A pear skin pectin-based cyanidin microcapsule and an application method thereof in sishen crisp pear soup

Abstract

This invention relates to a pear peel pectin-based anthocyanin microcapsule and its application in Four-Herb Pear Soup. The invention is characterized by: (1) adding whey protein powder to deionized water and stirring to dissolve it, obtaining a whey protein solution; (2) adding pear peel pectin to deionized water and stirring to dissolve it in a constant temperature water bath, obtaining a clear pectin solution, and cooling it; (3) pouring the whey protein solution into the pectin solution and continuing to add anthocyanins and stirring until homogeneous; (4) transferring the mixture to a high-pressure homogenizer for homogenization to form a fine and uniform emulsion; (5) adjusting the pH value to 3.8-4.2 using hydrochloric acid; (6) sending the pH-adjusted emulsion to a spray dryer for spray drying to obtain pear peel pectin-based anthocyanin microcapsules. Advantages of this invention: Applying pear peel pectin-based anthocyanin microcapsules to the preparation of Four-Herb Pear Soup ensures the activity and stability of anthocyanins, while simultaneously achieving a deep fusion of the flavors of the Four-Herb ingredients and the pear soup.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically the interdisciplinary field of functional ingredient encapsulation and food processing with medicinal properties, and relates to a pear peel pectin-based anthocyanin microcapsule and its application method in Si Shen Su Pear Soup. Background Technology

[0002] Pectin is an important natural water-soluble polysaccharide in the food industry, widely used as a thickener, emulsifier, and microcapsule wall material. Traditional commercial pectin production mainly uses citrus peel and apple pomace as raw materials, which is costly and involves limited resource utilization. Pear peel, as a major byproduct of pear processing, is rich in pectin, but it is currently mostly discarded, causing resource waste and environmental pollution. Existing pectin extraction technologies from pear peel (such as patent publication number CN106866836A) often employ complex processes involving compound enzymatic hydrolysis, low-power long-term ultrasound, and decolorization and concentration. These processes suffer from high enzyme costs, cumbersome steps, and long extraction times, and the pectin yield is generally low (approximately 12%), making industrial-scale promotion difficult.

[0003] Anthocyanins are natural functional antioxidants with high nutritional and application value. However, anthocyanins are highly sensitive to environmental factors such as temperature and pH, exhibiting poor thermal stability and are easily degraded and lost during high-temperature food processing. Microencapsulation is the mainstream technology for improving their stability. Currently, the wall materials of most anthocyanin microcapsules are a combination of commercially available pectin and whey protein, failing to consider the processing characteristics of pear products to achieve on-site high-value utilization of pear peel by-products. Furthermore, there are no reports on the application of encapsulated anthocyanin microcapsules in high-temperature cooking systems for pear soup, thus failing to simultaneously enhance the nutritional value and flavor of the pear soup.

[0004] As a health food with both medicinal and edible properties, Four-Ingredient Pear Soup combines the lung-moistening effects of Dangshan pears with the spleen-strengthening and dampness-removing effects of the Four-Ingredient ingredients, making it popular among consumers. However, the traditional preparation process has many drawbacks: high-temperature and long-term steaming can easily lead to the deterioration of the pear flavor and the loss of active ingredients, and the medicinal fishy smell of the Four-Ingredient ingredients is difficult to eliminate. In addition, the product does not contain any functional ingredients, resulting in low added value. If anthocyanins are added directly during the high-temperature steaming stage, they are easily degraded and become ineffective, making it impossible to upgrade the product's nutritional value.

