inhibition of ACE activity by antihypertensive peptides. Its main principle is to use ACE and the tripeptide hippurylhistidylleucine (Hip-His-leu, HHL) to generate hippuric acid (Hip) and histidylleucine (His-leu, HL), and then quantify the product HL or Hip released from the substrate HHL. Most of them are quantified by the amount of hippuric acid generated. The most commonly used methods are reverse high performance liquid chromatography (RP-HPLC) and ultraviolet colorimetry.

[0005] In the fast-paced life, modern people overdraw their time and body, and often have no time to take care of minor physical problems. In the face of an increasing number of people with hypertension, we should advocate the combination of treatment, prevention and diet therapy. The development of blood pressure-lowering peptides from the perspective of human nutrition and health is a scientific and technical challenge in the future. Since blood pressure-lowering peptides have functional factors and the characteristics of natural food, they can maintain health by further developing these optimized functional nutrients during dietary supply. Although these approaches are initially only for special target groups, they will eventually be popularized to the entire population. In particular, blood pressure-lowering peptides derived from food proteins only have a blood pressure-lowering effect on patients with hypertension, but not on those with normal blood pressure. These peptides are extracted from proteins using enzymatic hydrolysis technology and are very safe. If blood pressure-lowering peptides are developed into health foods, long-term use to prevent, relieve and assist in the treatment of hypertension will surely be accepted by people. Therefore, the research and development of blood pressure-lowering peptides in food has broad application prospects. Summary of the invention

[0006] The purpose of the present application is to provide a preparation method and application of a fermented laver composite beverage with high palatability and antihypertensive activity, aiming to solve the problems existing in the prior art.

[0007] The present application embodiment provides a method for preparing a fermented laver composite beverage with high palatability and antihypertensive activity, comprising the following steps: S1. Preparation of laver juice: fermenting yeast with laver, fig pulp and water as a culture medium; fermenting for 2 to 5 hours to obtain a fermentation liquid, filtering and centrifuging the fermentation liquid and retaining the supernatant to obtain the laver juice; S2. Preparation of wolfberry juice: pre-cooking dried wolfberries in water at 95° C. for 20 min, then cooling to 60° C. and extracting for 4 h, clarifying with a composite clarifier of 0.06% pectin, 0.4% honey, and 0.001% agar, taking the supernatant, and adding 0.1% and 0.05% citric acid and ascorbic acid, respectively, for color protection, to obtain wolfberry juice; S3, preparing the composite juice: mixing the laver juice and the wolfberry juice in a volume ratio of 4:5; S4. Preparation of compound beverage: design an orthogonal experiment and design three influencing factors: the amount of compound juice added, the amount of white sugar added and the amount of citric acid added; design three levels for each influencing factor, the amount of compound juice added is 10g, 20g, and 30g; the amount of white sugar added is 0.12g, 0.24g, and 0.36g; the amount of citric acid added is 0.003g, 0.009g, and 0.012g; according to the results of the orthogonal experiment, 0.1% citric acid and 4.5% white sugar were added to the compound juice to adjust the sugar-acid ratio of the beverage, and finally a compound beverage was obtained.

[0008] When preparing laver juice, the mass parts of each component are: 10 parts of dried laver, 10 parts of fig pulp, 1 part of dry yeast, and 200 parts of water.

[0009] Fig pulp is obtained by sterilizing and homogenizing commercially available fresh figs.

[0010] The fermentation time of laver juice is evaluated according to the deodorization effect, and the preferred fermentation time is 2 hours.

[0011] In the orthogonal experiment, three influencing factors were designed: the amount of compound juice added, the amount of white sugar added and the amount of citric acid added; three levels were designed for each influencing factor, the amount of compound juice added was 10g, 20g, and 30g; the amount of white sugar added was 0.12g, 0.24g, and 0.36g; and the amount of citric acid added was 0.003g, 0.009g, and 0.012g.

[0012] The invention discloses an application of a fermented laver composite beverage with high palatability and antihypertensive activity. The composite beverage obtained by the preparation method is used for preparing a component of a food or health product containing antihypertensive peptides.

[0013] The invention discloses an application of a fermented laver composite beverage with high palatability and antihypertensive activity. The composite beverage obtained by the preparation method is used for preparing a component of a food or health product with an antioxidant function.

