Preparation method of boxthorn leaf superfine powder

Abstract

The invention discloses a preparation method of boxthorn leaf superfine powder, and belongs to the technical field of agricultural product processing. The method comprises the steps of raw material pretreatment (1%-3% sodium carbonate soaking, 95-100 DEG C blanching, 0-10 DEG C cold water soaking and-30--35 DEG C quick freezing), multi-stage normal pressure-vacuum alternate drying, coarse grinding and superfine grinding, and active ingredients such as flavone and polyphenol in the boxthorn leaves are reserved to the maximum extent while the bright green color of the boxthorn leaves is kept. The prepared boxthorn leaf superfine powder can be used as a source of natural dietary fibers, vitamins and antioxidants to be added into food, health care products, medicines, cosmetics and feeds.

Description

Technical Field

[0001] This invention belongs to the field of agricultural product processing and functional food technology, and specifically relates to a method for preparing ultrafine powder of wolfberry leaves. Background Technology

[0002] Goji berry leaves are rich in a variety of bioactive substances, including flavonoids, alkaloids, phenolic compounds and organic acids, which endow them with potential antioxidant, antibacterial and anti-inflammatory bioactivities.

[0003] In existing technologies, the powdering of plant leaves has been applied, such as the preparation of carbon dots from eucalyptus leaves and the synthesis of silver nanoparticles mediated by bamboo leaves. This indicates that the effective components of plant leaves can be retained or enriched after appropriate treatment, making them suitable for the development of high-value-added products. Currently, ultrafine powders, compared to coarse powders, achieve a cell wall breakage rate of over 90%, a significantly increased specific surface area, and a 30%–50% improvement in bioavailability, resulting in more complete dissolution of active ingredients. They also exhibit better solubility and dispersibility, are easier to mix during processing, require less dosage, and have a delicate texture and uniform color. Their functional effects are more significant in various fields, significantly enhancing product added value and market competitiveness. The application of ultrafine powder material preparation technology in the food and pharmaceutical industries provides technical support for the high-value utilization of wolfberry leaves.

[0004] However, existing wolfberry leaf processing methods suffer from imperfections. When wolfberry leaves are processed into ultrafine powder, browning easily occurs due to the combined effects of enzymatic and non-enzymatic reactions; water-soluble, heat-sensitive, and easily oxidized nutrients (flavonoids, polyphenols, vitamins, etc.) are largely lost due to water contact, high temperatures, and oxygen exposure. Existing technologies for enzyme inactivation, drying, and pulverization are flawed, exacerbating these problems and resulting in poor product appearance, low functionality, and low added value. Summary of the Invention This invention provides a method for preparing ultrafine powder of wolfberry leaves. The method involves a raw material pretreatment process of soaking in sodium carbonate, blanching, soaking in cold water and quick-freezing, as well as a multi-stage alternating drying process of normal pressure and vacuum, coarse powder and ultrafine pulverization process to maintain the bright green color of wolfberry leaves, while maximizing the retention of active ingredients such as flavonoids and polyphenols in wolfberry leaves.

[0005] This invention provides a method for preparing ultrafine powder of wolfberry leaves, comprising the following steps: S1. Raw material pretreatment: Soak wolfberry leaves in 1%~3% sodium carbonate, then blanch them in hot water at 95~100℃, then soak them in cold water to cool, and finally quick-freeze them; S2. Drying treatment: A multi-stage alternating atmospheric and vacuum drying process is adopted, which consists of drying at 65℃ atmospheric pressure for 0.5h, drying at 65℃ vacuum for 5h, drying at 55℃ atmospheric pressure for 0.5h, drying at 55℃ vacuum for 5h, drying at 50℃ atmospheric pressure for 15min, drying at 50℃ vacuum for 45min, drying at 55℃ atmospheric pressure for 0.5h, drying at 55℃ vacuum for 5h, and drying at 55℃ atmospheric pressure for 0.5h. S3. Grinding: The dried wolfberry leaves are first coarsely ground, and then ultra-finely ground using a ball mill to obtain wolfberry leaf ultra-fine powder. Furthermore, in step S1, the sodium carbonate soaking time is 15-25 seconds, the blanching time is 60-80 seconds, the cold water soaking temperature is 0-10℃, the cold water soaking time is 0.5-1 hour, the quick-freezing temperature is -30℃ to -35℃, and the quick-freezing time is 1-3 hours.

[0006] Furthermore, the vacuum degree of the vacuum drying in step S2 is 450 Pa.

[0007] Furthermore, in step S3, the ball mill used for ultrafine grinding has a steel ball diameter of 13-16 mm, a ball-to-material mass ratio of 20:1, a loading of 4 / 9, a rotation speed of 3800 r / min, a grinding temperature of 10-25℃, and a grinding time of 2-4 h.

