Preparation method of grape seed solid beverage

Abstract

The invention relates to the technical field of beverages, in particular to a preparation method of a grape seed solid beverage, which comprises the following steps: cleaning and drying grape seeds, and controlling the moisture content of the grape seeds to obtain pretreated grape seeds; the pretreated grape seeds are coated with protective components, and protective layers are formed on the surfaces of the grape seeds; carrying out segmented temperature control baking on the coated grape seeds under a low-oxygen condition to obtain protected baked grape seeds; crushing the protected baked grape seeds to obtain grape seed powder; and uniformly mixing the grape seed powder with auxiliary materials, granulating and drying to obtain the grape seed solid beverage. According to the invention, through the synergistic effect of a double-layer synergistic protection structure and segmented temperature control baking, the effects of flavor improvement and functional component retention in grape seed processing are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of beverage technology, and more specifically, to a method for preparing grape seed solid beverages. Background Technology

[0002] Grape seeds are a major byproduct of winemaking and are rich in various bioactive substances such as proanthocyanidins, resveratrol, and polyphenols. Among them, oligomeric proanthocyanidins have attracted much attention for their excellent free radical scavenging ability and antioxidant activity, and are the core component for grape seeds to achieve their health function positioning. In order to improve the convenience of consumption and flavor acceptance, developing grape seeds into solid beverages that can be directly brewed has become an important direction for deep processing.

[0003] However, the currently commonly used direct high-temperature baking or long-term baking methods have drawbacks: the core functional components in grape seeds, such as proanthocyanidins and polyphenols, are extremely sensitive to heat and oxygen. Under processing conditions that exceed their stability threshold, they are prone to thermal degradation, polymerization, or oxidative inactivation, resulting in a significant reduction in biological activity. In view of this, we propose a method for preparing grape seed solid beverages. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing grape seed solid beverages, in order to solve the problem mentioned in the background art that the core functional components of grape seeds, such as proanthocyanidins and polyphenols, are extremely sensitive to heat and oxygen, and are prone to thermal degradation, polymerization or oxidative inactivation under processing conditions that exceed their stability threshold, resulting in a significant reduction in biological activity.

[0005] This invention provides a method for preparing grape seed solid beverage, comprising the following steps:

[0006] S1.1 The grape seeds are washed and dried to control the moisture content to 6%-10% to obtain pretreated grape seeds;

[0007] S1.2. The pretreated grape seeds are coated with a protective component to form a protective layer on the surface of the grape seeds;

[0008] S1.3 Under low-oxygen conditions, the grape seeds treated in S1.2 are subjected to segmented temperature-controlled baking to obtain protected baked grape seeds;

[0009] S1.4. The protected baked grape seeds are crushed to obtain grape seed powder;

[0010] S1.5 After mixing grape seed powder and excipients evenly, add purified water as a wetting agent. The amount of purified water added is 8%-15% of the total mass of grape seed powder and excipients. After adding purified water as a wetting agent, wet granulation is performed using a swing granulator through a 20-mesh sieve. Then, the wet granules are placed in a fluidized bed dryer and dried at an inlet air temperature of 60℃ for 30-50 minutes to obtain grape seed solid beverage.

[0011] Preferably, in S1.2, the protective component is configured as a double-layer combined protective structure, which includes:

[0012] The inner protective component is an antioxidant that adsorbs onto the surface of grape seeds to provide inner chemical antioxidant protection;

[0013] The outer protective component is a film-forming agent that coats the inner layer to form an outer physical barrier;

[0014] The inner and outer protective components are applied to the surface of grape seeds sequentially through a stepwise coating process.

[0015] Preferably, the inner protective component is rosemary extract or ascorbic acid;

[0016] The outer protective layer consists of maltodextrin or gum arabic with a DE value of 10-15.

[0017] Preferably, the process for applying the inner protective component is as follows: dissolving the inner protective component in an aqueous ethanol solution with a volume fraction of 75%-95% to prepare a solution with a mass fraction of 1%-5%.

[0018] Using a sprayer, the solution is evenly sprayed onto the surface of the pretreated grape seeds, with the amount of solution sprayed being 2%-5% of the grape seed mass. Then, under circulating hot air at 40-60℃, the seeds are dried for 5-15 minutes until the inner protective component forms a uniform and fixed inner protective film on the surface of the grape seeds.

[0019] Preferably, the application process of the outer protective component is as follows: dissolve the outer protective component in warm water at 40-60°C to prepare a solution with a mass fraction of 10%-30%.