[0005] Therefore, developing an integrated process for pear peel pectin extraction, anthocyanin microcapsule preparation, and application in Sishen Crisp Pear Soup, to achieve high-value utilization of pear peel resources, improve the thermal stability of anthocyanins, optimize the flavor and nutrition of Sishen Crisp Pear Soup, and simultaneously ensure the industrial adaptability of the process, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of waste of pear peel resources, poor thermal stability of anthocyanins, loss of active ingredients and poor flavor in the processing of Sishen Crispy Pear Soup in the prior art. This invention provides a pear peel pectin-based anthocyanin microcapsule and its application method in Sishen Crispy Pear Soup. This invention realizes the resource utilization of pear peel by-products, simplifies the pectin extraction process and reduces costs, and provides anthocyanin microcapsules with high encapsulation rate and good thermal stability. When applied to Sishen Crispy Pear Soup, it can significantly improve the nutritional and sensory quality of the product. Moreover, all process parameters are set to be adapted to the fluctuation range of industrial production and can be promoted on a large scale.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing pear peel pectin, characterized by comprising the following steps: (1) Pear peel pretreatment: Peel fresh Dangshan pears and put them in a boiling water bath for 5-7 minutes to inactivate enzymes (to eliminate the pear peel's own endogenous enzymes and prevent pectin from being degraded in subsequent processes); then put the pear peels in an oven to dry (dry at 65-75℃ for 20-28 hours), pulverize them to obtain uniform pear peel powder, and seal them for later use. (2) Construction of enzymatic hydrolysis system: Pear peel powder and distilled water were mixed at a material-to-liquid ratio of 1:18 to 1:22 (g / mL), and the pH of the system was adjusted to 4.0 to 5.0 with 1 mol / L dilute hydrochloric acid (this pH range is the optimal range for cellulase activity); 0.2% to 0.8% of cellulase by weight of pear peel powder was added to the mixture, and the mixture was placed in a constant temperature water bath at 38 to 42℃ for 2.5 to 3.5 h for enzymatic hydrolysis. (3) Post-enzymatic hydrolysis treatment: After enzymatic hydrolysis, the mixture is placed in a water bath at 85~95℃ for 8~12min to inactivate the enzyme (to quickly inactivate cellulase and avoid excessive enzymatic hydrolysis that could damage the pectin structure). After cooling to room temperature, it is ultrasonically treated with 450~550W power for 15~25min (using the high-power cavitation effect to break the cell walls of the pear peel and further promote pectin dissolution. Compared with the existing low-power long-time ultrasonic process, the ultrasonic time is greatly shortened and the production efficiency is improved). After ultrasonic treatment, the mixture is filtered to remove solid residues and the clear filtrate is used for later use. (4) Alcohol precipitation and drying: Add an equal volume of anhydrous ethanol to the filtrate, mix thoroughly and let stand for 10-16 hours to allow pectin to precipitate fully; place the precipitate mixture in a centrifuge and centrifuge at 2800-3200 rpm for 15-25 minutes, and collect the pectin precipitate at the bottom; place the precipitate in an oven at 50-60℃ and dry to constant weight to obtain pear peel pectin product. The pectin yield under this process is ≥12%, and the yield can reach 14.2% under the optimal process conditions.

[0008] This invention uses Dangshan pear peel as raw material and employs a simplified process to extract pear peel pectin, which combines single enzymatic hydrolysis with high-temperature instantaneous enzyme inactivation and high-power short-time ultrasonic extraction. This process differs from the existing technologies that use complex enzymatic hydrolysis, low-power long-time ultrasonic extraction, and decolorization and concentration steps. The process parameters are set within a reasonable range, and the optimal pectin yield of 14.2% can be achieved within this range.

