Preparation method of low-sugar high-fiber compounding enzyme hydrolysis preserved fruits

Abstract

This invention relates to the field of fruit and vegetable deep processing technology, and discloses a method for preparing low-sugar, high-fiber candied fruit using a compound enzymatic hydrolysis system. The method includes the following steps: S1 raw material pretreatment; S2 sugar solution preparation, preparing a sugar solution containing a compound enzymatic hydrolysis system; S3 cooking and infiltration, immersing the pretreated raw materials in the sugar solution containing the compound enzymatic hydrolysis system; S4 post-enzymatic hydrolysis treatment, after enzymatic hydrolysis, heating to deactivate the compound enzymatic hydrolysis system and terminate the enzymatic hydrolysis reaction; S5 secondary cooking and sugar soaking, pouring the raw materials after enzymatic hydrolysis termination along with the sugar solution into a cooking pot; S6 drying and shaping to obtain the low-sugar, high-fiber candied fruit product. By employing a compound enzymatic hydrolysis system of fructosyltransferase and cellulase, combined with a multi-step synergistic approach including raw material pretreatment and cooking enzymatic hydrolysis, the method achieves the simultaneous reduction of sugar content and increase of fiber in candied fruit, significantly improving product quality. It solves the problem of simultaneously achieving low sugar content and dietary fiber content, and the difficulty in balancing product nutrition and taste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep processing of fruits and vegetables, in particular to a preparation method of candied fruits with low sugar and high fiber through complex enzymatic hydrolysis. BACKGROUND

[0002] Candied fruits are a traditional and characteristic fruit and vegetable processing product. Fresh fruits and vegetables are used as raw materials to produce candied fruits through sugar pickling, cooking, drying and other processes. Because of its unique taste, long shelf life and easy storage and transportation, it is widely loved by consumers and occupies an important position in the field of deep processing of fruits and vegetables. As a leisure food with both flavor and convenience, the market demand for candied fruits is continuously strong, but the product quality and nutritional characteristics have gradually become the core of consumer attention, especially with the popularization of healthy diet concept, candied fruit products with low sugar and high nutrition have more market competitiveness.

[0003] In the existing candied fruit preparation process, most of them use single enzymatic hydrolysis or no enzymatic hydrolysis technical scheme, which is difficult to realize the synchronous improvement of low sugar and high fiber. Single enzymatic hydrolysis process can only optimize single index, and cannot meet the dual needs of reducing sucrose content and increasing dietary fiber content. The no enzymatic hydrolysis process completely relies on traditional sugar pickling method, resulting in the common problems of high sugar and low fiber in products, which cannot meet the low sugar requirement of modern consumers for healthy food, and it is also difficult to enhance the nutritional properties of products by increasing the content of dietary fiber, and at the same time, it is easy to cause the imbalance between nutrition and taste, which cannot meet the health attributes and eating experience of products. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a preparation method of candied fruits with low sugar and high fiber through complex enzymatic hydrolysis, which solves the problem that it cannot meet the low sugar requirement and the content of dietary fiber, and the nutrition and taste of the product are difficult to balance.

[0005] In order to achieve the above purpose, the present application realizes the following technical scheme: a preparation method of candied fruits with low sugar and high fiber through complex enzymatic hydrolysis, comprising the following steps: S1, raw material pretreatment: selecting fresh, non-rotten and non-diseased and insect-damaged fruit and vegetable raw materials, cleaning and cutting, drying in a constant temperature environment to a preset water content, and obtaining pretreated raw materials; S2, sugar solution preparation: based on the mass of the pretreated raw materials obtained in S1, a sugar solution containing a complex enzymatic hydrolysis system is prepared, the sugar solution is composed of sucrose, deionized water and a complex enzymatic hydrolysis system, and the preparation is completed and standby; S3, cooking and penetration: the pretreated raw materials obtained in S1 are put into the sugar solution containing the complex enzymatic hydrolysis system prepared in S2, high-temperature cooking is carried out to make the raw materials preliminarily softened and the sugar solution preliminarily penetrated, and then low-temperature incubation is carried out to realize the preliminary enzymatic hydrolysis reaction; S4, Post-enzymatic hydrolysis treatment: Transfer the raw materials that have undergone preliminary cooking and permeation in S3 together with the sugar solution to the enzymatic hydrolysis tank, continue enzymatic hydrolysis under preset conditions, and after the enzymatic hydrolysis is completed, raise the temperature to deactivate the compound enzymatic hydrolysis system and terminate the enzymatic hydrolysis reaction. S5, Secondary cooking and sugaring: Pour the raw materials from S4, after the enzymatic hydrolysis has been terminated, into the cooking pot along with the sugar solution. Heat and stir to cook and concentrate the sugar solution. After cooking, cool down and keep warm for sugaring. S6, Drying and Shaping: The raw materials that have undergone secondary sugaring in S5 are taken out, drained of surface sugar liquid, and then vacuum dried. After drying, they are cooled to room temperature, sorted, and packaged to obtain low-sugar, high-fiber candied fruit products.

[0006] By adopting the above technical solution, the use of a compound enzymatic hydrolysis system and a multi-process collaborative preparation method integrates enzymatic hydrolysis into the entire process of sugar solution preparation, cooking and penetration, achieving seamless connection between enzymatic hydrolysis and sugaring and drying processes. At the same time, the parameters of each step are precisely controlled. Therefore, the effect of achieving low sugar content and high fiber content in candied fruit at the same time, with stable product quality and excellent taste is obtained.

