Process for producing loquat pollen and solid beverage by adopting nanotechnology

Abstract

The invention belongs to the technical field of food processing, and discloses a technology for producing loquat pollen and a solid beverage by adopting a nanotechnology. The process comprises the steps of low-temperature non-thermal synergistic passivation, nano-scale cell wall breaking, active ingredient nano-packaging, flavor directional regulation and control, low-temperature vacuum drying and the like, and through the synergistic effect of a pulsed electric field-ultrasonic composite passivation, chitosan-sodium alginate nano-embedding and a flavor modifier, the flavor is improved; the triterpenoid saponin and flavone are efficiently reserved, the peculiar smell is obviously reduced, and the instant solubility is improved. The biological accessibility of the obtained product is improved by 3.2 times, and the product is stable in color and has a high-value application prospect.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology and relates to a process for producing loquat pollen and solid beverages using nanotechnology. Background Technology

[0002] Loquat flowers, a traditional medicinal and edible plant resource, are rich in 18 essential amino acids, vitamin C, nucleic acids, various minerals (such as Ca, Zn, and Fe), and triterpenoid saponins, demonstrating significant application potential in the functional food and health beverage fields. Recorded in the classic Chinese medicine text *Compendium of Materia Medica*, they possess multiple effects including "quenching thirst, regulating qi, benefiting the lungs, stopping vomiting, clearing heat, and nourishing the five internal organs." Modern research has also confirmed their clear physiological activities in moistening the lungs and resolving phlegm, clearing heat and detoxifying, enhancing immunity, and improving respiratory health. In recent years, with the continuous growth of consumer demand for natural plant-based health drinks, developing substitute teas or solid beverages using loquat flowers as a raw material has become an important direction for the food industry.

[0003] Currently, the industrial production of loquat flower tea generally follows traditional tea processing techniques, including picking, withering, fixation, rolling, and drying. This process is highly mature in conventional teas such as green tea and oolong tea, effectively deactivating enzyme activity, preserving aroma, and creating specific sensory qualities. However, loquat flowers differ fundamentally from tea in terms of plant tissue structure, chemical composition, and the distribution of heat-sensitive substances. Loquat flowers contain a high proportion of protein, polysaccharides, and volatile terpenes. These components are highly susceptible to Maillard reactions, lipid oxidation, or thermal degradation during high-temperature fixation or prolonged drying, resulting not only in unpleasant fishy or burnt odors but also significantly affecting color stability and flavor harmony. Consequently, finished loquat flower tea often exhibits a dark brown or grayish-yellow color, cloudy liquor, dull aroma, and astringent taste, severely diminishing its market acceptance and consumer experience as a high-end functional beverage. Summary of the Invention

[0004] To achieve the above-mentioned objectives, this invention provides a process for producing loquat pollen and solid beverages using nanotechnology. This process fundamentally solves the technical problems of structural damage to heat-sensitive active ingredients, generation of undesirable flavor substances, poor product solubility, and low bioavailability in existing loquat flower processing by constructing a low-temperature non-thermal synergistic processing system, a nanoscale cell wall disruption and active ingredient stabilization and encapsulation integrated system, and a flavor-color-function three-in-one regulation mechanism.

[0005] The process described in this invention includes the following steps: raw material pretreatment, low-temperature non-thermal synergistic passivation, nanoscale cell wall disruption, selective enrichment and nano-encapsulation of active ingredients, flavor-oriented regulation, low-temperature vacuum drying, and micronization. Each step is executed sequentially under strictly controlled process parameters, forming a closed-loop continuous production process.

[0006] In the raw material pretreatment stage, fresh loquat flowers with intact petals and a moisture content between 78% and 82% and 3-5 days after full bloom were selected as raw materials. After impurities were removed by air separation, the raw materials were placed in a 4℃ environment for gradient decompression drying. The environmental pressure was gradually reduced from atmospheric pressure to 60 kPa for 90 minutes, so that the free water content on the flower surface was reduced to below 15%, while maintaining the integrity of cell membranes and preventing premature activation of endogenous enzymes.

[0007] In the low-temperature non-thermal synergistic passivation stage, the pretreated loquat flowers are placed in a composite field treatment chamber, and a pulsed electric field and an ultrasonic field are applied simultaneously. The pulsed electric field strength is 12kV / cm, the pulse width is 20 microseconds, the pulse frequency is 300Hz, and the total processing time is 180 seconds; the ultrasonic frequency is 28kHz, the power density is 0.8W / cm², and the action time is 150 seconds.

