A method for preparing pineapple fruit powder by boiling granulation

Abstract

The present application belongs to the technical field of food production and processing, and particularly relates to a method for preparing pineapple fruit powder by boiling granulation, which comprises the following steps: adding γ-cyclodextrin into pineapple juice, stirring and dissolving to obtain an inclusion liquid; subjecting the inclusion liquid to ceramic membrane microfiltration to obtain a dialysate; subjecting the dialysate to vacuum decompression concentration and filtration to obtain a concentrated liquid; weighing auxiliary materials according to the total solid mass of the concentrated liquid, and dividing the auxiliary materials into first auxiliary materials and second auxiliary materials; placing the first auxiliary materials into a boiling granulator, spraying the concentrated liquid to obtain shaped particles; preparing an embedding solution from the second auxiliary materials, and performing spray embedding, drying and sieving on the shaped particles to obtain pineapple fruit powder. The pineapple fruit powder prepared by the method has high solubility, good fluidity, low hygroscopicity, high nutrient retention rate, low processing cost and long product shelf life.

Description

Technical Field

[0001] This invention belongs to the field of food production and processing technology, specifically, it relates to a method for preparing pineapple powder using boiling granulation. Background Technology

[0002] Pineapple is not only rich in nutrients, containing abundant fructose, glucose, vitamin B, vitamin C, citric acid, and protease, but it also has medicinal value. According to the Compendium of Materia Medica, pineapple is neutral in nature, sweet, slightly sour, slightly astringent, and slightly cold in taste, possessing the effects of relieving summer heat and thirst, aiding digestion and stopping diarrhea, tonifying the spleen and stomach, strengthening vital energy, and benefiting blood and qi, removing dampness, and promoting weight loss. However, fresh pineapple has a short shelf life and is prone to spoilage, so it is currently mainly sold fresh. With continuous technological upgrades and development, depending on different production processes, pineapple can be processed into canned pineapple, juice, jam, dried fruit, fruit wine, fruit powder, and other products.

[0003] Patent CN201610960714.6 discloses a method for processing pineapple fruit powder solid beverage. The method involves slicing ripe pineapple into thin slices, quickly immersing them in boiling water to deactivate enzymes, then pouring the slices into a blender, adding one-third water to homogenize the mixture, and then adding cellulase and pectinase for enzymatic hydrolysis. Maltodextrin is added to the hydrolyzed pineapple pulp, and the mixture is stirred evenly. A compound anti-caking agent is added and stirred evenly. The mixture is then freeze-dried using a vacuum freeze-drying method to obtain pineapple fruit powder, which is then pulverized to obtain the pineapple fruit powder solid beverage.

[0004] Patent CN201810454770.1 discloses a pineapple whole fruit powder and its preparation method. Fresh, ripe pineapples are peeled, and the pulp is soaked in an ice-water mixture before being cut into pieces. After cutting, the pieces are soaked in a citric acid-sodium citrate buffer solution with a pH of 3-5, with a color-protecting agent added. After soaking, 0.8-1 times the mass of water is added for pulping. After pulping, polygalacturonase is added first, followed by cellulase for enzymatic hydrolysis. The enzymatically hydrolyzed pineapple pulp is then subjected to colloidal grinding. The pulp after colloidal grinding is freeze-dried, continuously vacuum low-temperature dried, or spray-dried to prepare dried powder, which is then pulverized to obtain pineapple whole fruit powder.

[0005] Patent CN202411820680.1 discloses a method for preparing hygroscopic pineapple whole fruit powder. Fresh, ripe pineapples are washed, peeled, juiced, and passed through an 80-mesh sieve. The pineapple juice and pineapple pulp are collected. The pineapple pulp is rinsed and dried until the moisture content is below 5%, then pulverized and sieved. The pulverized and sieved pineapple pulp powder is mixed with gluten and maltodextrin to obtain an hygroscopic agent. The obtained hygroscopic agent is added to the pineapple juice at 60%~80wt% of the pineapple juice solids content, and the mixture is stirred until homogeneous to obtain a liquid mixture. The liquid mixture is treated with dynamic high-pressure microjet 2-4 times, and then spray-dried to obtain a dried powder. Silica is added, and the mixture is stirred until homogeneous to obtain pineapple whole fruit powder.

[0006] However, the above processing methods are relatively simple, with long production cycles and short product shelf life. On the one hand, the addition of processing aids such as enzymes in the intermediate steps will introduce exogenous proteins and off-flavors, destroying the original flavor of pineapple. On the other hand, the pineapple powder obtained by freeze-drying or spray drying has high hygroscopicity, low solubility, and the particle size of the powder cannot be controlled. Summary of the Invention

[0007] The problem to be solved by the present invention is to provide a method for preparing pineapple fruit powder by fluidized bed granulation, which produces pineapple fruit powder with high solubility, good flowability, low hygroscopicity, and high nutrient retention.

[0008] The problem to be solved by this invention is to provide a method for preparing pineapple fruit powder by fluidized bed granulation, which has low processing cost and long product shelf life.

[0009] To solve the above problems, the present invention is achieved through the following technical solution: A method for preparing pineapple powder by fluidized bed granulation includes the following specific steps: (1) Add γ-cyclodextrin to pineapple juice, stir to dissolve, and obtain inclusion solution; (2) The inclusion solution is microfiltered through a ceramic membrane to obtain a dialysate; (3) The dialysate is concentrated under vacuum and filtered to obtain a concentrated solution; (4) Weigh the excipients according to the total solids mass of the concentrate, and divide the excipients into first excipients and second excipients; (5) Place the first auxiliary material in a fluidized bed granulator and spray the concentrated liquid to obtain shaped granules; (6) Prepare the second auxiliary material into an encapsulation solution, spray encapsulate the shaped particles, dry them, and sieve them to obtain pineapple powder.

[0010] Preferably, in step (1), the addition of γ-cyclodextrin to the pineapple juice and the stirring to dissolve it to obtain an inclusion solution includes: Wash and cut the pineapple into chunks, add pure water and juice it. Then, sieve the juice through a 350-400 mesh screen to obtain pineapple juice. Add γ-cyclodextrin to the pineapple juice and stir until completely dissolved to obtain an inclusion solution.

[0011] Preferably, the mass ratio of the pineapple to pure water is 1:(0.3~0.5). The amount of γ-cyclodextrin added is 5% to 10% of the total solids of the pineapple juice.

[0012] Preferably, in step (2), the pore size of the ceramic membrane used for ceramic membrane microfiltration is 200~800nm.

[0013] Preferably, in step (3), the dialysate is concentrated under vacuum and filtered to obtain a concentrated solution, comprising: The vacuum degree for vacuum concentration is set to -0.05~0.08 MPa, and the temperature is set to 50~70℃. The dialysate is concentrated to a solids content of 20-25%, and then sieved through a 200-300 mesh sieve to obtain a concentrated solution.

[0014] Preferably, in step (4), the excipients are weighed according to the total solids mass of the concentrate, and the excipients are divided into first excipients and second excipients, including: Based on the total solids mass M of the concentrate, weigh out the auxiliary materials with a total mass m in a certain proportion; Based on the total solids mass of the concentrate and the total mass of the excipients, a second excipient with a mass of m1 is separated, and the remaining mass of the excipient is the first excipient.