[0020] After the grape seeds to be formed into the inner layer are cooled to 20-30℃, the outer layer solution is sprayed, and the amount of solution sprayed is 5%-10% of the mass of the grape seeds; then, it is continuously dried at 50-70℃ for 20-40 minutes until the outer protective component forms a continuous and dense solid outer protective film on the outer surface of the inner protective film.

[0021] Preferably, in step S1.3, the segmented temperature-controlled baking includes:

[0022] The first stage is a low-temperature dehydration stage, with a baking temperature of 60-90℃ and a processing time of 20-40 minutes;

[0023] The second stage is the flavor enhancement stage, with a baking temperature of 100-130℃ and a processing time of 10-20 minutes.

[0024] Preferably, in step S1.3, the baking process is carried out in a low-oxygen environment formed by continuous purging with inert gas, and the oxygen volume fraction in the baking chamber is not higher than 3%, wherein the inert gas is nitrogen or carbon dioxide.

[0025] Preferably, in step S1.3, after baking, the protected baked grape seeds are rapidly cooled by forced ventilation to cool them to below 40°C within 5-10 minutes.

[0026] Preferably, in step S1.4, the pulverization process adopts a low-temperature pulverization process, and the material temperature is controlled to be no higher than 40°C during the pulverization process by means of jacket cooling, and the pulverized grape seed powder passes through an 80-mesh sieve.

[0027] Preferably, in step S1.5, the excipients include honey powder, citric acid, and maltodextrin.

[0028] The amount of honey powder added is 0.5%-1.5% based on the weight of grape seed powder;

[0029] The amount of citric acid added is 0.05%-0.15% based on the mass of grape seed powder;

[0030] The amount of maltodextrin added is 15%-20% based on the mass of grape seed powder.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] In the preparation method of grape seed solid beverage of this invention, the combined effect of a double-layer protective structure and segmented temperature-controlled baking effectively improves the flavor enhancement and functional component retention during grape seed processing. The inner layer antioxidant (such as rosemary extract) can actively remove free radicals on the surface and adjacent areas of grape seeds, providing chemical protection; the outer layer film-forming agent (such as gum arabic) forms a dense physical barrier layer, blocking most of the oxygen intrusion. The inner chemical protection and the outer physical barrier reduce the oxidative loss of active ingredients from different mechanisms. The two complement each other and reduce the probability of thermal oxidation. Segmented temperature-controlled baking (first dehydration at 60-90℃, then aroma enhancement at 100-130℃) avoids the thermal shock caused by rapid temperature changes, allowing the active ingredients to be stabilized in a gentle gradient temperature increase. The combination of the two can significantly improve the retention rate of polyphenolic active ingredients such as proanthocyanidins while fully developing the roasted flavor. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] The grape seeds were purchased from Shanghai Chunshi Biotechnology Co., Ltd.

[0035] Rosemary extract (CAS No.: 84604-14-8) was purchased from Xi'an Lavia Biotechnology Co., Ltd., and the mass fraction of the key active ingredient carrageenan was not less than 20%.

[0036] Ascorbic acid (CAS No.: 50-81-7) was purchased from Shandong Aicai Biotechnology Co., Ltd.

[0037] Maltodextrin (CAS No.: 9050-36-6) and gum arabic (CAS No.: 9000-01-5) were both purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0038] The honey powder was purchased from Fufeng Sinote Biotechnology Co., Ltd., and the honey solids content is no less than 60%.

[0039] Citric acid (CAS No.: 77-92-9) was purchased from Shanghai Haoyuan Biomedical Technology Co., Ltd.

[0040] The inner protective component is rosemary extract or ascorbic acid; the outer protective component is maltodextrin or gum arabic with a DE value of 10-15; in this embodiment of the invention, the inner protective component is preferably rosemary extract, and the outer protective component is preferably maltodextrin.

[0041] The inert gas is either nitrogen or carbon dioxide, and in this embodiment of the invention, nitrogen is preferred.

[0042] This invention selects maltodextrin with a DE value of 10-15 as the outer film-forming agent. The glass transition temperature (Tg) of maltodextrin in this DE value range is between 140-160℃, which is higher than the second stage baking temperature (100-130℃). Therefore, the outer protective film remains in the glassy state throughout the baking process, which can maintain good mechanical integrity and gas barrier properties.

