Extraction process of insect tea polysaccharide

Abstract

The invention discloses an insect tea polysaccharide extraction process which comprises the following steps: S1, raw material pretreatment: crushing insect tea to 40-60 meshes, and drying at the temperature of 60-70 DEG C until the moisture content is less than or equal to 8% to obtain pretreated insect tea; s2, water extraction: mixing the pretreated insect tea with distilled water according to a solid-liquid ratio of 1: (25-35) (g / mL), adjusting the pH value of the system to 8-10, and extracting at 65-75 DEG C for 80-100 minutes to obtain a water extract; s3, solid-liquid separation: centrifuging the water extract at the rotating speed of 3,000 to 5,000 rpm for 10 to 15 minutes, and taking supernate; s4, concentration: carrying out rotary evaporation concentration on the supernate under the conditions that the vacuum degree is 0.08-0.09 MPa and the temperature is 50-60 DEG C, so as to obtain a concentrated solution with the relative density of 1.10-1.15; and S5, carrying out alcohol precipitation: adding 95% food-grade ethanol into the concentrated solution to enable the volume concentration of the ethanol to reach 70%-80%, standing for 12-16 hours at low temperature, centrifuging for 10 minutes at the rotating speed of 3000-5000 rpm, collecting precipitates, and carrying out vacuum drying at 60-70 DEG C until the weight is constant, so as to obtain the insect tea crude polysaccharide.

Description

Technical Field

[0001] This invention relates to the field of polysaccharide extraction, specifically to an extraction process for insect tea polysaccharides. Background Technology

[0002] China has abundant tea resources and a long history of application. Insect tea, a unique forestry resource insect product in my country, is a special tea product that is different from traditional tea. It is not made directly from plant leaves, but from the excrement of specific insects (such as rice weevils) after they feed on the leaves of plants such as eagle tea and jujube leaves. The excrement is then processed through screening, sterilization, and drying. Insect tea is often used to clear heat and relieve summer heat, and to aid digestion. It is a unique resource that combines traditional drinking value with ethnic medicinal attributes.

[0003] Modern nutritional and pharmacological studies have shown that insect tea is rich in protein, amino acids, vitamins, minerals, and various bioactive substances, among which polysaccharides are one of its core active substances. Polysaccharides, as natural macromolecules widely found in plants and animals, have been proven to possess various physiological functions such as antioxidation, immune regulation, hypoglycemia, and hypolipidemia. For example, the proportion of sugar components in the dry matter of tea leaves reaches 20-25%, and the strong antioxidant activity of tea polysaccharides has been verified by various in vitro experiments such as DPPH and ABTS. Analogous to tea polysaccharides, insect tea polysaccharides, as an active ingredient in insect tea that integrates the essence of both plants and animals, are gradually attracting attention from the scientific research field for their potential health benefits and application prospects. Especially at present, with the shortage of natural antioxidants and the surge in consumer demand for "green functional foods," the development and utilization of insect tea polysaccharides is of great significance for expanding the raw material sources for the food and pharmaceutical industries.

[0004] With the deepening of natural product research, various technical routes have been developed for tea polysaccharide extraction, such as water extraction and alcohol precipitation, ultrasound-assisted extraction, microwave-assisted extraction, and enzymatic extraction. Among these, water extraction and alcohol precipitation has become a classic method for tea polysaccharide extraction due to its simplicity, low cost, and absence of organic solvent residue risk. However, compared to the mature traditional tea polysaccharide extraction technology, research on insect tea polysaccharides is still in the initial exploratory stage. Existing extraction processes have many problems that urgently need to be solved, such as low extraction rates, poor stability, and insufficient retention of polysaccharide activity. Summary of the Invention

[0005] The present invention aims to provide an extraction process for insect tea polysaccharides. Based on the unique structure of insect tea raw materials and the physicochemical properties of polysaccharides, the process achieves the goal of high extraction rate and activity retention by synergistically optimizing key parameters.

