Fruit-flavored sandwich hard candy and preparation method thereof

Abstract

The invention relates to the field of food processing, and particularly discloses a fruity sandwich hard candy and a preparation method thereof. The preparation method of the fruity sandwich hard candy comprises the following steps: immersing fruit slices into a treating fluid, and performing ultrahigh-pressure soaking; fruit slices are crushed into fruit pulp, pectin is added, casting and vacuum freeze drying are carried out, and a freeze-dried material is prepared; fruit slices are mixed with tea leaves, the mixture and solid sugar are alternately placed layer by layer, permeation treatment, filtration and concentration are performed, and the fruity syrup is prepared; mixing the fruity syrup with the freeze-dried material, soaking, and freezing to obtain a core material; boiling sugar liquid, and casting into an upper half shell and a lower half shell; and placing the core material in the lower half shell, bonding the upper half shell and the lower half shell, and demolding. The sandwich hard candy has good fruit flavor, is fresh and delicious, and has good long-term storage stability.

Description

Technical Field

[0001] The present application relates to the technical field of food processing, and more specifically, it relates to a fruit-flavored sandwich hard candy and a preparation method thereof. Background Art

[0002] Candies are popular leisure foods loved by the majority of consumers, especially teenagers, and are known as "sweet foods". At present, candies of different shapes, colors, textures, and flavors have emerged on the market. However, the main ingredients of traditional candies are sweeteners such as sucrose and glucose.

[0003] At present, the common sandwich candies on the market are prepared by boiling and other high-temperature heat treatments of dried fruit powder or the pulp of fleshy fruits together with gelatin to prepare the sandwich filling. As a result, fresh fruit flavor substances, such as volatile aromatic components, are decomposed by heat, and the aroma loss is serious, the taste is not fresh, and the high-temperature treatment destroys the heat-sensitive nutrients in fruits, such as vitamin C and polyphenolic substances, reducing the nutritional value of the product; another common sandwich candy is to add fruit and vegetable pulp. When the user bites through the outer sugar body, they can taste the delicious fruit and vegetable pulp. However, since the fruit and vegetable pulp is liquid and has a high water activity, water migrates through the outer sugar body during storage, resulting in the core material penetrating and eroding the outer sugar body, causing the outer sugar body to dissolve and recrystallize, leading to the rupture or transparency decrease of the outer sugar body. Moreover, water migration will also cause the growth of microorganisms, resulting in a shortened shelf life. In order to achieve an ideal shelf life, the main method is to reduce the water content of the fruit and vegetable flavor core material. However, a lower water content is likely to cause the weakening of the flavor of the fruit and vegetable flavor core material. In addition, using liquid fruits and vegetables as the pulp for the core material has too strong fluidity during biting, easily causing taste imbalances such as being overly sweet or concentrated flavor release, which is not synergistic with the chewing experience of traditional hard candies. Summary of the Invention

[0004] In order to enable sandwich candies with a liquid fruit flavor core material to have a relatively ideal shelf life, the present application provides a fruit-flavored sandwich hard candy and a preparation method thereof.

[0005] In the first aspect, the present application provides a preparation method of a fruit-flavored sandwich hard candy, adopting the following technical solution: A preparation method of a fruit-flavored sandwich hard candy, comprising the following steps: Using plasma-activated water as a treatment liquid, immersing fruit slices in the treatment liquid, and soaking and treating under ultra-high pressure conditions; Crushing the soaked fruit slices into fruit pulp, adding 1-2 wt% of pectin based on the mass of the fruit pulp, mixing evenly, pouring into a mold, and vacuum freeze-drying to obtain a freeze-dried material; The fruit slices are mixed with tea leaves to prepare a mixture, the mixture and solid sugar are placed alternately in layers, osmotic treatment is performed at 3-5°C for 150-168 hours, and filtration and concentration are performed to prepare a fruit-flavored syrup with a soluble solid content greater than 70° Brix, the amount of solid sugar used is 100-120% of the amount of the mixture, and the mass ratio of the fruit slices to the tea leaves is 1:0.3-0.6; The fruit-flavored syrup and the freeze-dried material are mixed, soaked, the freeze-dried material is taken out, and frozen to obtain the core material; White sugar, glucose syrup, sorbitol, citric acid, DL-malic acid, modified soybean lecithin, maltodextrin, vitamin C, vegetable oil and edible flavor are mixed and boiled into sugar solution, and then cast into hollow upper and lower shells when cooled to 75-85°C; The core material is placed in the lower half shell, the upper half shell is bonded to the lower half shell, and the mold is removed to obtain a fruit-flavored hard candy.

[0006] By adopting the above technical scheme, firstly, plasma activated water is used to soak the fruit slices, and ultra-high pressure treatment is used during soaking. Plasma activated water is a new type of green, low-residue and broad-spectrum physical sterilization method. Soaking the fruit slices in it can increase the water content of the tissue cells of the fruit slices and the supporting force on the cell membrane, and at the same time maintain the color and aroma of the fruit slices, and maintain the freshness of the fruit slices. Ultra-high pressure is also a non-thermal sterilization technology. During the sterilization process, a low temperature is always maintained, which can better retain the heat-sensitive components in the fruit slices and reduce the influence of temperature on the nutritional components in the fruit slices. Then, the fruit slices are broken into pulp, and pectin is used as a binder to cast them into molds of various shapes. After vacuum freeze drying, the water in the fruit slices is directly sublimated from the ice crystal state to gas, leaving more gaps, so that the prepared freeze-dried material has more pore structures and stronger hygroscopicity.

[0007] After slicing the fruits and mixing them with tea leaves, they are laid layer by layer alternately with solid sugar, and a fruit - flavored syrup is made by the solid - low - temperature impregnation method. There is no need for boiling. The soluble solid content is high, and it has unique fruit - flavored substances. Nutritional components and heat - sensitive substances are better retained in the fruit - flavored syrup, avoiding enzymatic browning during the production process. Adding tea leaves during solid - low - temperature impregnation can improve the fresh taste of the fruit - flavored syrup, reduce the sweetness, increase the richness of the taste, and at the same time improve the antibacterial ability of the fruit - flavored syrup and extend the shelf life. Then, using the freeze - dried material made by vacuum freeze - drying as a carrier, due to its porous structure, when it comes into contact with the fruit - flavored syrup, due to capillary action and the hygroscopicity of the freeze - dried material, the fruit - flavored syrup will be sucked into the interior of the freeze - dried material. Moreover, the interaction between the viscosity of the fruit - flavored syrup and the water - absorbency of the freeze - dried material also helps the freeze - dried material absorb the fruit - flavored syrup. This interaction enables the fruit - flavored syrup to penetrate into the interior of the freeze - dried material, increasing its taste and flavor, while avoiding the overly concentrated taste caused by directly using fruit pulp as the core material.

