Preparation method of coated peanuts containing black rice anthocyanin

Abstract

The invention relates to the technical field of food processing, in particular to a preparation method of coated peanuts containing black rice anthocyanin. Peanuts, waxy corn starch, pregelatinized starch, flour, glutinous rice flour, maltitol, black rice extract and blueberry concentrated juice are used as main raw materials, preheated peanuts are wrapped with wrapping slurry and wrapping powder in a wrapping machine and then baked, and wrapped peanuts are obtained; dissolving the black rice extract in an edible ethanol solution, mixing with the blueberry concentrated juice, mixing with a magnetic stirrer, and adjusting the pH value to obtain an anthocyanin ethanol solution; spraying an anthocyanin ethanol solution on the surface of the coated peanut under a rolling condition, and drying by hot air to completely remove the edible ethanol to obtain a finished product. The prepared coated peanuts are low in sugar content, smooth in surface, moderate in crispness and bulkiness and good in taste, meanwhile, the anthocyanin spraying method is simple and convenient, the production cost is low, the color endowing and fresh keeping effects are achieved, and the quality loss in the storage process is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and particularly relates to a preparation method of coated peanuts containing black rice anthocyanins. Background Art

[0002] Peanuts, as a high-fat and high-protein oil crop, are rich in dietary fiber and micronutrients. They can not only provide energy for the human body but also prevent various diseases, having high nutritional value. Among peanut snack products, coated peanuts are deeply loved by consumers because of their crispy taste and high nutritional value. As a non-fried high-temperature baked peanut product, coated peanuts retain the aroma and nutritional components of peanuts themselves and reduce the allergenicity of peanuts. Therefore, they have a broad sales market.

[0003] In actual production, coated peanuts, as high-fat and fatty acid foods, are affected by external factors such as oxygen, high temperature, and high humidity during storage, which will accelerate the oxidation of unsaturated fatty acids, resulting in a significant increase in the rate of oxidative rancidity, thus reducing the edible quality and even causing food safety problems and economic losses. Currently, the main method to inhibit the oxidation of coated peanuts is to add antioxidants to coated peanuts. However, synthetic antioxidants such as BHT (butylated hydroxytoluene) and BHA (butylated hydroxybenzoic acid) may have potential negative impacts on human health. And with the increasing attention to healthy diets, some consumers are skeptical about synthetic additives and prefer to choose additive-free or natural foods. Therefore, finding a natural antioxidant to maintain the safety quality and flavor of coated peanuts during the shelf life is an urgent problem to be solved.

[0004] Black rice anthocyanin is a natural plant pigment mainly present in black rice and belongs to polyphenolic compounds. Its color changes with different pH values and shows a purplish-red color in an acidic environment. On the one hand, it can endow coated peanuts with a bright purplish-red color and enhance the visual attractiveness of the product; on the other hand, it can play a role in blocking ultraviolet rays. The presence of black rice anthocyanin can form a physical barrier to reduce the penetration of ultraviolet rays into the internal structure of coated peanuts and reduce the damage to nutritional components. Its mechanism of action is to absorb ultraviolet rays in the UVA and UVB bands through the conjugated double bond structure and then convert or dissipate its energy to prevent oxidative stress and other damages caused by energy accumulation. The ultraviolet-blocking effect of anthocyanin can indirectly reduce the oxidative damage of coated peanuts, while its antioxidant effect directly protects the nutritional components in coated peanuts.

[0005] Black rice anthocyanins have powerful antioxidant properties. They can directly capture superoxide anion radicals, hydroxyl radicals, and singlet oxygen, reducing the damage of these radicals to cells and tissues. They can also react with free radicals through their phenolic hydroxyl groups to form stable compounds, thus effectively neutralizing free radicals. Moreover, anthocyanins can inhibit the lipid peroxidation reaction in coated peanuts, reducing the generation of lipid peroxides. At the same time, they can combine with fatty acids to form stable complexes, preventing the breakage of fatty acid chains and the generation of free radicals, playing a role in stabilizing fatty acids. In addition, black rice anthocyanins also have the ability to chelate metal ions, which can prevent metal ion-catalyzed oxidation reactions, thereby further enhancing their antioxidant effect. Through the dual protection mechanism of ultraviolet blocking and antioxidant effects, anthocyanins protect vitamins, lipids, and proteins in coated peanuts, extending the shelf life of the product and improving the overall quality.