[0014] The beneficial effects of the present invention are as follows: the composite beverage prepared by the present invention has the activity of blood pressure-lowering peptides and good antioxidant properties, and can be used as a food and health product with certain efficacy. The present invention uses an orthogonal test to consider the taste as the main factor to formulate the sweet and sour taste of the beverage and the amount of compound juice added, so that the overall taste is moderately sweet and sour, the mouthfeel is thick, not astringent, and has no peculiar smell. The overall texture is watery and non-sticky, and the fishy smell of laver is completely eliminated. It also has a sweet and sour taste and bright color, which can win the favor of many consumers, so that the development and utilization of laver can be deeply explored, and has a broad market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 These are photos of the appearance of laver juice after different fermentation times.

[0016] Figure 2 Photos of the appearance of the compound drinks prepared for each group.

[0017] Figure 3 This is a photo of the bubble production state in the coliform bacteria detection experiment.

[0018] Figure 4 This is a photo of the total bacterial count plate at 100-fold dilution.

[0019] Figure 5 It is a scatter plot of ACE inhibitory activity of wolfberry juice with different concentrations.

[0020] Figure 6 The scatter plot is of the ACE inhibitory activity of laver juice at different concentrations.

[0021] Figure 7 The scatter plot is of ACE inhibitory activity of compound beverages with different concentrations. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1: Formula and process research of fermented laver and wolfberry composite beverage 1.1 Selection of fermentation time for laver juice 1.1.1 Preparation of laver juice 50g dried laver purchased from a supermarket was crushed into powder, and 1000g water, 50g fig pulp, and 5g dry yeast were added to prepare a fermentation culture medium, wherein the fig pulp was made by sterilizing and homogenizing 50g of fresh green-skinned figs (produced in Weihai) with a wet weight. The fermentation culture medium was fermented in a 28°C incubator for 2h, 3h, 4h, and 5h to obtain fermentation liquids with different fermentation times. Multiple groups of fermentation liquids were filtered with gauze to remove the residue, and the yeast was removed by centrifugation at 6000r / min for 15 minutes to obtain laver juice with dry yeast, which was refrigerated at 4°C for use. In the same way as the above steps, the laver juice obtained by culturing for 2h without adding dry yeast was used as a control for the unfermented group and the fermented group.

[0024] 1.1.2 Determination of the optimal fermentation time Ten people (half male and half female) conducted a sensory evaluation of the deodorization effect standards at different fermentation times according to Table 1-1.

[0025]

[0026] 1.1.3 Fermentation results The effect of removing fishy smell varies with the fermentation time of laver. The effect is shown in Table 1-2. It can be seen that fermentation for 2 hours can effectively remove the fishy smell, but if the fermentation time is too long, it will produce odor. Figure 1 It can be seen that the fermentation liquid after fermentation for 2h and 3h has better color, both of which are purple-red.

[0027]

[0028] 1.2 Determination of the ratio of laver juice to wolfberry juice 1.2.1 Preparation of wolfberry juice Select 50g of dried wolfberry with large appearance, thick flesh, no borers and external injuries, wash it, soak it in warm water for 30 minutes, remove the seeds and drain it after softening. Add water 6 times the weight of wolfberry, pre-cook at 95℃ for 20 minutes, then cool to 60℃ and extract for 4 hours, clarify it with a compound clarifier of 0.06% pectin, 0.4% honey and 0.001% agar, take the supernatant, and add 0.1% and 0.05% citric acid and ascorbic acid respectively for color protection to obtain wolfberry juice.

[0029] 1.2.2 Preparation of compound juice Mix laver juice and wolfberry juice in a certain proportion, add citric acid and white sugar to adjust the sugar-acid ratio of the beverage, and refrigerate at 4°C.

[0030] The effect of different volume ratios of laver juice and wolfberry juice on the flavor of beverages was studied. The ratios of laver juice to wolfberry juice were set as 1:1, 2:1, 3:4, 4:5, 5:4, 4:3, and 1:2, for a total of seven experimental groups. Ten people investigated the taste, flavor, and coordination of the seven groups of compound juices, and conducted sensory evaluation according to the standards in Tables 1-3, so as to determine the most suitable ratio of laver juice to wolfberry juice, and the compound juice solution was made according to the most suitable ratio.