[0043] Example 1: A method for preparing grape seed solid beverage, comprising the following steps:

[0044] S1.1 The grape seeds are washed and dried to control the moisture content to 8%, thus obtaining pretreated grape seeds;

[0045] S1.2 Dissolve the rosemary extract in an 80% (v / v) aqueous ethanol solution to prepare a 3% (w / w) solution;

[0046] Using a sprayer, the solution was evenly sprayed onto the surface of the pretreated grape seeds, with the amount of solution sprayed being 3% of the grape seed mass; then, it was dried for 10 minutes under circulating hot air at 50°C until the inner protective component formed a uniform and fixed inner protective film on the surface of the grape seeds.

[0047] Dissolve maltodextrin in warm water at 50°C to prepare a 20% (w / w) solution.

[0048] After the grape seeds to be formed into the inner layer are cooled to 25°C, the outer layer solution is sprayed, and the amount of solution sprayed is 8% of the mass of the grape seeds; then, it is dried continuously at 60°C for 30 minutes until the outer layer protective component forms a continuous and dense solid outer layer protective film on the outer surface of the inner layer protective film.

[0049] S1.3. Under the continuous purging of nitrogen gas to ensure that the oxygen volume fraction in the baking chamber does not exceed 3%, the grape seeds treated in S1.2 are baked in a segmented temperature-controlled environment to obtain protected baked grape seeds.

[0050] The first stage is a low-temperature dehydration stage, with a baking temperature of 75℃ and a processing time of 30 minutes;

[0051] The second stage is the flavor enhancement stage, with a baking temperature of 115℃ and a processing time of 15 minutes;

[0052] Forced ventilation was used to rapidly cool the protected roasted grape seeds, reducing them to below 40°C within 8 minutes.

[0053] S1.4. The protected roasted grape seeds are pulverized at low temperature (material temperature not higher than 40℃), and then passed through an 80-mesh sieve to obtain grape seed powder.

[0054] S1.5 After mixing grape seed powder with honey powder, citric acid and maltodextrin evenly, purified water is added as a wetting agent. The amount of purified water added is 12% of the total mass of grape seed powder and excipients. Wet granulation is performed using a swing granulator through a 20-mesh sieve. Then the wet granules are placed in a fluidized bed dryer and dried at an inlet air temperature of 60°C for 40 minutes to obtain grape seed solid beverage.

[0055] The amount of honey powder added was 1.0% based on the weight of grape seed powder;

[0056] The amount of citric acid added is 0.10% based on the mass of grape seed powder;

[0057] The amount of maltodextrin added was 18% based on the mass of grape seed powder.

[0058] Example 2: The difference between this example and Example 1 is that the amount of the inner protective component solution sprayed is 2% of the grape seed mass.

[0059] Example 3: The difference between this example and Example 1 is that the amount of the inner protective component solution sprayed is 5% of the grape seed mass.

[0060] Example 4: The difference between this example and Example 1 is that the amount of the outer protective component solution sprayed is 5% of the grape seed mass.

[0061] Example 5: The difference between this example and Example 1 is that the amount of the outer protective component solution sprayed is 10% of the grape seed mass.

[0062] Example 6: The difference between this example and Example 1 is that the baking temperature in the second stage is 100°C.

[0063] Example 7: The difference between this example and Example 1 is that the baking temperature in the second stage is 130°C.

[0064] Example 8: A method for preparing grape seed solid beverage, comprising the following steps:

[0065] S1.1 The grape seeds are washed and dried to control the moisture content to 6% to obtain pretreated grape seeds;

[0066] S1.2 Dissolve the rosemary extract in an 80% (v / v) aqueous ethanol solution to prepare a 1% (w / w) solution;

[0067] Using a sprayer, the solution was evenly sprayed onto the surface of the pretreated grape seeds, with the amount of solution sprayed being 3% of the grape seed mass; then, it was dried for 5 minutes under circulating hot air at 40°C until the inner protective component formed a uniform and fixed inner protective film on the surface of the grape seeds.

[0068] Dissolve maltodextrin in warm water at 40°C to prepare a 10% (w / w) solution.

[0069] After the grape seeds to be formed into the inner layer are cooled to 20°C, the outer layer solution is sprayed, and the amount of solution sprayed is 8% of the mass of the grape seeds; then, it is dried continuously at 50°C for 20 minutes until the outer layer protective component forms a continuous and dense solid outer layer protective film on the outer surface of the inner layer protective film.

[0070] S1.3. Under the continuous purging of nitrogen gas to ensure that the oxygen volume fraction in the baking chamber does not exceed 3%, the grape seeds treated in S1.2 are baked in a segmented temperature-controlled environment to obtain protected baked grape seeds.