[0015] Preferably, in step (4), the mass ratio of total solids to excipients in the concentrate is M:m = 1:(0.8~1.5). The mass of the second auxiliary material m1 = (8%~12%) * (M + m); The excipient is any one or two of maltodextrin and γ-cyclodextrin, wherein when the excipient is maltodextrin and γ-cyclodextrin, the mass ratio of maltodextrin to γ-cyclodextrin is (8.5~9.5):1.

[0016] Preferably, in step (5), the first auxiliary material is placed in a fluidized bed granulator, and the concentrated liquid is sprayed onto it to obtain shaped granules, including: Set the inlet air temperature of the fluidized bed granulator to 50~100℃ and preheat the drying process for 15~30 minutes; Place the first auxiliary material into the fluidized bed granulator, control the fan frequency to 20~25Hz, adjust the air inlet temperature to 60~75℃, and heat up to the material temperature of 50~60℃. Turn on the peristaltic pump and control its speed to 5-15 rpm. Adjust the fan frequency to 25-40 Hz. Spray atomized pineapple concentrate through the spray gun and mix it with the first auxiliary material in the fluidized bed granulator to form uniform fine powder particles, thus obtaining shaped granules. Among the shaped granules, the mass percentage of particles passing through a 40-mesh sieve is ≥95%, and the mass percentage of particles passing through a 120-mesh sieve is ≤20%.

[0017] Preferably, in step (6), the process of preparing the second excipient into an encapsulation solution, spray-encapsulating the shaped particles, drying, and sieving to obtain pineapple powder includes: The second excipient is added to pure water to prepare a solution with a concentration of 15-25%, which is the encapsulation solution. The encapsulation solution is sprayed into a fluidized bed granulator to encapsulate the shaped particles, thereby obtaining the shaped material. After spray encapsulation is completed, adjust the inlet air temperature to 75~80℃ and dry the molded material until the moisture content is ≤4.0%; Once the temperature of the molded material drops below 40°C, it is sieved through a 40-120 mesh screen to obtain pineapple powder.

[0018] Accordingly, the present invention provides a pineapple fruit powder prepared by fluidized bed granulation, which is obtained by the aforementioned method for preparing pineapple fruit powder by fluidized bed granulation.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a method for preparing pineapple powder by fluidized bed granulation. γ-cyclodextrin is added before concentration, utilizing its hydrophobic cavity to encapsulate esters and aldehydes in the pineapple, forming a "host-guest inclusion complex," which fundamentally prevents flavor volatilization and oxidation. In addition, vacuum decompression concentration at a lower temperature also protects heat-sensitive substances in the pineapple, significantly improving the nutrient retention rate of the pineapple. Simultaneously, γ-cyclodextrin, in conjunction with maltodextrin as an excipient, achieves efficient retention of small molecule flavor substances in the fluidized bed granulation process, while maltodextrin acts as a carrier to provide the granulation framework.

[0020] (2) This invention provides a method for preparing pineapple fruit powder by fluidized bed granulation. Pineapple juice is extracted and passed through a 350-400 mesh sieve, and then γ-cyclodextrin is added to obtain an inclusion solution. The solution is then microfiltered through a 200-800 nm ceramic membrane and concentrated under vacuum to obtain a concentrated solution. The 350-400 mesh sieve and the 200-800 nm membrane microfiltration work synergistically to remove the macromolecular fibers and colloids of pineapple, resulting in a homogeneous solution. This solution is then concentrated to a solid content of 20-25%, precisely controlling the viscosity of the binder. This allows the concentrated solution to be dispersed at the molecular level in the excipients during the subsequent fluidized bed granulation process, forming dense microspheres and achieving high flowability.

[0021] (3) This invention provides a method for preparing pineapple fruit powder using fluidized bed granulation. It employs a combination of fluidized bed granulation and spray encapsulation. First, pineapple concentrate and excipients are granulated using fluidized bed granulation. Then, an encapsulation solution prepared from the reserved excipients is spray-encapsulated onto the granulated particles, forming a "core-shell structure." The granulated particles are porous cores with strong hydrophilicity and rapid dissolution, while the encapsulation layer is a dense shell with strong hydrophobicity and low hygroscopicity, fundamentally solving the contradiction between hygroscopicity and rapid dissolution in pineapple fruit powder. Furthermore, in the fluidized bed granulation process, this invention controls the material temperature to 50-60°C, granulating at a lower temperature. This not only preserves the original fresh flavor of the pineapple but also retains the microporous structure inside the granulated particles, achieving rapid dissolution.

[0022] Therefore, this invention, through the synergistic effect of the above-mentioned process steps and the combination of auxiliary materials, enhances the dissolution of active substances in pineapple, reduces the decomposition of heat-sensitive substances and the loss of flavor substances during the pineapple juice concentration and drying processes, and strengthens the aroma recovery and formation of highly soluble microspheres of fruit powder during the drying process, thereby enhancing the key product characteristics of pineapple fruit powder, such as aroma, flavor, and shape. The preparation method provided by this invention can achieve a polyphenol and vitamin C retention rate of over 30% in pineapple fruit powder, a coumaric acid flavor retention rate of over 20%, and a solubility of over 95%, making it suitable for large-scale production conversion.

[0023] In addition, the present invention provides a method for preparing pineapple powder by boiling granulation, which produces uniform and fine powder particles with the unique aroma of pineapple and improves the color reproduction of pineapple powder. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for preparing pineapple powder using fluidized bed granulation. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0026] like Figure 1 As shown, the present invention provides a method for preparing pineapple fruit powder by fluidized bed granulation, comprising the following specific steps: S100. Add γ-cyclodextrin to pineapple juice, stir to dissolve, and obtain an inclusion solution; Preferably, S100 includes the following steps: S101. Wash and cut the pineapple into chunks, add pure water and juice it, then sieve it through a 350-400 mesh screen to obtain pineapple juice; S102. Add γ-cyclodextrin to the pineapple juice and stir until it is completely dissolved to obtain an inclusion solution.

[0027] Preferably, the mass ratio of pineapple to pure water is 1:(0.3~0.5). After pulping and juicing, the juice is sieved through a 350~400 mesh screen to remove fruit pulp fragments and most of the insoluble solids, making the pineapple juice highly clear and laying the foundation for subsequent concentration.

[0028] It should be noted that the amount of γ-cyclodextrin added is 5% to 10% of the total solids of the pineapple juice. Within the above range, γ-cyclodextrin uses its hydrophobic cavity to encapsulate the esters and aldehydes in the pineapple, forming a "host-guest inclusion complex", which fundamentally prevents flavor volatilization and oxidation.

[0029] S200. The inclusion solution is microfiltered through a ceramic membrane to obtain a dialysate; Preferably, the inclusion solution is microfiltered through a ceramic membrane with a pore size of 200~800nm ​​to further remove macromolecular fibers and colloids from the inclusion solution, resulting in a uniform and clear dialysate. This allows the concentrate to be dispersed in the excipients at the molecular level during subsequent boiling granulation, reducing mass transfer resistance and enabling the formation of a more uniform microporous structure inside the granules, thereby significantly improving the wettability and dispersibility of the fruit powder.