[0008] After mixing and soaking the fruit - flavored syrup and the freeze - dried material and then freezing, the loss of the fruit - flavored syrup is reduced, and it is convenient for placing the core material in the lower half - shell later. Using the upper half - shell and the lower half - shell to enclose the core material in the middle can prevent the loss of the fruit - flavored syrup. If the freeze - dried material soaked with the fruit - flavored syrup is directly put into the sugar solution, the sugar solution has a certain temperature, which will make the frozen fruit - flavored syrup return to a flowing state and flow out from the freeze - dried material. Therefore, the core material made of the frozen fruit - flavored syrup and the freeze - dried material is operated to be placed in the lower half - shell at a temperature lower than the melting temperature of the fruit - flavored syrup, preferably lower than 20°C.

[0009] Placing the core material made by the freeze - dried material absorbing the fruit - flavored syrup between the lower half - shell and the upper half - shell to make a sandwich hard candy. When biting through the shell, the internal fruit - flavored syrup and the freeze - dried material can bring a rich taste. At the same time, the freeze - dried material can have a certain adsorption effect on the fruit - flavored syrup, reducing the leakage of the fruit - flavored syrup, reducing the erosion of the core material on the shell, extending the storage period, and both the freeze - dried material and the fruit - flavored syrup are not subjected to high - temperature treatment, so that the nutritional substances and flavor substances in the fruits can be better retained.

[0010] Optionally, tartaric acid and β - cyclodextrin are also added to the treatment liquid, and the mass ratio of plasma - activated water, tartaric acid, and β - cyclodextrin is 1:0.05 - 0.075:0.02 - 0.04.

[0011] By adopting the above technical solution, tartaric acid and β-cyclodextrin are added to the plasma-activated water. Tartaric acid can inhibit the enzymatic browning during the processing of fruit slices, improve the color of the fruit slices, and moreover, tartaric acid can combine with the plasma-activated water to enhance the antibacterial effect, thereby improving the shelf life of the filling. β-cyclodextrin has an embedding effect and can gradually penetrate into the fruit slices through the osmotic action of ultra-high pressure, encapsulating the effective flavor in its internal cavity to prevent the flavor substances from volatilizing and oxidizing during processing and storage, ensuring that the filling can maintain its original flavor for a long time. Moreover, the fruit slices contain natural pigment components, and β-cyclodextrin can also play its embedding role to prevent the pigment from contacting with oxygen in the external environment and prevent the oxidation and fading of the pigment, making the filled candy maintain a bright and stable color. At the same time, the embedding of β-cyclodextrin can also improve the taste of the candy filling, making the taste more delicate and smooth, improving the overall uniformity, enhancing the quality of the candy, and at the same time extending the shelf life of the candy filling.

[0012] Optionally, the inner walls and edges of the upper shell and the lower shell are evenly coated with a glue solution, and the glue solution contains guar gum, honey and ginger oleoresin in a mass ratio of 1:2 - 5:0.4 - 0.6.

[0013] By adopting the above technical solution, guar gum can rapidly form a highly viscous colloidal solution in cold water. Therefore, the prepared glue solution will not affect the structures of the upper half shell and the lower half shell, and will not cause the shell to melt due to coating. Moreover, guar gum can form a gel layer, and ginger oleoresin has strong antibacterial properties and has different degrees of inhibitory effects on Staphylococcus aureus, Escherichia coli, etc. Moreover, ginger oleoresin contains flavor components such as gingerone, gingerol, and gingerol, and has the effects of inducing sweating and relieving exterior syndrome, warming the middle-jiao and stopping vomiting. Honey plays a role in neutralizing the taste and adhesiveness. Therefore, the glue solution can form a gel layer on the inner walls of the upper half shell and the lower half shell, and form a gel layer at the joint of the upper half shell and the lower half shell. When using the sugar solution to bond the upper half shell and the lower half shell, the sugar solution is coated on the gel layer. Therefore, a ring of gel layer is formed at the joint of the upper half shell and the lower half shell, which can increase the compactness at the joint of the upper half shell and the lower half shell, reduce the penetration of the fruit-flavored syrup, reduce the erosion of the shell, and at the same time can further enhance the antibacterial ability of the core material.

[0014] Optionally, the glue solution is prepared by the following method: Filter, boil, concentrate and pulverize the blueberry fermented wine residue to obtain wine residue powder; Add guar gum to water, stir and dissolve to obtain a solution with a concentration of 1 - 1.5 wt%, add honey, ginger oleoresin and wine residue powder, and stir evenly to obtain the glue solution. The mass ratio of the wine residue powder to the guar gum is 1:0.2 - 0.4.

[0015] By adopting the above technical solution, the blueberry fermented wine dregs are by-products after blueberry wine-making, which contain anthocyanins, dietary fiber, etc. However, usually the blueberry fermented wine dregs will be directly discarded. Therefore, in this application, turning waste into treasure can improve the economic benefits of the enterprise. The blueberry fermented wine dregs are filtered to remove impurities, boiled to remove alcohol, concentrated and then crushed to obtain wine dregs powder containing anthocyanins. The wine dregs powder is mixed with guar gum, ginger oleoresin and honey as the glue solution, which is brushed on the inner part and the edge of the upper half shell and the lower half shell, can increase the viscosity of the glue solution, improve the protection effect on the core material, and at the same time enhance the antibacterial ability.

[0016] Optionally, the brushing thickness of the glue solution is 0.3 - 0.5 mm.

[0017] By adopting the above technical solution, an appropriate brushing thickness will not affect the adhesion of the upper half shell and the lower half shell, and at the same time will not affect the placement of the core material.

[0018] Optionally, the raw material percentages of the upper shell and the lower shell are as follows: 50 - 55% glucose syrup, 1 - 1.2% sorbitol, 0.5 - 0.6% citric acid, 0.4 - 0.5% DL - malic acid, 0.5 - 0.7% modified soy phospholipid, 0.4 - 0.5% maltodextrin, 0.2 - 0.3% vitamin C, 0.3 - 0.5% vegetable oil and 0.1 - 0.3% edible essence, and the balance is white granulated sugar.

[0019] By adopting the above technical solution, substances such as glucose syrup, sorbitol, citric acid, etc. are boiled and then cast, and the made upper half shell and lower half shell have appropriate sweetness, and at the same time can make the upper half shell and lower half shell be cast into any shape.

[0020] Optionally, the wall thickness of the upper half shell and the lower half shell is 1 - 1.5 mm.