[0006] However, black rice anthocyanins are easily degraded under conditions such as light and heat, so they cannot be directly added during the high-temperature baking process. If simply added at other stages, it may lead to uneven distribution of anthocyanins, poor antioxidant effects in some peanuts, and the inability to fully play its role in extending the shelf life. It will also cause inconsistent product colors, affecting aesthetics and quality stability, and reducing consumers' willingness to purchase. Therefore, the present invention proposes a method of spraying a compound ethanol solution of blueberry concentrated juice and black rice extract under rolling conditions, which can evenly attach black rice anthocyanins to the surface of coated peanuts in a short time under conditions far lower than the baking temperature, reduce the thermal degradation of black rice anthocyanins, and improve the retention rate. Summary of the Invention

[0007] Aiming at the above-mentioned shortcomings of the prior art, the present invention provides a preparation method of coated peanuts containing black rice anthocyanins, which can effectively solve the problems mentioned in the prior art.

[0008] To achieve the above objectives, the present invention is realized through the following technical solutions: The present invention provides a preparation method of coated peanuts containing black rice anthocyanins, including the following steps: Step 1: The peanuts are slightly heated in an oven, and the peanuts with intact red skins are selected. Step 2: Prepare a coating powder containing waxy corn starch (amylopectin content ≥ 95%), pregelatinized starch (viscosity at 25°C is 7000 mpa·s), flour, and glutinous rice flour. Step 3: Prepare a coating slurry containing water, solid maltitol, compound leavening powder (40% sodium acid pyrophosphate, 40% sodium bicarbonate, 10% calcium dihydrogen phosphate, 5% calcium carbonate, 5% citric acid), and blueberry concentrated juice (10-fold concentrated, Brix ≥ 65). Step 4: Sequentially add the peanuts processed in Step 1, the coating slurry prepared in Step 3, and the coating powder prepared in Step 2 into the coating machine. Each coating interval is 1 - 5 minutes, and repeat the coating operation until the coating quality accounts for 20 - 40% of the peanut quality, until the peanut red skin is completely covered; Step 5: Put the coated peanuts into the oven and bake at a temperature of 155 - 175 °C for 15 - 20 minutes until the moisture content of the peanuts is 1% - 3%. The coated peanuts are baked in the oven until the surface is golden yellow, and then cooled to room temperature; Step 6: Prepare an anthocyanin ethanol solution containing blueberry concentrate (10 - fold concentrate, Brix ≥ 65), black rice extract (anthocyanin content 20%), and edible ethanol solution (95%), and then adjust the pH to 3 - 4 using a sodium dihydrogen phosphate - citric acid buffer solution; Step 7: Spray the anthocyanin ethanol solution prepared in Step 6 on the surface of the coated peanuts in Step 5, and remove the edible ethanol by hot air drying to obtain the finished product.

[0009] The preferred technical solution is that the baking temperature in Step 1 is set at 125 - 145 °C and the baking time is set at 4 - 8 minutes. The purpose is to kill or inhibit the microorganisms on the peanut surface, remove the moisture on the peanut surface, and prevent the peanut red skin from cracking, avoiding the cracking and peeling of the coating layer during baking.

[0010] The preferred technical solution is that the main premix powder of the coating powder in Step 2 is composed of waxy corn starch, glutinous rice flour, flour, and pre - gelatinized starch in a mass ratio of 1:1:1:1. The synergistic effect of the four powders ensures the uniformity of the coating, and at the same time is conducive to the balance of the crispness, toughness, and chewiness of the coated peanuts, enhancing the layering of the taste.

[0011] The preferred technical solution is that the main body of the coating slurry in Step 3 is a maltitol aqueous solution with a concentration of 50 - 70%. This concentration ensures that the coating has a certain sweetness without affecting the peanut flavor, and at the same time makes its viscosity moderate, so that the coating is uniform. The addition amount of the bulking powder is 0.5 - 1.5% (w / w) of the maltitol aqueous solution, and the addition amount of the blueberry concentrate is 1 - 5% (w / w) of the maltitol aqueous solution.

