Fresh gastrodia elata preserved fruit and preparation method thereof

Abstract

The invention discloses fresh rhizoma gastrodiae preserved fruits and a preparation method thereof. The preparation method comprises the following steps: (1) pretreatment; (2) freeze thawing treatment; (3) steaming with honey; (4) performing ultrahigh-pressure honey processing and sugar permeation treatment; (5) coating treatment; (6) drying at variable temperature; and (7) packaging and sterilizing. According to the method disclosed by the invention, citric acid color protection is combined with coating liquid treatment, so that browning is effectively inhibited, and the color and luster preservation period is prolonged; a freeze-thawing combined ultrahigh pressure honey processing synergistic process is innovatively adopted, so that the sugar soaking time is greatly shortened, the production efficiency is improved, efficient and uniform sugar soaking can be realized, the sugar distribution is uniform, and the taste is better; the variable-temperature drying process reduces loss of heat-sensitive nutritional ingredients (such as gastrodin), the unique flavor of the fresh gastrodia elata is reserved to the maximum extent, and the honey gradually permeates and is fused with the flavor of the gastrodia elata to form a composite flavor, so that the product has both leisure flavor and health value.

Description

Technical Field

[0001] This invention relates to the field of food processing, specifically to a fresh Gastrodia elata preserve and its preparation method. Background Technology

[0002] Gastrodia elata is a plant of the Orchidaceae family (Gastrodia elata is a type of orchid). Gastrodia elata Bl. Gastrodia elata Bl. Gastro The dried tuber of the plant is sweet in taste and neutral in nature. It has the effects of calming wind and stopping spasms, suppressing liver yang, and dispelling wind and unblocking meridians. It is used to enhance intelligence and brain function, calm the nerves and induce sleep, improve immunity, relieve pain and lower blood pressure, and has anticonvulsant and anti-epileptic effects. It has important value in clinical research and the development of health food.

[0003] As living standards continue to improve, people are paying more and more attention to health and wellness and dietary supplements. The concept of food and medicine sharing the same origin is highly valued, and health foods or health supplements with fresh gastrodia elata as the main ingredient are extremely scarce.

[0004] In the food processing industry, candied fruit, as a traditional snack food, has had its preparation methods developed for many years, but there are still many problems in actual production and product quality: First, poor color protection and prominent browning problems; Second, low sugar soaking efficiency and uneven sugar distribution; Third, high-temperature processing leads to a large loss of nutrients; Fourth, the texture is either too hard or too soft, lacking a sense of layering. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing fresh Gastrodia elata candied fruit. This method solves the problems of easy browning, low sugar soaking efficiency, large loss of nutrients, poor taste and short shelf life in traditional Gastrodia elata processing through multi-process synergistic innovation.

[0006] This invention is achieved through the following technical solution: A method for preparing fresh Gastrodia elata preserves includes the following steps: (1) Pretreatment: Peel and slice the fresh Gastrodia elata, and soak it in citric acid solution; (2) Freeze-thaw treatment: The soaked fresh Gastrodia elata slices are subjected to freeze-thaw treatment; (3) Honey steaming treatment: Place the frozen and thawed fresh Gastrodia elata slices in a honey solution for honey steaming treatment; (4) Ultra-high pressure honey-sugar infiltration treatment: Fresh gastrodia elata slices that have been steamed with honey are placed in a honey solution for ultra-high pressure honey-sugar infiltration treatment; (5) Coating treatment: The fresh Gastrodia elata slices obtained in step (4) are placed in the coating solution for coating treatment; (6) Variable temperature drying: The fresh Gastrodia elata slices after being coated are dried at a variable temperature until the moisture content is 20%-25%; (7) Packaging and sterilization: The dried fresh Gastrodia elata slices are vacuum packaged and sterilized by ultra-high pressure combined with medium temperature sterilization method to obtain fresh Gastrodia elata candied fruit.

[0007] The fresh Gastrodia elata is selected in the present application, and from the perspective of nutrition, the effective components of the fresh Gastrodia elata are retained to the maximum extent. Compared with the processed Gastrodia elata, the fresh Gastrodia elata has higher nutritional value and more obvious efficacy.