[0008] This complex field effect causes reversible electroporation of the cell membrane and induces localized denaturation of protein conformation, effectively inactivating key deterioration-related enzyme systems such as lipoxygenase, peroxidase, and protease. Their residual activities are reduced to below 8%, 6%, and 5% of their initial values, respectively, while triterpenoid saponins do not undergo significant degradation and retain more than 95%. This process is carried out entirely in a 5°C circulating cooling medium, and the core temperature of the material never exceeds 12°C.

[0009] In the nanoscale cell wall disruption stage, the passivated material is transferred to a high-energy ball milling system. This system uses zirconia grinding media with a particle size distribution of 0.3 mm to 0.5 mm, a fill rate of 70%, a rotation speed of 1200 rpm, and a processing time of 45 minutes. Under the combined action of centrifugal force and shear force, the cell walls are mechanically peeled off and broken down to the nanoscale.

[0010] Laser particle size analyzer measurements showed that over 90% of the particles in the resulting slurry had a diameter less than 200 nm, with 50% of the particles falling within the 80 nm to 120 nm range. This size range ensures sufficient exposure of intracellular contents while avoiding excessive grinding that could lead to the oxidative polymerization of polyphenols.

[0011] In the stage of selective enrichment and nano-encapsulation of active ingredients, a food-grade chitosan-sodium alginate composite wall material solution is added to the cell-wall-broken slurry. The chitosan has a degree of deacetylation of not less than 90% and a molecular weight of 150 kDa; the sodium alginate has a viscosity of 400 mPa·s (1% aqueous solution, 25℃), and the mass ratio of the two is 3:2. The total amount of wall material added is 18% of the dry matter mass of the slurry.

[0012] The mixture was stirred at 40°C for 60 minutes in a buffer environment with a pH of 4.8 to form electrostatically self-assembled nanocapsules. Triterpenoid saponins, flavonoid glycosides, and trace element complexes were selectively encapsulated in the capsule core, with encapsulation efficiencies of 92%, 89%, and 85%, respectively. The nanocapsules had an average particle size of 150 nm, an absolute zeta potential greater than 30 mV, and exhibited good colloidal stability.

[0013] In the flavor-directed regulation stage, a flavor modifier composition is introduced into the encapsulated system. The composition is a compound of β-cyclodextrin, L-ascorbic acid palmitate, and γ-aminobutyric acid in a mass ratio of 5:2:3, with a total addition amount of 5% of the dry basis mass of the system.

[0014] β-Cyclodextrin masks residual C6-C9 volatile aldehydes such as hexanal and nonanal through host-guest inclusion complexation; L-ascorbyl palmitate, as a fat-soluble antioxidant, inhibits the chain reaction of unsaturated fatty acid oxidation; and γ-aminobutyric acid (GABA) lowers the astringency threshold by regulating taste receptor signaling pathways.

[0015] In the low-temperature vacuum drying stage, the flavor-adjusted slurry is pumped into a belt vacuum dryer. The absolute pressure inside the drying chamber is maintained at 8 kPa, and the temperature gradient of the heating plates is set as follows: Zone 1 35℃, Zone 2 40℃, Zone 3 45℃, with a total material residence time of 120 minutes. The moisture content is reduced from the initial 65% to below 5%. This drying mode avoids the damage to the nanocapsule structure caused by high temperatures, maintaining a capsule integrity rate of over 90%, and producing a uniform light beige product with an L value of 82, an a value of -1.5, and a b value of 18, significantly superior to the L value of 65, a value of 3.2, and b value of 35 of products dried by traditional hot air drying.

[0016] In the micronization and forming stage, the dried flake material is cryogenically frozen to -40°C and then fed into an air jet mill. The grinding gas is clean compressed air pre-cooled with liquid nitrogen at a pressure of 0.7 MPa, and the classifying wheel speed is 3600 rpm. The resulting powder has a D90 particle size of 15 μm, an angle of repose of 28°, and a bulk density of 0.45 g / cm³, exhibiting excellent flowability and rapid solubility.

[0017] The powder is mixed with maltodextrin (DE value 15) and erythritol at a mass ratio of 70:20:10. After mixing for 15 minutes in a three-dimensional mixer, it is pressed into round tablets with a diameter of 12 mm and a thickness of 5 mm using a rotary tablet press to obtain the finished loquat flower solid beverage. This product completely dissolves in water at 25℃ within 30 seconds without precipitation or flocculation.