[0030] S300. The dialysate is concentrated under vacuum and filtered to obtain a concentrated solution; Preferably, S300 includes the following steps: S301. Set the vacuum degree of vacuum concentration to -0.05~0.08Mpa and the temperature to 50~70℃; S302. Concentrate the dialysate to a solids content of 20-25%, and sieve it through a 200-300 mesh screen to obtain a concentrated solution.

[0031] The clarified dialysate was concentrated under vacuum at 50-70°C to a solids content of 20-25%, precisely controlling the concentration of the concentrate. In subsequent fluidized bed granulation, if the concentrate concentration is too high, it will not only cause difficulty in atomization but also lead to sticky powder particles, resulting in particle adhesion and adhesion to the inner wall of the fluidized bed granulator. If the concentrate concentration is too low, insufficient binding force will result in weak particle bonding, easy breakage, a high proportion of fine powder, and poor flowability.

[0032] Therefore, controlling the concentration of the concentrate is a key prerequisite for achieving high flowability of pineapple powder.

[0033] S400. Weigh the excipients according to the total solids mass of the concentrate, and divide the excipients into first excipients and second excipients; Preferably, S400 includes the following steps: S401. Based on the total solids mass M of the concentrate, weigh out the auxiliary materials with a total mass m in a certain proportion; S402. Based on the total solids mass of the concentrate and the total mass of the excipients, separate the second excipient with a mass of m1, and the remaining mass of the excipients is the first excipient.

[0034] Specifically, pineapple concentrate is used as a binder, the first excipient is used as a solid absorbent in the subsequent fluidized bed granulation process to obtain shaped granules, and the second excipient is reserved for the subsequent preparation of an encapsulation solution to spray-encapsulate the shaped granules.

[0035] Preferably, the mass ratio of total solids to excipients in the concentrate is M:m = 1:(0.8~1.5). The mass of the second auxiliary material m1 = (8%~12%) * (M+m). Within the above range, it can make the particle uniformity and flowability of subsequent fluidized bed granulation better, reduce the risk of clumping, sticking to the wall, sticking to the spray gun, fragility, and excessive fine powder, and improve the success rate of particle forming.

[0036] Preferably, the excipient is any one or two of maltodextrin and γ-cyclodextrin, wherein when the excipient is maltodextrin and γ-cyclodextrin, the mass ratio of maltodextrin to γ-cyclodextrin is (8.5~9.5):1.

[0037] Furthermore, maltodextrin provides a granulation framework as a carrier, while γ-cyclodextrin can efficiently retain small-molecule flavor substances in pineapple concentrate, reducing flavor loss.

[0038] S500. Place the first auxiliary material in a fluidized bed granulator and spray the concentrated liquid to obtain shaped granules; Preferably, S500 includes the following steps: S501. Set the inlet air temperature of the fluidized bed granulator to 50~100℃, and preheat the dryer for 15~30 minutes; S502. Place the first auxiliary material into the fluidized bed granulator, control the fan frequency to 20~25Hz, adjust the air inlet temperature to 60~75℃, and heat up to the material temperature of 50~60℃. S503. Turn on the peristaltic pump, control the peristaltic pump speed to 5~15 rpm, adjust the fan frequency to 25~40 Hz, spray the atomized pineapple concentrate through the spray gun, mix it with the first auxiliary material in the fluidized bed granulator, form uniform fine powder particles, and obtain shaped granules. Among the shaped granules, the mass percentage of particles passing through a 40-mesh sieve is ≥95%, and the mass percentage of particles passing through a 120-mesh sieve is ≤20%.

[0039] It should be noted that the sieve aperture size corresponding to the 40-mesh sieve is 425μm, and the sieve aperture size corresponding to the 120-mesh sieve is 125μm. That is, the formed particles with a particle size ≤425μm exceed 95%, and the formed particles with a particle size ≤125μm do not exceed 20%. This indicates that the formed particles produced are basically free of coarse particles, and also avoid excessive fine powder, which is conducive to achieving good flowability.

[0040] In the fluidized bed granulation process, this invention controls the material temperature to 50~60℃, granulating at a lower temperature, which not only preserves the original fresh flavor of pineapple, but also retains the microporous structure inside the shaped granules, enabling rapid dissolution.

[0041] If the temperature is too high, the pineapple concentrate will lose water quickly, causing the atomized droplets to become too viscous before contacting the auxiliary powder. This makes them prone to clumping and clogging on the walls of the fluidized bed granulator or the nozzle, eventually leading to bed collapse. If the temperature is too low, the granules will have poor flowability and dry slowly, resulting in overly wet granules that clump together.

[0042] Therefore, by controlling the fan frequency, air inlet temperature, and peristaltic pump speed of the fluidized bed granulator, low-temperature fluidized bed granulation is achieved, which not only avoids the loss of small molecule flavor substances in pineapple, but also successfully avoids the process risks of high-viscosity pineapple concentrate being prone to bed collapse and wall adhesion, thus producing high-quality granules with uniform particle size.

[0043] S600. Prepare an encapsulation solution from the second auxiliary material, spray-encapsulate the shaped particles, dry, and sieve to obtain pineapple powder.

[0044] Preferably, S600 includes the following steps: S601. Add the second excipient to pure water to prepare a solution with a concentration of 15-25% to obtain an encapsulation solution; S602. The encapsulation solution is sprayed into a fluidized bed granulator to encapsulate the shaped particles, thereby obtaining the shaped material; S603. After spray encapsulation is completed, adjust the inlet air temperature to 75~80℃ and dry the molded material until the moisture content is ≤4.0%; S604. After the temperature of the molding material drops below 40°C, it is sieved through a 40-120 mesh sieve to obtain pineapple powder.

[0045] Preferably, the second excipient is added to pure water to prepare a solution with a concentration of 15-25%. If the concentration of the encapsulation solution is too low, the formed particles will absorb a large amount of water before they can dry, causing the particle surface to become sticky, or even causing the particles to stick together and resulting in "secondary granulation". Moreover, the originally uniformly sized particles will also agglomerate, resulting in uneven particle size in the final particles. If the concentration of the encapsulation solution is too high, the high viscosity of the solution will cause atomization difficulties, leading to cracking of the encapsulation layer.

[0046] The reserved second auxiliary material is prepared into an encapsulation solution with a concentration of 15-25%. This ensures that the sprayed droplets are fine and uniform without introducing excessive water. When the droplets come into contact with the formed particles in the fluidized bed granulator, the water evaporates rapidly, forming a dense encapsulation layer on the surface of the formed particles, maintaining the original shape and structure of the formed particles. More preferably, the reserved second auxiliary material is prepared into an encapsulation solution with a concentration of 20%, but it is not limited to this.

[0047] Furthermore, by adjusting the air inlet temperature, the molding material is dried to a moisture content of ≤4.0%, making the encapsulation layer more robust and dense, tightly locking in the pineapple flavor substances inside, and preventing flavor loss or oxidation.