[0021] By adopting the above technical solution, an appropriate wall thickness can make the upper half shell and the lower half shell have a good anti - leakage effect, reduce the penetration of the core material, reduce the erosion of the core material on the shell, and extend the shelf life.

[0022] Optionally, during the penetration treatment, ultrasonic treatment is carried out at the penetration times of 48 h, 60 h and 84 h respectively, the ultrasonic frequency is 40 - 50 kHz, the power is 500 - 550 W, and the ultrasonic time for each time is 20 - 30 min.

[0023] By adopting the above technical solution, under the action of ultrasonic cavitation and mechanical force, numerous micro-channels are formed on the surface and inside of the mixture of fruit slices and tea leaves, and the number of micro-channels will increase with the extension of the ultrasonic treatment time, which is beneficial to the precipitation of water in the mixture. Therefore, under the action of ultrasonic waves, the mixture is dehydrated more thoroughly, absorbs more water, dissolves more solid sugar, and the yield of the obtained fruit-flavored syrup increases. In addition, ultrasonic waves can also damage the permeable tissue, form more microscopic channels, increase the mass of the permeating solution, and improve the permeation efficiency.

[0024] Optionally, the solid sugar is selected from at least one of yellow rock sugar, polycrystalline white rock sugar, single-crystalline white rock sugar and granulated sugar, and the particle size of the solid sugar is 10-20 mesh.

[0025] Optionally, the method of soaking under ultra-high pressure is as follows: the pressure is increased to 500-600 MPa within 20-30 s, the pressure is maintained for 30-40 min, and then the pressure is reduced to atmospheric pressure within 5-10 s. The temperature during ultra-high pressure soaking is 30-40 °C.

[0026] By adopting the above technical solution, ultra-high pressure can facilitate the penetration of plasma-activated water, achieve the effect of further sterilization at the same time, and can also maintain the appearance color and nutritional quality of fruit slices, making their taste fresh and delicious.

[0027] Optionally, the fruit is selected from at least one of mango, cherry, hawthorn, kiwifruit, banana, apple, orange, pineapple, strawberry, watermelon, grape, waxberry, pomelo.

[0028] By adopting the above technical solution, when preparing sandwich hard candies, the freeze-dried materials and the fruit slices of the fruit-flavored syrup can choose the same fruit, or different fruits can be selected and matched with each other to obtain a more rich taste.

[0029] Optionally, mango slices are used when preparing the freeze-dried materials, and mango slices are used when preparing the fruit-flavored syrup.

[0030] Optionally, apple slices and strawberry slices are used when preparing the freeze-dried materials, and mango slices are used when preparing the fruit-flavored syrup.

[0031] Optionally, mango slices are used when preparing the freeze-dried materials, and mango slices, strawberry slices and apple slices are used when preparing the fruit-flavored syrup.

[0032] In the second aspect, the present application provides a fruit-flavored sandwich hard candy, adopting the following technical solution: A fruit-flavored sandwich hard candy is made by using the preparation method of the fruit-flavored sandwich hard candy.

[0033] To sum up, the present application has the following beneficial effects: 1. The present application adopts the method of crushing fruit slices into pulp after being treated with ultra-high pressure immersion of plasma activated water, mixing with gelatin for casting, and vacuum freeze-drying to obtain freeze-dried material, which is then blended with fruit-flavored syrup formed by solid low-temperature impregnation of fruit slices, tea leaves, and solid sugar, and then frozen, and then placed between the upper shell and the lower shell to obtain sandwich hard candy. The freeze-dried material and the fruit-flavored syrup provide different soft and hard tastes for the sandwich hard candy. At the same time, the freeze-dried material can reduce the leakage of the fruit-flavored syrup, reduce the erosion of the shell, and extend the shelf life.

[0034] 2. In the present application, it is preferred to add tartaric acid and β-cyclodextrin to plasma activated water, which can improve the color of fruit slices, prevent the oxidation and fading of pigments, and make the taste more delicate and smooth.

[0035] 3. In the present application, glue is applied on the inner wall and edge of the upper half shell and the lower half shell. The glue contains ingredients such as guar gum, honey and ginger oleoresin, which can form a gel layer on the inner wall and edge of the shell to further prevent leakage of the core material. DETAILED DESCRIPTION

[0036] The following examples further illustrate the present application in detail. Example

[0037] Embodiment 1: A method for preparing a fruit-flavored hard candy, comprising the following steps: S1. Using plasma activated water as a treatment liquid, cutting mango into mango slices with a thickness of 3 mm, immersing the mango slices in the treatment liquid, with a solid-liquid ratio of 1:2, and soaking treatment under ultra-high pressure conditions. The method of ultra-high pressure soaking is: increasing the pressure to 600 MPa within 30 seconds, maintaining the pressure for 30 minutes, and then reducing the pressure to atmospheric pressure within 10 seconds. The coordinated treatment temperature in the whole process is 40° C. The plasma activated water is prepared by treating deionized water for 60 seconds under the conditions of a voltage of 40 V, a current of 0.7 A, and a jet plasma spraying distance of 6 mm; S2, the soaked mango slices were crushed into pulp, 1 wt% pectin was added to the pulp, and the mixture was cast into a silica gel mold with a size of 9 mm×4 mm×4 mm in length, width and height, and then demolded to obtain fruit slices, and the fruit slices were vacuum freeze-dried to obtain freeze-dried material. The specific method of vacuum freeze-drying was: pre-freezing at -80°C for 24h, and then freeze-drying at a vacuum degree of 60Pa and a temperature of -40°C until the moisture content was less than 4%, and the pectin was selected from Hefei Bomei Biotechnology, and the item number was GP8471; S3. Mix the mango slices and tea leaves in a mass ratio of 1:0.6 to obtain a mixture. Lay the mixture at the bottom layer of the container, spread a layer of solid sugar on the mixture, and then alternately place 200 g of the mixture and 240 g of solid sugar layer by layer. The top layer is solid sugar. Conduct osmotic treatment at 5°C for 168 h, filter and concentrate to obtain a fruit-flavored syrup with a soluble solid content greater than 70°Brix. During the osmotic treatment, ultrasonic treatment is carried out at 48 h, 60 h, and 80 h. Each time the ultrasonic power is 550 W, the frequency is 40 kHz, and the time is 30 min. The solid sugar is yellow rock sugar with a particle size of 20 mesh, and the tea leaves are Lapsang Souchong black tea; S4. Mix the fruit-flavored syrup and the freeze-dried material, and soak for 1 h. The material-liquid ratio of the freeze-dried material to the fruit-flavored syrup during soaking is 1:2. Freeze at -40°C for 2 h to obtain the core material, and store it at 0°C for standby; S5. Mix 46% white granulated sugar, 50% glucose syrup, 1% sorbitol, 0.5% citric acid, 0.5% DL-malic acid, 0.5% modified soy phospholipid, 0.5% maltodextrin, 0.3% vitamin C, 0.5% vegetable oil, and 0.3% edible flavor. Boil them into a sugar solution at 140°C, cool to 75°C, and then pour it into a mold to form a hollow upper shell and a lower shell. The wall thickness of the upper shell and the lower shell is 1 mm. After the upper shell and the lower shell are combined, an oval-shaped cyst is formed. The length of the cyst is 16 mm and the diameter is 8 mm. The modified soy phospholipid is selected from Jiangsu Hanmao Biotechnology Co., Ltd., with the product number 025. The edible flavor is Baihe flavor, and the vegetable oil is linseed oil; S6. Quickly place the core material into the lower half shell at a temperature below 20°C, and then bond the upper half shell and the lower half shell with the sugar solution, and demold to obtain the fruit-flavored sandwich hard candy.