[0006] An extraction process for insect tea polysaccharides includes: S1. Raw material pretreatment: Pulverize the insect tea to 40-60 mesh, dry it at 60-70℃ until the moisture content is ≤8%, and obtain pretreated insect tea. S2. Water extraction: The pretreated insect tea is mixed with distilled water at a material-to-liquid ratio of 1:25-35 (g / mL), the pH of the system is adjusted to 8-10, and the mixture is extracted at 65-75℃ for 80-100 min to obtain the water extract. S3. Solid-liquid separation: Centrifuge the aqueous extract at 3000-5000 rpm for 10-15 min and collect the supernatant; S4. Concentration: The supernatant is concentrated by rotary evaporation under a vacuum of 0.08-0.09 MPa and a temperature of 50-60°C to obtain a concentrated solution with a relative density of 1.10-1.15; S5. Alcohol precipitation: Add 95% food-grade ethanol to the concentrate to make the ethanol volume concentration reach 70% to 80%, let it stand at low temperature for 12 to 16 hours, centrifuge at 3000 to 5000 rpm for 10 minutes, collect the precipitate, and vacuum dry at 60 to 70°C to constant weight to obtain insect tea crude polysaccharide.

[0007] Working principle and beneficial effects of the present invention: Insect tea is not traditional tea, but rather the excrement of insects after feeding on plant leaves. The surface of the excrement is coated with metabolic products of insect digestive enzymes (such as pectin). These substances, with galacturonic acid as the main component, form a dense coating layer that hinders solvent penetration. The cell walls of the excrement particles are denser than those of traditional tea leaves. The insect digestion process alters the fibrous structure of plant cell walls, reducing the pores and making it difficult for polysaccharides to dissolve naturally.

[0008] The insect tea is pulverized to 40-60 mesh to increase the specific surface area for solvent contact, and then dried at 60-70℃ until the moisture content is ≤8%. This removes excess moisture and protects the polysaccharide structure because the temperature is below the polysaccharide hydrolysis threshold (80℃). The process then proceeds to the water extraction stage, where the pretreated insect tea is mixed with distilled water at a ratio of 1:25-35 (g / mL). The pH of the system is adjusted to 8-10 to promote the hydrolysis of pectin on the surface of the insect tea and open the cell wall permeation channels. The mixture is then extracted at 65-75℃ for 80-100 minutes. This process both increases the solvent permeation rate and accelerates the dissolution of polysaccharides by using a suitable temperature, and keeps the polysaccharide hydrolysis rate below 2% by keeping the temperature below 80℃, thus obtaining the water extract. Next, solid-liquid separation is performed. The aqueous extract is centrifuged at 3000–5000 rpm for 10–15 min to ensure that the 40–60 mesh insect tea residue settles fully while preventing excessive centrifugal force from damaging the polysaccharide macromolecular structure. In the subsequent concentration step, the supernatant is concentrated by rotary evaporation to a relative density of 1.10–1.15 under vacuum conditions of 0.08–0.09 MPa and 50–60 °C. The vacuum environment is used to lower the boiling point of the solvent to achieve low-temperature concentration, while controlling the density of the concentrate to reduce the amount of ethanol used in subsequent alcohol precipitation. Finally, alcohol precipitation and drying are performed: 95% food-grade ethanol is added to the concentrate to bring the ethanol volume concentration to 70%–80%. Precipitation is achieved by utilizing the reduced solubility of polysaccharides in high-concentration ethanol. This concentration also reduces the simultaneous precipitation of impurities such as proteins and caffeine. After standing at low temperature for 12–16 hours, the precipitate is collected by centrifugation at 3000–5000 rpm and then vacuum dried at 60–70°C to constant weight. This low-temperature drying further avoids the thermal degradation of polysaccharides and ensures that the final crude polysaccharide from the insect tea meets the moisture content standard.

[0009] In the optimized form, the insect tea in S1 is at least one of Guizhou local insect tea, Hunan Chengbu insect tea, or Guangxi Longsheng insect tea.

[0010] The optimized solution-to-liquid ratio in S2 is 1:30 (g / mL), the pH of the system is adjusted to 9, the extraction temperature is 70℃, and the extraction time is 90 min.

[0011] The optimized solution for adjusting the pH in S2 is either a 0.1 mol / L NaOH solution or a 0.1 mol / L HCl solution.

[0012] The optimized centrifugation speed in S3 is 4000 rpm, and the centrifugation time is 12 min.