[0071] The first stage is a low-temperature dehydration stage, with a baking temperature of 60℃ and a processing time of 20 minutes;

[0072] The second stage is the flavor enhancement stage, with a baking temperature of 115℃ and a processing time of 10 minutes;

[0073] Forced ventilation was used to rapidly cool the protected roasted grape seeds, reducing them to below 40°C within 5 minutes.

[0074] S1.4. The protected roasted grape seeds are pulverized at low temperature (material temperature not higher than 40℃) to obtain grape seed powder;

[0075] S1.5 After mixing grape seed powder with honey powder, citric acid and maltodextrin evenly, purified water is added as a wetting agent. The amount of purified water added is 10% of the total mass of grape seed powder and excipients. Wet granulation is carried out using a swing granulator through a 20-mesh sieve. Then the wet granules are placed in a fluidized bed dryer and dried at an inlet air temperature of 60°C for 30 minutes to obtain grape seed solid beverage.

[0076] The amount of honey powder added is 0.5% based on the mass of grape seed powder;

[0077] The amount of citric acid added is 0.05% based on the mass of grape seed powder;

[0078] The amount of maltodextrin added is 15% based on the mass of grape seed powder.

[0079] Example 9: A method for preparing grape seed solid beverage, comprising the following steps:

[0080] S1.1 The grape seeds are washed and dried to control the moisture content to 10%, thus obtaining pretreated grape seeds;

[0081] S1.2 Dissolve the rosemary extract in an 80% (v / v) aqueous ethanol solution to prepare a 5% (w / w) solution;

[0082] Using a sprayer, the solution was evenly sprayed onto the surface of the pretreated grape seeds, with the amount of solution sprayed being 3% of the grape seed mass; then, it was dried for 15 minutes under circulating hot air at 60°C until the inner protective component formed a uniform and fixed inner protective film on the surface of the grape seeds.

[0083] Dissolve maltodextrin in warm water at 60°C to prepare a 30% (w / w) solution.

[0084] After the grape seeds to be formed into the inner layer are cooled to 30°C, the outer layer solution is sprayed, and the amount of solution sprayed is 8% of the mass of the grape seeds; then, it is dried continuously at 70°C for 40 minutes until the outer layer protective component forms a continuous and dense solid outer layer protective film on the outer surface of the inner layer protective film.

[0085] S1.3. Under the continuous purging of nitrogen gas to ensure that the oxygen volume fraction in the baking chamber does not exceed 3%, the grape seeds treated in S1.2 are baked in a segmented temperature-controlled environment to obtain protected baked grape seeds.

[0086] The first stage is a low-temperature dehydration stage, with a baking temperature of 90℃ and a processing time of 40 minutes;

[0087] The second stage is the flavor enhancement stage, with a baking temperature of 115℃ and a processing time of 20 minutes;

[0088] Forced ventilation was used to rapidly cool the protected roasted grape seeds, reducing them to below 40°C within 10 minutes;

[0089] S1.4. The protected roasted grape seeds are pulverized at low temperature (material temperature not higher than 40℃), and then passed through an 80-mesh sieve to obtain grape seed powder.

[0090] S1.5 After mixing grape seed powder with honey powder, citric acid and maltodextrin evenly, purified water is added as a wetting agent. The amount of purified water added is 13% of the total mass of grape seed powder and excipients. Wet granulation is carried out using a swing granulator through a 20-mesh sieve. Then the wet granules are placed in a fluidized bed dryer and dried at an inlet air temperature of 60°C for 50 minutes to obtain grape seed solid beverage.

[0091] The amount of honey powder added is 1.5% based on the weight of grape seed powder;

[0092] The amount of citric acid added was 0.15% based on the mass of grape seed powder;

[0093] The amount of maltodextrin added is 20% based on the mass of grape seed powder.

[0094] Procedure for determining proanthocyanidin content: Accurately weigh a certain amount (e.g., 0.1g) of grape seed solid beverage sample. To eliminate interference from the surface protective components on the extraction and determination of internal components, first rinse the sample surface rapidly with an appropriate amount of anhydrous ether and a small amount of room temperature water alternately to wash away the outer film-forming agent and the inner added antioxidant. After filtration and evaporation of residual solvent, place the sample in a stoppered test tube. Add 10 ml of methanol and extract with ultrasonic assistance for 30 minutes. Then centrifuge (e.g., 4000 rpm for 10 minutes) and take the supernatant as the test solution. Accurately pipette a certain volume (e.g., 1 ml) of the sample test solution into another test tube. Add 5 ml of freshly prepared vanillin-hydrochloric acid reagent (1% vanillin methanol solution and concentrated hydrochloric acid mixed at a volume ratio of 1:1), and shake well; place the reaction tube in a certain temperature (e.g., 20℃ or 30℃) in the dark for a certain time (e.g., 15 minutes), and immediately measure its absorbance at a wavelength of 500 nm using a spectrophotometer; prepare proanthocyanidin standard solutions (e.g., catechin) of different concentrations, process them according to the same color development and measurement steps as above, and plot the concentration-absorbance standard curve; calculate the content of proanthocyanidins in the sample based on the standard curve, usually expressed as mg catechin equivalents / g sample.