[0008] Preferably, in step (1), the thickness of the Gastrodia elata slice is 3-5 mm.

[0009] Preferably, in step (1), the mass concentration of the citric acid solution is 0.1-0.3%, and the soaking time is 10-15 min.

[0010] The present application innovatively combines freeze-thaw treatment and ultra-high pressure honey-making sugar infiltration process. During the freeze-thaw process, the formation and melting of ice crystals in the cells of Gastrodia elata are promoted at the micro level, and the Gastrodia elata tissue becomes loose and porous. Subsequently, the ultra-high pressure honey-making sugar infiltration process is used, and the ultra-high pressure environment increases the driving force for the sugar solution to infiltrate from the surface to the inside, so that the sugar solution rapidly and uniformly infiltrates into the Gastrodia elata. Compared with traditional sugar immersion, the sugar infiltration time is greatly shortened, and the sugar solution is more uniformly distributed, avoiding the problems of local oversweetness or non-infiltration.

[0011] Preferably, in step (2), the freeze-thaw treatment is to freeze the soaked fresh Gastrodia elata slice at-25 to-30℃ for 3-4 h, and then thaw it at 4℃ for 10-20 min.

[0012] Preferably, in step (3), the mass concentration of the honey solution is 15%-20%, and the honey steaming treatment time is 30-35 min.

[0013] Preferably, in step (4), the mass concentration of the honey solution is 25%-30%, and the pressure of the ultra-high pressure honey-making sugar infiltration treatment is 200-400 MPa, and the time is 10-15 min.

[0014] The use of a lower concentration (15%-20%) during the honey steaming stage in the present application is beneficial to the uniform entry of honey into the tissue and prevents the rapid dehydration of surface cells caused by excessively high osmotic pressure. The higher concentration (25%-30%) during the ultra-high pressure honey-making stage can meet the sensory and texture requirements. The use of ultra-high pressure is used to increase the penetration driving force and overcome the diffusion resistance caused by high viscosity, effectively promoting the penetration of honey into the inside of the Gastrodia elata tissue.

[0015] In the present application, the Gastrodia elata slice after honey steaming is soaked in a coating liquid, which can form a transparent film on the surface of the Gastrodia elata. On the one hand, it can block the contact between oxygen in the air and the components of the Gastrodia elata, delay the secondary browning in subsequent processing and storage, and prolong the shelf life. On the other hand, it can lock the internal moisture of the Gastrodia elata, avoid the hard texture during storage, reduce the loss of honey sugar, and improve the softness and flavor level of the preserved fruit.

[0016] The coating solution used in this invention can be prepared by the following method: Tea polyphenols were dissolved in water to prepare a tea polyphenol solution; β-cyclodextrin was dissolved in water to prepare a β-cyclodextrin solution. A beaker containing the β-cyclodextrin solution was placed on a magnetic stirrer and stirred at medium-high speed at a constant temperature of 60°C until fully dissolved. The tea polyphenol solution was added dropwise to the continuously stirred β-cyclodextrin solution. After the addition was complete, the entire reaction system was refrigerated to allow the inclusion complex to fully form and crystallize. The refrigerated mixture was filtered, the solid was collected, dried in an oven, and then ground into a fine powder to obtain the tea polyphenol-β-cyclodextrin inclusion complex. Sodium alginate was weighed and dissolved in water, and stirred evenly to prepare a sodium alginate solution. The sodium alginate solution was placed on a magnetic stirrer and the temperature was set to 60°C. The tea polyphenol-β-cyclodextrin inclusion complex was slowly added to the sodium alginate solution. During this process, continuous stirring was required to ensure that it was evenly dispersed, and finally the inclusion complex coating solution was obtained.