[0007] Preferably, in step S1, obtaining the pretreated raw materials includes: Select fresh, unrotten, and pest-free fruits and vegetables. Clean the selected fruits and vegetables thoroughly and cut them into pieces, slices, or strips with a thickness of 0.5-2cm according to the type of raw materials. Remove impurities and inedible parts from the raw materials. The chopped fruit and vegetable raw materials are placed in a constant temperature environment of 60-70℃ and dried until the moisture content of the raw materials is 50-60%, thus obtaining pre-treated raw materials. The fruit and vegetable raw materials include any one or more of hawthorn, apple, peach, bayberry, winter melon, and red dates.

[0008] By adopting the above technical solutions, targeted raw material screening and cutting processes are used to control the moisture content of the raw materials and broaden the applicable range of fruit and vegetable raw materials. While removing impurities from the raw materials, the uniform quality of the raw materials is ensured. Therefore, the raw material utilization rate is improved, the subsequent enzymatic hydrolysis and sugaring effects are more stable, and it is suitable for processing a variety of fruits and vegetables.

[0009] Preferably, in step S2, the preparation of the sugar solution containing the compound enzymatic hydrolysis system includes: Based on the quality of the pretreated raw materials obtained in S1, a sugar solution containing a compound enzymatic hydrolysis system is prepared. The sugar solution consists of sucrose, deionized water and the compound enzymatic hydrolysis system. The prepared solution is then set aside for later use. Add 30-50% of the sucrose by weight of the pretreated raw materials to deionized water and stir until completely dissolved; Add 0.1-0.5% of the pretreated raw material mass to the compound enzymatic hydrolysis system, stir evenly, adjust the sugar solution temperature to 45-55℃, keep warm for 10-15 minutes, and complete the sugar solution preparation.

[0010] By adopting the above technical solution, the addition ratio of sucrose to the compound enzymatic hydrolysis system is precisely controlled, and the sugar solution preparation temperature and holding time are optimized, allowing the compound enzyme to adapt to the reaction environment in advance. Therefore, the effects of improved enzymatic hydrolysis efficiency, uniform sugar solution concentration, and more thorough penetration during subsequent cooking are achieved.

[0011] Preferably, in step S2, the composition of the compound enzymatic hydrolysis system includes: The compound enzymatic hydrolysis system is a ternary complex system of fructosyltransferase, cellulase and sucrase, in which the mass ratio of fructosyltransferase to cellulase is 1:1-3, and sucrase accounts for 15% to 25% of the total mass of the complex enzyme; The complex enzyme system works synergistically to simultaneously decompose sucrose, convert sucrose into fructooligosaccharides, and enrich dietary fiber in situ in the raw materials, without the need for additional exogenous dietary fiber.

[0012] By employing a ternary combination of fructosyltransferase, cellulase, and sucrose, and limiting the proportion of each enzyme, sucrase is used to pre-decompose sucrose substrates, followed by isomerization by fructosyltransferase and dietary fiber modification by cellulase. The synergistic effect of multiple enzymes eliminates the need for additional exogenous dietary fiber, significantly improving sugar conversion efficiency and fiber enrichment, further enhancing the sweet taste of candied fruit and reducing its cloying sweetness.

[0013] Preferably, in step S3, the boiling and permeation includes: The pretreated raw material obtained in S1 is added to the sugar solution containing the compound enzymatic hydrolysis system prepared in S2. The mass ratio of raw material to sugar solution is 1:1.5-1:3. First, cook the ingredients at 80-90℃ for 10-15 minutes to soften them and allow the sugar syrup to penetrate them. Then, control the temperature to 45-55℃ and soak for 20-30 minutes in a low-temperature insulated soaking environment to achieve the initial enzymatic hydrolysis reaction.

[0014] By adopting the above technical solution, and by controlling the ratio of raw materials to sugar solution, and by using a step-by-step method of high-temperature cooking to soften the raw materials and low-temperature soaking to start enzymatic hydrolysis, the effect of uniform softening of raw materials, sufficient initial penetration of sugar solution, and stable start of enzymatic hydrolysis reaction can be achieved.

[0015] Preferably, in step S4, the post-enzymatic hydrolysis treatment includes: The raw materials that have undergone preliminary cooking and permeation in S3 are transferred together with the sugar solution to an enzymatic hydrolysis tank and enzymatically hydrolyzed for 30-60 minutes at a temperature of 45-55℃ and a stirring speed of 30-50r / min. After enzymatic hydrolysis is complete, raise the temperature to 85-95℃ and keep it at that temperature for 10-15 minutes to completely inactivate the compound enzymatic hydrolysis system and terminate the enzymatic hydrolysis reaction.

[0016] By adopting the above technical solution, the temperature, stirring speed and time of compound enzymatic hydrolysis are optimized, and the reaction is terminated by timely inactivation after enzymatic hydrolysis. Therefore, the effect of sufficient enzymatic hydrolysis, stable sugar solution composition and avoidance of product quality abnormalities caused by continuous enzymatic hydrolysis in subsequent processes are achieved.

[0017] Preferably, in step S5, the secondary cooking and sugar-preserving include: Pour the raw material after S4 enzymatic hydrolysis is completed and the sugar solution into a cooking pot. Cook at 70-80℃ and a stirring speed of 20-30r / min for 20-30 minutes and concentrate the sugar solution to 60-70°Brix. After cooking, cool down to 40-50℃ and keep it warm for 30-40 minutes.

[0018] By adopting the above technical solution, the sugar concentration is precisely concentrated and the sugar is preserved at a low temperature by controlling the temperature, stirring speed and time of the second cooking. Therefore, the sugar solution is fully penetrated, the product has uniform sweetness, delicate taste and flavor is preserved.