[0012] The preferred technical solution is that the peanut coating interval in Step 4 is 1 - 5 minutes to ensure uniform coating and prevent adhesion; repeat the coating until the coating quality accounts for 20 - 40% of the peanut quality to ensure that the coating layer increases the crispness of the product without affecting the flavor of the peanuts themselves.

[0013] Preferably, in step 5, the baking temperature is 155 - 175 °C. This temperature range can effectively heat the coating layer evenly, promote the caramelization of sugars and other components, thereby enhancing the aroma and flavor of peanuts; the baking time is 15 - 20 minutes until the moisture content of peanuts is 1% - 3%, ensuring the evaporation of moisture in peanuts and guaranteeing the crispness of peanuts.

[0014] Preferably, in step 6, the addition amount of black rice extract in the anthocyanin ethanol solution is 0.25 - 1.25‰ (w / w), and the addition amount of blueberry concentrated juice is 1 - 5% (w / w). It needs to be mixed evenly by a magnetic stirrer and finally the pH is adjusted to 3 - 4, making the solution purplish red and ensuring the stability of anthocyanins therein.

[0015] Preferably, in step 7, anthocyanins are sprayed using an air pump spray gun with a spray gun air pressure of 25 Pai, and sprayed under rolling conditions until the color of the surface of the coated peanuts is completely covered; the hot air drying temperature is 65 - 95 °C, and the drying time is 10 - 15 minutes to minimize the degradation of anthocyanins while ensuring the complete removal of edible ethanol.

[0016] The technical solution provided by the present invention has the following beneficial effects compared with the known prior art: (1) The coating powder of the present invention uses a compound powder of flour, waxy corn starch, glutinous rice flour, and pregelatinized starch. Among them, flour is rich in proteins such as gluten, which can provide structural support, enhance the strength and durability of the coating layer, and prevent the coating layer from cracking or falling off during processing and storage; waxy corn starch has good dispersibility and fluidity, which is conducive to the uniform adhesion of the coating powder. At the same time, it has hygroscopicity and expansibility, making the coating layer denser, effectively locking in moisture, reducing oil absorption, and enhancing the crispness; glutinous rice flour has a delicate and soft texture and a high amylopectin content, which can rapidly expand when heated to form a fluffy coating layer, making the product taste more delicate; pregelatinized starch has high viscosity and can form a film quickly. Because its viscosity rapidly increases after absorbing water, the usage amount of the coating slurry is reduced. As an adhesive during the coating process, it can quickly form a uniform coating on the surface of peanuts, avoiding uneven or agglomerated coating materials, and making the appearance of the coated peanuts more regular and smooth. The synergistic effect of these four powders can improve the taste, effectively balancing the crispness, toughness, and chewiness of the coated peanuts; and improving the appearance, making the coating uniform and shiny, making the finished product more attractive to consumers. And the white granulated sugar in the coating slurry is replaced with maltitol, which can effectively reduce the total calories of the product and help meet the needs of a healthy diet.