[0095] Antioxidant activity assay procedure: Prepare methanol extracts of the samples after the above washing and pretreatment, and dilute to an appropriate concentration gradient; prepare a 0.1 mmol / L DPPH radical solution with methanol and store it in the dark; take 2 mL of sample solutions of different concentrations, add 2 mL of DPPH solution, vortex mix, and let stand at room temperature in the dark for 30 minutes; simultaneously set up a blank control with an equal volume of methanol instead of the sample solution, and a sample background control with an equal volume of methanol instead of the DPPH solution; measure the absorbance of each reaction system at a wavelength of 517 nm using a spectrophotometer; the DPPH radical scavenging rate is calculated according to the following formula: scavenging rate (%) = [1 - (sample absorbance - sample background absorbance) / blank control absorbance] × 100%; usually, the half-maximal scavenging concentration (IC50) is used. 50 The IC50 value (the sample concentration required to achieve a 50% clearance rate) is used to evaluate the strength of antioxidant capacity. 50 The lower the value, the stronger the antioxidant capacity.

[0096] Sensory evaluation method: A review panel composed of 10 trained sensory evaluators evaluated each grape seed solid beverage sample. The samples were prepared by mixing the samples with 60℃ warm water at a ratio of 1g:100mL. The samples were scored based on three dimensions: intensity of roasted aroma, degree of astringency, and overall acceptability. Each dimension was evaluated using a 10-point scale (1 being the lowest and 10 the highest; a lower astringency score indicates stronger astringency). The average score of all evaluators was taken as the final score.

[0097] Table 1 Performance data of grape seed solid beverage

[0098] Proanthocyanidin content <![CDATA[DPPH free radical scavenging rate IC 50 > Example 1 58.2 mg / g 26.5 μg / mL Example 2 52.1 mg / g 31.8 μg / mL Example 3 56.8 mg / g 27.9 μg / mL Example 4 54.3 mg / g 30.2 μg / mL Example 5 57.5mg / g 28.1 μg / mL Example 6 60.5mg / g 25.0 μg / mL Example 7 48.7mg / g 35.4 μg / mL Example 8 51.1 mg / g 33.5 μg / mL Example 9 54.8 mg / g 29.5 μg / mL

[0099] Data from Example 2 (2% coating amount) shows that when the inner layer protection is insufficient, the proanthocyanidin content (52.1 mg / g) and antioxidant activity (IC50) are significantly reduced. 50 The values ​​(31.8 μg / mL) all decreased significantly, demonstrating the necessity of providing direct chemical antioxidant protection in the early stages of baking; however, the effect of Example 3 (5% spraying amount) did not surpass that of Example 1. This may be related to the decrease in the uniformity of solution distribution on the grape seed surface after the spraying amount was increased. Excessive solution is prone to local accumulation on the particles, which to some extent affects the uniformity of the inner layer coating and the smoothness of the subsequent outer layer film formation. However, the difference between the two is small (58.2 vs 56.8 mg / g), indicating that the effect of the inner layer spraying amount on the final effect is limited in the range of 2%-5%.

[0100] Performance degradation in Example 4 (outer layer solution spraying amount 5%) (proanthocyanidin content 54.3 mg / g, IC50) 50 The value of 30.2 μg / mL directly demonstrates that an incomplete physical barrier can lead to oxygen penetration and damage to the active ingredients. The data of Example 5 (10% of the outer layer solution spraying amount) is similar to that of Example 1 but slightly lower, indicating that after the effective film thickness is achieved, further increasing the amount will have little benefit and may even slightly affect water evaporation or flavor formation due to excessive film thickness.

[0101] The baking temperature in the second stage affects the retention of active ingredients; Example 6 (100°C) yielded the highest proanthocyanidin content (60.5 mg / g) and the strongest antioxidant activity (IC50). 50 The value was 25.0 μg / mL, but the lower baking temperature was insufficient in terms of flavor development (see Table 3 for sensory evaluation data).