[0009] A method for preparing pear peel pectin-based anthocyanin microcapsules, characterized by comprising the following steps: (1) Preparation of whey protein solution: Add whey protein powder to deionized water and stir at room temperature (25~35min) to dissolve, so as to obtain a whey protein solution with a mass concentration of 2%~4% (w / v), and seal for later use; (2) Preparation of pear peel pectin solution: Pear peel pectin was added to deionized water and stirred and dissolved in a constant temperature water bath at 55~65℃ (1.5~2.5h) to obtain a clear pectin solution with a mass concentration of 0.8%~1.2% (w / v). The solution was cooled to room temperature and then used for later use. (3) Preparation of mixture and addition of anthocyanins: The mass ratio of pear peel pectin to whey protein is 1:2 to 1:4. While stirring, slowly pour the whey protein solution into the pectin solution (to avoid excessive local concentration that may cause the wall material to agglomerate). Then add 20 to 30% of the mass of the mixture to the mixture (mixed wall material solution) and stir evenly (so that the anthocyanins are evenly distributed in the wall material system, laying the foundation for subsequent encapsulation). (4) High-pressure homogenization: Transfer the anthocyanin-containing mixture into a high-pressure homogenizer, set the homogenization speed to 9000~13000 rpm, homogenize for 2~6 minutes, repeat the homogenization operation 2~3 times to make the mixture form a fine and uniform emulsion (to improve the encapsulation effect of the wall material on anthocyanins and enhance the compactness of the microcapsule structure). (5) pH adjustment: Use 1 mol / L hydrochloric acid solution to adjust the pH to 3.8~4.2 (this pH range enables the whey protein and pear peel pectin composite wall material to form a stable gel structure, further improving the encapsulation stability and thermal stability of the microcapsules). (6) Spray drying to prepare microcapsules: The emulsion with adjusted pH value is fed into the spray dryer, the inlet air temperature is set to 160~180℃, the outlet air temperature is set to 85~95℃, and the feed speed is set to 4%~6%. The equipment is started to carry out spray drying, and the dried powder product is collected to obtain pear peel pectin-based anthocyanin microcapsules.

[0010] Furthermore, in step (3), the mass ratio of pear peel pectin to whey protein is 1:3.

[0011] Furthermore, the storage method of the pear peel pectin-based anthocyanin microcapsules is as follows: the prepared anthocyanin microcapsules are placed in a sealed bag, excess air is removed from the bag, and then the bag is sealed and stored in a refrigerated environment at 2~6℃.

[0012] This invention uses pear peel pectin as one of the wall materials. Pear peel pectin and whey protein are compounded at a mass ratio of 1:2 to 1:4 to encapsulate anthocyanins. The process parameters are set within a reasonable range. Under the optimal conditions within the range, the microcapsule encapsulation rate can reach 95.03% (≥90%).

[0013] A method for applying pear peel pectin-based anthocyanin microcapsules in Four-Ingredient Pear Soup, characterized by the following steps: (1) Raw material processing: Select Dangshan crisp pears that are moderately ripe, free from pests and diseases, and free from mechanical damage (to ensure that the pear flesh is soft and glutinous and to avoid affecting the quality of pear soup due to raw material defects), peel and core them and set them aside; (2) First stage of steaming: Add the processed crisp pears to purified water, control the mass ratio of Dangshan crisp pears to purified water to be 18~22:23~27, and then place them in a steaming device. Set the power to 1900~2100W and the temperature to 210~230℃, and simmer for 50~60 minutes (to soften the pear flesh initially, fully release the pear aroma and flavor substances, and lay the foundation for subsequent flavor fusion) to obtain pear soup; (3) Second stage of steaming: Add 3.5~4.5g each of Poria cocos, lotus seeds, yam slices, and Euryale ferox to the pear soup, along with zero-calorie sugar and vitamin C. Control the mass ratio of Dangshan crisp pears to Poria cocos, lotus seeds, yam slices, Euryale ferox, zero-calorie sugar, and vitamin C to 180~220:3.5~4.5:3.5~4.5:3.5~4.5:3.5~4.5:4.0~5:0.08~0.12. Continue steaming at 1900~2100W power and 210~230℃ for 50~60 minutes (to fully dissolve the effective components of the four ingredients, adjust the sweetness of the pear soup with zero-calorie sugar, and enhance the antioxidant properties of the pear soup with vitamin C. This steaming process also allows the four ingredients to fully blend with the pear soup, effectively eliminating the medicinal smell). (4) Low-temperature preparation and sterilization: After steaming, the pear soup is naturally cooled to 55~65℃. Add 0.1-0.4% of the weight of Dangshan crisp pear pectin-based anthocyanin microcapsules to the pear soup, stir evenly and seal immediately. Sterilize at 55~65℃ for 20~30 minutes to obtain Sishen crisp pear soup.