[0038] Example 2: A preparation method of a fruit-flavored sandwich hard candy, comprising the following steps: S1. Use plasma-activated water as the treatment liquid. Cut the mango into mango slices with a thickness of 3 mm, immerse the mango slices in the treatment liquid, and the material-liquid ratio is 1:2. Conduct soaking treatment under ultra-high pressure. The method of ultra-high pressure soaking is: increase the pressure to 500 MPa within 20 s, keep the pressure for 40 min, and then reduce the pressure to atmospheric pressure within 5 s. During the whole process, the cooperative treatment temperature is 30°C. The plasma-activated water is prepared by treating deionized water under the conditions of a voltage of 40 V, a current of 0.7 A, and a jet plasma spraying distance of 6 mm for 60 s; S2. Crush the soaked mango slices into pulp, add pectin accounting for 2 wt% of the mass of the pulp to the pulp, mix well and then pour it into a silicone mold with the specifications of 9 mm×4 mm×4 mm in length, width and height. Then demold to obtain fruit slices, and perform vacuum freeze-drying on the fruit slices to obtain freeze-dried materials. The specific method of vacuum freeze-drying is: pre-freeze at -80°C for 24 h, and then perform freeze-drying at a vacuum degree of 60 Pa and a temperature of -40°C until the moisture content is lower than 4%. The pectin is selected from Hefei Bomei Biotechnology Co., Ltd., and the product number is GP8471; S3. Mix the mango slices and tea leaves in a mass ratio of 1:0.3 to obtain a mixture. Lay the mixture at the bottom layer of the container, spread a layer of solid sugar on the mixture, and then alternately place 200 g of the mixture and 200 g of solid sugar layer by layer. The top layer is solid sugar. Perform osmotic treatment at 3°C for 150 h, filter and concentrate to obtain a fruit-flavored syrup with a soluble solid content greater than 70°Brix. During the osmotic treatment, perform ultrasonic treatment at 48 h, 60 h and 80 h. Each time the ultrasonic power is 500 W, the frequency is 50 kHz, and the time is 20 min. The solid sugar is yellow rock sugar with a particle size of 20 mesh, and the tea leaves are Lapsang Souchong black tea; S4. Mix the fruit-flavored syrup and the freeze-dried materials, and perform soaking treatment for 1 h. When soaking, the material-liquid ratio of the freeze-dried materials to the fruit-flavored syrup is 1:2. Freeze at -40°C for 2 h to obtain core materials, and store them at 0°C for standby; S5. Mix 46% white granulated sugar, 50% glucose syrup, 1% sorbitol, 0.5% citric acid, 0.5% DL-malic acid, 0.5% modified soy phospholipid, 0.5% maltodextrin, 0.3% vitamin C, 0.5% vegetable oil, and 0.3% edible essence, and boil them into a sugar solution at 140°C. After cooling to 75°C, pour it into a mold to form a hollow upper shell and a lower shell. The wall thickness of the upper shell and the lower shell is 1.5 mm. After the upper shell and the lower shell are combined, an oval-shaped cyst is formed. The length of the cyst is 16 mm and the diameter is 8 mm. The modified soy phospholipid is selected from Jiangsu Hanmao Biotechnology Co., Ltd., and the product number is 025. The edible essence is Baihe essence, and the vegetable oil is linseed oil; S6. Quickly place the core materials into the lower half shell at a temperature below 20°C, bond the upper half shell and the lower half shell with the sugar solution, and demold to obtain fruit-flavored sandwich hard candies.

[0039] Example 3: A method for preparing fruit-flavored sandwich hard candies, comprising the following steps: S1. Use the plasma-activated water as the treatment liquid. Cut the mangoes into slices with a thickness of 3 mm, and immerse the mango slices in the treatment liquid. The ratio of material to liquid is 1:2. Immerse and treat under ultra-high pressure. The method of ultra-high pressure immersion is as follows: Raise the pressure to 550 MPa within 20 s, hold the pressure for 35 min, then reduce the pressure to atmospheric pressure within 10 s, and the co-treatment temperature is 35 °C throughout the process. The plasma-activated water is prepared by treating deionized water under the conditions of a voltage of 40 V, a current of 0.7 A, and a jet plasma spraying distance of 6 mm for 60 s. S2. Crush the mango slices treated by immersion into pulp, add pectin accounting for 1.5 wt% of the mass of the pulp, mix well and then pour it into a silicone mold. The specifications of the mold are 9 mm × 4 mm × 4 mm in length, width and height. Then demold to obtain fruit slices, and perform vacuum freeze-drying on the fruit slices to obtain freeze-dried materials. The specific method of vacuum freeze-drying is as follows: Pre-freeze at -80 °C for 24 h, and then freeze-dry at a vacuum degree of 60 Pa and a temperature of -40 °C until the moisture content is lower than 4%. The pectin is selected from Hefei Bomei Biotechnology Co., Ltd., and the product number is GP8471. S3. Mix the mango slices and tea leaves according to a mass ratio of 1:0.4 to obtain a mixture. Lay the mixture at the bottom layer of the container, spread a layer of solid sugar on the mixture, and then alternately place 200 g of the mixture and 220 g of solid sugar layer by layer. The top layer is solid sugar. Perform osmotic treatment at 5 °C for 160 h, filter and concentrate to obtain a fruit-flavored syrup with a soluble solid content greater than 70 °Brix. During the osmotic treatment, ultrasonic treatment is performed at 48 h, 60 h and 80 h. The ultrasonic power is 500 W each time, the frequency is 50 kHz, and the time is 20 min. The solid sugar is yellow rock sugar with a particle size of 20 mesh, and the tea leaves are Lapsang Souchong black tea. S4. Mix the fruit-flavored syrup and the freeze-dried materials, soak and treat for 1 h. The ratio of material to liquid of the freeze-dried materials to the fruit-flavored syrup during soaking is 1:2. Freeze at -40 °C for 2 h to obtain the core material, and store it at 0 °C for standby. S5. Mix 46% white granulated sugar, 50% glucose syrup, 1% sorbitol, 0.5% citric acid, 0.5% DL-malic acid, 0.5% modified soy phospholipid, 0.5% maltodextrin, 0.3% vitamin C, 0.5% vegetable oil, and 0.3% edible essence, and boil them into a sugar solution at 140 °C. After cooling to 75 °C, pour it into a mold to form a hollow upper shell and a lower shell. The wall thickness of the upper shell and the lower shell is 1.5 mm. After the upper shell and the lower shell are combined, an oval-shaped sac body is formed. The length of the sac body is 16 mm and the diameter is 8 mm. The modified soy phospholipid is selected from Jiangsu Hanmao Biotechnology Co., Ltd., and the product number is 025. The edible essence is Baihe essence, and the vegetable oil is linseed oil. S6. Quickly place the core material into the lower half shell at a temperature below 20°C, bond the upper half shell and the lower half shell with sugar solution, and demold to obtain a fruit - flavored hard candy with a sandwich filling.