[0048] Accordingly, the present invention provides a pineapple fruit powder prepared by fluidized bed granulation, which is obtained by the aforementioned method for preparing pineapple fruit powder by fluidized bed granulation.

[0049] Therefore, this invention utilizes the inclusion effect of γ-cyclodextrin, followed by membrane microfiltration and low-temperature vacuum concentration, and then low-temperature boiling granulation and spray encapsulation to produce pineapple fruit powder that not only has high solubility, good flowability, low hygroscopicity, and significantly improved nutrient retention, but also enhances the dissolution of pineapple active substances, reduces the decomposition of heat-sensitive substances and loss of flavor substances during the pineapple juice concentration and drying process, and strengthens the aroma recovery and formation of highly soluble microsphere fruit powder during the drying process. This enhances the key product characteristics of pineapple fruit powder, such as aroma, flavor, and shape, while also having low processing costs and a long shelf life.

[0050] The following will provide further details with reference to specific embodiments.

[0051] To verify whether peeling or not peeling pineapple affects the nutritional components and flavor compounds of pineapple juice, this invention conducted the following investigation, including the following steps: (1) Take a pineapple, wash it, cut it in half, peel off the skin of one half, cut it into pieces, add 1 / 3 of its weight of pure water, and juice it to obtain peeled and juiced pineapple juice. (2) The other part is not peeled, cut into pieces, added with 1 / 3 of its weight of pure water, and juiced to obtain unpeeled pineapple juice; (3) Test the juice of peeled and unpeeled pineapples separately.

[0052] The test results are shown in Table 1: Table 1. Comparison of pineapple juice extracted with and without peel.

[0053] The results showed that whether or not the pineapple peel was removed had no significant impact on the nutritional components and flavor compounds of the pineapple juice. Therefore, this study adopted the method of juicing without peeling for subsequent research.

[0054] (a) Preparation Example 1 Embodiment 1 of the present invention provides a method for preparing pineapple fruit powder by fluidized bed granulation, comprising the following steps: (1) Add γ-cyclodextrin to pineapple juice, stir to dissolve, and obtain inclusion solution; Take a pineapple, wash it, cut it into pieces, add 1 / 3 of its weight in pure water, blend it into a pulp, extract the juice, and pass it through a 350-mesh sieve to obtain pineapple juice. Add 5% of the total solids of the pineapple juice in γ-cyclodextrin, stir to dissolve, and obtain an inclusion solution.

[0055] (2) The inclusion solution is microfiltered through an 800nm ​​ceramic membrane to obtain a dialysis solution.

[0056] (3) The dialysate is concentrated under vacuum and filtered to obtain a concentrated solution; Vacuum concentration was performed with a vacuum level of -0.05 MPa to -0.08 MPa and a temperature of 60°C. The solution was concentrated until the solid content was 25%, and then passed through a 200-mesh sieve to obtain the concentrate.

[0057] (4) Weigh the excipients according to the total solids mass of the concentrate, and divide the excipients into first excipients and second excipients; Based on the mass ratio of total solids in the concentrate to excipients M:m = 1:1, the total mass of excipients is weighed as m. Among them, the excipients are weighed by mixing maltodextrin and γ-cyclodextrin in a ratio of 9:1. The second excipient with a mass of m1 is separated out, and the remaining mass of excipients is the first excipient. The second excipient is reserved for subsequent encapsulation treatment, and the amount of reserved excipients is 10% of the sum of the total amount of excipients and the total solids in the concentrate.

[0058] (5) Place the first auxiliary material in a fluidized bed granulator and spray the concentrated liquid to obtain shaped granules; Set the inlet air temperature of the fluidized bed granulator to 100℃ and preheat for 15 minutes. Place the first auxiliary material in the fluidized bed granulator, control the fan frequency to 20~25Hz, adjust the inlet air temperature to 75℃, and heat to 50℃. Turn on the peristaltic pump and control the peristaltic pump speed to 5~15rpm. Spray in the pineapple concentrate, and observe the material flow during this process. Adjust the fan frequency to 25~40Hz according to the material flow. After the pineapple concentrate is sprayed in, maintain the inlet air temperature at 60±5℃, adjust the fan frequency to 25Hz, and dry for 20 minutes to obtain shaped granules. Among the shaped granules, 98% of the granules by mass can pass through a 40-mesh sieve, and 9% of the granules by mass can pass through a 120-mesh sieve.

[0059] (6) Prepare the second auxiliary material into an encapsulation solution, spray encapsulate the shaped particles, dry them, and sieve them to obtain pineapple powder.

[0060] Control the fan frequency to 20~25Hz, maintain the inlet air temperature at 60℃ and the material temperature at 50℃, control the peristaltic pump speed to 5~15rpm, add the second auxiliary material to pure water to prepare a 20% concentration encapsulation solution, spray it into the fluidized bed granulator to spray encapsulate the formed granules, after completion, adjust the inlet air temperature to 80℃, dry the material until the moisture content is less than 4.0% (using a rapid moisture analyzer (120℃, 10 minutes)), turn off the electric heating, and wait for the material temperature to drop below 40℃ before discharging. Pass the obtained material through a 40~120 mesh sieve to obtain pineapple fruit powder.

[0061] Example 2 Embodiment 2 of the present invention provides a method for preparing pineapple fruit powder by fluidized bed granulation, comprising the following steps: (1) Add γ-cyclodextrin to pineapple juice, stir to dissolve, and obtain inclusion solution; Take a pineapple, wash it, cut it into pieces, add 1 / 3 of its weight in pure water, blend it into a pulp, extract the juice, and pass it through a 350-mesh sieve to obtain pineapple juice. Add 10% of the total solids of the pineapple juice in γ-cyclodextrin, stir to dissolve, and obtain an inclusion solution.

[0062] (2) The inclusion solution is microfiltered through a 200nm ceramic membrane to obtain a dialysis solution.

[0063] (3) The dialysate is concentrated under vacuum and filtered to obtain a concentrated solution; Vacuum concentration was performed with a vacuum level of -0.05 MPa to -0.08 MPa and a temperature of 60°C. The solution was concentrated until the solid content was 25%, and then passed through a 200-mesh sieve to obtain the concentrate.

[0064] (4) Weigh the excipients according to the total solids mass of the concentrate, and divide the excipients into first excipients and second excipients; Based on the mass ratio of total solids in the concentrate to excipients M:m = 1:1, weigh out the total mass of excipients as m, where the excipient is maltodextrin. Separate out the second excipient with a mass of m1, and the remaining mass of excipients is the first excipient. The second excipient is reserved for subsequent encapsulation treatment, and the amount of reserved excipient is 10% of the sum of the total excipients and the total solids in the concentrate.