[0018] In a preferred embodiment of the present invention, the nanoscale cell disruption stage employs a combined wet media milling and high-pressure homogenization process. The material is first treated with the aforementioned high-energy ball milling for 30 minutes, and then homogenized three times in a high-pressure homogenizer at 120 MPa pressure. This combined process increases the cell disruption rate to 98%, with a narrower particle size distribution and a PDI value below 0.2.

[0019] In another preferred embodiment of the present invention, magnetic field-assisted self-assembly technology is introduced in the nano-encapsulation stage of the active ingredient. Iron oxide nanoparticles (10 nm in diameter) at a concentration of 0.5% are pre-dispersed in a chitosan-sodium alginate mixture, and a static magnetic field of 0.3T is applied during the reaction. The magnetic field induces the nanoparticles to align orderly along the electric field direction, forming a magnetically responsive core-shell structure. This not only improves the encapsulation efficiency to over 95%, but also endows the product with controllable release capability under an applied alternating magnetic field, making it suitable for targeted delivery applications.

[0020] The loquat pollen and solid beverage produced by the process described in this invention have a triterpenoid saponin content of not less than 8.5 mg / g, a total flavonoid content of not less than 12 mg / g, a vitamin C retention rate of over 88%, and a total amino acid content of not less than 150 mg / g. In in vitro simulated gastrointestinal digestion model tests, the bioavailability of triterpenoid saponins is 3.2 times higher than that of products produced by traditional processes. The product's aqueous solution has a light transmittance of 92% at a wavelength of 680 nm, and the soup is clear and bright. The relative content of pleasant terpenes (such as linalool and geraniol) in volatile flavor compounds is increased by 40%, while off-flavor aldehydes and ketones are reduced by more than 80%.

[0021] This invention replaces traditional high-temperature blanching with low-temperature non-thermal synergistic passivation, blocking the heat-induced degradation pathway at its source; it achieves efficient release and stabilization of poorly soluble active ingredients through nanoscale cell wall disruption and selective encapsulation; and it reconstructs the balance of sensory quality through precise intervention with flavor modifiers. These three elements constitute an organically unified technical system, resolving the fundamental contradiction between efficacy and quality preservation in loquat flower processing.

[0022] Furthermore, the process described in this invention is carried out entirely in a closed, clean environment, with sealed pipelines used for transport between each step to avoid secondary contamination. All equipment surfaces in contact with materials are coated with food-grade 316L stainless steel or polytetrafluoroethylene, meeting GMP requirements. Process parameters can be monitored and adjusted in real time via a central control system to ensure batch-to-batch consistency, with a coefficient of variation of less than 3%.

[0023] The loquat pollen described in this invention can be directly used as a functional food additive in dairy products, baked goods, or nutrition bars; the solid beverage can be packaged in single-dose aluminum foil bags or bottles, and the active ingredient attenuation rate is less than 10% and the sensory quality does not change significantly within 12 months when stored at room temperature away from light.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a systematic, engineered, and scalable high-value processing technology for loquat flowers, which not only significantly improves the functionality, sensory quality, and physical properties of the product, but also provides a replicable technical solution for the intensive processing of other heat-sensitive medicinal and edible plant resources. Detailed Implementation

[0025] This invention provides a process for producing loquat flower pollen and solid beverages using nanotechnology, aiming to systematically solve the technical problems of structural damage to heat-sensitive active ingredients, generation of undesirable flavor substances, poor product solubility, and low bioavailability in existing loquat flower processing methods. The technical solution of this invention is described in detail below with reference to specific embodiments.

[0026] Example 1: Raw material pretreatment: airflow sorting speed 4.5 m / s, gradient decompression rate 5 kPa, after drying, the positive staining rate for cell membrane integrity was less than 3%; Low-temperature non-thermal synergistic passivation: pulsed electric field strength 12 kV / cm, pulse width 20 μs, frequency 300 Hz, processing time 180 seconds; ultrasonic frequency 28 kHz, power density 0.8 W / cm², processing time 150 seconds, with cooling at 5°C throughout. Nanoscale cell disruption: High-energy ball milling at 1200 rpm for 45 minutes, with zirconia grinding media particle size of 0.3-0.5 mm; Active ingredient nano-encapsulation: chitosan-sodium alginate mass ratio 3:2, total addition 18%, pH 4.8, reaction at 40℃ for 60 minutes; Flavor-oriented modulation: β-cyclodextrin:L-ascorbate palmitate:γ-aminobutyric acid = 5:2:3, addition amount 5%; Low-temperature vacuum drying: 8 kPa absolute pressure, gradient heating of 35℃→40℃→45℃, drying for 120 minutes; Micronization and molding: Frozen to -40℃, air-jet milling and classifying wheel speed 3600 rpm, powder mixed with maltodextrin and erythritol in a 70:20:10 ratio and compressed into tablets.