[0102] In contrast, the active ingredient in Example 7 (130°C) underwent severe thermal degradation (proanthocyanidins only 48.7 mg / g), demonstrating that even with a protective layer, excessively high temperatures can still exceed its protective limit. It should be noted that although the maltodextrin with a DE value of 10-15 selected in this invention has a Tg of approximately 140-160°C, and the outer membrane remains in a glassy state at 130°C, 130°C is close to the lower limit of the Tg range, resulting in a decrease in the membrane's barrier properties. Simultaneously, the oxidation rate of oxalic acid in the inner rosemary extract significantly accelerates at 130°C, and the inner layer's chemical protective ability weakens significantly in the later stages of high temperature, leading to an overall insufficient protective effect to resist thermal oxidation losses at this temperature.

[0103] Example 8 uses a combination of lower limit values ​​for each process parameter (1% inner layer solution concentration, drying at 40℃ for 5 min, drying at 50℃ for 20 min, baking at 60℃ / 20 min + 115℃ / 10 min). Its proanthocyanidin content is 51.1 mg / g, which is lower than that of Example 1. The main reason is that the inner layer solution concentration is only 1%, and there are fewer effective antioxidant components per unit spray amount, resulting in relatively weak chemical protection of the inner layer. At the same time, the drying temperature and time of the outer layer are both taken at the lower limit, and the film density is also insufficient.

[0104] Example 9 used a combination of upper limits for each process parameter (5% inner layer solution concentration, drying at 60℃ for 15 min, drying the outer layer at 70℃ for 40 min, and baking at 90℃ / 40 min + 115℃ / 20 min). Its proanthocyanidin content was 54.8 mg / g, higher than Example 8 but still lower than Example 1 (58.2 mg / g). The main reason is that the first stage baking temperature in Example 9 was 90℃ for 40 min, resulting in a significantly higher total heat exposure (cumulative temperature × time) than Example 1 (75℃ / 30 min). Although the coating quality of the protective layer was improved due to the higher concentration of the solution and more thorough drying conditions, the higher cumulative heat load still led to the degradation of some active ingredients. Furthermore, the inner layer rosemary extract was gradually consumed during prolonged heat exposure, and the chemical protective ability decreased over time. This indicates that in optimizing process parameters, there is an overall matching relationship between the protective layer conditions and the baking conditions; simply taking the upper limit of each parameter does not necessarily yield the optimal effect.

[0105] Based on the above measurements, Example 1 showed good results in terms of activity retention and flavor development (proanthocyanidin content 58.2 mg / g, IC50). 50 An equilibrium was reached between the values ​​(26.5 μg / mL), therefore Example 1 was selected as the optimal example;

[0106] Comparative Example 1: The difference between this example and Example 1 is that the protection step S1.2 is omitted, and the sample is baked at 130°C for 30 minutes in an air environment, and then crushed and mixed.

[0107] Comparative Example 2: The difference between this example and Example 1 is that only the outer layer of maltodextrin solution spraying in S1.2 is performed, and the inner layer of rosemary extract spraying is omitted.

[0108] Comparative Example 3: The difference between this example and Example 1 is that segmented temperature control was not used, and the product was directly baked at a constant temperature of 115°C for 45 minutes (the total baking time was the same as in Example 1).

[0109] Comparative Example 4: The difference between this example and Example 1 is that the inner rosemary extract in S1.2 is replaced with starch, while the outer layer and other steps are the same as in Example 1.

[0110] Comparative Example 5: The difference between this example and Example 1 is that only the inner layer of rosemary extract ethanol solution is sprayed in S1.2, and the outer layer of maltodextrin solution is omitted.

[0111] Table 2 Performance data of grape seed solid beverage

[0112] Proanthocyanidin content <![CDATA[DPPH free radical scavenging rate IC 50 > Example 1 58.2 mg / g 26.5 μg / mL Comparative Example 1 38.5mg / g 42.0 μg / mL Comparative Example 2 52.0 mg / g 31.5 μg / mL Comparative Example 3 55.2 mg / g 28.8 μg / mL Comparative Example 4 50.8 mg / g 33.0 μg / mL Comparative Example 5 46.8 mg / g 35.2 μg / mL

[0113] Table 3 Sensory evaluation results of representative examples and comparative examples

[0114] Baking aroma intensity Astringency rating Overall Acceptability Example 1 7.6±0.8 6.8±0.6 7.8±0.7 Example 6 5.2±0.9 7.5±0.5 6.3±0.8 Example 7 8.5±0.7 3.5±0.9 5.0±1.0 Comparative Example 1 8.2±0.8 2.8±0.8 4.3±0.9

[0115] Comparative Example 1 simulated the traditional extensive processing method, which involved baking under harsh conditions of no protection, high temperature (130°C), and oxygen-rich air. The results showed that its proanthocyanidin content (only 38.5 mg / g) was the lowest, which is a huge difference from Example 1 (58.2 mg / g). This directly demonstrates that the traditional process causes severe thermal oxidative degradation of the active ingredients due to complete exposure to high temperature and oxygen-rich environment, highlighting the great advantages of the overall technical solution of this invention.