[0065] (5) Place the first auxiliary material in a fluidized bed granulator and spray the concentrated liquid to obtain shaped granules; Set the inlet air temperature of the fluidized bed granulator to 100℃ and preheat for 15 minutes. Place the first auxiliary material in the fluidized bed granulator, control the fan frequency to 20~25Hz, adjust the inlet air temperature to 75℃, and heat to 50℃. Turn on the peristaltic pump and control the peristaltic pump speed to 5~15rpm. Spray in the pineapple concentrate, and observe the material flow during this process. Adjust the fan frequency to 25~40Hz according to the material flow. After the pineapple concentrate is sprayed in, maintain the inlet air temperature at 60±5℃, adjust the fan frequency to 25Hz, and dry for 20 minutes to obtain shaped granules. Among the shaped granules, 99% of the granules by mass can pass through a 40-mesh sieve, and 11% of the granules by mass can pass through a 120-mesh sieve.

[0066] (6) Prepare the second auxiliary material into an encapsulation solution, spray encapsulate the shaped particles, dry them, and sieve them to obtain pineapple powder.

[0067] Control the fan frequency to 20~25Hz, maintain the inlet air temperature at 60℃ and the material temperature at 50℃, control the peristaltic pump speed to 5~15rpm, add the second auxiliary material to pure water to prepare a 20% concentration encapsulation solution, spray it into the fluidized bed granulator to spray encapsulate the formed granules, after completion, adjust the inlet air temperature to 80℃, dry the material until the moisture content is less than 4.0% (using a rapid moisture analyzer (120℃, 10 minutes)), turn off the electric heating, and wait for the material temperature to drop below 40℃ before discharging. Pass the obtained material through a 40~120 mesh sieve to obtain pineapple fruit powder.

[0068] Example 3 Example 3 of this invention provides a method for preparing pineapple fruit powder by fluidized bed granulation, comprising the following steps: (1) Add γ-cyclodextrin to pineapple juice, stir to dissolve, and obtain inclusion solution; Take a pineapple, wash it, cut it into pieces, add 1 / 3 of its weight in pure water, blend it into a pulp, extract the juice, and pass it through a 350-mesh sieve to obtain pineapple juice. Add 10% of the total solids of the pineapple juice in γ-cyclodextrin, stir to dissolve, and obtain an inclusion solution.

[0069] (2) The inclusion solution is microfiltered through a 200nm ceramic membrane to obtain a dialysis solution.

[0070] (3) The dialysate is concentrated under vacuum and filtered to obtain a concentrated solution; Vacuum concentration was performed with a vacuum level of -0.05 MPa to -0.08 MPa and a temperature of 60°C. The solution was concentrated until the solid content was 25%, and then passed through a 200-mesh sieve to obtain the concentrate.

[0071] (4) Weigh the excipients according to the total solids mass of the concentrate, and divide the excipients into first excipients and second excipients; Based on the mass ratio of total solids in the concentrate to excipients M:m = 1:1, the total mass of excipients is weighed as m. Among them, the excipients are weighed by mixing maltodextrin and γ-cyclodextrin in a ratio of 9:1. The second excipient with a mass of m1 is separated out, and the remaining mass of excipients is the first excipient. The second excipient is reserved for subsequent encapsulation treatment, and the amount of reserved excipients is 10% of the sum of the total amount of excipients and the total solids in the concentrate.

[0072] (5) Place the first auxiliary material in a fluidized bed granulator and spray the concentrated liquid to obtain shaped granules; Set the inlet air temperature of the fluidized bed granulator to 100℃ and preheat for 15 minutes. Place the first auxiliary material in the fluidized bed granulator, control the fan frequency to 20~25Hz, adjust the inlet air temperature to 75℃, and heat to 50℃. Turn on the peristaltic pump and control the peristaltic pump speed to 5~10rpm. Spray in pineapple concentrate, and observe the material flow during this process. Adjust the fan frequency to 25~40Hz according to the material flow. After the pineapple concentrate is sprayed in, maintain the inlet air temperature at 60±5℃, adjust the fan frequency to 25Hz, and dry for 20 minutes to obtain shaped granules. Among the shaped granules, 99% of the granules by mass can pass through a 40-mesh sieve, and 10% of the granules by mass can pass through a 120-mesh sieve.

[0073] (6) Prepare the second auxiliary material into an encapsulation solution, spray encapsulate the shaped particles, dry them, and sieve them to obtain pineapple powder.

[0074] Control the fan frequency to 20~25Hz, maintain the inlet air temperature at 60℃ and the material temperature at 50℃, control the peristaltic pump speed to 5~15rpm, add the second auxiliary material to pure water to prepare a 20% concentration encapsulation solution, spray it into the fluidized bed granulator to spray encapsulate the formed granules, after completion, adjust the inlet air temperature to 80℃, dry the material until the moisture content is less than 4.0% (using a rapid moisture analyzer (120℃, 10 minutes)), turn off the electric heating, and wait for the material temperature to drop below 40℃ before discharging. Pass the obtained material through a 40~120 mesh sieve to obtain pineapple fruit powder.

[0075] Comparative Example 1 Comparative Example 1 of this invention provides a method for preparing pineapple fruit powder, comprising the following steps: (1) Select fresh and ripe pineapple, wash it, peel and remove the core, cut it into thin slices of about 1cm, cut it into chunks, and set aside.

[0076] (2) Place the pineapple slices on a steaming tray and steam for 1 minute to inactivate the enzymes. Remove them and place them in an ice bath at 4~10℃. Quickly cool them to room temperature, then add one-third of their weight of pure water and blend for 1 minute to obtain pineapple pulp.

[0077] (3) Add 0.10% cellulase (w / w, percentage of total weight of pulp) and 0.3% pectinase (w / w, percentage of total weight of pulp) to the pineapple pulp, control the pH of the pineapple pulp to 4.5, and enzymatically hydrolyze for 2 hours at 50℃. (4) Add 120% maltodextrin to the enzymatically hydrolyzed pineapple pulp, stir evenly, and use vacuum freeze-drying method to obtain pineapple powder. Crush and sieve to obtain pineapple powder.

[0078] Comparative Example 2 Comparative Example 2 of this invention provides a method for preparing pineapple fruit powder, comprising the following steps: (1) Take a fresh, ripe pineapple, wash it, cut it into pieces, add 1 / 3 of its weight of pure water, blend it into a pulp, juice it, and pass it through a 350-mesh sieve to obtain pineapple juice.

[0079] (2) Add 10% of the total solids of pineapple juice with γ-cyclodextrin, concentrate under vacuum, set the vacuum degree to -0.05Mpa~-0.08Mpa, the temperature to 60℃, concentrate until the solids content is 20%, pass through a 200-mesh sieve to obtain pineapple concentrate.

[0080] (3) Add maltodextrin equal to the amount of pineapple concentrate solids, heat and stir to dissolve evenly, spray dry, set the air inlet temperature to 170℃~190℃ (preferably 175℃) and the air outlet temperature to 85℃~95℃ (preferably 90℃), collect the spray-dried powder, sieve it to obtain pineapple fruit powder.

[0081] Comparative Example 3 Comparative Example 3 of this invention provides a method for preparing pineapple fruit powder, comprising the following steps: (1) Take a fresh, ripe pineapple, wash it, cut it into pieces, add 1 / 3 of its weight of pure water, blend it into a pulp, juice it, and pass it through a 350-mesh sieve to obtain pineapple juice.