[0014] This invention applies the pear peel pectin-based anthocyanin microcapsules prepared above to the preparation of Spring Nourishing Four Gods Crispy Pear Soup. The process involves segmented steaming at 1900~2100W / 210~230℃ followed by low-temperature addition of microcapsules at 55~65℃ to avoid high-temperature damage to the microcapsule structure, ensuring the activity and stability of anthocyanins, and simultaneously achieving a deep fusion of the flavors of the Four Gods ingredients and the pear soup.

[0015] Compared with the prior art, the present invention has the following advantages: (1) The pear peel pectin extraction process of the present invention has the following advantages: ① The use of cellulase as a single enzymatic hydrolysate to replace the compound enzyme of the existing technology significantly reduces the enzyme cost, and the enzyme dosage range is accurately screened through single-factor experiments, providing controllable parameter basis for industrial production; ② High-temperature instantaneous enzyme inactivation avoids excessive degradation of pectin, and high-power short-time ultrasonic-assisted extraction replaces low-power long-time ultrasonic extraction, shortening the process time and improving production efficiency; ③ The decolorization and concentration steps in the existing process are eliminated, and direct alcohol precipitation and drying are performed, simplifying the process, and the purity of the obtained pear peel pectin meets the requirements for use as a wall material for food microcapsules, without the need for additional refining; the raw material and process costs are significantly reduced, and the pectin yield is ≥12%, reaching 14.2% under optimal conditions, which is better than the existing pear peel pectin extraction process.

[0016] (2) The preparation process of anthocyanin microcapsules of the present invention has the following advantages: ① Pectin extracted from pear peel, a by-product of pear processing, is used to replace commercial pectin, realizing the local high-value utilization of pear peel resources, reducing the cost of microcapsule wall materials, and the compatibility of pear peel pectin with pear soup system is better, avoiding problems such as turbidity and precipitation; ② The optimal compounding ratio of pear peel pectin to whey protein of 1:3 was determined. This ratio makes the composite wall material have both good emulsification and film-forming properties, significantly improving the encapsulation rate, which is much higher than the encapsulation effect of single wall materials. The encapsulation rate of the prepared anthocyanin microcapsules is ≥90%, reaching 95.03% under optimal conditions; ③ By adding microcapsules at a low temperature of 55~65℃, the damage to microcapsules caused by high-temperature cooking is avoided; the combination of high-pressure homogenization and precise pH control makes the microcapsule structure dense, greatly improving the thermal stability of anthocyanins, providing technical support for their application in the high-temperature processing system of pear soup, and realizing the nutritional upgrade of pear soup.

[0017] (3) The preparation process of the Four Gods Pear Soup of the present invention has the following advantages: ① The segmented steaming process at 1900~2100W / 210~230℃, compared with the traditional single long-term steaming, ensures that the pear flesh is soft and glutinous, the effective components of the Four Gods ingredients are fully dissolved, and avoids the deterioration of the flavor of the pear soup. At the same time, it effectively eliminates the medicinal smell of the Four Gods ingredients; ② The addition of microcapsules at a low temperature of 55~65℃ avoids the destruction of the microcapsule structure during the high-temperature steaming process, ensures the activity and stability of anthocyanins, and realizes the nutritional upgrade of the pear soup; ③ The addition of pear peel pectin-based microcapsules not only gives the pear soup a natural pink color and improves the color sensory of the product, but also improves the antioxidant properties of the product. Moreover, the microcapsules have good compatibility with the pear soup system, with no precipitation or turbidity, further improving the product quality; The prepared Four Gods Pear Soup has a double improvement in flavor and nutrition, excellent sensory quality, sensory score ≥88 points, and reaches 91.22 points under optimal conditions, which is far superior to the traditional Four Gods Pear Soup.