[0008] Furthermore, the grinding time for ultrafine grinding in the ball mill described in step S3 is 3 hours. On the other hand, the present invention provides an application of the wolfberry leaf ultrafine powder prepared according to the above preparation method, wherein the application refers to adding wolfberry leaf powder to food, health products, medicine, cosmetics, and feed as a source of natural dietary fiber, vitamins and antioxidants.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention effectively solves the problems of browning of wolfberry leaves and loss of active ingredients caused by traditional high-temperature processing by using a combination of "sodium carbonate greening + hot water blanching + low temperature quick freezing + multi-stage normal pressure-vacuum alternating drying + ultra-fine pulverization".

[0010] (2) Compared with direct hot air drying, the present invention increases the retention rate of polyphenols and flavonoids in wolfberry leaf ultrafine powder by 30.91% and 216.59% respectively, and reduces the color a value by 2.0 to 2.4 times (the lower the a value, the brighter the green).

[0011] (3) The present invention uses a ball mill for ultrafine grinding. When the grinding time is 2-4h, the prepared wolfberry leaf ultrafine powder is bright green. When the grinding time reaches 3h, the wolfberry leaf ultrafine powder is the brightest green. Compared with the grinding time of 1.5h and 4.5h, the color a value is reduced by 36.15% and 20.59%, respectively.

[0012] (4) The ultrafine powder of wolfberry leaves prepared by this invention can be directly added to a variety of foods, breaking through the application limitations of traditional medicinal extracts of wolfberry leaves and broadening its application scenarios. When added to food, health products, medicine, cosmetics and feed, it can serve as a source of natural dietary fiber, vitamins and antioxidants.

[0013] (5) The process of this invention is simple and easy to operate. The required equipment is commonly used in the food processing field. It is easy to scale up industrial production. The raw material, wolfberry leaves, is widely available and has low cost, which has significant economic value and social benefits. Detailed Implementation

[0014] Example 1 (1) Raw material pretreatment: Select 500g of fresh, disease-free wolfberry leaves, soak them in 2% sodium carbonate solution for 20s; then blanch them in 95℃ hot water for 60s; quickly remove them and soak them in 5℃ cold water for 1h; remove them, drain the water, and quick-freeze them at -35℃ for 2h.

[0015] (2) Drying treatment: The quick-frozen wolfberry leaves were placed in a vacuum drying oven and dried according to the following process: 65℃ normal pressure hot air drying for 0.5h, 65℃ vacuum drying for 5h; 55℃ normal pressure hot air drying for 0.5h, 55℃ vacuum drying for 5h; 50℃ normal pressure hot air drying for 15min, 50℃ vacuum drying for 45min; 55℃ normal pressure hot air drying for 0.5h, 55℃ vacuum drying for 5h; 55℃ normal pressure hot air drying for 0.5h, and the dried wolfberry leaves were obtained after drying.

[0016] (3) Grinding: Put the dried wolfberry leaves into a Chinese medicine pulverizer and coarsely grind for 30 seconds to obtain coarse powder; put the coarse powder into a ball mill, select steel balls with a diameter of 15mm, ball-to-material mass ratio of 20:1, filling amount of 4 / 9, set the rotation speed of 3800r / min, grinding temperature of 20℃, grinding time of 3h to obtain wolfberry leaf ultrafine powder.

[0017] Example 2 (1) Raw material pretreatment: Select 500g of fresh, disease-free wolfberry leaves, soak them in 3% sodium carbonate solution for 25s; then blanch them in 100℃ hot water for 60s; quickly remove them and soak them in 0℃ cold water for 0.8h; remove them, drain the water, and quick freeze them at -30℃ for 3h.

[0018] (2) Drying treatment: The leaves were dried according to the multi-stage atmospheric pressure-vacuum alternating drying process in Example 1 to obtain dried wolfberry leaves.

[0019] (3) Crushing: After the dried wolfberry leaves are coarsely crushed, they are put into a ball mill. 13mm diameter steel balls are selected, the ball-to-material mass ratio is 20:1, the filling amount is 4 / 9, the rotation speed is set to 3800r / min, the crushing temperature is 15℃, and the crushing time is 2h to obtain wolfberry leaf ultrafine powder.

[0020] Example 3 (1) Raw material pretreatment: Select 500g of fresh, disease-free wolfberry leaves, soak them in 1% sodium carbonate solution for 25s; then blanch them in 100℃ hot water for 70s; quickly remove them and soak them in 10℃ cold water for 0.5h; remove them, drain the water, and quick-freeze them at -30℃ for 1h.

[0021] (2) Drying treatment: The leaves were dried according to the multi-stage atmospheric pressure-vacuum alternating drying process in Example 1 to obtain dried wolfberry leaves.

