A kind of preparation method of sea buckthorn fruit powder

Abstract

The present invention relates to the technical field of preparation of seabuckthorn fruit powder, and in particular to a preparation method of seabuckthorn fruit powder, comprising: picking seabuckthorn branches and fruits, freezing the seabuckthorn branches and fruits, breaking and threshing them, washing them, draining them and sending them to a pulper for pulping to obtain pulp, squeezing the pulp and separating and removing impurities from the peel to obtain a coarse pulp, using an oil-water centrifuge to separate part of the fruit oil from the coarse pulp, using an ultrasonic vibration screen to separate part of the pulp, and degassing the pulp after separation to obtain a to-be-sterilized pulp; sterilizing the to-be-sterilized pulp at high temperature and then transporting it to a filling room for filling and storage to obtain seabuckthorn pulp, and placing the seabuckthorn pulp in a vacuum freeze dryer equipped with a low-voltage electrostatic field device for freeze drying to obtain seabuckthorn fruit powder. The present invention improves the retention rate of nutrients.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of seabuckthorn fruit powder, in particular to a preparation method of seabuckthorn fruit powder. Background Art

[0002] Seabuckthorn is rich in various nutrients, such as vitamins, proteins, phenolic acids, flavonoids, unsaturated fatty acids, etc. Seabuckthorn fruit, seabuckthorn bark, seabuckthorn branches, seabuckthorn leaves, seabuckthorn seeds, etc. are rich in active substances, so their medicinal and health-improving effects have attracted more and more attention, and seabuckthorn has also been given the reputation of "green gold". Seabuckthorn fruit can be eaten fresh and tastes delicious, but due to its high acidity, it is difficult to pick and difficult to store and transport, and the sales of fresh fruit is very small, so it is often processed into products. Processing fresh seabuckthorn into other products is a major way to promote the development of the seabuckthorn industry. However, traditional seabuckthorn primary processed products such as seabuckthorn juice, seabuckthorn wine, and seabuckthorn seed oil can no longer meet market demand. Fruit and vegetable powder is a product made by drying and crushing fresh fruits and vegetables into powder. It not only has the advantages of unique flavor, rich nutrition, good storage stability and easy transportation, but also can enrich product categories, meet special consumer needs and achieve efficient comprehensive utilization.

[0003] Chinese patent publication number: CN110637960A discloses a method for preparing seabuckthorn fruit powder, comprising the following steps: storing seabuckthorn branches and fruits in a cold storage at -40°C for 48 hours, breaking and threshing, and washing after separation; draining the water on the surface of the washed seabuckthorn peel; sending the drained seabuckthorn fruit into a pulping machine for pulping; squeezing the pulp and dregs after pulping through a screw press; separating the pressed seabuckthorn raw pulp to remove peel impurities; separating part of the fruit oil and fine pulp after separation; degassing after separation; the degassed raw pulp is then sterilized in a UHT high-temperature instant sterilizer; the sterilized raw pulp is transported to the aseptic filling and sealing machine in the filling room through a pipeline pump for filling and storage; the stored seabuckthorn raw pulp is placed in a tray and placed in a vacuum freeze dryer for freeze-drying and packaging. The invention solves the problem of loss of nutrients, especially vitamin C, caused by seabuckthorn fruit powder produced by the prior art.

[0004] It can be seen that the preparation method of sea buckthorn fruit powder has the following problems: although the invention solves the problem of loss of nutrients, especially loss of vitamin C, caused by sea buckthorn fruit powder produced by the prior art, the invention lacks monitoring of the preparation process of sea buckthorn fruit powder and cannot ensure the retention of nutrients in the sea buckthorn fruit powder. Summary of the invention

[0005] To this end, the present invention provides a method for preparing seabuckthorn fruit powder, so as to overcome the problem of serious loss of nutrients during the processing of the fruit powder in the prior art.

[0006] To achieve the above object, the present invention provides a method for preparing seabuckthorn fruit powder, comprising:

[0007] Picking seabuckthorn branches and fruits, freezing the seabuckthorn branches and fruits, breaking them up, threshing them and washing them, draining them and sending them to a pulping machine for pulping to obtain pulp, squeezing the pulp and separating and removing impurities from the peel to obtain a coarse pulp;

[0008] The crude pulp is separated into a part of the fruit oil by using an oil-water centrifuge, and a part of the fruit pulp is separated by using an ultrasonic vibration screen, and after the separation, degassing is performed to obtain the raw pulp to be sterilized;

[0009] The raw pulp to be sterilized is sterilized at high temperature and then transported to a filling room for filling and storage to obtain seabuckthorn raw pulp, and the seabuckthorn raw pulp is placed in a vacuum freeze dryer equipped with a low-voltage electrostatic field device for freeze drying to obtain seabuckthorn fruit powder;

[0010] Obtaining a drying rate curve of the seabuckthorn fruit powder, determining the eligibility of the drying process of the seabuckthorn fruit powder based on the drying rate curve, and for an unqualified drying process, adjusting the electric field strength by adjusting the distance between the electrode plates to determine again whether the drying process of the seabuckthorn fruit powder is qualified;

[0011] Based on the qualified drying process, the water absorption index of the sea buckthorn fruit powder is corrected according to the color difference evaluation value of the sea buckthorn fruit powder to determine whether the fruit oil separation process is qualified, and whether the pulp separation process is qualified according to the water solubility index of the sea buckthorn fruit powder. For unqualified processes, the rotation speed of the oil-water centrifuge and / or the vibration frequency of the ultrasonic vibration screen are adjusted.