[0018] (4) Integrated process, adapted to industrial production: The process of "pear peel pectin extraction - anthocyanin microcapsule preparation - Sishen crisp pear soup application" is integrated. All process parameters are set within a reasonable range to adapt to process fluctuations in industrial production. All step parameters are clear and controllable. The equipment used is commonly used in the food industry and does not require special customization. The process is simplified, time is short, and production efficiency is high, making it suitable for large-scale industrial promotion.

[0019] (5) High added value of products and significant economic and social benefits: The technical solution of this invention significantly reduces the production cost of pectin wall material and Four Gods Crispy Pear Soup. At the same time, by adding anthocyanin microcapsules, the nutritional and sensory quality of the products is improved, and the added value of the products is increased. The recycling of pear peel resources is in line with the concept of green food processing and has significant economic and social benefits. Attached Figure Description

[0020] Figure 1 Curve showing the effect of different cellulase dosages on pectin yield from pear peel; Figure 2 Scanning electron microscope image of pear peel pectin-based anthocyanin microcapsules, where 1-unencapsulated anthocyanin powder; 2-anthocyanin microcapsule powder; Figure 3 The graph shows the results of sensory evaluation based on the interaction between the pre-cooking time of pears and the amount of each ingredient in the Four Gods recipe. The left graph is a surface plot, and the right graph is a contour plot. Figure 4 The graph shows the results of the interaction between the pre-cooking time of Dangshan crisp pear and the amount of zero-calorie sugar on the sensory evaluation. The left graph is a surface plot and the right graph is a contour plot. Figure 5 The graph shows the results of the interaction between the amount of each ingredient in the Four Gods Divine Soup and the amount of zero-calorie sugar on sensory evaluation. The left graph is a surface plot and the right graph is a contour plot. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0022] The Four-Ingredient Pear Soup prepared according to this invention was professionally evaluated according to the sensory evaluation standard for spring pear soup (color 25 points, clarity 25 points, aroma 25 points, taste 25 points, total score 100 points). The pear soup prepared within the process parameter range of this invention achieved a sensory score ≥88 points, and the average sensory score under optimal process conditions reached 91.22 points. Specific sensory characteristics are as follows: Color: It is a uniform and bright pink color, without fading or browning, with a color score of 23-25. Clarity: Clear and transparent, without sediment or turbidity, with a clarity score of 23-25 ​​points; Aroma: It has a rich pear scent and a light floral scent, with no medicinal smell or strange fragrance. The aroma score is 22-24 points. Taste: The pear flesh is soft and sweet, with a refreshing taste and no hard or mushy texture. Taste score: 21-23 points. Example 1

[0023] A method for preparing pear peel pectin, the specific implementation steps of which are as follows: (1) Pear peel pretreatment: Fresh Dangshan pears are peeled, boiled in water for 6 minutes to inactivate enzymes, dried in an oven at 70℃ for 24 hours and then pulverized into pear peel powder; (2) Enzymatic hydrolysis: Weigh 2g of pear peel powder, add 40mL of distilled water (material-liquid ratio 1:20), adjust the pH to 4.5 with 1mol / L dilute hydrochloric acid, add 0.6% of cellulase (0.012g) by weight of pear peel powder, and enzymatically hydrolyze in a constant temperature water bath at 40℃ for 3h. (3) Post-treatment: Inactivate enzymes in a 90℃ water bath for 10 min, cool and then sonicate at 500W for 20 min, and filter to obtain clear filtrate; (4) Alcohol precipitation and drying: Add an equal volume of anhydrous ethanol to the filtrate, mix well and let stand overnight (12h), centrifuge at 3000rpm for 20min and collect the precipitate; place the precipitate in a 55℃ oven and dry to constant weight to obtain 0.284g of pear peel pectin, with a pectin yield of 14.2%. Example 2