[0019] Preferably, in step S6, the drying and molding process includes: After the raw materials that have undergone secondary sugar curdling in S5 are removed and the surface sugar liquid is drained, they are vacuum dried under vacuum conditions of -0.06~-0.08MPa and drying temperature of 55-65℃. The material is dried until the moisture content is 15-20%. After drying, it is cooled to room temperature. Damaged and deformed finished products are sorted and removed before being sealed and packaged to obtain low-sugar, high-fiber candied fruit.

[0020] By adopting the above technical solution, and by using vacuum drying to control the vacuum level, temperature and moisture content of the material, combined with sorting and packaging, the product achieves the effect of meeting the moisture content standard, extending the shelf life, and making the appearance and quality more stable.

[0021] Preferably, after the compound enzymatic hydrolysis system is deactivated, it enters step S5 along with the sugar solution to participate in the secondary cooking and sugar-soaking process.

[0022] By adopting the above technical solution, since the deactivated compound enzymatic hydrolysis system participates in the secondary cooking and sugaring process along with the sugar solution, no additional separation treatment is required. Therefore, the process steps are simplified, production efficiency is improved, and resource waste is avoided.

[0023] Preferably, during the sealing and packaging process, the food-grade sealed bag is filled with an inert gas, namely nitrogen, and the filling pressure is controlled at 0.02-0.05 MPa.

[0024] By adopting the above technical solution, by filling the sealed packaging with nitrogen and controlling the filling pressure to isolate it from air, the product's antioxidant capacity is improved, its shelf life is further extended, and flavor loss and quality deterioration are avoided during storage.

[0025] This invention provides a method for preparing low-sugar, high-fiber candied fruit by enzymatic hydrolysis. It has the following beneficial effects: 1. This invention employs a ternary complex enzymatic hydrolysis system of fructosyltransferase, cellulase, and sucrase, combined with a multi-step synergistic approach involving raw material pretreatment and cooking enzymatic hydrolysis. This achieves the simultaneous reduction of sugar content and increase of fiber content in candied fruit, resulting in a significant improvement in product quality. Compared to existing candied fruit preparation methods that rely on single or no enzymatic hydrolysis, this invention solves the problem of failing to balance low sugar requirements with dietary fiber content and the difficulty in achieving a balance between product nutrition and taste.

[0026] 2. This invention adopts a synergistic process that seamlessly integrates enzymatic hydrolysis, sugar infiltration, and drying, combined with a technical solution for precise control of enzyme inactivation. This achieves stable product quality and a highly efficient and controllable production process. Compared with existing technologies that have chaotic process sequences and missing enzyme inactivation steps, this invention solves the problems of disordered sugar composition, uneven taste, short shelf life, and unstable quality in the product.

[0027] 3. This invention uses food-grade reagents, simplifies the production process, and eliminates the need for complex equipment, achieving the technical effects of green and safe production of candied fruit, reduced production costs, and scalable promotion. Compared with existing technologies that have complex production processes, high equipment requirements, and are prone to generating harmful substances or wasting resources, this invention solves the problems of high production costs, difficulty in large-scale production, and non-compliance with the concept of green and healthy production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the steps in the preparation method of a compound candied fruit with enzymatic hydrolysis for low sugar and high fiber according to the present invention. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see the appendix Figure 1 The following is a further description with reference to the embodiments: Example 1, a method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis, comprising the following steps: S1, Raw material pretreatment: Select fresh hawthorn, wash it clean, cut it into slices with a thickness of 1cm, and remove the pits; soak the cut hawthorn slices in a vitamin C solution with a mass concentration of 0.2% for 15 minutes, take them out and rinse them twice with deionized water, drain the surface water, and obtain pretreated hawthorn slices.

[0031] S2, Preparation of compound enzymatic hydrolysate: Based on pretreated hawthorn slices, prepare compound enzymatic hydrolysate; the amount of sucrose added is 40% of the mass of pretreated hawthorn slices, the amount of compound enzyme preparation added is 0.3% of the mass of pretreated hawthorn slices, and the amount of citric acid added is 0.1% of the total mass of compound enzymatic hydrolysate; the mass ratio of fructosyltransferase to cellulase in the compound enzyme preparation is 2:1, and sucrase accounts for 20% of the total mass of the compound enzyme; add sucrose and citric acid to deionized water, stir until completely dissolved, adjust the temperature of the sugar solution to 50℃, add the compound enzyme preparation, stir evenly, and keep warm for 12 minutes to obtain compound enzymatic hydrolysate.

[0032] S3, Cooking and Enzymatic Hydrolysis: Place the pretreated hawthorn slices into the compound enzymatic hydrolysis solution. The mass ratio of raw materials to compound enzymatic hydrolysis solution is 1:2. Turn on the stirring and stir at a speed of 40 r / min. Heat to 55℃ and cook at a constant temperature for 45 min to obtain enzymatically hydrolyzed sugar-preserved hawthorn slices.

[0033] S4, Enzyme inactivation treatment: The enzymatically hydrolyzed candied hawthorn slices are heated to 90℃ and kept at a constant temperature for 12 minutes to completely inactivate the compound enzyme preparation. The temperature is then naturally cooled to 45℃ to obtain inactivated candied hawthorn slices.

[0034] S5, Post-sugaring treatment: Place the inactivated sugar-soaked hawthorn slices in a vacuum sugar-soaking device, control the vacuum degree to -0.07MPa, maintain the temperature at 45℃, vacuum sugar soaking for 25min, release the vacuum to normal pressure, let stand for 12min, repeat the above operation twice, take them out and drain the excess sugar liquid on the surface to obtain sugar-soaked hawthorn slices.

[0035] S6, Drying and Shaping: Place the sugar-soaked hawthorn slices into a drying device, control the drying temperature at 60℃, and dry until the moisture content of the material is 18%. During the drying process, turn the material over once every 12 minutes. After drying, cool to room temperature, sort and package to obtain the finished low-sugar, high-fiber hawthorn preserve.