[0017] (2)In the present invention, a compound of blueberry concentrated juice and black rice extract in an edible ethanol solution is applied to the surface of coated peanuts by means of atomized spraying with an air pump spray gun. The fine droplets formed by atomized spraying can better penetrate the surface of the coating, enhancing the adhesion and permeability of the extract, and at the same time enhancing the uniformity of coating; the precise spraying of the spray gun reduces the amount of extract required while maintaining the effect, reducing the production cost; after spraying, the fine droplets quickly evaporate on the surface, reducing the residence time of the ethanol solution on the surface, contributing to rapid drying and maintaining the crispy texture of the coated peanuts. The purple-red color provided by the added blueberry concentrated juice acts synergistically with the color of anthocyanins, making the color of the coated peanuts more uniform and playing a better color covering role. During the spraying process, hot air drying is combined, which can stably and uniformly attach black rice anthocyanins to the surface of coated peanuts at a relatively low temperature and in a short time, reducing the thermal degradation of anthocyanins; while not affecting the flavor of the coated peanuts, it imparts a beautiful purple-red color and plays a role in blocking light; at the same time, it delays the oxidative rancidity of the coated peanuts and also avoids the potential negative impact of synthetic antioxidants on human health, having a relatively broad market prospect. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 Process flow chart of the present invention; Figure 2 Effect of black rice anthocyanin content on the color of black rice anthocyanin-coated peanuts; Figure 3 Effect of coating powder mass ratio on the texture properties of black rice anthocyanin-coated peanuts; Figure 4 Sensory evaluation of black rice anthocyanin-coated peanuts; Figure 5 Actual photo of black rice anthocyanin-coated peanuts; Figure 6 Crispness of black rice anthocyanin-coated peanuts; Figure 7 Hardness of black rice anthocyanin-coated peanuts; Figure 8 Peroxide value of black rice anthocyanin-coated peanuts; Figure 9 Acid value of black rice anthocyanin-coated peanuts. Detailed Description of the Invention

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] The following further describes the present invention in conjunction with embodiments.

[0022] Embodiment 1: Step 1: Bake peanuts in an oven at 125°C for 5 minutes until the moisture content of the peanuts is 7%, and after cooling, select peanuts of the same size with intact red skins. Step 2: Preparation of the coating powder: Uniformly mix waxy corn starch, glutinous rice flour, flour, and pregelatinized starch in a mass ratio of 1:1:1:1.

[0023] Step 3: Preparation of the coating slurry: Dissolve maltitol in distilled water to obtain a 50% maltitol solution; then add 0.5% (w / w) of the bulking agent and 1% (w / w) of blueberry concentrate, and stir evenly.

[0024] Step 4: Sequentially add the peanuts from Step 1, the coating slurry from Step 3, and the coating powder from Step 2 into a coating machine. After the surface of the peanuts is dry, coat them again at intervals of 1 minute, and repeat the coating operation until the coating quality accounts for 20% of the mass of the peanuts. Step 5: Put the coated peanuts obtained in Step 4 into an oven and bake at 155°C for 15 minutes to make the moisture content of the peanuts 3%. After taking them out, cool them to room temperature. Step 6: Preparation of the anthocyanin ethanol solution: Dissolve black rice anthocyanin in 95% edible ethanol to obtain a 0.25‰ black rice extract edible ethanol solution, and then add 1% of blueberry concentrate. After mixing evenly, adjust the pH to 3 with a sodium dihydrogen phosphate-citric acid buffer solution. Step 7: Spray and coat the anthocyanin ethanol solution obtained in Step 6 on the surface of the coated peanuts obtained in Step 5 in the form of atomized spraying with an air pump spray gun; dry at 70°C for 10 minutes until all the edible ethanol is completely removed to obtain the finished product.

[0025] Embodiment 2: Step 1: Bake peanuts in an oven at 135°C for 6 minutes until the moisture content of the peanuts is 6%, and after cooling, select peanuts of the same size with intact red skins. Step 2: Preparation of the coating powder: Uniformly mix waxy corn starch, glutinous rice flour, flour, and pregelatinized starch in a mass ratio of 1:1:1:1.

[0026] Step 3: Preparation of the coating slurry: Dissolve maltitol in distilled water to obtain a 50% maltitol solution; then add 1.0% (w / w) of the bulking agent and 3% (w / w) of blueberry concentrate, and stir evenly.

[0027] Step 4: Sequentially add the peanuts from Step 1, the coating slurry from Step 3, and the coating powder from Step 2 into the coating machine. After the surface of the peanuts is dry, perform the coating operation again at an interval of 3 minutes. Repeat the coating operation until the coating quality accounts for 30% of the mass of the peanuts. Step 5: Place the coated peanuts obtained in Step 4 into an oven and bake at 165°C for 18 minutes to make the moisture content of the peanuts 2%. Take them out and cool to room temperature. Step 6: Preparation of the anthocyanin ethanol solution: Dissolve black rice anthocyanin in 95% edible ethanol to obtain a 0.75‰ black rice extract edible ethanol solution, and then add 3% of blueberry concentrate. After mixing evenly, adjust the pH to 3.5 with sodium dihydrogen phosphate-citric acid buffer solution. Step 7: Spray and coat the anthocyanin ethanol solution obtained in Step 6 on the surface of the coated peanuts obtained in Step 5 by means of air pump spray gun atomization; dry at 80°C for 13 minutes until all the edible ethanol is completely removed to obtain the finished product.