[0040] Example 4: A method for preparing a fruit - flavored hard candy with a sandwich filling, comprising the following steps: S1. Use plasma - activated water as the treatment liquid. Cut mangoes into mango slices with a thickness of 3 mm, immerse the mango slices in the treatment liquid, with a material - liquid ratio of 1:2, and soak and treat under ultra - high pressure. The method of ultra - high - pressure soaking is as follows: Increase the pressure to 500 MPa within 20 s, keep the pressure for 40 min, then decrease the pressure to atmospheric pressure within 5 s, and the co - treatment temperature is 30°C throughout the process. The plasma - activated water is prepared by treating deionized water under the conditions of a voltage of 40 V, a current of 0.7 A, and a jet plasma spraying distance of 6 mm for 60 s. S2. Crush the soaked mango slices into fruit pulp, add pectin accounting for 2 wt% of the mass of the fruit pulp to the fruit pulp, mix well, then pour it into a silicone mold with a specification of 9 mm×4 mm×4 mm in length, width, and height, and then demold to obtain fruit slices. Vacuum freeze - dry the fruit slices to obtain freeze - dried materials. The specific method of vacuum freeze - drying is as follows: Pre - freeze at - 80°C for 24 h, and then freeze - dry at a vacuum degree of 60 Pa and a temperature of - 40°C until the moisture content is less than 4%. The pectin is selected from Hefei Bomei Biotechnology Co., Ltd., and the product number is GP8471. S3. Mix apple slices, strawberry slices, and mango slices in a mass ratio of 1:1:1, and then mix the fruit slices and tea in a mass ratio of 1:0.3 to obtain a mixture. Lay the mixture at the bottom layer of the container, spread a layer of solid sugar on the mixture, and then alternately place 200 g of the mixture and 200 g of solid sugar layer by layer. The top layer is solid sugar. Perform osmotic treatment at 3°C for 150 h, filter and concentrate to obtain a fruit - flavored syrup with a soluble solid content greater than 70°Brix. During the osmotic treatment, ultrasonic treatment is performed at 48 h, 60 h, and 80 h, with an ultrasonic power of 500 W, a frequency of 50 kHz, and a time of 20 min each. The solid sugar is yellow rock sugar with a particle size of 20 mesh, and the tea is Lapsang Souchong black tea. S4. Mix the fruit - flavored syrup and the freeze - dried materials, soak and treat for 1 h. When soaking, the material - liquid ratio of the freeze - dried materials and the fruit - flavored syrup is 1:2, and freeze at - 40°C for 2 h to obtain the core material, which is stored at 0°C for standby. S5. Mix 46% white granulated sugar, 50% glucose syrup, 1% sorbitol, 0.5% citric acid, 0.5% DL-malic acid, 0.5% modified soy lecithin, 0.5% maltodextrin, 0.3% vitamin C, 0.5% vegetable oil, and 0.3% edible flavor. Boil the mixture into a sugar solution at 140°C, cool it to 75°C, and then pour it into a mold to form a hollow upper shell and a lower shell. The wall thickness of the upper and lower shells is 1.5 mm. After the upper and lower shells are combined, an oval-shaped sac-like body is formed. The length of the sac-like body is 16 mm and the diameter is 8 mm. The modified soy lecithin is selected from Jiangsu Hanmao Biotechnology Co., Ltd., with the product number 025. The edible flavor is Baihe Flavor, and the vegetable oil is linseed oil. S6. At a temperature below 20°C, quickly place the core material into the lower half shell, bond the upper half shell and the lower half shell with the sugar solution, and then demold to obtain a fruit-flavored hard candy with a filling.