[0036] Example 2, a method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis, comprising the following steps: S1, Raw material pretreatment: Select fresh apples, wash them clean, cut them into slices with a thickness of 1.5cm, and remove the peel and core; soak the cut apple slices in a vitamin C solution with a mass concentration of 0.1% for 20 minutes, take them out and rinse them 3 times with deionized water, drain the surface water, and obtain pretreated apple slices.

[0037] S2, Preparation of compound enzymatic hydrolysate: Based on pretreated apple slices, prepare compound enzymatic hydrolysate; the amount of sucrose added is 30% of the mass of pretreated apple slices, the amount of compound enzyme preparation added is 0.1% of the mass of pretreated apple slices, and the amount of citric acid added is 0.05% of the total mass of compound enzymatic hydrolysate; the mass ratio of fructosyltransferase to cellulase in the compound enzyme preparation is 1:1, and sucrase accounts for 18% of the total mass of the compound enzyme; add sucrose and citric acid to deionized water, stir until completely dissolved, adjust the temperature of the sugar solution to 45℃, add the compound enzyme preparation, stir evenly, and keep warm for 15 minutes to obtain compound enzymatic hydrolysate.

[0038] S3, Cooking and Enzymatic Hydrolysis: Place the pretreated apple slices into the compound enzymatic hydrolysis solution. The mass ratio of raw materials to compound enzymatic hydrolysis solution is 1:1.5. Turn on the stirring and stir at a speed of 30 r / min. Heat to 50℃ and cook at a constant temperature for 60 min to obtain enzymatically hydrolyzed candied apple slices.

[0039] S4, Enzyme inactivation treatment: The enzymatically hydrolyzed candied apple slices are heated to 85°C and kept at a constant temperature for 15 minutes to completely inactivate the compound enzyme preparation. The temperature is then naturally cooled to 40°C to obtain inactivated candied apple slices.

[0040] S5, Post-sugaring treatment: Place the inactivated sugar-soaked apple slices in a vacuum sugar-soaking device, control the vacuum degree to -0.06MPa, maintain the temperature at 40℃, vacuum sugar soaking for 30min, release the vacuum to normal pressure, let stand for 15min, repeat the above operation 3 times, take them out and drain the excess sugar liquid on the surface to obtain sugar-soaked apple slices.

[0041] S6, Drying and Shaping: Place the sugar-soaked apple slices into a drying device, control the drying temperature at 55℃, and dry until the moisture content of the material is 15%. During the drying process, turn the material over once every 10 minutes. After drying, cool to room temperature, sort, and package to obtain the low-sugar, high-fiber apple preserve product.

[0042] Example 3, a method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis, comprising the following steps: S1, Raw material pretreatment: Select fresh red dates, wash them clean, remove the pits, and cut them in half; soak the cut red dates in a 0.3% vitamin C solution for 10 minutes, take them out and rinse them twice with deionized water, drain the surface water, and obtain pretreated red dates.

[0043] S2, Preparation of compound enzymatic hydrolysate: Based on pretreated jujubes, prepare compound enzymatic hydrolysate; the amount of sucrose added is 50% of the mass of pretreated jujubes, the amount of compound enzyme preparation added is 0.5% of the mass of pretreated jujubes, and the amount of citric acid added is 0.15% of the total mass of compound enzymatic hydrolysate; the mass ratio of fructosyltransferase to cellulase in the compound enzyme preparation is 3:1, and sucrase accounts for 20% of the total mass of the compound enzyme; add sucrose and citric acid to deionized water, stir until completely dissolved, adjust the temperature of the sugar solution to 55℃, add the compound enzyme preparation, stir evenly, keep warm for 10 minutes, and obtain compound enzymatic hydrolysate.

[0044] S3, Cooking and Enzymatic Hydrolysis: Place the pretreated red dates into the compound enzymatic hydrolysis solution. The mass ratio of the raw materials to the compound enzymatic hydrolysis solution is 1:3. Turn on the stirring and stir at a speed of 50 r / min. Heat to 60℃ and cook at a constant temperature for 30 minutes to obtain enzymatically hydrolyzed sugar-preserved red dates.

[0045] S4, Enzyme inactivation treatment: The enzymatically hydrolyzed sugar-preserved red dates are heated to 95℃ and kept at a constant temperature for 10 minutes to completely inactivate the compound enzyme preparation. The temperature is then naturally cooled to 50℃ to obtain inactivated sugar-preserved red dates.

[0046] S5, Post-sugaring treatment: Place the inactivated sugar-soaked red dates in a vacuum sugar-soaking device, control the vacuum degree to -0.08MPa, maintain the temperature at 50℃, vacuum sugar soaking for 20 minutes, release the vacuum to normal pressure, let stand for 10 minutes, repeat the above operation twice, take them out and drain the excess sugar liquid on the surface to obtain sugar-soaked red dates.

[0047] S6, Drying and Shaping: Place the sugar-soaked red dates into a drying device, control the drying temperature at 65℃, and dry until the moisture content of the material is 20%. During the drying process, turn the material over once every 15 minutes. After drying, cool to room temperature, sort and package to obtain the finished product of low-sugar, high-fiber red date preserves.

[0048] Example 4 differs from Example 3 in that: the raw material is fresh bayberry, cut into 0.8cm slices; the mass ratio of fructosyltransferase to cellulase in the compound enzyme preparation is 1.5:1; sucrose accounts for 18% of the total mass of the compound enzyme; and the enzyme inactivation treatment is performed at 90℃ for 12 minutes. The remaining steps and parameters are the same as in Example 3.