[0082] (2) Add 10% of the total solids of pineapple juice with γ-cyclodextrin, stir to dissolve, and filter through a 200nm ceramic membrane to obtain dialysate. Then concentrate under vacuum, setting the vacuum degree to -0.05Mpa~-0.08Mpa and the temperature to 60℃, until the solids content is 20%. Pass through a 200-mesh sieve to obtain pineapple concentrate.

[0083] (3) Add maltodextrin equal to the amount of pineapple concentrate solids, heat and stir to dissolve evenly, and spray dry. Set the air inlet temperature to 170℃~190℃ (preferably 175℃) and the air outlet temperature to 85℃~95℃ (preferably 90℃) to obtain pineapple spray-dried powder.

[0084] (4) Control the fan frequency to 20~25Hz, the air inlet temperature to 60℃, the material temperature to 50℃, and the peristaltic pump speed to 5~15rpm. Weigh the auxiliary materials according to the ratio of pineapple spray powder to auxiliary materials = 1:1. The auxiliary materials are weighed by mixing maltodextrin and γ-cyclodextrin in a ratio of 9:1. Prepare a 20% concentration solution and spray it into the fluidized bed granulator to spray and encapsulate the pineapple spray powder. After spraying, set the air inlet temperature to 80℃ and dry the material until the moisture content is less than 4.0% (using a rapid moisture analyzer (120℃, 10 minutes)). Turn off the electric heating and wait until the material temperature drops below 40℃ before discharging. The obtained material is passed through a 40~120 mesh sieve to obtain pineapple fruit powder.

[0085] Comparative Example 4 Comparative Example 4 of this invention provides a method for preparing pineapple fruit powder, comprising the following steps: (1) Take a pineapple, wash it, cut it into pieces, add 1 / 3 of its weight of pure water, blend it into a pulp, juice it, and pass it through a 350-mesh sieve to obtain pineapple juice.

[0086] (2) The pineapple juice was microfiltered through a 200nm ceramic membrane to obtain a dialysate, which was then concentrated under vacuum. The vacuum was set to -0.05Mpa~-0.08Mpa and the temperature was 60℃. The concentration was carried out until the solid content was 20%, and then passed through a 200-mesh sieve to obtain the pineapple concentrate.

[0087] (3) Weigh the excipients according to the ratio of total solids of pineapple concentrate to excipients = 1:1. The excipients are weighed by mixing maltodextrin and γ-cyclodextrin in a ratio of 9:1. Reserve a portion of the excipients for subsequent encapsulation treatment. The amount of the reserved excipients is 10% of the total amount of excipients and the total solids of the concentrate.

[0088] (4) Set the inlet air temperature of the fluidized bed granulator to 100℃, preheat for 15 minutes, place the remaining mass of auxiliary material into the fluidized bed granulator, control the fan frequency to 20~25Hz, the inlet air temperature to 75℃, raise the temperature to 50℃, turn on the peristaltic pump, control the peristaltic pump speed to 5~10rpm, spray in the pineapple concentrate, observe the material flow state during the process, adjust the fan frequency to 25~40Hz according to the material flow state, after the pineapple concentrate is sprayed in, maintain the inlet air temperature at 60±5℃, adjust the fan frequency to 25Hz, and dry for 20 minutes.

[0089] (5) Control the fan frequency to 20~25Hz, the air inlet temperature to 60℃, the material temperature to 50℃, and the peristaltic pump speed to 5~15rpm. Add the reserved auxiliary materials to pure water to prepare a 20% concentration solution, spray it into the fluidized bed granulator for spray coating, and after completion, adjust the air inlet temperature to 80℃. Dry the material until the moisture content is less than 4.0% (using a rapid moisture analyzer (120℃, 10 minutes)). Turn off the electric heating. When the material temperature drops below 40℃, the material can be discharged. Pass the obtained material through a 40~120 mesh sieve to obtain pineapple powder.

[0090] Comparative Example 5 Comparative Example 5 of this invention provides a method for preparing pineapple fruit powder, comprising the following steps: (1) Take a pineapple, wash it, cut it into pieces, add 1 / 3 of its weight of pure water, blend it into a pulp, juice it, and pass it through a 350-mesh sieve to obtain pineapple juice.

[0091] (2) Add 10% of the total solids of pineapple juice with γ-cyclodextrin, stir to dissolve, and use a membrane separation device to first pass it through a 200nm ceramic membrane, and then take the dialysate to separate and concentrate it through a reverse osmosis membrane until the solids content is 15%, to obtain pineapple concentrate.

[0092] (3) Weigh the excipients according to the ratio of total solids of pineapple concentrate to excipients = 1:1. The excipients are weighed by mixing maltodextrin and γ-cyclodextrin in a ratio of 9:1. Reserve a portion of the excipients for subsequent encapsulation treatment. The amount of the reserved excipients is 10% of the total amount of excipients and the total solids of the concentrate.

[0093] (4) Set the inlet air temperature of the fluidized bed granulator to 100℃, preheat for 15 minutes, place the remaining mass of auxiliary material into the fluidized bed granulator, control the fan frequency to 20~25Hz, the inlet air temperature to 75℃, raise the temperature to 50℃, turn on the peristaltic pump, control the peristaltic pump speed to 5~10rpm, spray in the pineapple concentrate, observe the material flow state during the process, adjust the fan frequency to 25~40Hz according to the material flow state, after the pineapple concentrate is sprayed in, maintain the inlet air temperature at 60±5℃, adjust the fan frequency to 25Hz, and dry for 20 minutes.

[0094] (5) Control the fan frequency to 20~25Hz, the air inlet temperature to 60℃, the material temperature to 50℃, and the peristaltic pump speed to 5~15rpm. Add the reserved auxiliary materials to pure water to prepare a 20% concentration solution, spray it into the fluidized bed granulator for spray coating, and after completion, adjust the air inlet temperature to 80℃. Dry the material until the moisture content is less than 4.0% (using a rapid moisture analyzer (120℃, 10 minutes)). Turn off the electric heating. When the material temperature drops below 40℃, the material can be discharged. Pass the obtained material through a 40~120 mesh sieve to obtain pineapple powder.

[0095] (II) Testing 1. The pineapple fruit powders obtained in Examples 1-3 and Comparative Examples 1-5 were tested using the following methods: (1) The properties of pineapple powder were evaluated using flowability (angle of repose), hygroscopicity, bulk density and solubility as indicators; among them, solubility was evaluated by adding 1g of pineapple powder to 100mL of hot water and stirring until completely dissolved, and the dissolution time was used as the evaluation.

[0096] (2) The polyphenols, vitamin C and p-coumaric acid in pineapple powder were determined separately to evaluate the nutritional components of pineapple powder.

[0097] S210. Polyphenol Detection Method: S211. Preparation of solutions To prepare 10% Folin-Citrophenol reagent (freshly prepared): Transfer 10 mL of Folin-Citrophenol reagent to a 100 mL volumetric flask, dilute to the mark with distilled water, and shake well. To prepare a 7.5% sodium carbonate solution: Weigh 7.5g of sodium carbonate, dissolve it in an appropriate amount of distilled water, transfer it to a 100mL volumetric flask, dilute to the mark, and shake well. To prepare a 70% ethanol solution: Measure 700 mL of anhydrous ethanol, dissolve it in distilled water, transfer it to a 1000 mL volumetric flask, dilute to the mark, and shake well. Prepare a 0.1 mg / ml gallic acid standard solution (freshly prepared): Weigh 10.0 mg (0.1 mg accuracy) of gallic acid standard into a 100 mL volumetric flask, dissolve in distilled water, dilute to the mark, and shake well.