[0041] Example 5: A method for preparing a fruit-flavored hard candy with a filling, comprising the following steps: S1. Use plasma-activated water as the treatment liquid. Cut apples into apple slices with a thickness of 3 mm and strawberries into strawberry slices with a thickness of 3 mm. Immerse apple slices and strawberry slices with a mass ratio of 1:1:1 into the treatment liquid, with a material-liquid ratio of 1:2, and perform soaking treatment under ultra-high pressure. The method of ultra-high pressure soaking is as follows: Increase the pressure to 500 MPa within 20 s, keep the pressure for 40 min, and then reduce the pressure to atmospheric pressure within 5 s. The co-treatment temperature is 30°C throughout the process. The plasma-activated water is prepared by treating deionized water for 60 s under the conditions of a voltage of 40 V, a current of 0.7 A, and a jet plasma spraying distance of 6 mm. S2. Crush the soaked apple slices and strawberry slices into fruit pulp, add 2 wt% pectin based on the mass of the fruit pulp to the fruit pulp, mix well and pour it into a silicone mold with a specification of 9 mm×4 mm×4 mm in length, width, and height, and then demold to obtain fruit slices. Vacuum freeze-dry the fruit slices to obtain freeze-dried materials. The specific method of vacuum freeze-drying is as follows: Pre-freeze at -80°C for 24 h, and then freeze-dry at a vacuum degree of 60 Pa and a temperature of -40°C until the moisture content is less than 4%. The pectin is selected from Hefei Bomei Biotechnology Co., Ltd., with the product number GP8471. S3. Cut the mangoes into slices with a thickness of 3 mm, then mix the mango slices with tea leaves at a mass ratio of 1:0.3 to obtain a mixture. Lay the mixture at the bottom layer of the container, spread a layer of solid sugar on the mixture, and then alternately stack 200 g of the mixture and 200 g of solid sugar layer by layer. The top layer is solid sugar. Perform osmotic treatment at 3°C for 150 h, filter and concentrate to obtain a fruit-flavored syrup with a soluble solid content greater than 70 °Brix. During the osmotic treatment, ultrasonic treatment is carried out at 48 h, 60 h, and 80 h, with an ultrasonic power of 500 W, a frequency of 50 kHz, and a time of 20 min each. The solid sugar is yellow rock sugar with a particle size of 20 mesh, and the tea leaves are Lapsang Souchong black tea; S4. Mix the fruit-flavored syrup and the freeze-dried material, and soak for 1 h. The material-liquid ratio of the freeze-dried material to the fruit-flavored syrup during soaking is 1:2. Freeze at -40°C for 2 h to obtain the core material, and store it at 0°C for standby; S5. Mix 46% white granulated sugar, 50% glucose syrup, 1% sorbitol, 0.5% citric acid, 0.5% DL-malic acid, 0.5% modified soy phospholipid, 0.5% maltodextrin, 0.3% vitamin C, 0.5% vegetable oil, and 0.3% edible flavor. After mixing, boil into a sugar solution at 140°C. After cooling to 75°C, pour it into a mold to form a hollow upper shell and a lower shell. The wall thickness of the upper shell and the lower shell is 1.5 mm. After the upper shell and the lower shell are combined, an oval-shaped capsule is formed. The length of the capsule is 16 mm and the diameter is 8 mm. The modified soy phospholipid is selected from Jiangsu Hanmao Biotechnology Co., Ltd., with the product number 025. The edible flavor is Baihe flavor, and the vegetable oil is linseed oil; S6. At a temperature below 20°C, quickly place the core material into the lower half shell, bond the upper half shell and the lower half shell with the sugar solution, and demold to obtain the fruit-flavored hard candy with a filling.

[0042] Example 6: A method for preparing a fruit-flavored hard candy with a filling, which is different from Example 5 in that tartaric acid and β-cyclodextrin are also added to the treatment liquid. The mass ratio of plasma-activated water, tartaric acid, and β-cyclodextrin is 1:0.075:0.04.

[0043] Example 7: A method for preparing a fruit-flavored hard candy with a filling, which is different from Example 5 in that tartaric acid and β-cyclodextrin are also added to the treatment liquid. The mass ratio of plasma-activated water, tartaric acid, and β-cyclodextrin is 1:0.05:0.02.

[0044] Example 8: A method for preparing a fruit-flavored hard candy with a filling, which is different from Example 6 in that tartaric acid is added to the treatment liquid. The mass ratio of plasma-activated water and tartaric acid is 1:0.115.

[0045] Example 9: A method for preparing a fruit - flavored hard candy with a sandwich filling. The difference from Example 6 is that β - cyclodextrin is added to the treatment liquid, and the mass ratio of plasma - activated water to β - cyclodextrin is 1:0.04.

[0046] Example 10: A method for preparing a fruit - flavored hard candy with a sandwich filling. The difference from Example 6 is that a glue solution is applied to the inner walls and edges of the upper shell and the lower shell, and the thickness of the applied glue solution is 0.5 mm. The preparation method of the glue solution is as follows: Filter the blueberry fermented wine residue to remove the wine juice, boil it to 100 °C and concentrate it. After cooling, it is ultrafinely pulverized and sieved through an 80 - mesh sieve to obtain the wine residue powder. The blueberry fermented wine residue is selected from a certain blueberry fermentation winery, and its basic composition is shown in Table 1; Add 60 g of guar gum to water, stir and dissolve it to obtain a solution with a concentration of 1.5 wt%. Then add honey, ginger oleoresin and the wine residue powder, and stir evenly to prepare the glue solution. The mass ratio of guar gum to honey, ginger oleoresin, and wine residue powder is 1:5:0.6:0.4.

[0047] Table 1 Basic composition of blueberry fermented wine residue Ingredient Moisture Ash Protein Fat Dietary Fiber Carbohydrate wt / % 78.5 0.51 4.02 0.62 15.54 0.81 Example 11: A method for preparing a fruit - flavored hard candy with a sandwich filling. The difference from Example 6 is that a glue solution is applied to the inner walls and edges of the upper shell and the lower shell, and the thickness of the applied glue solution is 0.3 mm. The preparation method of the glue solution is as follows: Filter the blueberry fermented wine residue to remove the wine juice, boil it to 100 °C and concentrate it. After cooling, it is ultrafinely pulverized and sieved through an 80 - mesh sieve to obtain the wine residue powder. The blueberry fermented wine residue is selected from a certain blueberry fermentation winery, and its basic composition is shown in Table 1; Add 60 g of guar gum to water, stir and dissolve it to obtain a solution with a concentration of 1 wt%. Then add honey, ginger oleoresin and the wine residue powder, and stir evenly to prepare the glue solution. The mass ratio of guar gum to honey, ginger oleoresin, and wine residue powder is 1:2:0.4:0.2.

[0048] Example 12: A method for preparing a fruit - flavored hard candy with a sandwich filling. The difference from Example 10 is that a glue solution is applied to the inner walls and edges of the upper shell and the lower shell, and the thickness of the applied glue solution is 0.5 mm. The preparation method of the glue solution is as follows: Add 60 g of guar gum to water, stir and dissolve it to obtain a solution with a concentration of 1.5 wt%. Then add honey, ginger oleoresin, and stir evenly to prepare the glue solution. The mass ratio of guar gum to honey, ginger oleoresin is 1:5:0.6.

[0049] Example 13: A method for preparing a fruit - flavored hard candy with a sandwich filling. The difference from Example 10 is that a glue solution is applied to the inner walls and edges of the upper shell and the lower shell, and the thickness of the applied glue solution is 0.5 mm. The preparation method of the glue solution is as follows: 60 g of guar gum was added to water. After stirring and dissolving, a solution with a concentration of 1.5 wt% was obtained. Honey was added and stirred evenly to prepare a gum solution. The mass ratio of guar gum to honey was 1:5.

[0050] Comparative Example Comparative Example 1: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that the mango slices were not soaked in the treatment liquid and were not subjected to ultra - high pressure treatment.

[0051] Comparative Example 2: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that when soaked in the treatment liquid, ultra - high pressure treatment was not used.

[0052] Comparative Example 3: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that deionized water of equal mass was used to replace the plasma - activated water as the treatment liquid, and the mango slices were soaked under ultra - high pressure conditions. The other parameters were the same as those in Example 1.

[0053] Comparative Example 4: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that tea leaves were not added when preparing the fruit - flavored syrup.