[0049] Example 5 differs from Example 3 in that the raw material is fresh peaches, cut into 1.2cm pieces. The secondary cooking and sugaring are carried out at 75°C, stirring speed of 25r / min, cooking for 25min, and sugar solution concentrated to 65°Brix. The drying and shaping are carried out under vacuum of -0.07MPa and drying temperature of 62°C. The remaining steps and parameters are the same as in Example 3.

[0050] Example 6 differs from Example 3 in that the raw material is fresh winter melon, cut into 1.5cm strips. The cooking and permeation process involves cooking at 85℃ for 12 minutes and soaking at 50℃ for 25 minutes. After the compound enzymatic hydrolysis system is deactivated, it is carried into the secondary cooking and sugar-soaking steps along with the sugar solution. The remaining steps and parameters are the same as in Example 3.

[0051] Comparative Example 1 differs from Example 3 in that it does not use a ternary combination of fructosyltransferase and sucrase, but only uses cellulase as the enzyme preparation, and it is added only in the cooking enzymatic hydrolysis step, not in the sugar solution preparation stage; the remaining process parameters are the same as in Example 3.

[0052] Comparative Example 2 differs from Example 3 in that the enzyme inactivation treatment in S4 is omitted, and the process proceeds directly to the sugar infusion post-treatment step after the cooking and enzymatic hydrolysis are completed; the remaining process parameters are the same as in Example 3.

[0053] Comparative Example 3 differs from Example 3 in that the vacuum sugar infusion post-treatment in S5 is replaced with traditional atmospheric pressure sugar infusion, and the vacuum sugar infusion and atmospheric pressure standing repeated operations are not performed; the remaining process parameters are the same as those in Example 3.

[0054] Comparative Example 4 differs from Example 3 in that the process sequence is adjusted. First, boiling and permeation are performed, then the compound enzymatic hydrolysis sugar solution is prepared and added to the boiled material for enzymatic hydrolysis. That is, the order of S2 and S3 is reversed; the remaining process parameters are the same as those in Example 3.

[0055] The performance differences between Examples 1-6 and Comparative Examples 1-4 will be further illustrated below with experimental examples: In Experiment 1, the sucrose content in candied fruit was tested according to GB5009.8-2016 "National Food Safety Standard - Determination of Fructose, Glucose, Sucrose, Maltose and Lactose in Food". High performance liquid chromatography was used to select finished candied fruit samples and remove unqualified individuals such as those that were damaged, deformed, or contained impurities. First, freeze-dry the sample and grind it. Then, pass it through a 0.45mm standard sieve. Accurately weigh 5.00g of the sieved sample and place it in a 50mL volumetric flask. Add 30mL of deionized water and heat in a 60℃ water bath for 30min, shaking continuously to fully dissolve the sucrose. After cooling to room temperature, dilute to the mark with deionized water, shake well, and filter through a 0.45μm filter membrane to obtain the test solution. Prepare a series of sucrose standard working solutions of different concentrations and set the chromatographic conditions as follows: use an amino column (4.6 mm × 250 mm, 5 μm), mobile phase (acetonitrile-water volume ratio 70:30), flow rate (1.0 mL / min), column temperature (30℃), detector (differential refractive index detector), injection volume (10 μL), test each sample in parallel three times, remove the maximum and minimum values ​​and take the average value, and calculate the sucrose reduction using the formula: sucrose reduction = (sucrose content of traditional candied fruit - sucrose content of sample) ÷ sucrose content of traditional candied fruit × 100%. During the test, maintain an ambient temperature of 25 ± 2℃ and a relative humidity of 60 ± 5%, and allow the samples to equilibrate under these conditions for 30 min before the test.

[0056] In Experiment 2, the total dietary fiber content in candied fruit was tested according to GB5009.88-2014 "National Food Safety Standard - Determination of Dietary Fiber in Food". Equipment such as constant temperature oven, high speed centrifuge, and glass fiber filter membrane were used. Candied fruit samples were selected, and unqualified individuals such as those that were damaged, deformed, or contained impurities were removed. First, freeze-dry the sample and grind it. Then, pass it through a 0.45mm standard sieve. Accurately weigh 2.00g of the sieved sample and place it in a 50mL centrifuge tube. Add 25mL of petroleum ether (boiling range 30~60℃), shake for 10min, centrifuge at 3000r / min for 10min, discard the supernatant, and repeat the extraction twice to remove the fat from the sample. Place the residue in a 60℃ oven to dry and cool to room temperature for later use. Add 20 mL of pH 6.0 phosphate buffer to the residue, heat in a 95-100℃ water bath for 15 min, cool to 60℃, and then add heat-resistant α-amylase solution, protease solution, and glucosidase solution in sequence. Incubate in a 60℃ water bath for 30 min each time with continuous shaking. After enzymatic hydrolysis, add 40 mL of anhydrous ethanol pre-cooled to 4℃, shake well, and let stand at 4℃ for 1 h. Filter with a pre-weighed glass fiber membrane, and wash the residue in sequence with 78% ethanol, 95% ethanol, and acetone. Each sample group was tested in parallel three times. After removing the maximum and minimum values, the average value was taken. The dietary fiber increase was calculated using the formula: Dietary fiber increase = (sample dietary fiber content - traditional candied fruit dietary fiber content) ÷ traditional candied fruit dietary fiber content × 100%. During the test, maintain an ambient temperature of 25±2℃ and a relative humidity of 60±5%. The samples were equilibrated under this environment for 30 min before the test.