[0024] A method for preparing pear peel pectin-based anthocyanin microcapsules, the specific implementation steps of which are as follows: (1) Preparation of whey protein solution: Add 6.0g of whey protein to 200mL of deionized water and stir at room temperature for 30min until completely dissolved to obtain a homogeneous whey protein solution; (2) Preparation of pear peel pectin solution: 2.0g of pear peel pectin obtained in Example 1 was added to 200mL of deionized water and stirred for 2h under constant temperature water bath at 60℃ until completely dissolved to obtain a clear pectin solution; (3) Mixing and embedding: Slowly pour the whey protein solution into the pectin solution while stirring until it is evenly mixed. Add 2.0g of anthocyanin and continue stirring until it is evenly dispersed. (4) High-pressure homogenization: Transfer the mixture into a high-pressure homogenizer and homogenize at 11,000 rpm for 4 minutes. Repeat the homogenization operation twice to obtain a fine and uniform emulsion. (5) pH adjustment: Add 1 mol / L hydrochloric acid solution dropwise to the emulsion, monitor and adjust the pH value to 4.0 in real time, and stir evenly; (6) Spray drying: The emulsion is fed into the spray dryer, and the inlet air temperature is set to 170°C, the outlet air temperature to 90°C, and the feed speed to 5%. After spray drying, the powdered microcapsules are collected. (7) Testing and storage: The microcapsule encapsulation rate was 95.03% after testing. The microcapsules were sealed and stored in a refrigerated environment at 4°C. Example 3

[0025] A method for applying pear peel pectin-based anthocyanin microcapsules in Four-Ingredient Pear Soup, the specific implementation steps are as follows: (1) Raw material processing: Select 200g of Dangshan crisp pears that are free from pests and diseases and mechanical damage, peel and core them and set them aside; (2) First stage of steaming: Add the processed pears to 250mL of purified water, place them in a steaming device, set the power to 2000W and the temperature to 220℃, and steam for 55min; (3) Second stage of steaming: Add 4g each of Poria cocos, lotus seeds, yam slices and Euryale ferox, 4.5g of zero-calorie sugar and 0.1g of vitamin C to the pear soup, and continue to steam for 55 minutes at 2000W and 220℃. (4) Low-temperature preparation: Cool the pear soup naturally to 60°C, add 0.2g of pear peel pectin-based anthocyanin microcapsules obtained in Example 2, and stir well; (5) Sterilization: After stirring evenly, seal immediately and pasteurize at 60℃ for 25 minutes. After cooling to room temperature, you will get Four Gods Pear Soup (Spring Version).

[0026] Sensory evaluation: Ten food professionals evaluated the product according to the sensory scoring standards for Chunkuan Pear Soup. The average sensory score was 91.22. The product is a bright, uniform pink color, clear and transparent without sediment, with a rich pear aroma and a light floral fragrance, no medicinal smell, soft and glutinous pear flesh, sweet and sour taste, and refreshing taste. Example 4

[0027] To verify the validity of the process parameter ranges in the claims of this invention, experiments were conducted with different parameters selected within the ranges. The remaining steps were the same as in Examples 1-3, and the experimental results are as follows: (1) Pectin extraction from pear peel: The pectin yield was 12.1% when the enzyme content was 0.2% and 13.8% when the enzyme content was 0.8%, both ≥12%; the pectin yield was 12.5% ​​when the ultrasonic power was 450W and 13.5% when the ultrasonic power was 550W, both achieving effective pectin extraction; (2) Microcapsule preparation: The encapsulation rate was 90.2% when the homogenization speed was 9000 rpm, 91.5% when the homogenization speed was 13000 rpm, and 90.5% when the spray drying inlet air temperature was 160℃ / outlet air temperature was 85℃, all ≥90%; (3) Preparation of Four Gods Pear Soup: The sensory score was 89.5 when the cooking power was 1900W / 210℃, the sensory score was 89.8 when the cooking power was 2100W / 230℃, and the sensory score was 88.6 when microcapsules were added at 55℃ / sterilization at 55℃. All scores were ≥88.