[0022] (3) Crushing: After the dried wolfberry leaves are coarsely crushed, they are put into a ball mill. 16 mm diameter steel balls are selected, the ball-to-material mass ratio is 20:1, the filling amount is 4 / 9, the rotation speed is set to 3800 r / min, the crushing temperature is 25℃, and the crushing time is 4h to obtain wolfberry leaf ultrafine powder.

[0023] Example 4 (1) Raw material pretreatment: Select 500g of fresh, disease-free wolfberry leaves, soak them in 2% sodium carbonate solution for 25s; then blanch them in 100℃ hot water for 80s; quickly remove them and soak them in 10℃ cold water for 0.5h; remove them, drain the water, and quick-freeze them at -30℃ for 1h.

[0024] (2) Drying treatment: The leaves were dried according to the multi-stage atmospheric pressure-vacuum alternating drying process in Example 1 to obtain dried wolfberry leaves.

[0025] (3) Crushing: After the dried wolfberry leaves are coarsely crushed, they are put into a ball mill. 16 mm diameter steel balls are selected, the ball-to-material mass ratio is 20:1, the filling amount is 4 / 9, the rotation speed is set to 3800 r / min, the crushing temperature is 25℃, and the crushing time is 4h to obtain wolfberry leaf ultrafine powder.

[0026] Comparative Example 1 The specific steps are the same as in Example 1, except that in step (2), the quick-frozen wolfberry leaves are placed in a normal pressure hot air dryer and dried for 20 hours.

[0027] Comparative Example 2 The specific steps are the same as in Example 1, except that in step (3), the grinding time of the ball mill is 1.5 hours.

[0028] Comparative Example 3 The specific steps are the same as in Example 1, except that in step (3), the grinding time of the ball mill is 4.5 h.

[0029] Comparative Example 4 The specific steps are the same as in Example 1, except that in step (1), the blanching time is 90 seconds.

[0030] Comparative Example 5 The specific steps are the same as in Example 1, except that in step (1), the blanching time is 50 seconds.

[0031] Performance testing Color detection: The a value of wolfberry leaf powder was determined using a colorimeter.

[0032] Active ingredient detection: Polyphenol content was determined by the Folin-phenol method (T / NAIA 097-2021); flavonoid content was determined by the sodium nitrite-aluminum nitrate-sodium hydroxide colorimetric method (GB / T 20574-2006). The results are shown in Table 1.

[0033] Table 1: Values ​​of Flavonoid Content, Polymer Content, and Color in Lycium barbarum Leaf Powder

[0034] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing ultrafine powder of wolfberry leaves, characterized in that, Includes the following steps: S1. Raw material pretreatment: Soak wolfberry leaves in 1%~3% sodium carbonate, then blanch at 95~100℃, then soak in cold water to cool, and finally quick-freeze; S2. Drying treatment: A multi-stage alternating atmospheric and vacuum drying process is adopted, which consists of drying at 65℃ atmospheric pressure for 0.5h, drying at 65℃ vacuum for 5h, drying at 55℃ atmospheric pressure for 0.5h, drying at 55℃ vacuum for 5h, drying at 50℃ atmospheric pressure for 15min, drying at 50℃ vacuum for 45min, drying at 55℃ atmospheric pressure for 0.5h, drying at 55℃ vacuum for 5h, and drying at 55℃ atmospheric pressure for 0.5h. S3. Grinding: The dried wolfberry leaves are first coarsely ground, and then ultra-finely ground using a ball mill to obtain wolfberry leaf ultra-fine powder.

2. The preparation method according to claim 1, characterized in that, In step S1, the sodium carbonate soaking time is 15-25 seconds, the blanching time is 60-80 seconds, the cold water soaking temperature is 0-10℃ and the time is 0.5-1 hour, and the quick-freezing temperature is -30℃ to -35℃ and the quick-freezing time is 1-3 hours.

3. The preparation method according to claim 1, characterized in that, In step S1, the sodium carbonate concentration is 2%~3%, the cold water soaking time is 0.5~1h, and the quick-freezing temperature is -30~-35℃.

4. The preparation method according to claim 1, characterized in that, In step S3, the ball mill used for ultrafine grinding has a steel ball diameter of 13-16 mm, a ball-to-material mass ratio of 20:1, a loading of 4 / 9, a rotation speed of 3800 r / min, a grinding temperature of 10-25℃, and a grinding time of 2-4 h.

5. The preparation method according to claim 1, characterized in that, The grinding time for ultrafine grinding in the ball mill described in step S3 is 3 hours.

6. The application of the ultrafine powder of wolfberry leaves prepared by any one of claims 1 to 5, characterized in that, The wolfberry leaf powder can be added to food, health products, medicine, cosmetics, and feed as a source of natural dietary fiber, vitamins, and antioxidants.

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