[0057] In Experiment 3, the shelf life of candied fruit was tested in accordance with GB / T20884-2011 "General Rules for Candied Fruit" and GB7098-2015 "National Food Safety Standard for Canned Food". Constant temperature and humidity incubators and microbial detection equipment were used. Samples of finished candied fruit were selected, and three parallel samples were selected for each group. The packaging specifications of each sample were consistent with the actual finished product. Samples with damaged packaging, leakage, or contamination were removed. First, the samples were placed in a constant temperature and humidity incubator. The storage conditions were set as follows: temperature 25±2℃, relative humidity 60±5%, and storage in a dark and odorless environment. The testing cycle was set as follows: once every 7 days for the first month, once every 15 days for the first 1-3 months, and once a month thereafter. The sensory status of the samples was observed and microbial indicators were tested. Each group of samples was tested in parallel with 3 groups. The time when each group of samples deteriorated was recorded. After removing the maximum and minimum values, the average value was taken as the shelf life of the sample. The deterioration criteria were as follows: total bacterial count > 1000 cfu / g, mold > 100 cfu / g, or the appearance of any sensory deterioration phenomenon, the sample was judged to be deteriorated. During the test, the set storage environment conditions were strictly maintained to avoid fluctuations in temperature and humidity.

[0058] Table 1, Performance Test Data Table

[0059] Based on the differences between Examples 1-6 and Comparative Examples 1-4 and the performance test data table, it can be seen that the synergistic process of raw material pretreatment, compound enzymatic hydrolysis solution preparation, cooking enzymatic hydrolysis, enzyme inactivation treatment, sugar penetration post-treatment, and drying and shaping in this invention has a significant impact on the reduction of sucrose, the increase of dietary fiber, shelf life, taste, and compliance with low sugar and high fiber standards in candied fruit. Moreover, each process step has a positive effect on the excellent quality of raw materials, high efficiency of enzymatic hydrolysis, uniform sugar penetration, stable product quality, and reliable test results, thus achieving the dual goals of low sugar and high fiber production of candied fruit and improved product taste and flavor.

[0060] Comparative Example 1 did not use a compound enzymatic hydrolysis system, but only used cellulase as an enzyme preparation. Moreover, it was only added in the cooking enzymatic hydrolysis step and not in the sugar solution preparation stage. As a result, the synergistic effect of enzymatic hydrolysis was lost, the conversion of sucrose and the enrichment of dietary fiber could not be carried out synchronously, and the connection with the subsequent enzyme inactivation and sugar infiltration process was not smooth. The reduction of sucrose was reduced to a poor level, the increase of dietary fiber was significantly reduced, the taste was rough and the flavor was bland. It became the group with poor overall performance and could not meet the requirements of low sugar and high fiber, thus failing to meet the basic needs of modern consumers for healthy eating. Comparative Example 2 omitted the enzyme inactivation treatment and directly entered the sugar infusion post-treatment step after the cooking and enzymatic hydrolysis were completed. The enzyme activity termination effect was canceled, which led to the continuous enzymatic hydrolysis reaction, disordered sugar solution composition, and the reduction of sucrose to a moderate level. The dietary fiber was unevenly distributed. Although the appearance indicators did not show a significant decline beyond the shelf life, the product quality stability was significantly reduced, the shelf life was shortened to 3 months, and there were abnormal tastes such as local over-sweetness and local astringency, which affected the product's market competitiveness. Comparative Example 3 replaced the post-sugar infiltration treatment with traditional atmospheric pressure sugar infiltration, without performing vacuum sugar infiltration and repeated atmospheric pressure static standing operations. The elimination of the precise vacuum sugar infiltration effect resulted in insufficient sugar solution penetration, high sucrose residue, and a moderate reduction in sucrose content. Dietary fiber could not be evenly distributed. Although the increase in dietary fiber was not significantly abnormal, the product had a hard texture and uneven sweetness. The preparation efficiency and synergistic preparation efficiency were significantly reduced, and the raw material utilization rate was low, resulting in sugar solution waste and affecting production cost control. Comparative Example 4 adjusted the process sequence, first performing boiling and infiltration, then preparing the compound enzymatic hydrolysis solution and adding it to the boiled material for enzymatic hydrolysis. That is, the preparation of the compound enzymatic hydrolysis solution and the boiling and enzymatic hydrolysis steps were reversed, resulting in an unsuitable enzymatic hydrolysis environment, a significant decrease in enzymatic hydrolysis efficiency, a poor reduction in sucrose, and a significant decrease in the increase in dietary fiber. Although the feasibility of the preparation process was not obviously abnormal, the product had a hard texture, serious loss of flavor, and was prone to cracking and flavor fading during long-term storage. The low-sugar, high-fiber candied fruit prepared in the examples exhibited excellent core performance indicators, fully meeting the preset performance requirements: sucrose was reduced by 38%-45%, dietary fiber was increased by 25%-32%, shelf life reached 6 months, and taste was rated as good, all meeting the requirements for low sugar and high fiber. At the same time, it achieved the production of candied fruit with low sugar and high fiber while preserving its natural flavor. The preparation process contained no harmful additives, making the product safe and healthy. It can effectively improve the quality of candied fruit products, reduce production costs, and increase the utilization rate of raw materials.

[0061] Among them, Examples 1, 2, 4, 5, and 6 are slightly inferior to Example 3 in performance due to process parameters being at the boundary of the set range or differences in raw material types, but still maintain good overall advantages. Example 1 is suitable for fruit and vegetable raw materials with high acidity, such as hawthorn. By optimizing parameters such as enzymatic hydrolysis temperature and time, it takes into account both taste and low sugar and high fiber effects, and can be widely used in the large-scale production of candied fruit such as hawthorn and bayberry. Example 2 is suitable for fruit and vegetable raw materials with a crisp texture, such as apple. It adopts mild enzymatic hydrolysis and drying parameters to retain the natural flavor of the raw materials to the greatest extent, and is suitable for the production scenarios of mid-to-high-end candied fruit with high flavor requirements. Examples 4, 5, and 6 are respectively suitable for different types of fruit and vegetable raw materials such as bayberry, peach, and winter melon. The process parameters are adjusted in a targeted manner, which broadens the scope of application of the present invention. It can be flexibly adapted according to the characteristics of raw materials to meet the production needs of different fruit and vegetable candied fruits.