[0054] Comparative Example 5: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that the freeze - dried material was not prepared, and only the fruit - flavored syrup was used as the core material. The fruit - flavored syrup was injected into the lower half of the shell, and the upper half of the shell was bonded to the lower half of the shell with sugar solution and then demolded to obtain the fruit - flavored sandwich hard candy. The raw material usage and preparation method of the upper half and the lower half of the shell were the same as those in Example 1.

[0055] Comparative Example 6: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that the fruit - flavored syrup was not prepared, and only the freeze - dried material was used as the core material. The freeze - dried material was placed into the lower half of the shell, and the upper half of the shell was bonded to the lower half of the shell with sugar solution and then demolded to obtain the fruit - flavored sandwich hard candy. The raw material usage and preparation method of the upper half and the lower half of the shell were the same as those in Example 1. Comparative Example 7: A method for preparing a fruit - flavored sandwich hard candy, which is different from Example 1 in that the core material was mango pulp made by crushing mangoes. The mango pulp was injected into the lower half of the shell, and the upper half of the shell was bonded to the lower half of the shell with sugar solution and then demolded to obtain the fruit - flavored sandwich hard candy. The raw material usage and preparation method of the upper half and the lower half of the shell were the same as those in Example 1.

[0056] Performance Detection Test I. Sensory Detection of Freeze - Dried Material Twelve members of the sensory evaluation panel were selected to conduct sensory evaluation on the freeze - dried materials prepared in Examples 1 - 9 and Comparative Examples 1 - 3. The sensory parameters included color, taste, and appearance. The specific evaluation criteria are shown in Table 2. The average value of the scores of 12 people was taken for each test result, and the test results are shown in Table 3.

[0057] Table 2 Sensory Evaluation Criteria for Freeze-Dried Materials Table 3 Sensory Evaluation Results for Freeze-Dried Materials It can be seen from the sensory evaluation criteria in Table 2 and the sensory evaluation data in Table 3 that in Examples 1-5, plasma-activated water was used to treat fruit slices under the action of ultra-high pressure, and then they were crushed into fruit pulp and cast into fruit slices. Through sensory evaluation, it can be seen that the fruit slices thus produced have relatively uniform and consistent colors, good gloss, unique flavors and textures, and plump shapes.

[0058] Compared with Example 5, tartaric acid and β-cyclodextrin were also added to the treatment liquid in Examples 6 and 7. It can be seen from the sensory evaluation results in Table 3 that the fruit slices produced in Examples 6 and 7 have better shapes and colors, indicating that tartaric acid and β-cyclodextrin can improve the shape conditions of the freeze-dried materials and enhance the sensory quality.

[0059] Compared with Example 6, in Example 8, tartaric acid was used to equivalently replace β-cyclodextrin. It can be seen from the sensory evaluation data in Table 3 that the external sensory evaluation score of the produced freeze-dried materials decreased slightly; compared with Example 6, in Example 9, only β-cyclodextrin was added to the treatment liquid. As shown in Table 3, the scores of the color, shape, taste, etc. of the freeze-dried materials were all affected.

[0060] Compared with Example 1, in Comparative Example 1, the mango slices were not soaked in the treatment liquid under ultra-high pressure. It can be seen that the color score of the produced freeze-dried materials decreased significantly; compared with Example 1, in Comparative Example 2, only the soaking treatment with the treatment liquid was used, and ultra-high pressure was not used during soaking. It can be seen that the sensory score of the freeze-dried materials decreased slightly, but the score was higher than that of Comparative Example 1. In Comparative Example 3, deionized water was used as the treatment liquid for ultra-high pressure soaking. The sensory evaluation such as the color of the freeze-dried materials produced in Comparative Example 3 decreased, indicating that using plasma-activated water in combination with ultra-high pressure to treat fruit slices, then crushing them into fruit pulp, casting, and freeze-drying can produce freeze-dried materials with good colors, tastes and shapes, and thus can obtain better textures and appearances.

[0061] II. Detection of Fruit-Flavored Hard Candies with Fillings 1. Sensory Evaluation Detection: The produced hard candies with fillings were evaluated by 10 sensory evaluation panelists from aspects such as texture, morphology, color, flavor, and texture. The scoring method was used, and the average score of the 10 people's evaluations was taken for each sensory score. According to the characteristics of the hard candies themselves, their sensory evaluation criteria were formulated, and the specific details are shown in Table 4.

[0062] 2. Storage conditions of the sandwich candies: Take 1000 sandwich candies made in each example and comparative example, and store them in an environment with a temperature of 25°C, a humidity of 50%, and a light intensity of 30% for 1 month. Then count the number of sandwich hard candies showing quality problems, such as syrup leakage from the upper and lower shells and cracks in the joint seams between the upper and lower shells. Then, refer to GB 4789.2-2016 "Determination of total number of colonies in food microbiological examination" to detect the total number of colonies, and refer to GB 4789.15-2016 "Enumeration of molds and yeasts in food microbiological examination" to detect the mold content.

[0063] Table 4 Sensory evaluation criteria for fruit-flavored sandwich hard candies Table 5 Test results of fruit-flavored sandwich candies Continued Table 5 Combined with the sensory evaluation criteria in Table 4 and the sensory evaluation results in Table 5, it can be seen that for the sandwich candies made with different fruit slices and different fruit-flavored syrups as the core materials in Examples 1-5, the sweetness is pure, the taste is fresh, there is no bad taste, and the hardness of the sugar body is moderate, not sticky to the teeth, with a high sensory evaluation. Moreover, after freeze-drying the fruit slices and mixing them with the fruit-flavored syrup and then freezing, and putting them into the cavity formed by the upper and lower shells, as the temperature changes, the frozen fruit-flavored syrup continuously melts. When the upper and lower shells are bitten, the core materials, namely the freeze-dried materials and the fruit-flavored syrup, are exposed. The flowing fruit-flavored syrup brings a sweet taste, and the freeze-dried materials bring a more abundant chewing texture. Moreover, the core materials are not prone to leakage and have a long storage period.

[0064] Compared with Example 5, tartaric acid and β-cyclodextrin are also added to the treatment liquid in Examples 6 and 7. It can be seen that the sensory evaluation scores of the sandwich hard candies made in Examples 6 and 7 are not much different from those in Example 5, and the total number of colonies after long-term storage has decreased, and the storage period has been extended. Similarly, the sensory evaluation results of the sandwich hard candies prepared in Examples 8 and 9 are similar to those in Example 5, but their total number of colonies has slightly increased, indicating that tartaric acid and β-cyclodextrin can improve the storage period of the candies to a certain extent.