[0028] The above experimental results demonstrate that the process parameter range of the present invention can achieve the corresponding technical effects, adapt to process fluctuations in industrial production, and has good industrial promotion value. Comparative Example 1

[0029] Pear peel pectin was extracted using a combination of enzymatic hydrolysis (cellulase + acidic protease), 175W ultrasound for 70 minutes, and decolorization and concentration processes, with the remaining raw materials and processing steps being the same as in Example 1. The results showed that the enzyme cost of this process was 60% higher than that of the present invention, the ultrasound time was 3.5 times that of the present invention, the pectin yield was only 12.0%, and the process steps were cumbersome and time-consuming, making it unsuitable for industrial production. Comparative Example 2

[0030] Commercial citrus pectin was used to replace the pear peel pectin of this invention. Anthocyanin microcapsules were prepared using the same compounding ratio and process, with the remaining steps being the same as in Examples 2-3. The results showed that the encapsulation rate of the microcapsules was only 85.1%. When applied to Si Shen Su Pear Soup, the pear soup became slightly cloudy, and the sensory score was 82.5 points. Moreover, the cost of commercial citrus pectin was more than 10 times that of the pear peel pectin of this invention, resulting in a significant increase in product production costs. Comparative Example 3

[0031] The pear peel pectin-based anthocyanin microcapsules prepared in Example 2 of this invention were directly added during the second stage of cooking at 220°C, with the remaining steps the same as in Example 3. The results showed that high-temperature cooking destroyed the microcapsule structure, and the anthocyanins were degraded in large quantities. The pear soup had no natural pink color. The anthocyanin retention rate was only 35.2%, which was far lower than the anthocyanin retention rate of the low-temperature addition at 55~65°C in this invention.

Claims

1. A method for preparing pear peel pectin, characterized in that... Includes the following steps: (1) Pear peel pretreatment: Peel fresh Dangshan pears and put them in a boiling water bath to inactivate enzymes for 5-7 minutes; then dry the pear peels in an oven, pulverize them to obtain uniform pear peel powder, and seal them for later use. (2) Construction of enzymatic hydrolysis system: Pear peel powder and distilled water were mixed at a material-to-liquid ratio of 1:18 to 1:22 (g / mL), and the pH of the system was adjusted to 4.0 to 5.0 with 1 mol / L dilute hydrochloric acid; 0.2% to 0.8% of cellulase by weight of pear peel powder was added to the mixture, and the mixture was placed in a constant temperature water bath at 38 to 42℃ for 2.5 to 3.5 h for enzymatic hydrolysis. (3) Post-enzymatic hydrolysis treatment: After the enzymatic hydrolysis is completed, the mixture is placed in a water bath at 85~95℃ for 8~12 min to inactivate the enzyme. After cooling to room temperature, it is ultrasonically treated with 450~550W power for 15~25 min. After ultrasonic treatment, the mixture is filtered to remove solid residues and the clear filtrate is used for later use. (4) Alcohol precipitation and drying: Add an equal volume of anhydrous ethanol to the filtrate, mix thoroughly and let stand for 10-16 hours to allow the pectin to precipitate fully; place the precipitate mixture in a centrifuge and centrifuge at 2800-3200 rpm for 15-25 minutes, and collect the pectin precipitate at the bottom; place the precipitate in an oven at 50-60℃ and dry to constant weight to obtain the pear peel pectin product.

2. The method for preparing pear peel pectin according to claim 1, characterized in that... The drying temperature in step (1) is 65~75℃ and the drying time is 20~28h.