[0098] S212. Sample Preparation Weigh 1g of pineapple fruit powder accurately and place it in a 50mL volumetric flask. Add 30mL of 70% ethanol solution and sonicate for 60min under an ultrasonic power of 400W. After cooling, add 70% ethanol to the mark, shake well, centrifuge, and keep the supernatant for later use. This is the sample test solution.

[0099] S213. Preparation of Standard Curve and Sample Measurement Accurately pipette 0 mL, 0.2 mL, 0.3 mL, 0.4 mL, 0.5 mL, and 0.6 mL of gallic acid standard solution and 1 mL of sample test solution into separate 10 mL graduated test tubes. Add water to a final volume of 0.5–1 mL, add 5.0 mL of 10% Folin-Ciocalteu reagent, and mix well. Within 3–8 minutes of reaction, add 4.0 mL of 7.5% sodium carbonate solution and mix well. Incubate at room temperature in the dark for 60 minutes. Using a 10 mm cuvette, measure the absorbance using a spectrophotometer at a wavelength of 765 nm. Plot a standard curve based on the results.

[0100] Based on the standard curve and dilution factor, the polyphenol content in the sample is expressed as a mass fraction w, calculated using the following formula:

[0101] In the formula, m1: the polyphenol content in the sample solution obtained from the standard curve, in micrograms (μg). n: Sample dilution factor; m2: Sample mass, in grams (g).

[0102] S220. Vitamin C Detection Method: S221. Chromatographic conditions and system suitability test Chromatographic column: A C18 (Shimadzu-speaker) column was used, with a length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 5 μm; Mobile phase: Phase A uses 0.02 mol / L potassium dihydrogen phosphate, dissolved in distilled water and brought to a final volume of 1 L, and the pH is adjusted to 2.7~2.8 with phosphoric acid. Phase B uses 100% methanol, measured at A:B = 98:2 and mixed, then filtered through a 0.45 μm filter membrane and ultrasonically degassed. The flow rate was set to 0.7 mL / min; the column temperature was set to 25 °C; and an ultraviolet detector or a diode array detector was used, with the detection wavelength set to 245 nm.

[0103] S222. Preparation of solutions Preparation of L(+)-ascorbic acid standard stock solution: Accurately weigh an appropriate amount of L(+)-ascorbic acid standard, and dilute to 50 mL with 20 g / L metaphosphoric acid solution. This stock solution can be stored for one week under the protection of light at 2℃~8℃, and is prepared into a solution containing approximately 50 μg per mL.

[0104] Prepare a series of L(+)-ascorbic acid standard working solutions (freshly prepared): Take L(+)-ascorbic acid standard stock solution and dilute it to volume with 20 g / L metaphosphoric acid solution so that the concentrations of L(+)-ascorbic acid in the standard series working solutions are 0 μg / mL, 0.5 μg / mL, 5.0 μg / mL, 10.0 μg / mL, 25.0 μg / mL, and 50.0 μg / mL, respectively.

[0105] S223. Preparation of test solution Take 2-5g (accurate to 0.001g) of pineapple fruit powder, place it in a 50mL beaker, dissolve it with 20g / L metaphosphoric acid solution, transfer the sample to a 50mL brown volumetric flask, shake to dissolve and make up to volume, shake well, and then transfer the whole sample to a 50mL centrifuge tube. After ultrasonic extraction for 5min, centrifuge at 4000r / min for 5min, take the supernatant and filter it through a 0.45μm aqueous phase filter membrane to obtain the test solution.

[0106] S224. Determination Method Accurately pipette 5 μl each of L(+)-ascorbic acid solution and test solution from the standard series working solutions, inject them into the liquid chromatograph, record the chromatograms, and quantify using the external standard method based on peak area.

[0107] S230. Method for detecting coumaric acid: S231. Chromatographic conditions Chromatographic column: Acquity UPLC BEH C18 (2.1mm×50.0mm, 1.7μm) was used as the chromatographic column, and Acquity UPLC BEH C18 (2.1mm×5.0mm, 1.7μm) was used as the guard column; the column temperature was 30℃.

[0108] Mobile phase: Mobile phase A was 0.1% formic acid acetonitrile, and mobile phase B was 0.1% formic acid water for chromatographic condition testing; The mobile phase elution procedure is shown in Table 2: Table 2 shows the mobile phase elution procedure.

[0109] S232. Mass Spectrometry Conditions An electrospray ionization source (ESI) was used, with an ESI ionization voltage of -0.6 kV; a negative ion mode was used, with an ion source temperature of 150℃; a desolventization temperature of 600℃; a desolventization gas (N2) flow rate of 1000 L / h; and a cone gas (N2) flow rate of 50 L / h.

[0110] The mass spectrometry conditions for p-coumaric acid are shown in Table 3: Table 3 shows the mass spectrometry conditions for p-coumaric acid.

[0111] S233. Preparation of working solutions for reference standard series Accurately weigh p-coumaric acid reference standard, dissolve it in methanol, and prepare solutions with concentrations of 0.04 µg / mL, 0.08 µg / mL, 0.2 µg / mL, 0.4 µg / mL, 1 µg / mL, 2 µg / mL, and 5 µg / mL, respectively.

[0112] S234. Preparation of test solution Take 1-2g (accurate to 0.001g) of pineapple fruit powder, accurately weigh it into a stoppered conical flask, accurately add 20mL of methanol, stopper tightly, weigh it, set the ultrasonic power to 400W and the frequency to 40kHz, sonicate for 30min, cool it, weigh it again, make up the lost mass with methanol, shake well, filter it through a 0.22μm microporous membrane to obtain the test solution.

[0113] S235. Determination Method Accurately pipette 2 μl of each of the reference standard series working solution and the test solution, inject them into the liquid chromatograph, record the chromatograms, and quantify using the external standard method based on peak area.

[0114] 2. The test results are shown in Tables 4 and 5: Table 4 compares the properties of pineapple powder from the examples and comparative examples.

[0115] Table 5 shows the nutritional components of pineapple powder from the examples and comparative examples.