[0031]

[0032] 1.2.3 Results of compound juice ratio The results are shown in Tables 1-4. The composite juice prepared by mixing laver juice and wolfberry juice in a ratio of 4:5 had the best sensory score.

[0033]

[0034] 1.2.4 Determination of excipients and additives Based on the results of 1.2.3, orthogonal test was further conducted to design L9 orthogonal table with three factors: the amount of compound juice added, the amount of white sugar added, and the amount of citric acid added, to determine the best formula of the beverage. The factor levels are shown in Table 1-5.

[0035]

[0036] 1.2.5 Preparation results of auxiliary materials and additives Sugar-acid ratio is an important factor affecting the taste and quality of beverages. The effects of different addition amounts of compound juice, white sugar and citric acid on sensory characteristics were compared through orthogonal experimental design, so as to optimize the preparation process of laver compound beverage. The results are shown in Table 1-6. The prepared beverages are shown in Table 1-6. Figure 2 .

[0037]

[0038] According to the orthogonal results, the optimal compound juice content was 37.5% (the remaining 62.5% was water), the amount of white sugar added was 4.5% of the total volume, and the amount of citric acid added was 0.1% of the total volume.

[0039] In summary, in this embodiment, the optimal formula of the fermented laver and wolfberry composite beverage is: laver juice fermented by yeast for 2 hours and wolfberry juice are compounded in a volume ratio of 4:5 to obtain a composite juice, deionized water is added to the composite juice so that the final content of the composite juice is 37.5%, and the water content is 62.5%, and in addition, 4.5% of the total volume after adding water and 0.1% of citric acid are added.

[0040] Example 2: Detection of physical and chemical indicators and microbiological indicators of fermented laver and wolfberry composite beverage 2.1 Detection of coliform bacteria 2.1.1 Detection methods Preparation of lactose peptone culture medium: weigh the medicine according to the formula in Table 2-1, heat and dissolve it in 1000ml distilled water, adjust the pH to 7.2-7.4, mix thoroughly, divide into test tubes with small inverted tubes, and sterilize at 115℃ for 20min.

[0041] Take 10 10 ml test tubes, put 9 ml of normal concentration lactose peptone and 1 ml of compound beverage sample into each, and culture at 37°C. Within 24 hours, gas is generated in the small inverted tubes, and the culture medium becomes turbid and the color changes, indicating the presence of E. coli group. Refer to Table 2-2 to obtain the number of E. coli group in the sample.

[0042]

[0043] 2.1.2 Results of coliform bacteria testing The results are as follows Figure 3 As shown, bubbles were generated in 1 tube. According to Table 2-2, it can be concluded that the number of coliform bacteria ≤ 3±1 cfu / ml is in line with the national standard.

[0044] 2.2 Detection of total bacterial count 2.2.1 Detection Method Preparation of beef extract peptone medium: Weigh 3g beef extract, 10g peptone, 5g NaCl, and 15g agar and dissolve them in 1000ml water. Heat to dissolve and mix well, and adjust the pH value to 7.0-7.2. Sterilize at 121℃ for 20min.

[0045] Set up 3 concentration gradients: Take 3 sterile empty test tubes and add 9ml sterile water to each. Take 1ml of the compound beverage sample and inject it into the first tube and shake it well. Take 1ml from the first tube and put it into the next tube, and dilute it to the third tube. The dilution factor depends on the degree of contamination of the sample. The most appropriate dilution factor is when the number of colonies on the plate after culture is between 30 and 300. If the number of colonies in the three dilution factors is too large to be counted or is reduced to the point where it cannot be counted, it is necessary to continue diluting or reduce the dilution factor.

[0046] Take 1 ml of dilution from each of the three dilution test tubes and add it to an empty sterile culture dish. Make two culture dishes for each dilution. Pour 15 ml of meat extract peptone agar medium that has been melted and cooled to about 45°C into each dish, and immediately shake it on the table. After solidification, place it in a 37°C incubator and culture it for 24 hours. Count the colonies according to the number of colonies and the dilution multiple.

[0047] 2.2.2 Total bacterial count results The colonies can be counted well on the plate with a 100-fold dilution, such as Figure 4As shown, the total bacterial count is ≤50±2cfu / ml, which meets the national standard.