[0062] Example 3 achieves an optimal balance between product quality and production efficiency. Its process parameters are highly adaptable, with thorough raw material pretreatment, precise preparation of compound enzymatic hydrolysis solution, efficient cooking and enzymatic hydrolysis, thorough enzyme inactivation, uniform sugar penetration, and standardized drying and shaping. The resulting jujube preserves outperform other examples in all aspects, with a 45% reduction in sucrose and a 32% increase in dietary fiber. They have a soft and glutinous texture, rich flavor, and a stable preparation process with high production efficiency. They do not require complex equipment and are easy to scale up for continuous production. Its comprehensive advantages are significant. Compared with Example 2, the reduction in sucrose is increased by 7%, and the increase in dietary fiber is increased by 7%. Compared with traditional preserve preparation processes, the sucrose content is reduced by more than 45%, and the dietary fiber content is increased by more than 32%. Compared with existing single enzymatic hydrolysis processes, the enzymatic hydrolysis efficiency is increased by more than 30%. It can be widely adapted to the production of various fruit and vegetable preserves such as jujubes, hawthorns, apples, bayberries, peaches, and winter melons, covering the full range of production needs for light to moderate low-sugar and high-fiber preserves.

[0063] The core processes in Examples 1-6 exhibit a deep synergistic effect: Raw material pretreatment and the preparation of compound enzymatic hydrolysis solutions work synergistically to optimize raw material quality and the enzymatic hydrolysis system, laying the foundation for subsequent cooking enzymatic hydrolysis and sugar infiltration, and reducing the risks of raw material browning and uneven enzymatic hydrolysis during preparation; the preparation of compound enzymatic hydrolysis solutions and cooking enzymatic hydrolysis work synergistically to construct an efficient compound enzymatic hydrolysis environment, enabling simultaneous sucrose conversion and in-situ enrichment of dietary fiber, thus improving enzymatic hydrolysis efficiency; cooking enzymatic hydrolysis and enzyme inactivation treatment work synergistically to precisely control the enzymatic hydrolysis process, terminate the enzymatic hydrolysis reaction, and ensure product quality stability; enzyme inactivation treatment and post-sugar infiltration treatment work synergistically to maintain a suitable sugar infiltration environment, promote the penetration of fructooligosaccharides and the uniform distribution of dietary fiber, and improve product taste; post-sugar infiltration treatment and drying and molding work synergistically to control product moisture content, extend shelf life, and retain product taste and flavor; all reagents used in each process are food-grade, achieving food safety compatibility without complex processing, further reducing production costs, and aligning with the development concepts of healthy food and green production.

[0064] Example 3 optimizes key parameters such as the mass ratio of the compound enzyme preparation (3:1), the cooking and enzymatic hydrolysis temperature (60℃), the enzyme inactivation temperature (95℃), the vacuum degree of the vacuum sugar penetration (-0.08MPa), and the drying temperature (65℃) to achieve seamless connection of each process step, maximize the synergistic advantages, and fully demonstrate the scientific nature, rationality, and feasibility of the process parameter range of the present invention.

[0065] Comparative Examples 1-4 suffered from the loss or alteration of a single process step, resulting in a break in the overall synergistic chain: Comparative Example 1 eliminated the compound enzymatic hydrolysis system and the reasonable addition method, disrupting the synergistic effect of enzymatic hydrolysis and the connection with subsequent processes; Comparative Example 2 eliminated the enzyme inactivation treatment, damaging the stability of product quality; Comparative Example 3 changed the sugar infiltration method, weakening the synergistic effect of sugar dissolution and taste improvement; Comparative Example 4 adjusted the process sequence, losing the guarantee of high efficiency in enzymatic hydrolysis. All of these examples demonstrate the irreplaceable nature of the key process steps and parameter selections in this invention, further illustrating that the synergistic effect of each process step is the core guarantee for achieving low-sugar, high-fiber production of candied fruit, improving product quality, and controlling production costs.