[0028] Example 3: Step 1: Bake the peanuts in an oven at 145°C for 8 minutes until the moisture content of the peanuts is 5%. After cooling, select peanuts with the same size and intact red skins. Step 2: Preparation of the coating powder: Uniformly mix waxy corn starch, glutinous rice flour, wheat flour, and pregelatinized starch in a mass ratio of 1:1:1:1.

[0029] Step 3: Preparation of the coating slurry: Dissolve maltitol in distilled water to obtain a 50% maltitol solution; then add 1.5% (w / w) of the bulking agent and 5% (w / w) of blueberry concentrate, and stir evenly.

[0030] Step 4: Sequentially add the peanuts from Step 1, the coating slurry from Step 3, and the coating powder from Step 2 into the coating machine. After the surface of the peanuts is dry, perform the coating operation again at an interval of 5 minutes. Repeat the coating operation until the coating quality accounts for 40% of the mass of the peanuts. Step 5: Place the coated peanuts obtained in Step 4 into an oven and bake at 175°C for 20 minutes to make the moisture content of the peanuts 1%. Take them out and cool to room temperature. Step 6: Preparation of the anthocyanin ethanol solution: Dissolve black rice anthocyanin in 95% edible ethanol to obtain a 1.25‰ black rice extract edible ethanol solution, and then add 5% of blueberry concentrate. After mixing evenly, adjust the pH to 4 with sodium dihydrogen phosphate-citric acid buffer solution. Step 7: Coat the surface of the coated peanuts obtained in Step 5 with the anthocyanin ethanol solution obtained in Step 6 by atomizing and spraying with an air pump spray gun; dry at 90 °C for 15 minutes until all the edible ethanol is completely removed to obtain the finished product.

[0031] Refer to Figure 1 —9, in combination with Examples 1 - 3, further analyze the finished product: It can be seen from Figure 2 that as the addition amount of anthocyanin increases, the overall color difference increases. The decrease in the L* value representing brightness means that the brightness of the sample decreases, indicating that as the anthocyanin concentration increases, the saturation of the sample increases and the color becomes darker; the a* value representing the color axis from green to red first rises and then falls, indicating that at first, as the anthocyanin increases, the red component in the sample increases. However, when a certain concentration is reached, the color saturation of the sample reaches its limit. The b* value representing the color axis from blue to yellow increases slowly, indicating that with the addition of anthocyanin, the color of the sample steadily tends to yellow or warm tones, which is consistent with Figure 5 the actual pictures in

[0032] It can be seen from Figure 5 that when the mass ratio of flour, glutinous rice flour, waxy corn starch, and pregelatinized starch is 1:1:1:1, the obtained coated peanuts have relatively high crispness and moderate hardness. Under this ratio, the toughness and hardness provided by the flour, the softness and moisture provided by the glutinous rice flour, the crispness provided by the waxy corn starch, and the viscosity and softness provided by the pregelatinized starch act together to form a rich taste level, making the coated peanuts have a crispy feeling when chewed without being too hard.

[0033] It can be seen from Figure 6 and 7 that as the baking temperature increases and the baking time prolongs, the crispness of the coated peanuts gradually improves, but the surface hardness also increases accordingly. At higher baking temperatures and longer baking times, the moisture in the coated peanuts will evaporate rapidly. The reduction of moisture will cause the structure of the product to become more compact, thereby increasing the crispness and hardness. And under high-temperature conditions, saccharification reactions (such as the Maillard reaction) and starch gelatinization occur, which will further enhance the hardness and crispness of the taste.