[0116] Comparative Example 1, after enzymatic hydrolysis, showed a pineapple powder with an angle of repose as high as 45° and a dissolution time as long as 10 seconds. The color changed significantly during dissolution, turning grayish-yellow. Furthermore, other odors produced during the enzymatic hydrolysis process were quite noticeable, masking the original pineapple flavor characteristics. Comparative Example 2, using a traditional spray drying process, suffered from severe thermosetting. The high-temperature air intake of 175°C caused the surface of the pineapple powder particles to harden and the internal pores to collapse, resulting in an angle of repose as high as 42° and an excessively high bulk density of 0.66. The concentration of pineapple powder was 100 g / ml, and the dissolution time was as long as 26 seconds. At the same time, the vitamin C retention rate was only 30.31%, resulting in a drastic loss of nutrients. Comparative Examples 3 and 2 also used the traditional spray drying process. Although a spray encapsulation process was added, due to the high temperature of spray drying, the vitamin C retention rate was only 28.18%, and the coumaric acid retention rate was 55.91%, resulting in a significant loss of nutrients. Comparative Example 4 did not add γ-cyclodextrin before vacuum concentration, resulting in a low vitamin C retention rate of only 42.16%. Comparative Example 5 simply used reverse osmosis membrane separation and concentration. Due to the solid content being concentrated to only 15%, the proportion of excipients in the pineapple powder was too high. Although filtered through a ceramic membrane, its hygroscopicity was still as high as 12%, and its solubility was poor, with a dissolution time of 3 seconds. More seriously, its vitamin C retention rate was extremely low, only 21.47%. This may be due to oxidative browning caused by shear force during membrane separation or prolonged low-temperature operation.

[0117] In contrast, the pineapple powder prepared by fluidized bed granulation provided in Examples 1-3 of this invention has a repose angle of 31°~33°, hygroscopicity controlled below 9%, bulk density maintained at 0.34~0.38 g / ml, dissolution time of only 1~2 seconds, and high nutrient retention rate. These superior physical properties are attributed to the following three key synergistic effects: First, the addition of γ-cyclodextrin during the concentration stage forms a host-guest inclusion complex, protecting flavor compounds and improving the thermoplasticity of the material. Simultaneously, γ-cyclodextrin, in conjunction with maltodextrin as an excipient, achieves efficient retention of small-molecule flavor compounds in the fluidized bed granulation process, while maltodextrin acts as a carrier providing the granulation framework. Second, the "membrane microfiltration + vacuum decompression concentration" precisely controls the solids concentration at 25%, providing the optimal binder viscosity for fluidized bed granulation, resulting in uniform and porous particle formation. Third, the "low-temperature fluidized bed granulation + spray encapsulation" process constructs a core-shell structure, where the outer excipient effectively isolates moisture, while the porous inner core accelerates moisture penetration. In summary, this specific combined process fundamentally improves the commercial application performance of pineapple powder by constructing a microspherical structure.

[0118] Therefore, the combined process of "γ-cyclodextrin synergistic with maltodextrin + membrane microfiltration + vacuum decompression concentration + low-temperature boiling granulation + spray encapsulation" adopted in this invention, through precise matching of process parameters, successfully solves the problems of poor solubility, poor flowability, high hygroscopicity, and low flavor content retention of pineapple powder.

[0119] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing pineapple fruit powder using fluidized bed granulation, characterized in that, The specific steps include the following: (1) Add γ-cyclodextrin to pineapple juice, stir to dissolve, and obtain inclusion solution; (2) The inclusion solution is microfiltered through a ceramic membrane to obtain a dialysate; (3) The dialysate is concentrated under vacuum and filtered to obtain a concentrated solution; (4) Weigh the excipients according to the total solids mass of the concentrate, and divide the excipients into first excipients and second excipients; (5) Place the first auxiliary material in a fluidized bed granulator and spray the concentrated liquid to obtain shaped granules; (6) Prepare the second auxiliary material into an encapsulation solution, spray encapsulate the shaped particles, dry them, and sieve them to obtain pineapple powder.

2. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 1, characterized in that, In step (1), the addition of γ-cyclodextrin to pineapple juice and the stirring to dissolve it to obtain an inclusion solution includes: Wash and cut the pineapple into chunks, add pure water and juice it. Then, sieve the juice through a 350-400 mesh screen to obtain pineapple juice. Add γ-cyclodextrin to the pineapple juice and stir until completely dissolved to obtain an inclusion solution.

3. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 2, characterized in that, The mass ratio of pineapple to pure water is 1:(0.3~0.5). The amount of γ-cyclodextrin added is 5% to 10% of the total solids of the pineapple juice.

4. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 1, characterized in that, In step (2), the pore size of the ceramic membrane used for ceramic membrane microfiltration is 200~800nm.

5. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 1, characterized in that, In step (3), the dialysate is concentrated under vacuum and filtered to obtain a concentrated solution, comprising: The vacuum degree for vacuum concentration is set to -0.05~0.08 MPa, and the temperature is set to 50~70℃. The dialysate is concentrated to a solids content of 20-25%, and then sieved through a 200-300 mesh sieve to obtain a concentrated solution.

6. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 1, characterized in that, In step (4), the excipients are weighed according to the total solids mass of the concentrate, and the excipients are divided into first excipients and second excipients, including: Based on the total solids mass M of the concentrate, weigh out the auxiliary materials with a total mass m in a certain proportion; Based on the total solids mass of the concentrate and the total mass of the excipients, a second excipient with a mass of m1 is separated, and the remaining mass of the excipient is the first excipient.

7. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 6, characterized in that, In step (4), the mass ratio of total solids to excipients in the concentrate is M:m = 1:(0.8~1.5). The mass of the second auxiliary material m1 = (8%~12%) * (M + m); The excipient is any one or two of maltodextrin and γ-cyclodextrin, wherein when the excipient is maltodextrin and γ-cyclodextrin, the mass ratio of maltodextrin to γ-cyclodextrin is (8.5~9.5):

1.

8. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 1, characterized in that, In step (5), the first auxiliary material is placed in a fluidized bed granulator, and the concentrated liquid is sprayed on it to obtain shaped granules, including: Set the inlet air temperature of the fluidized bed granulator to 50~100℃ and preheat the drying process for 15~30 minutes; Place the first auxiliary material into the fluidized bed granulator, control the fan frequency to 20~25Hz, adjust the air inlet temperature to 60~75℃, and heat up to the material temperature of 50~60℃. Turn on the peristaltic pump and control its speed to 5-15 rpm. Adjust the fan frequency to 25-40 Hz. Spray atomized pineapple concentrate through the spray gun and mix it with the first auxiliary material in the fluidized bed granulator to form uniform fine powder particles, thus obtaining shaped granules. Among the shaped granules, the mass percentage of particles passing through a 40-mesh sieve is ≥95%, and the mass percentage of particles passing through a 120-mesh sieve is ≤20%.

9. The method for preparing pineapple fruit powder by fluidized bed granulation according to claim 1, characterized in that, In step (6), the process of preparing the second excipient into an encapsulation solution, spray-encapsulating the shaped particles, drying, and sieving to obtain pineapple powder includes: The second excipient is added to pure water to prepare a solution with a concentration of 15-25%, which is the encapsulation solution. The encapsulation solution is sprayed into a fluidized bed granulator to encapsulate the shaped particles, thereby obtaining the shaped material. After spray encapsulation is completed, adjust the inlet air temperature to 75~80℃ and dry the molded material until the moisture content is ≤4.0%; Once the temperature of the molded material drops below 40°C, it is sieved through a 40-120 mesh screen to obtain pineapple powder.

10. A pineapple fruit powder prepared by fluidized bed granulation, characterized in that, It is prepared by the method for preparing pineapple fruit powder by fluidized bed granulation as described in any one of claims 1 to 9.

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