[0027] Example 2: Nanoscale cell disruption: First, high-energy ball milling for 30 minutes, then high-pressure homogenization at 120 MPa three times, with other parameters the same as in Example 1.

[0028] Example 3: Nanoencapsulation of active ingredients: 0.5% iron oxide nanoparticles were dispersed in a chitosan-sodium alginate solution, and a static magnetic field of 0.3T was applied. The other parameters were the same as in Example 1.

[0029] Example 4: Flavor-oriented regulation: β-cyclodextrin: L-ascorbate palmitate: γ-aminobutyric acid = 4:3:3, addition amount 5%, other parameters are the same as in Example 1.

[0030] Example 5: Nano-encapsulation of active ingredients: Chitosan-Sodium alginate mass ratio 2:3, total addition amount 18%, other parameters are the same as in Example 1.

[0031] Example 6: Low-temperature non-thermal synergistic passivation: pulsed electric field strength 10 kV / cm, ultrasonic frequency 40 kHz, other parameters are the same as in Example 1.

[0032] Example 7: Low-temperature vacuum drying: 8 kPa absolute pressure, gradient heating from 30°C to 35°C to 40°C, drying for 120 minutes, with other parameters the same as in Example 1.

[0033] Comparative Example 1: Raw material pretreatment: conventional sorting and spreading, without gradient pressure reduction; Blanching: Blanch at 120℃ for 3 minutes; Drying: Dry with hot air at 60℃ for 240 minutes; Grinding: Ordinary mechanical grinding to a D90 of 80 microns; No nano-encapsulation or flavor-directed regulation steps are required; maltodextrin is directly mixed and compressed into tablets.

[0034] Comparative Example 2: The low-temperature non-thermal synergistic passivation step was removed, and the pretreatment was directly dried with hot air at 60°C for 180 minutes. The other parameters were the same as in Example 1.

[0035] Comparative Example 3: The steps of selective enrichment and nano-encapsulation of active ingredients were removed, and the remaining parameters were the same as in Example 1.

[0036] Test method: Triterpenoid saponin retention rate: The retention rate was calculated based on the triterpenoid saponin content in fresh loquat flowers, determined by ultraviolet spectrophotometry.

[0037] Total flavonoid retention rate: The retention rate was determined by aluminum salt colorimetric method, and the total flavonoid content in fresh loquat flowers was used as the benchmark for calculation.

[0038] Odor reduction rate: The content of volatile aldehydes and ketones was detected by electronic nose, and the odor intensity reduction rate was calculated by combining the sensory evaluation on a 5-point scale.

[0039] Complete dissolution time: In deionized water at 25℃, with a stirring speed of 100 rpm, record the time it takes for the sample to completely dissolve without precipitation.

[0040] Bioavailability: An in vitro simulated gastrointestinal digestion model was used to determine the proportion of active ingredients that can be absorbed after digestion, and the relative multiples were calculated based on Comparative Example 1.

[0041] Color parameters: L value (brightness), a value (redness-greenness), and b value (yellowness-blueness) were measured using a colorimeter.

[0042] Transmittance: The transmittance of the sample aqueous solution was measured using a UV-Vis spectrophotometer at a wavelength of 680 nm.

[0043] Test data comparison table 1:

[0044] Test data comparison table 2:

[0045] The overall performance of Examples 1-7 is significantly better than that of Comparative Examples 1-3, demonstrating that the process of the present invention is highly effective in protecting active ingredients, improving flavor, enhancing solubility and bioavailability.

[0046] Regarding the retention of active ingredients, the retention rates of triterpenoid saponins and total flavonoids in Examples 1-3 all exceeded 90%, which is much higher than the 60% and 55% of Comparative Example 1. The core reason is that low-temperature non-thermal synergistic passivation avoids the degradation of ingredients caused by high temperature, and nano-encapsulation further locks in the active substances.

[0047] In terms of flavor and sensory quality, Examples 1-7 showed an off-odor reduction rate of over 74%, higher L-values ​​and a-values ​​closer to negative values, indicating higher product brightness and more uniform color. In contrast, Comparative Examples 1-2, lacking flavor control and low-temperature treatment, exhibited obvious off-odors and dull color.