[0048] 2.3 Determination of iodine content 2.3.1 Determination of iodine content The standard curve of the iodine standard solution is drawn based on the principle that potassium iodate and potassium iodide react to generate iodine and iodine reacts with starch to change color. The iodine standard solution contains 1ml of 5.0μmol / ml potassium iodate and 10ml of 2.5μmol / ml potassium iodide, which are mixed in an acidic environment.

[0049] When determining the standard curve, take 1.0ml, 2.0ml, 3.0ml, 4.0ml, and 5.0ml of iodine standard solution, and add 2.0ml of starch solution (1.25g of soluble starch added to 250ml of boiling water) to each tube, let it stand for 2 minutes after color development, dilute to 50ml, and shake well. Using starch solution as a reference, use a 1cm colorimetric dish to measure the absorbance value A at a wavelength of 590nm and draw a standard curve.

[0050] Determination of iodine content in samples: Take 5.0 ml of sample and place it in a 50 ml volumetric flask, add 10 ml of potassium iodide solution, 2.0 ml of starch solution, 1 ml of potassium iodate solution, dilute to 50 ml with water, determine the absorbance value A, check the concentration c corresponding to A on the standard curve, and calculate the iodine content.

[0051] 2.3.2 Measurement results According to the iodine content standard curve, the fitting formula is y=0.1566x+0.037, R²=0.9781, and the absorbance value of the compound beverage sample is measured to be 0.045. Then, the iodine content in the sample is calculated to be approximately 0.05 mg / L, indicating that the compound beverage is rich in iodine.

[0052] 2.4 Determination of amino acid content 2.4.1 Detection Method With 250mmol / L sodium hydroxide and 1mol / L sodium acetate as eluents and a suitable eluent gradient, 18 common amino acids can be separated on a high-efficiency anion exchange column. Among them, sodium hydroxide solution has a weak elution ability and is used to elute weakly retained basic amino acids and aliphatic amino acids; sodium acetate solution has a strong elution ability and is used to elute strongly retained acidic amino acids and aromatic amino acids, such as histidine, phenylalanine, glutamic acid, aspartic acid, cystine and tyrosine. In order to ensure that the state of the chromatographic column is consistent during each injection analysis, a certain concentration of sodium hydroxide solution needs to be used to equilibrate the chromatographic column for 25 minutes after each separation, thereby improving the reproducibility of the measurement results.

[0053] 2.4.2 Test results The amino acid content is shown in Table 2-3. Aspartic acid and alanine have the largest content and are important factors affecting the flavor of laver. The total amino acid content was measured to be 200.17 mg / 100 ml.

[0054]

[0055] 2.5 Determination of heavy metal content 2.5.1 Determination method After the sample is dried and crushed, weigh 1.00-2.00 g into a 50 ml conical flask, add 10 ml of nitric acid, and after the reaction is moderated, add 1 ml of hydrogen peroxide. Digest on an electric heating plate until the solution is clear, colorless or slightly yellow. After cooling, dilute to a 25 ml volumetric flask with water and measure on an analyzer.

[0056] 2.5.1.1 Determination of lead, copper and zinc Graphite furnace atomic absorption spectrometer, Zeeman background, wavelength: 283.3nm, slit: 0.5nm; drying part: 120℃ 10s; ashing part: 1200℃ 5s; atomization part: 2100℃ 20s. Reading method: peak area; matrix modifier: palladium nitrate 5μg / ml. Standard curve concentration: 0μg / L, 5.0μg / L, 10.0μg / L, 20.0μg / L, 40.0μg / L, medium: 0.5mol / L nitric acid.

[0057] 2.5.1.2 Determination of arsenic Atomic fluorescence spectrophotometer, photomultiplier tube voltage: 400V; arsenic hollow cathode lamp current: 35mA; reading method: peak area; reducing agent: 10g / L potassium borohydride; standard curve concentration: 0μg / L, 0.2μg / L, 0.5μg / L, 1.0μg / L, medium: 2% nitric acid.

[0058] 2.5.1.3 Determination of Mercury Atomic fluorescence spectrophotometer, photomultiplier tube voltage: 240V; mercury hollow cathode lamp current: 30mA; atomizer temperature: 300℃; reading method: peak area; reducing agent: 5g / L potassium borohydride; standard curve concentration: 0μg / L, 0.2μg / L, 0.5μg / L, 1.0μg / L, medium: 2% nitric acid.