[0116] To verify the necessity of both the inner layer chemical antioxidant protection and the outer layer physical barrier protection, Comparative Example 2 (outer layer only), Comparative Example 5 (inner layer only), and Comparative Example 4 (inner layer is ineffective starch) were established. All three comparative examples employed the low-oxygen environment and segmented temperature-controlled baking process of this invention, conditions far superior to Comparative Example 1. Therefore, their proanthocyanidin retention rates (52.0 mg / g, 46.8 mg / g, and 50.8 mg / g, respectively) were also higher than Comparative Example 1. However, compared to Example 1 (58.2 mg / g) under the same conditions, they still showed significant differences. The difference is significant; the proanthocyanidin content of Comparative Example 5 (inner layer only) was 46.8 mg / g, which was significantly lower than that of Comparative Example 2 (outer layer only) at 52.0 mg / g. This indicates that under low oxygen and segmented temperature control conditions, the physical barrier of the outer layer makes a significant contribution to the oxygen barrier effect. However, Comparative Example 2 (outer layer only) still has a difference of 6.2 mg / g compared with Example 1 (both inner and outer layers), indicating that the physical barrier of the outer layer alone cannot completely prevent the penetration of trace amounts of residual oxygen and the accumulation of free radicals generated inside the material. This part of the oxidation loss is compensated by the chemical antioxidants in the inner layer. It is worth noting that the sum of proanthocyanidin content in the inner layer only (Comparative Example 5, 46.8 mg / g) and the outer layer only (Comparative Example 2, 52.0 mg / g) increased by 8.3 mg / g and 13.5 mg / g (total 21.8 mg / g) relative to the baseline of Comparative Example 1, respectively, while the increase in Example 1 relative to the baseline of Comparative Example 1 was 19.7 mg / g. The two values ​​are close, indicating that the protective functions of the inner and outer layers are highly complementary. The outer layer reduces oxygen intrusion, thereby reducing the consumption rate of antioxidants in the inner layer, enabling the inner layer to maintain effective chemical protection for a longer period of time. The two protective mechanisms work together to achieve effective retention of active ingredients.

[0117] Comparative Example 3 (without segmented temperature control) had the closest performance (55.2 mg / g, 28.8 μg / mL) to Example 1 among the five comparative examples.

[0118] The proanthocyanidin content of Comparative Example 3 (55.2 mg / g) was approximately 5% lower than that of Example 1 (58.2 mg / g). The reason for this is that Comparative Example 3 was directly baked at a constant temperature of 115°C, omitting the first-stage low-temperature dehydration process. The material was directly introduced into a high-temperature environment from room temperature. In the initial stage of heating, the protective film and the interior of the grape seeds had not yet reached thermal stability. At this time, the degradation rate of active ingredients was higher than that under the gradient heating method. This indicates that segmented temperature control, by completing dehydration and establishing thermal stability at a relatively mild temperature in the first stage, provides a buffer for the high-temperature baking in the second stage, helping to reduce additional loss of active ingredients.

[0119] Table 3 shows the sensory evaluation results: Example 1 performed excellently in both roast aroma intensity (7.6 points) and overall acceptability (7.8 points), with a bitterness score of 6.8 points (relatively mild bitterness), and the best overall flavor balance. Example 6 (100℃) had the mildest bitterness (7.5 points), but insufficient roast aroma (only 5.2 points), and an overall acceptability score of only 6.3 points. This indicates that the Maillard reaction and caramelization reaction were insufficient at the 100℃ roasting temperature, limiting flavor development. Example 7 (130℃) had the strongest roast aroma (8.5 points), but was accompanied by severe bitterness and burnt bitterness (bitterness score of only 3.5 points), and the overall acceptability dropped to 5.0 points. The flavor characteristics of Comparative Example 1 (traditional process) were similar to those of Example 7, with a strong roast aroma (8.2 points) but extremely heavy bitterness (2.8 points), and the lowest overall acceptability (4.3 points). This is consistent with the rough bitterness produced by the excessive oxidation and polymerization of its polyphenolic components under high temperature and oxygen-rich conditions. The sensory evaluation data above confirms that the process conditions of Example 1 (segmented temperature control at 115°C) effectively avoid the unpleasant flavor caused by excessive heat treatment while obtaining sufficient roasted flavor. Combined with its optimal proanthocyanidin retention rate, it achieves a good balance between functional activity retention and flavor quality.