3. A method for preparing pear peel pectin-based anthocyanin microcapsules, characterized in that... Includes the following steps: (1) Preparation of whey protein solution: Add whey protein powder to deionized water and stir to dissolve at room temperature to obtain a whey protein solution with a mass concentration of 2%~4% (w / v), and seal for later use; (2) Preparation of pear peel pectin solution: Pear peel pectin is added to deionized water and stirred and dissolved in a constant temperature water bath at 55~65℃ to obtain a clear pectin solution with a mass concentration of 0.8%~1.2% (w / v). After cooling to room temperature, it is ready for use. (3) Preparation of mixture and addition of anthocyanins: The mass ratio of pear peel pectin to whey protein is 1:2 to 1:

4. While stirring, slowly pour the whey protein solution into the pectin solution; then add 20 to 30% of the mass of the mixture of anthocyanins to the mixture and stir evenly. (4) High-pressure homogenization: Transfer the anthocyanin-containing mixture into a high-pressure homogenizer, set the homogenization speed to 9000~13000 rpm, homogenize for 2~6 minutes, repeat the homogenization operation 2~3 times to make the mixture form a fine and uniform emulsion. (5) pH adjustment: Adjust the pH value to 3.8~4.2 using 1 mol / L hydrochloric acid solution; (6) Spray drying to prepare microcapsules: The emulsion with adjusted pH value is fed into the spray dryer, the inlet air temperature is set to 160~180℃, the outlet air temperature is set to 85~95℃, and the feed speed is set to 4%~6%. The equipment is started to carry out spray drying, and the dried powder product is collected to obtain pear peel pectin-based anthocyanin microcapsules.

4. The method for preparing pear peel pectin-based anthocyanin microcapsules according to claim 3, characterized in that: The stirring time in step (1) is 25~35 min.

5. The method for preparing pear peel pectin-based anthocyanin microcapsules according to claim 3, characterized in that: In step (2), the stirring time is 1.5 to 2.5 hours for dissolution.

6. The method for preparing pear peel pectin-based anthocyanin microcapsules according to claim 3, characterized in that: In step (3), the mass ratio of pear peel pectin to whey protein is 1:

3.

7. The method for preparing pear peel pectin-based anthocyanin microcapsules according to claim 3, characterized in that: The storage method for the pear peel pectin-based anthocyanin microcapsules is as follows: the prepared anthocyanin microcapsules are placed in a sealed bag, excess air is removed from the bag, and then the bag is sealed and stored in a refrigerated environment at 2~6℃.

8. A method for applying pear peel pectin-based anthocyanin microcapsules in Four-Ingredient Pear Soup, characterized in that... Includes the following steps: (1) Raw material processing: Select Dangshan crisp pears that are of moderate maturity, free from pests and diseases and mechanical damage, peel and core them and set them aside; (2) First stage of steaming: Add the processed crisp pears to pure water, control the mass ratio of Dangshan crisp pears to pure water to be 18~22:23~27, and then place them in a steaming device. Set the power to 1900~2100W and the temperature to 210~230℃, and simmer for 50~60 minutes to obtain pear soup. (3) Second stage of steaming: Add 3.5~4.5g each of Poria cocos, lotus seeds, yam slices, and Euryale ferox to the pear soup, along with zero-calorie sugar and vitamin C. Control the mass ratio of Dangshan crisp pears to Poria cocos, lotus seeds, yam slices, Euryale ferox, zero-calorie sugar, and vitamin C to 180~220:3.5~4.5:3.5~4.5:3.5~4.5:4.0~5:0.08~0.

12. Continue steaming at 1900~2100W power and 210~230℃ for 50~60 minutes. (4) Low-temperature preparation and sterilization: After steaming, the pear soup is naturally cooled to 55~65℃. Add 0.1-0.4% of the weight of Dangshan crisp pear pectin-based anthocyanin microcapsules to the pear soup, stir evenly and seal immediately. Sterilize at 55~65℃ for 20~30 minutes to obtain Sishen crisp pear soup.

Images