[0013] The optimized S5 has an ethanol volume concentration of 75%, a standing time of 14 hours, a vacuum drying temperature of 65°C, and a low temperature of 4°C. Detailed Implementation

[0014] The following detailed description illustrates the specific implementation method: Example 1: Take 500g of local Guizhou insect tea and grind it to 40-60 mesh using a closed swing-type pulverizer; place the pulverized insect tea in an electric constant temperature drying oven and dry it at 65℃ for 4 hours until the moisture content is ≤8%. Seal and store it as pre-treated insect tea for later use.

[0015] (1) Weigh 5g of pretreated insect tea per portion, for a total of 5 portions, and add distilled water at material-to-liquid ratios of 1:20, 1:30, 1:40, 1:50, and 1:60 (g / mL) respectively; adjust the pH of the system to 7 (neutral, initial fixed conditions), and place it in a 60℃ water bath for 90 min; after extraction, centrifuge at 3000 rpm for 15 min, take the supernatant, and calculate the extraction rate of polysaccharides; (2) Weigh 5g of pretreated insect tea per portion, for a total of 5 portions, with a fixed material-to-liquid ratio of 1:40 (g / mL), pH=7, and extraction time of 90min; place them in water baths at 50℃, 60℃, 70℃, 80℃, and 90℃ respectively for extraction; then centrifuge and calculate the extraction rate of polysaccharides. Weigh 5g of pretreated insect tea per portion, for a total of 5 portions, with a fixed material-to-liquid ratio of 1:40 (g / mL), pH=7, and extraction temperature of 60℃; extract for 30min, 60min, 90min, 120min, and 150min respectively; then centrifuge and calculate the extraction rate.

[0016] (3) Weigh 5g of pretreated insect tea per portion, for a total of 5 portions, with a fixed material-to-liquid ratio of 1:40 (g / mL), an extraction temperature of 60℃, and an extraction time of 90min; adjust the pH of the system to 3, 5, 7, 9, and 11 using 0.1mol / L HCl or 0.1mol / L NaOH; then centrifuge and calculate the extraction rate. The following data were obtained:

[0017] The extraction rate was highest when the material-to-liquid ratio was 1:40, the temperature was 60℃, the time was 90min, and the pH was 7.

[0018] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An extraction process for insect tea polysaccharides, characterized in that, include: S1. Raw material pretreatment: Pulverize the insect tea to 40-60 mesh, dry it at 60-70℃ until the moisture content is ≤8%, and obtain pretreated insect tea. S2. Water extraction: The pretreated insect tea is mixed with distilled water at a material-to-liquid ratio of 1:25-35 (g / mL), the pH of the system is adjusted to 8-10, and the mixture is extracted at 65-75℃ for 80-100 min to obtain the water extract. S3. Solid-liquid separation: Centrifuge the aqueous extract at 3000-5000 rpm for 10-15 min and collect the supernatant; S4. Concentration: The supernatant is concentrated by rotary evaporation under a vacuum of 0.08-0.09 MPa and a temperature of 50-60°C to obtain a concentrated solution with a relative density of 1.10-1.15; S5. Alcohol precipitation: Add 95% food-grade ethanol to the concentrate to make the ethanol volume concentration reach 70% to 80%, let it stand at low temperature for 12 to 16 hours, centrifuge at 3000 to 5000 rpm for 10 minutes, collect the precipitate, and vacuum dry at 60 to 70°C to constant weight to obtain insect tea crude polysaccharide.

2. The extraction process of insect tea polysaccharides according to claim 1, characterized in that, S1 insect tea is at least one of Guizhou local insect tea, Hunan Chengbu insect tea, or Guangxi Longsheng insect tea.

3. The extraction process of insect tea polysaccharides according to claim 2, characterized in that, The material-to-liquid ratio in S2 is 1:30 (g / mL), the pH of the system is adjusted to 9, the extraction temperature is 70℃, and the extraction time is 90 min.

4. The extraction process of insect tea polysaccharides according to claim 3, characterized in that, The reagent used to adjust the pH in S2 is either a 0.1 mol / L NaOH solution or a 0.1 mol / L HCl solution.

5. The extraction process of insect tea polysaccharides according to claim 4, characterized in that, The centrifugation speed described in S3 is 4000 rpm, and the centrifugation time is 12 min.

6. The extraction process of insect tea polysaccharides according to any one of claims 1 to 5, characterized in that, The ethanol volume concentration in S5 is 75%, the standing time is 14 hours, the vacuum drying temperature is 65°C, and the low temperature is 4°C.

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