[0120] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing grape seed solid beverage, characterized in that, Includes the following steps: S1.1 The grape seeds are washed and dried to control the moisture content to 6%-10% to obtain pretreated grape seeds; S1.

2. The pretreated grape seeds are coated with a protective component to form a protective layer on the surface of the grape seeds; S1.3 Under low-oxygen conditions, the grape seeds treated in S1.2 are subjected to segmented temperature-controlled baking to obtain protected baked grape seeds; S1.

4. The protected baked grape seeds are crushed to obtain grape seed powder; S1.5 After mixing grape seed powder and excipients evenly, add purified water as a wetting agent. The amount of purified water added is 8%-15% of the total mass of grape seed powder and excipients. Granulate using a wet granulation process and dry through a fluidized bed to obtain grape seed solid beverage.

2. The method for preparing grape seed solid beverage according to claim 1, characterized in that, In S1.2, the protective component is configured as a double-layer composite protective structure, which includes: The inner protective component is an antioxidant that adsorbs onto the surface of grape seeds to provide inner chemical antioxidant protection; The outer protective component is a film-forming agent that coats the inner layer to form an outer physical barrier; The inner protective component and the outer protective component are applied to the surface of grape seeds sequentially through a step-by-step coating process.

3. The method for preparing grape seed solid beverage according to claim 2, characterized in that, The inner protective component is rosemary extract or ascorbic acid; The outer protective layer consists of maltodextrin or gum arabic with a DE value of 10-15.

4. The method for preparing grape seed solid beverage according to claim 3, characterized in that, The process for applying the inner protective component is as follows: dissolve the inner protective component in an aqueous ethanol solution with a volume fraction of 75%-95% to prepare a solution with a mass fraction of 1%-5%. Using a sprayer, the solution is evenly sprayed onto the surface of the pretreated grape seeds, with the amount of solution sprayed being 2%-5% of the grape seed mass. Then, under circulating hot air at 40-60℃, dry for 5-15 minutes until the inner protective component forms a uniform and fixed inner protective film on the surface of the grape seeds.

5. The method for preparing grape seed solid beverage according to claim 4, characterized in that, The process for applying the outer protective component is as follows: dissolve the outer protective component in warm water at 40-60℃ to prepare a solution with a mass fraction of 10%-30%. After the grape seeds to be formed into the inner layer are cooled to 20-30℃, the outer layer solution is sprayed, and the amount of solution sprayed is 5%-10% of the mass of the grape seeds; then, it is continuously dried at 50-70℃ for 20-40 minutes until the outer protective component forms a continuous and dense solid outer protective film on the outer surface of the inner protective film.

6. The method for preparing grape seed solid beverage according to claim 1, characterized in that, In step S1.3, segmented temperature-controlled baking includes: The first stage is a low-temperature dehydration stage, with a baking temperature of 60-90℃ and a processing time of 20-40 minutes; The second stage is the flavor enhancement stage, with a baking temperature of 100-130℃ and a processing time of 10-20 minutes.

7. The method for preparing grape seed solid beverage according to claim 6, characterized in that, In step S1.3, the baking process is carried out in a low-oxygen environment formed by continuous purging with inert gas. The oxygen volume fraction in the baking chamber is not higher than 3%, and the inert gas is nitrogen or carbon dioxide.

8. The method for preparing grape seed solid beverage according to claim 7, characterized in that, In step S1.3, after baking, the protected baked grape seeds are rapidly cooled by forced ventilation to cool them to below 40°C within 5-10 minutes.

9. The method for preparing grape seed solid beverage according to claim 1, characterized in that, In S1.4, the crushing adopts a low-temperature crushing process, and the material temperature is controlled to not exceed 40°C during the crushing process by means of jacket cooling. The crushed grape seed powder passes through an 80-mesh sieve.

10. The method for preparing grape seed solid beverage according to claim 1, characterized in that, In S1.5, the excipients include honey powder, citric acid, and maltodextrin; The amount of honey powder added is 0.5%-1.5% based on the weight of grape seed powder; The amount of citric acid added is 0.05%-0.15% based on the mass of grape seed powder; The amount of maltodextrin added is 15%-20% based on the mass of grape seed powder.