[0048] Regarding solubility and bioavailability, the complete dissolution time of Examples 1-7 was within 35 seconds, with bioavailability reaching 2.9-3.5 times, while the dissolution time of Comparative Example 1 was as long as 180 seconds, with bioavailability only 1.0 times, demonstrating the improvement in material release efficiency brought about by nanoscale cell disruption and encapsulation.

[0049] The preferred implementation methods have obvious advantages. Examples 2 (wet milling + high pressure homogenization) and 3 (magnetic field assisted encapsulation) show the best performance in terms of bioaccessibility and retention rate of active ingredients, and can be used as preferred solutions for large-scale production.

[0050] Key steps are indispensable. The lack of low-temperature non-thermal passivation in Comparative Example 2 led to a significant decrease in the retention rate of active ingredients, and the lack of nano-encapsulation in Comparative Example 3 resulted in insufficient bioaccessibility. This proves that low-temperature non-thermal synergistic passivation and active ingredient nano-encapsulation are the core technical nodes of this process.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for producing loquat flower pollen and solid beverage using nanotechnology, characterized by, The process comprises the following steps in sequence: S1, raw material pretreatment: select fresh loquat flowers, air separation, gradient decompression and airing; S2, low-temperature non-thermal synergistic passivation: place the pretreated loquat flowers in a composite field treatment cavity, and simultaneously apply pulse electric field and ultrasonic field under cooling environment; S3, nanoscale cell wall breaking: transfer the passivated material to a high-energy ball milling system to obtain a slurry; S4, selective enrichment and nano-encapsulation of active ingredients: add a chitosan-sodium alginate composite wall material solution to the broken cell slurry; S5, flavor directional regulation: add a flavor modifier composition; S6, low-temperature vacuum drying: gradient heating belt drying under pressure; S7, micronization molding: freeze the dried sheet material, perform air flow crushing with liquid nitrogen pre-cooled compressed air, obtain powder, and then press into tablets to prepare a solid beverage.

2. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 1, characterized in that, In the chitosan-sodium alginate composite wall material solution, the chitosan has a degree of deacetylation of ≥90% and a molecular weight of 150 kDa, the sodium alginate has a viscosity of 400 mPa·s, the mass ratio of the two is 3:2, the total addition amount is 18% of the dry matter mass of the slurry, and the solution is stirred and reacted at pH 4.8 and 40°C for 60 minutes to form nanocapsules with an average particle size of 150 nm and a Zeta potential absolute value of >30 mV.

3. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 1, characterized in that, The flavor modifier composition consists of β-cyclodextrin, L-ascorbyl palmitate and γ-aminobutyric acid in a mass ratio of 5:2:3, and the total addition amount is 5% of the dry basis mass of the system.

4. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 1, characterized in that, The powder in S7 is mixed with malt dextrin and erythritol in a mass ratio of 70:20:10 and then pressed into tablets.

5. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 2, characterized in that, In the selective enrichment and nano-encapsulation step, 0.5% ferroferric oxide nanoparticles with a particle size of 10 nm are dispersed in the chitosan-sodium alginate composite wall material solution in advance, and a static magnetic field of 0.3T is applied during the reaction to form magnetic responsive core-shell structure nanocapsules.

6. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 5, characterized in that, The ferroferric oxide nanoparticles are surface modified with oleic acid, have good water dispersibility, and the formed nanocapsules have controllable release capacity under an external alternating magnetic field.

7. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 1, characterized in that, In S6, the material is subjected to gradient heating belt drying at 8kPa absolute pressure, 35°C→40°C→45°C for 120 minutes, and the moisture content is reduced to below 5%.

8. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 1, characterized in that, In S7, the dried sheet material is frozen to -40°C, and then air flow crushing is performed with liquid nitrogen pre-cooled compressed air, the classification wheel rotates at 3600 rpm to obtain a powder with a D90 of 15μm.

9. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 8, characterized in that, In S7, the obtained powder has a rest angle of 28°, a loose bulk density of 0.45g / cm³, completely dissolves in water at 25°C within 30 seconds, and has a 680nm wavelength light transmittance of 92%.

10. The process for producing loquat pollen and solid beverage using nanotechnology according to claim 1, characterized in that, In the raw material pretreatment step, the air separation wind speed is 4.5m / s, the gradient decompression rate is 5kPa per minute, and the cell membrane integrity staining positive rate is less than 3% at the end of airing.

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