[0017] Sodium alginate, a natural polysaccharide, possesses excellent film-forming properties, stability, and safety. The coating has no toxic side effects and can reduce bacterial contamination of food, effectively inhibiting the growth and reproduction of microorganisms on the coating surface. This reduces desiccation and juice loss during food storage, extending shelf life and thus maintaining food quality and taste. Tea polyphenols are natural antioxidants with certain antibacterial properties, maximizing the preservation of the color and flavor of candied fruit. β-cyclodextrin coating enhances the thermal stability and antioxidant stability of tea polyphenols. Encapsulation technology masks potential off-flavors and achieves a sustained-release effect of tea polyphenols, allowing them to continue to exert their effects throughout the product's shelf life.

[0018] Preferably, in step (5), the coating solution is made of sodium alginate and tea polyphenol-β-cyclodextrin inclusion complex, wherein the mass concentration of sodium alginate is 1.0~1.2%, the amount of tea polyphenol-β-cyclodextrin inclusion complex added is 1~2%, the mass ratio of tea polyphenol to β-cyclodextrin is 1:8~1:10, and the coating treatment time is 30-40 s.

[0019] Preferably, in step (6), the variable temperature drying involves drying the fresh Gastrodia elata slices after filming at 50-55℃ for 1-2 hours, at 55-60℃ for 1-2 hours, and at 50-55℃ until the moisture content is 20%-25%.

[0020] This invention employs a variable-temperature drying process to avoid the thermal decomposition of nutrients (such as gastrodin and polysaccharides) caused by high-temperature drying alone. Starting at a low temperature allows for slow evaporation of surface moisture, reducing the loss of internal nutrients due to moisture migration; the intermediate 60℃ stage accelerates moisture evaporation, shortening the total processing time; and finally, drying at 55℃ ensures that the finished product's moisture content remains stable at 20%-25% (this moisture content guarantees the soft and chewy texture of the candied fruit while inhibiting microbial growth), maximizing the preservation of the nutritional activity and natural flavor of fresh gastrodia elata.

[0021] This invention employs a combined ultra-high pressure and medium-temperature sterilization process. Ultra-high pressure sterilization can destroy the cell membrane structure of microorganisms, killing pathogenic bacteria, yeasts, molds, and spoilage bacteria. Medium-temperature sterilization can assist in the inactivation of heat-resistant microorganisms. With the synergistic effect of the two, the shelf life of candied fruit can be extended without the addition of chemical preservatives, and the damage to color and taste caused by high-temperature sterilization can be avoided.

[0022] Preferably, in step (7), the conditions for ultra-high pressure combined with medium temperature sterilization are: pressure 400-500MPa, temperature 40-60℃, and pressure holding time 15-20 min.

[0023] The present invention also provides a fresh Gastrodia elata candied fruit, which is prepared by the above-described preparation method.

[0024] Compared with the prior art, the present invention has the following advantages: This invention addresses the problems of poor color retention, low sugar extraction efficiency, significant nutrient loss, unpleasant taste, short shelf life, and low production efficiency in existing candied fruit preparation processes. Through multi-process synergistic innovation, the following technical effects are achieved: Citric acid color protection combined with coating solution treatment effectively inhibits browning and extends the color preservation period; the innovative use of a freeze-thaw combined with ultra-high pressure honey extraction process not only significantly shortens the sugar extraction time and improves production efficiency but also achieves efficient and uniform sugar extraction with even sugar distribution and superior taste; the variable-temperature drying process reduces the loss of heat-sensitive nutrients (such as gastrodin) and maximizes the preservation of the unique flavor of Gastrodia elata; the gradual penetration of honey and the fusion of the Gastrodia elata flavor create a complex flavor, giving the product both a leisurely taste and health benefits.

[0025] The process of this invention precisely meets consumers' core needs for "health and low sugar". It relies on the rich bioactive components in fresh Gastrodia elata to endow the candied fruit with unique health care functions, fills the market gap in the health attributes of traditional candied fruit, and perfectly conforms to the modern health consumption trend. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Preparation of the coating solution:

[0028] Dissolve 5g of tea polyphenols in 200ml of water to prepare a tea polyphenol solution; dissolve 40-50g of β-cyclodextrin in 1000ml of water to prepare a β-cyclodextrin solution. Place the beaker containing the β-cyclodextrin solution on a magnetic stirrer and stir at medium-high speed for 30 minutes at a constant temperature of 60℃ to ensure complete dissolution. Place the tea polyphenol solution in a separatory funnel and add it dropwise to the continuously stirred β-cyclodextrin solution at a rate of 1-2 drops per minute. After the addition is complete, refrigerate the entire reaction system for 12 hours to allow the inclusion complex to fully form and crystallize. Filter the refrigerated mixture, collect the solid material, dry it in a 50℃ oven, and then grind it into a fine powder to obtain the tea polyphenol-β-cyclodextrin inclusion complex. Sodium alginate was weighed and dissolved in water, and stirred evenly to prepare a sodium alginate solution. The sodium alginate solution was placed on a magnetic stirrer and the temperature was set to 60°C. The tea polyphenol-β-cyclodextrin inclusion complex was slowly added to the sodium alginate solution. During this process, continuous stirring was required to ensure that it was evenly dispersed, and finally the inclusion complex coating solution was obtained. Example 1:

[0029] A method for preparing fresh Gastrodia elata preserves includes the following steps: (1) Peel the fresh Gastrodia elata, cut it into 4mm pieces, and soak it in citric acid solution for 10 minutes. The mass concentration of the citric acid solution is 0.3%. (2) Take out the soaked fresh Gastrodia elata slices and freeze them in a -30℃ freezer for 3 hours. Thaw the frozen fresh Gastrodia elata slices in a 4℃ freezer for 15 minutes. (3) Place the frozen and thawed fresh Gastrodia elata slices into a honey solution with a mass concentration of 20%, stir, and then steam in a steamer for 30 minutes. (4) The fresh gastrodia elata slices after being steamed with honey were placed in honey with a mass concentration of 30% for ultra-high pressure honey slurry. The pressure of ultra-high pressure honey slurry was 200 MPa and the time was 15 min. (5) Soak the honey-processed fresh Gastrodia elata slices in the coating solution for 30 seconds; the coating solution is made of sodium alginate and tea polyphenol-β-cyclodextrin inclusion complex, wherein the mass concentration of sodium alginate is 1.0%, the amount of tea polyphenol-β-cyclodextrin inclusion complex added is 1.0%, and the mass ratio of tea polyphenol to β-cyclodextrin is 1:10.

[0030] (6) Place the honey-processed fresh Gastrodia elata slices into an electric heating drying oven for variable temperature drying. The temperature is set to 55℃ for 2 hours, then 60℃ for 1 hour, and finally 55℃ until the moisture content is 20%-25%. (7) Vacuum pack the dried fresh Gastrodia elata slices, and sterilize them for 17 minutes using ultra-high pressure (400MPa) combined with low temperature (50℃) after packaging. Example 2:

[0031] A method for preparing fresh Gastrodia elata preserves includes the following steps: (1) Peel the fresh Gastrodia elata, cut it into 3mm pieces, and soak it in a citric acid solution with a concentration of 0.3% for 15 minutes; (2) Take out the soaked fresh Gastrodia elata slices and put them in a -25℃ refrigerator for 4 hours. Thaw the frozen fresh Gastrodia elata slices in a 4℃ refrigerator for 20 minutes. (3) Place the frozen and thawed fresh Gastrodia elata slices into a solution of honey with a mass concentration of 17%, stir, and then steam in a steamer for 30 minutes. (4) The fresh Gastrodia elata slices after being steamed with honey were placed in honey with a mass concentration of 28% for ultra-high pressure honey sizing and sugar infiltration. The pressure of ultra-high pressure honey sizing and sugar infiltration was 400 MPa and the time was 10 min. (5) Soak the honey-processed fresh Gastrodia elata slices in the coating solution for 35 seconds; the coating solution is made of sodium alginate and tea polyphenol-β-cyclodextrin inclusion complex, wherein the mass concentration of sodium alginate is 1.2%, the amount of tea polyphenol-β-cyclodextrin inclusion complex added is 1.5%, and the mass ratio of tea polyphenol to β-cyclodextrin is 1:8. (6) Place the honey-processed fresh Gastrodia elata slices into an electric heating drying oven for variable temperature drying. Set the temperature to 55℃ for 2 hours, then 60℃ for 1 hour, and finally 55℃ until the moisture content is 20%-25%. (7) Vacuum pack the dried fresh Gastrodia elata slices, and sterilize them for 15 minutes using ultra-high pressure (500MPa) combined with low temperature (45℃) after packaging. Example 3:

[0032] A method for preparing fresh Gastrodia elata preserves includes the following steps: (1) Peel the fresh Gastrodia elata, cut it into 5mm pieces, and soak it in a citric acid solution with a concentration of 0.3% for 12 minutes; (2) Take out the soaked fresh Gastrodia elata slices and put them in a -35℃ refrigerator for 2 hours. Thaw the frozen fresh Gastrodia elata slices in a 4℃ refrigerator for 10 minutes. (3) Place the frozen and thawed fresh Gastrodia elata slices into a honey solution with a mass concentration of 15%, stir, and then steam in a steamer for 35 minutes. (4) The fresh gastrodia elata slices after being steamed with honey were placed in honey with a mass concentration of 25% for ultra-high pressure honey sizing and sugar infiltration. The pressure of ultra-high pressure honey sizing and sugar infiltration was 300 MPa and the time was 12 min. (5) Soak the honey-processed fresh Gastrodia elata slices in the coating solution for 40 seconds; the coating solution is made of sodium alginate and tea polyphenol-β-cyclodextrin inclusion complex, wherein the mass concentration of sodium alginate is 1.0%, the amount of tea polyphenol-β-cyclodextrin inclusion complex added is 2%, and the mass ratio of tea polyphenol to β-cyclodextrin is 1:9. (6) Place the honey-processed fresh Gastrodia elata slices into an electric heating drying oven for variable temperature drying. Set the temperature to 55℃ for 1 hour, then 60℃ for 2 hours, and finally 55℃ until the moisture content is 20%-25%. (7) Vacuum pack the dried fresh Gastrodia elata slices, and sterilize them for 20 minutes using ultra-high pressure (500MPa) combined with low temperature (55℃) after packaging.

[0033] Comparative Example 1: The difference from Example 1 is that the fresh Gastrodia elata slices were not soaked in citric acid solution for color protection, but otherwise the same as in Example 1.

[0034] Comparative Example 2: The difference from Example 1 is that freeze-thaw treatment is not performed in step (2), and the rest is the same as in Example 1.

[0035] Comparative Example 3: The difference from Example 1 is that in step (4), the sugar was infiltrated at room temperature and normal pressure for 2 hours, and the honey mass concentration was 30%. The rest is the same as in Example 1.

[0036] Comparative Example 4: The difference from Example 1 is that the coating liquid is not used for coating treatment in step (5), and the rest is the same as Example 1.

[0037] Comparative Example 5: The difference from Example 1 is that the composition of the coating solution added in step (5) is: 500ml water, 5g chitosan (1%), 0.75g glycerol (0.15%), 0.5g vitamin C (0.1%), and 5g edible citric acid (1%). The rest is the same as in Example 1.

[0038] Comparative Example 6: The difference from Example 1 is that the mass concentration of honey in step (3) honey steaming and step (4) honey processing is 30%, and the rest is the same as in Example 1.

[0039] Comparative Example 7: The difference from Example 1 is that in step (6), temperature-controlled drying is not performed. Instead, drying is carried out directly at 60°C until the moisture content is 20%-25%. The rest is the same as in Example 1.

[0040] Comparative Example 8: The difference from Example 1 is that in step (7), ultra-high pressure combined with low temperature sterilization is not performed, and sterilization is performed using a 120°C autoclave. 1. Sensory Indicator Scoring and Standards

[0041] Ten experienced tasters were randomly selected and evaluated on a 100-point scale, assessing the candied fruit products in terms of color, appearance, and taste. The specific scoring criteria are shown in Table 1.