[0034] It can be seen from Figure 8 and 9 that as the baking temperature increases and the baking time prolongs, the acid value and peroxide value of the coated peanuts increase. High temperature will accelerate the fat oxidation reaction, generating more free fatty acids, resulting in an increase in the acid value and peroxide value; long-term heating will increase the chance of fat oxidation, further increasing the acid value and peroxide value.

Claims

1. A method for preparing coated peanuts containing black rice anthocyanins, characterized in that: The following steps are involved: Step 1: Heat the peanuts slightly in the oven and select the peanuts with intact red skins; Step 2, preparing a coating powder comprising waxy corn starch, pregelatinized starch, flour, and glutinous rice flour; Step 3, preparing a coating slurry comprising water, solid maltitol, compound fluffy powder, and blueberry concentrated juice; Step 4, add the peanuts processed in step 1, the coating slurry prepared in step 3 and the coating powder prepared in step 2 into the coating machine in sequence, with an interval of 1-5 minutes between each coating, and repeat the coating operation until the coating mass accounts for 20-40% of the peanut mass, until the peanuts are completely covered with red skin; Step 5, put the coated peanuts into the oven and bake them at 155-175°C for 15-20 minutes until the moisture content of the peanuts is 1%-3%. The coated peanuts are baked in the oven until the surface is golden yellow, and then cooled to room temperature; Step 6, preparing an anthocyanin ethanol solution comprising blueberry concentrated juice, black rice extract, and edible ethanol solution, and then adjusting the pH to 3-4 using sodium dihydrogen phosphate-citric acid buffer solution; Step 7: spray the anthocyanin ethanol solution prepared in step 6 on the surface of the coated peanuts in step 5, and then dry with hot air to remove edible ethanol to obtain a finished product.

2. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: In step 1, the baking temperature is set to 125-145° C. and the baking time is set to 4-8 minutes, the purpose of which is to kill or inhibit microorganisms on the surface of the peanuts, remove moisture from the surface of the peanuts, prevent the red skin of the peanuts from cracking, and avoid the coating layer from cracking and falling off during baking.

3. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: The main premix of the coating powder in step 2 is prepared by mixing waxy corn starch, glutinous rice flour, flour and pregelatinized starch in a mass ratio of 1:1:1:

1. The synergistic effect of the four powders ensures the uniformity of the coating, while being beneficial to the balance of crispness, toughness and chewiness of the coated peanuts, thereby enhancing the layered taste.

4. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: The coating slurry in step 3 is mainly composed of a maltitol aqueous solution with a concentration of 50-70%. This concentration ensures that the coating has a certain sweetness but does not affect the peanut flavor, while making it moderately viscous and making the coating uniform. The amount of fluffy powder added is 0.5-1.5% of the maltitol aqueous solution, and the amount of blueberry concentrated juice added is 1-5% of the maltitol aqueous solution.

5. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: In step 4, the peanut coating interval is 1-5 minutes to ensure uniform coating and prevent sticking; the coating is repeated until the coating mass accounts for 20-40% of the peanut mass, ensuring that the coating layer increases the crispness of the product but does not affect the flavor of the peanuts themselves.

6. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: The baking temperature in step 5 is 155-175° C., which can effectively heat the coating layer evenly and promote the caramelization of sugar and other ingredients, thereby enhancing the aroma and flavor of the peanuts. The baking time is 15-20 minutes, until the moisture content of the peanuts is 1%-3%, ensuring the evaporation of moisture in the peanuts and ensuring the crispness of the peanuts.

7. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: The amount of black rice extract added to the anthocyanin ethanol solution in step 6 is 0.25-1.25‰, and the amount of blueberry concentrated juice added is 1-5%. The solution needs to be mixed evenly with a magnetic stirrer and the pH is finally adjusted to 3-4, so that the solution is purple-red and the stability of anthocyanins therein is ensured.

8. The method for preparing coated peanuts containing black rice anthocyanins according to claim 1, characterized in that: In step 7, anthocyanins are sprayed using an air pump spray gun with an air pressure of 25 Pai, and sprayed under rolling conditions until the color of the surface of the coated peanuts is completely covered; the hot air drying temperature is 65-95° C., and the drying time is 10-15 minutes to ensure that the edible ethanol is completely removed while minimizing the degradation of anthocyanins.

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