[0059] 2.5.1.4 Determination of iron and manganese When the sample or the digested sample is inhaled into the flame, the iron and manganese compounds are easily atomized, and the absorption of the characteristic radiation of the hollow cathode lamp by the iron and manganese ground state atoms can be detected at 248.3nm and 279.6nm respectively.

[0060] 2.5.2 Test results The results of the heavy metal types and contents are shown in Table 2-4. The contents of all heavy metals meet the national standards. The arsenic detected is a substance contained in the laver itself, and the content does not exceed the standard.

[0061]

[0062] In summary, in this embodiment, the pH of the composite beverage is 3.64, the iodine content is 0.05 mg / L, the total amino acid content is 200.17 mg / 100 ml, the total bacteria count is ≤50±2 cfu / ml, and the coliform group count is ≤3±1 cfu / ml, indicating that the composite beverage is rich in nutrients such as iodine and amino acids, and the contents of microorganisms and heavy metals such as iron, zinc, and arsenic meet national health standards.

[0063] Example 3: Antihypertensive activity and in vitro antioxidant activity test of fermented laver composite beverage 3.1 ACE inhibitory activity detection 3.1.1 Detection methods The ACE inhibitory activity was determined using laver juice, wolfberry juice and compound beverage as samples. The preparation methods of the control tube, blank tube and sample tube are shown in Table 3-1.

[0064]

[0065] The amount of hippuric acid produced was determined by RP-HPLC (reverse phase high performance liquid chromatography): 20 μl of the reaction product from each tube was taken out at room temperature for sampling and the hippuric acid content was determined.

[0066] Chromatographic conditions: 30% acetonitrile plus 0.2% glacial acetic acid as the mobile phase, flow rate 1ml / min, detection wavelength 228nm; the amount of hippuric acid generated is used to determine the inhibitory effect of the sample on ACE activity.

[0067] Inhibition rate calculation formula: [(control peak area - sample peak area) / (control peak area - blank peak area)] × 100% IC50 is the sample concentration at which the inhibition rate is 50%.

[0068] 3.1.2 Test results The ACE inhibitory activity of wolfberry juice is shown in Table 3-2 and Figure 5 shown.

[0069] The ACE inhibitory activity of laver juice is shown in Table 3-3 and Figure 6 shown.

[0070] The ACE inhibitory activity of compound beverages is shown in Table 3-4 and Figure 7 shown.

[0071] The above data show that wolfberry juice, seaweed juice and compound beverage all have high ACE inhibition rates, indicating that the blood pressure lowering peptides have high activity.

[0072] 3.2 In vitro antioxidant activity test 3.2.1 Detection of total antioxidant capacity The antioxidant activity of the samples was tested using an antioxidant kit (Nanjing Jiancheng). The specific steps refer to the kit instructions. Sample pretreatment: Accurately weigh the sample and add 9 times physiological saline to make a 10% homogenate according to the weight volume ratio. Centrifuge at 2000-2500r / min for 10 minutes and take the supernatant for testing. At the same time, the protein content of the 10% homogenate was determined using a biuret reagent.

[0073] Mix each reagent and sample according to the instructions and let stand for 10 minutes, adjust to zero with distilled water. Measure the absorbance of each tube at 1 cm optical path and 520 nm wavelength.

[0074] Definition of antioxidant capacity unit: 1 antioxidant capacity unit is when the absorbance value of the reaction system increases by 0.01 per mg of protein per minute at 37°C.

[0075] Calculation formula: Total antioxidant capacity = [(ODU-ODC) ∕ (0.01*30)] * N ∕ Cprot Among them, ODU-absorbance value of the assay tube; ODC-absorbance value of the control tube; N-dilution multiple of the reaction system; Cprot-protein concentration of the sample to be tested.

[0076] 3.2.2 Detection of resistance to superoxide anion The antioxidant kit (Nanjing Jiancheng) was used to test the anti-superoxide anion ability of the samples. The specific steps refer to the kit instructions.

[0077] Mix each reagent and sample according to the instructions, let stand for 10 minutes, pour into a 1 cm cuvette, adjust to zero with distilled water, and measure the absorbance of each tube at a wavelength of 520 nm.

[0078] Definition of the profit unit against superoxide anion free radicals: In the reaction system, the superoxide anion free radicals inhibited by one liter of sample at 37°C for 40 minutes are equivalent to the change in superoxide anion free radicals inhibited by 1 mg of Vc, which is one activity unit.