[0042] Table 1 Sensory ratings of fresh Gastrodia elata candied fruit

[0043] 2. Determination of gastrodin and p-hydroxybenzyl alcohol According to the Chinese Pharmacopoeia (2025 edition), high performance liquid chromatography (HPLC) was used to determine the quality of Gastrodia elata candied fruit. A C18 column was used with acetonitrile-0.05% phosphoric acid solution (3:97) as the mobile phase, and the detection wavelength was 220 nm. Extraction was performed according to the method in the pharmacopoeia. The extract was diluted with the mobile phase, shaken well, filtered through a 0.22 μm filter membrane, and the filtrate was collected for analysis. Specific data are shown in Table 2.

[0044] 3. Determination of hardness and chewiness The textural properties of Gastrodia elata were tested using a texture analyzer. Parameters from three parts of the candied Gastrodia elata were measured each time, and the average value was taken. A P / 2N probe was used for measurement. The test conditions were: initial velocity 2.00 mm / s, test velocity 1.00 mm / s, post-test velocity 10.00 mm / s, compression rate 70%, holding time 5 s, and trigger force 5 g. Specific data are shown in Table 2.

[0045] 4. Determination of brightness, total color difference, and browning index. The L* (brightness), a* (redness), and b* (yellowness) of the Gastrodia elata candied fruit were measured using a colorimeter. The total color difference ΔE (browning index BI) was calculated, and the specific data are shown in Table 2. The calculation formula is as follows: .

[0046] 5. Water loss rate = (initial weight - final weight) / initial weight × 100%, see Table 3 for details.

[0047] Table 2 Results of quality determination of Gastrodia elata preserves

[0048] As shown in the table above, Comparative Example 1, which did not use citric acid for color protection, had a significantly higher browning index and total color difference than Example 1, and the contents of gastrodin and p-hydroxybenzyl alcohol were also significantly reduced. This indicates that the addition of citric acid can lower the pH to a certain extent, further inhibiting the activity of polyphenol oxidase (PPO), reducing the oxidative degradation of gastrodin during processing, and decreasing the content of p-hydroxybenzyl alcohol.

[0049] In Comparative Example 2, no freeze-thaw treatment was performed, and no porous structure was formed. Under the same honey-steaming time, compared to freeze-thaw, the honey permeability was lower and the permeation was uneven, resulting in a decline in the sensory quality of the product, increased hardness and chewiness, decreased brightness, and a higher overall color difference than in Example 1.

[0050] In Comparative Example 3, sugar infiltration was performed at room temperature and pressure. The sugar solution infiltration was slow and uneven, requiring a longer time to complete. The active ingredients were more likely to be degraded during the long-term processing, resulting in a lower sensory score, decreased brightness, and higher total color difference and browning index than in Example 1.

[0051] In Comparative Example 4, which was not coated, the total color difference and browning index were higher than those in Example 1, while the contents of gastrodin and p-hydroxybenzyl alcohol were reduced, indicating that coating treatment can effectively block oxygen and reduce oxidative browning and oxidative degradation of active ingredients.

[0052] Comparative Example 5 used chitosan + glycerol + vitamin C + citric acid as the coating solution. Its total color difference and browning index were higher than those of Example 1, while the contents of gastrodin and p-hydroxybenzyl alcohol were lower, and the coating effect was not obvious. This may be because, during the later heating, drying, and sterilization processes, the aldehydes generated from the decomposition of vitamin C may exacerbate browning; simultaneously, the chitosan membrane may experience a decrease in oxygen barrier properties due to molecular chain breakage or structural relaxation. This could make the polyphenols in Gastrodia elata more susceptible to contact with oxygen and potentially lead to non-enzymatic browning, promoting the degradation of active ingredients and the occurrence of browning.

[0053] In Comparative Example 6, 30% high-concentration honey was used in both the honey steaming and honey processing stages. Its brightness was lower than that of Example 1, and its total color difference and browning index were slightly higher. This indicates that the high-concentration sugar solution in the early stage may promote non-enzymatic browning reaction, and the excessively high osmotic pressure caused the cells to dehydrate too quickly. At the same time, the high-concentration sugar promoted non-enzymatic browning such as Maillard reaction, resulting in a decline in sensory quality.