[0066] In summary, this invention, through its core technology design encompassing raw material pretreatment, preparation of compound enzymatic hydrolysis solution, cooking enzymatic hydrolysis, enzyme inactivation treatment, post-sugar infiltration treatment, and drying and shaping, combined with the synergistic optimization of various process parameters, effectively solves the technical problems of traditional candied fruit preparation processes, such as high sugar content, low fiber content, and rough texture, as well as the low efficiency, limited dietary fiber enhancement, unstable product quality, high production costs, and difficulty in large-scale production of existing enzymatic hydrolysis processes. It significantly improves the quality and production efficiency of candied fruit products, enabling low-sugar, high-fiber, and green production of various fruit and vegetable candied fruits. Simultaneously, it simplifies the production process, controls production costs, eliminates the need for complex equipment, and uses safe and environmentally friendly reagents, aligning with the development concepts of healthy eating and green production, and has broad application prospects.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis, characterized in that, Includes the following steps: S1, Raw material pretreatment: Select fresh, non-rotten, and pest-free fruits and vegetables, clean them, cut them into pieces, and dry them in a constant temperature environment to the preset moisture content to obtain pretreated raw materials. S2, Sugar solution preparation: Based on the mass of the pretreated raw materials obtained in S1, prepare a sugar solution containing a compound enzymatic hydrolysis system. The sugar solution consists of sucrose, deionized water and the compound enzymatic hydrolysis system. After preparation, it is ready for use. S3, Cooking and Penetration: The pretreated raw material obtained in S1 is put into the sugar solution containing the compound enzymatic hydrolysis system prepared in S2. First, it is cooked at high temperature to soften the raw material and allow the sugar solution to penetrate it. Then, it is soaked at low temperature to realize the initial enzymatic hydrolysis reaction. S4, Post-enzymatic hydrolysis treatment: Transfer the raw materials that have undergone preliminary cooking and permeation in S3 together with the sugar solution to the enzymatic hydrolysis tank, continue enzymatic hydrolysis under preset conditions, and after the enzymatic hydrolysis is completed, raise the temperature to deactivate the compound enzymatic hydrolysis system and terminate the enzymatic hydrolysis reaction. S5, Secondary cooking and sugaring: Pour the raw materials from S4, after the enzymatic hydrolysis has been terminated, into the cooking pot along with the sugar solution. Heat and stir to cook and concentrate the sugar solution. After cooking, cool down and keep warm for sugaring. S6, Drying and Shaping: The raw materials that have undergone secondary sugaring in S5 are taken out, drained of surface sugar liquid, and then vacuum dried. After drying, they are cooled to room temperature, sorted, and packaged to obtain low-sugar, high-fiber candied fruit products.

2. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In step S1, obtaining the pre-treated raw materials includes: Select fresh, unrotten, and pest-free fruits and vegetables. Clean the selected fruits and vegetables thoroughly and cut them into pieces, slices, or strips with a thickness of 0.5-2cm according to the type of raw materials. Remove impurities and inedible parts from the raw materials. The chopped fruit and vegetable raw materials are placed in a constant temperature environment of 60-70℃ and dried until the moisture content of the raw materials is 50-60%, thus obtaining pre-treated raw materials. The fruit and vegetable raw materials include any one or more of hawthorn, apple, peach, bayberry, winter melon, and red dates.

3. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In step S2, the preparation of the sugar solution containing the compound enzymatic hydrolysis system includes: Based on the quality of the pretreated raw materials obtained in S1, a sugar solution containing a compound enzymatic hydrolysis system is prepared. The sugar solution consists of sucrose, deionized water and the compound enzymatic hydrolysis system. The prepared solution is then set aside for later use. Add 30-50% of the sucrose by weight of the pretreated raw materials to deionized water and stir until completely dissolved; Add 0.1-0.5% of the pretreated raw material mass to the compound enzymatic hydrolysis system, stir evenly, adjust the sugar solution temperature to 45-55℃, keep warm for 10-15 minutes, and complete the sugar solution preparation.

4. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In S2, the composition of the compound enzymatic hydrolysis system includes: The compound enzymatic hydrolysis system is a ternary complex system of fructosyltransferase, cellulase and sucrase, with the mass ratio of fructosyltransferase to cellulase being 1:1-3, and sucrase accounting for 15% to 25% of the total mass of the complex enzyme; The complex enzyme system works synergistically to simultaneously decompose sucrose, convert sucrose into fructooligosaccharides, and enrich dietary fiber in situ in the raw materials, without the need for additional exogenous dietary fiber.

5. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In step S3, the boiling and permeation process includes: The pretreated raw material obtained in S1 is added to the sugar solution containing the compound enzymatic hydrolysis system prepared in S2. The mass ratio of raw material to sugar solution is 1:1.5-1:

3. First, cook the ingredients at 80-90℃ for 10-15 minutes to soften them and allow the sugar syrup to penetrate them. Then, control the temperature to 45-55℃ and soak for 20-30 minutes in a low-temperature insulated soaking environment to achieve the initial enzymatic hydrolysis reaction.

6. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In step S4, the post-enzymatic hydrolysis treatment includes: The raw materials that have undergone initial cooking and permeation in S3 are transferred together with the sugar solution to an enzymatic hydrolysis tank and enzymatically hydrolyzed for 30-60 minutes at a temperature of 45-55℃ and a stirring speed of 30-50r / min. After enzymatic hydrolysis is complete, raise the temperature to 85-95℃ and keep it at that temperature for 10-15 minutes to completely inactivate the compound enzymatic hydrolysis system and terminate the enzymatic hydrolysis reaction.

7. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In step S5, the secondary cooking and sugar-preserving processes include: Pour the raw material after S4 enzymatic hydrolysis is completed and the sugar solution into a cooking pot. Cook at 70-80℃ and a stirring speed of 20-30r / min for 20-30 minutes and concentrate the sugar solution to 60-70°Brix. After cooking, cool down to 40-50℃ and keep it warm for 30-40 minutes.

8. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 1, characterized in that, In step S6, drying and molding includes: After the raw materials that have undergone secondary sugar curdling in S5 are removed and the surface sugar liquid is drained, they are vacuum dried under vacuum conditions of -0.06~-0.08MPa and drying temperature of 55-65℃. The material is dried until the moisture content is 15-20%. After drying, it is cooled to room temperature. Damaged and deformed finished products are sorted and removed before being sealed and packaged to obtain low-sugar, high-fiber candied fruit.

9. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 4, characterized in that, After the compound enzymatic hydrolysis system is deactivated, it enters step S5 along with the sugar solution to participate in the secondary cooking and sugar-soaking process.

10. The method for preparing a compound candied fruit with low sugar and high fiber through enzymatic hydrolysis according to claim 8, characterized in that, During the sealing and packaging process, the food-grade sealed bag is filled with an inert gas, namely nitrogen, and the filling pressure is controlled at 0.02-0.05 MPa.

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