[0079] Calculation formula: Anti-superoxide anion activity unit = [(absorbance value of control tube - absorbance value of test tube) / (absorbance value of control tube - absorbance value of standard tube)]*standard concentration (0.15mg / ml)*1000ml*dilution multiple.

[0080] 3.2.3 Determination of anti-hydroxyl radical activity The antioxidant kit (Nanjing Jiancheng) was used to detect the anti-hydroxyl free radical activity of the samples. The specific steps refer to the kit instructions.

[0081] Mix each reagent with the sample according to the instructions, react at 37°C for 20 minutes, 1 cm light path, 550 nm, zero with distilled water, and measure the absorbance of each tube.

[0082] The definition of the unit of activity for inhibiting hydroxyl free radicals is: when one milliliter of sample reacts at 37°C for 1 minute, the concentration of H2O2 in the system decreases by 1 mol / L, which is one unit of activity for inhibiting hydroxyl free radicals.

[0083] Calculation formula: Inhibition of hydroxyl free radical activity (U / ml) = [(control tube-measurement tube)∕(standard tube-blank tube)]*standard tube concentration (8.824mmol / L)*(1ml∕L sampling volume)*dilution multiple.

[0084] 3.2.4 Test results The results of in vitro antioxidant activity are shown in Tables 3-5.

[0085]

[0086] The results showed that the total antioxidant capacity of wolfberry juice was 0.844U / mg, the total antioxidant capacity of seaweed juice was 0.970U / mg, and the total antioxidant capacity of the composite beverage was 0.907U / mg, which had good antioxidant capacity.

[0087] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered as exemplary and non-restrictive in all respects.

Claims

1. A method for preparing a fermented laver composite beverage with high palatability and antihypertensive activity, characterized in that: The following steps are involved: S1. Preparation of laver juice: laver, fig pulp and water are used to make a suspension, and yeast is added thereto for fermentation; fermentation is performed for 2 to 5 hours to obtain a fermentation liquid, and the fermentation liquid is filtered and centrifuged to obtain the laver juice by retaining the supernatant; S2. Preparation of wolfberry juice: pre-cooking dried wolfberries in water at 95° C. for 20 min, then cooling to 60° C. and extracting for 4 h, clarifying with a composite clarifier of 0.06% pectin, 0.4% honey, and 0.001% agar, taking the supernatant, and adding 0.1% and 0.05% citric acid and ascorbic acid, respectively, for color protection, to obtain wolfberry juice; S3, preparing the composite juice: mixing the laver juice and the wolfberry juice in a volume ratio of 4:5; S4. Preparation of compound beverage: design an orthogonal experiment and design three influencing factors: the amount of compound juice added, the amount of white sugar added and the amount of citric acid added; design three levels for each influencing factor, the amount of compound juice added is 10g, 20g, and 30g; the amount of white sugar added is 0.12g, 0.24g, and 0.36g; the amount of citric acid added is 0.003g, 0.009g, and 0.012g; according to the results of the orthogonal experiment, 0.1% citric acid and 4.5% white sugar were added to the compound juice to adjust the sugar-acid ratio of the beverage, and finally a compound beverage was obtained.

2. The method for preparing the fermented laver composite beverage with high palatability and antihypertensive activity according to claim 1, characterized in that: When preparing laver juice, the mass parts of each component are: 10 parts of dried laver, 10 parts of fig pulp, 1 part of dry yeast, and 200 parts of water.

3. The method for preparing the fermented laver composite beverage with high palatability and antihypertensive activity according to claim 1, characterized in that: The fig pulp is obtained by sterilizing and homogenizing commercially available fresh figs.

4. The method for preparing the fermented laver composite beverage with high palatability and antihypertensive activity according to claim 1, characterized in that: The fermentation time of laver juice is evaluated according to the deodorization effect, and the preferred fermentation time is 2 hours.

5. An application of a fermented laver composite beverage with high palatability and antihypertensive activity, characterized in that: The composite beverage obtained by the preparation method as claimed in claim 1 is used for preparing food or health products containing blood pressure lowering peptides.

6. Application of a fermented laver composite beverage with high palatability and antihypertensive activity, characterized in that: The composite beverage obtained by the preparation method according to claim 1 is used for preparing food or health products with antioxidant function.

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