[0054] In Comparative Example 7, a single high-temperature drying method was used instead of variable-temperature drying. The total color difference and browning index were significantly higher than those in Example 1. The contents of gastrodin and p-hydroxybenzyl alcohol were significantly reduced, indicating that continuous high temperature accelerated the degradation of heat-sensitive active ingredients. At the same time, high temperature promoted PPO activity and non-enzymatic browning reaction, resulting in a significant reduction in active ingredients.

[0055] In Comparative Example 8, high-temperature and high-pressure sterilization was used instead of ultra-high pressure combined with medium-temperature sterilization. The content of gastrodin and p-hydroxybenzyl alcohol was the lowest, and the browning index was significantly higher than that of Example 1. This indicates that the high-temperature and high-pressure environment has a strong destructive effect on gastrodin, which not only causes thermal degradation but may also lead to changes in molecular structure and a significant increase in browning.

[0056] Table 3. Quality test results of Gastrodia elata preserves after two months of room temperature storage.

[0057] As can be seen from Table 3, after two months of storage, in Comparative Example 4, which was not coated, the active ingredients were easily exposed to air, and the moisture evaporated easily. As a result, the total color difference, browning index, hardness and water loss rate increased significantly, while the contents of gastrodin and p-hydroxybenzyl alcohol decreased significantly.

Claims

1. A method for preparing fresh Gastrodia elata preserves, characterized in that, Includes the following steps: (1) Pretreatment: Peel and slice the fresh Gastrodia elata, and soak it in citric acid solution; (2) Freeze-thaw treatment: The soaked fresh Gastrodia elata slices are subjected to freeze-thaw treatment; (3) Honey steaming treatment: Place the frozen and thawed fresh Gastrodia elata slices in a honey solution for honey steaming treatment; (4) Ultra-high pressure honey-sugar infiltration treatment: Fresh gastrodia elata slices that have been steamed with honey are placed in a honey solution for ultra-high pressure honey-sugar infiltration treatment; (5) Coating treatment: The fresh Gastrodia elata slices obtained in step (4) are placed in the coating solution for coating treatment; (6) Variable temperature drying: The fresh Gastrodia elata slices after being coated are dried at a variable temperature until the moisture content is 20%-25%; (7) Packaging and sterilization: The dried fresh Gastrodia elata slices are vacuum packaged and sterilized by ultra-high pressure combined with medium temperature sterilization method to obtain fresh Gastrodia elata candied fruit.

2. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (1), the thickness of the fresh Gastrodia elata slices is 3-5 mm.

3. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (1), the mass concentration of the citric acid solution is 0.1~0.3%, and the soaking time is 10-15 min.

4. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (2), the freeze-thaw treatment involves freezing the soaked fresh Gastrodia elata slices at -25~-30℃ for 3-4 hours and then thawing them at 4℃ for 10-20 minutes.

5. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (3), the mass concentration of the honey solution is 15%-20%, and the honey steaming time is 30-35 min.

6. The method for preparing fresh Gastrodia elata preserves according to claim 1, characterized in that: In step (4), the mass concentration of the honey solution is 25%-30%; the pressure of the ultra-high pressure honey syrup treatment is 200-400 MPa, and the time is 10-15 min.

7. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (5), the coating solution is made of sodium alginate and tea polyphenol-β-cyclodextrin inclusion complex, wherein the mass concentration of sodium alginate is 1.0~1.2%, the amount of tea polyphenol-β-cyclodextrin inclusion complex added is 1~2%, the mass ratio of tea polyphenol to β-cyclodextrin is 1:8~1:10, and the coating treatment time is 30-40 s.

8. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (6), the variable temperature drying involves drying the fresh Gastrodia elata slices after filming at 50-55℃ for 1-2 hours, at 55-60℃ for 1-2 hours, and at 50-55℃ until the moisture content is 20%-25%.

9. The method for preparing fresh gastrodia elata preserves according to claim 1, characterized in that: In step (7), the conditions for ultra-high pressure combined with medium temperature sterilization are: pressure 400-500MPa, temperature 40-60℃, and pressure holding time 15-20 min.

10. A type of fresh Gastrodia elata preserve, prepared by the preparation method according to any one of claims 1-9.

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