[0065] Compared with Example 6, in Example 10 and Example 11, a glue solution containing components such as guar gum, honey, and ginger oleoresin was also applied to the inner walls and edges of the upper half shell and the lower half shell. It can be seen that the number of leakages of the made sandwich candies decreased, and the number of connections at the joints decreased, indicating that the glue solution can further protect against the leakage of the fruit - flavored syrup in the core material, thereby reducing the erosion of the outer sugar body and further reducing the impact on the shelf life, and the sensory evaluation score is higher.

[0066] The glue solution in Example 12 does not contain the lees powder made from blueberry fermented lees. Compared with Example 10, the number of leakages of the hard candies made in Example 12 increased, and the total number of colonies increased after one - month storage, and the storage period may become shorter; the glue solution in Example 13 does not contain lees powder and ginger oleoresin, and it can be seen that the anti - leakage effect of the made candies is slightly weakened.

[0067] Compared with Example 1, in Comparative Example 1, the treatment solution and ultra - high pressure were not used for treatment. In Comparative Example 2, only the treatment solution was used for soaking without using ultra - high pressure treatment. In Comparative Example 3, deionized water was used to replace the plasma - activated water. It can be seen that the taste of the sandwich candies prepared in Comparative Examples 1 - 3 decreased slightly, the number of permeated candies changed little compared with Example 1, but the total number of colonies increased significantly after 1 - month storage, indicating that both the plasma - activated water and ultra - high pressure treatment can improve the antibacterial ability and extend the storage period.

[0068] Compared with Example 1, in Comparative Example 4, tea leaves were not added when preparing the fruit - flavored syrup. It can be seen that the initial evaluation of the candies changed little, the number of leakages changed little, but its ability to prevent the generation of colonies decreased.

[0069] In Comparative Example 5, a compound fruit - flavored syrup was used as the core material and injected into the upper half shell and the lower half shell. Compared with Example 1, the number of leaking candies increased significantly, and the number of colonies increased significantly after one - month storage.

[0070] In Comparative Example 6, freeze - dried material was used as the core material and fruit - flavored syrup was not used. It can be seen that the number of leaking candies is zero, and the number of cracks generated is similar to that in Example 1, but its taste evaluation decreased.

[0071] In Comparative Example 7, mango juice was used as the core material. Compared with Example 1, the number of leaking candies increased, and the total number of colonies increased significantly.

[0072] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing a fruit - flavored hard candy with a filling, characterized in that, The steps include: Using plasma-activated water as the treatment liquid, dipping the sliced fruits into the treatment liquid, and soaking them under ultra-high pressure conditions; Crushing the soaked sliced fruits into fruit pulp, adding 1-2 wt% pectin based on the mass of the fruit pulp, mixing well, pouring it into a mold, and performing vacuum freeze-drying to obtain a freeze-dried material; Mixing the sliced fruits with tea leaves to obtain a mixture, placing the mixture and solid sugar layer by layer alternately, performing osmotic treatment at 3-5 °C for 150-168 h, filtering and concentrating to obtain a fruit-flavored syrup with a soluble solid content greater than 70 °Brix. The dosage of solid sugar is 100-120% of the dosage of the mixture, and the mass ratio of sliced fruits to tea leaves is 1:0.3-0.6; Mixing the fruit-flavored syrup and the freeze-dried material, performing soaking treatment, taking out the freeze-dried material, and freezing to obtain a core material; Mixing white granulated sugar, glucose syrup, sorbitol, citric acid, DL-malic acid, modified soy phospholipid, maltodextrin, vitamin C, vegetable oil, and edible essence, boiling them into a sugar solution, and casting it into a hollow upper half shell and a lower half shell when cooled to 75-85 °C; Placing the core material in the lower half shell, bonding the upper half shell and the lower half shell, and demolding to obtain a fruit-flavored sandwich hard candy.

2. The preparation method of the fruit-flavored hard candy with a sandwich as claimed in claim 1, characterized in that: Tartaric acid and β-cyclodextrin are also added to the treatment liquid, and the mass ratio of plasma-activated water, tartaric acid, and β-cyclodextrin is 1:0.05-0.075:0.02-0.

04.

3. The preparation method of the fruit-flavored hard candy with a sandwich as claimed in claim 1, wherein: Before putting the core material into the upper shell and the lower shell, the following pre-treatment is carried out: Evenly brushing a glue solution on the inner walls and edges of the upper shell and the lower shell. The glue solution contains guar gum, honey, and ginger oleoresin with a mass ratio of 1:2-5:0.4-0.

6.

4. The preparation method of the fruit-flavored hard candy with a sandwich as claimed in claim 3, characterized in that: The glue solution is prepared by the following method: Filtering, boiling, concentrating, and pulverizing blueberry fermented wine residue to obtain wine residue powder; Adding guar gum to water, stirring and dissolving it to obtain a solution with a concentration of 1-1.5 wt%, adding honey, ginger oleoresin, and wine residue powder, and stirring evenly to obtain the glue solution. The mass ratio of wine residue powder to guar gum is 1:0.2-0.

4.

5. The preparation method of the fruit-flavored hard candy with a sandwich according to claim 3, characterized in that: The brushing thickness of the glue solution is 0.3-0.5 mm.

6. The preparation method of the fruit-flavored hard candy with a sandwich according to claim 1, characterized in that: The raw material percentages of the upper shell and the lower shell are as follows: 50-55% glucose syrup, 1-1.2% sorbitol, 0.5-0.6% citric acid, 0.4-0.5% DL-malic acid, 0.5-0.7% modified soy phospholipid, 0.4-0.5% maltodextrin, 0.2-0.3% vitamin C, 0.3-0.5% vegetable oil, and 0.1-0.3% edible essence, and the balance is white granulated sugar.

7. The preparation method of the fruit - flavored hard candy with a sandwich according to claim 6, characterized in that: The wall thickness of the upper half shell and the lower half shell is 1-1.5 mm.

8. The preparation method of the fruit-flavored hard candy with a sandwich as claimed in claim 1, wherein: During the osmotic treatment, ultrasonic treatment is carried out at osmotic times of 48 h, 60 h, and 84 h respectively. The ultrasonic frequency is 40-50 kHz, the power is 500-550 W, and the ultrasonic time for each time is 20-30 min.

9. The preparation method of the fruit-flavored hard candy with a sandwich as claimed in claim 1, wherein: The method of soaking under ultra-high pressure conditions is: increasing the pressure to 500-600 MPa within 20-30 s, maintaining the pressure for 30-40 min, and then reducing the pressure to atmospheric pressure within 5-10 s. The temperature during ultra-high pressure soaking is 30-40 °C.

10. A fruit - flavored hard candy with a filling, characterized in that: Prepared by the preparation method according to any one of claims 1-9.

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