[0012] Further, the process of determining whether the drying process of the seabuckthorn fruit powder is qualified based on the drying rate curve includes:

[0013] Periodically test the moisture content of sea buckthorn puree in the vacuum freeze dryer;

[0014] Draw a drying rate curve with the detection time as the horizontal axis and the moisture content as the vertical axis;

[0015] Calculate respectively a first area enclosed by the drying rate curve and the horizontal and vertical axes, and a second area enclosed by the standard drying rate curve and the horizontal and vertical axes;

[0016] comparing the first area to the second area;

[0017] Based on the comparison result that the first area is greater than the second area, it is determined that the drying process of the sea buckthorn fruit powder is unqualified.

[0018] Furthermore, the conditions for applying a low-voltage electrostatic field to freeze-dry the seabuckthorn puree are: the cold trap temperature is -30°C, and the freeze-drying is performed for 48 hours after pre-freezing for 48 hours.

[0019] Further, the process of adjusting the electric field strength for the unqualified drying process includes:

[0020] subtracting the first area from the second area to obtain an area difference;

[0021] comparing the area difference value with a preset area difference value;

[0022] Determining to reduce the electrode plate spacing by a first amplitude based on a comparison result that the area difference is greater than the preset area difference;

[0023] Determining to reduce the electrode plate spacing by a second amplitude based on a comparison result that the area difference is less than or equal to the preset area difference;

[0024] The smaller the distance between the electrode plates, the greater the electric field strength.

[0025] Furthermore, the water absorption index detection process includes:

[0026] Weigh the second preset weight m s The sea buckthorn fruit powder is placed in a centrifuge tube, a preset volume of distilled water is added, and the mixture is stirred for a preset time and then centrifuged;

[0027] Pour the supernatant after centrifugation into the evaporating dish and weigh the remaining gel. g ;

[0028] m g With m s The ratio is the water absorption index.

[0029] Furthermore, under qualified drying process conditions, the process of correcting the water absorption index of seabuckthorn fruit powder based on the color difference evaluation value includes:

[0030] Comparing the color difference evaluation value with a preset evaluation value;

[0031] Based on the comparison result that the color difference evaluation value is greater than the preset evaluation value, it is determined to increase the water absorption index by a preset index correction coefficient.

[0032] Further, the process of determining whether the separation process of the fruit oil is qualified based on the water absorption index includes:

[0033] comparing the water absorption index with a preset water absorption index;

[0034] Determining that the separation process of the fruit oil is unqualified based on the comparison result that the water absorption index is less than the preset water absorption index;

[0035] Further, the process of determining whether the pulp separation process is qualified based on the water solubility index includes:

[0036] comparing the water solubility index with a preset water solubility index;

[0037] The pulp separation process is determined to be unqualified based on the comparison result that the water solubility index is less than the preset water solubility index.

[0038] Furthermore, based on the condition that the separation process of the fruit oil is unqualified, several adjustment methods are set for the rotation speed of the oil-water centrifuge according to the water absorption difference between the preset water absorption index and the water absorption index, and each adjustment method increases the rotation speed by a different amount.

[0039] Furthermore, based on the condition that the pulp separation process is unqualified, several adjustment methods are set for the vibration frequency of the ultrasonic vibration screen according to the preset water solubility index and the water solubility difference of the water solubility index, and each adjustment method increases the vibration frequency by a different amount.

[0040] Compared with the prior art, the beneficial effect of the present invention lies in that the present invention accelerates the migration and sublimation of water in the sea buckthorn puree and the drying process by applying a low-voltage electrostatic field during the freeze-drying process of the sea buckthorn fruit powder, and at the same time, the low-voltage electrostatic field technology can also change the morphology and distribution of ice crystals during the freeze-drying process, reduce the mechanical damage to the microstructure of the fruit tissue, reduce the loss of juice after thawing, and thus improve the retention rate of nutrients.

[0041] Furthermore, whether the electric field strength of the drying process is qualified is determined by the drying rate curve of the sea buckthorn fruit powder, and the judgment is made based on the area enclosed by the drying rate curve and the coordinate axis, thereby avoiding the judgment error caused by the unqualified drying rate at a certain point. The judgment of the drying rate of the entire freeze-drying process of the sea buckthorn puree is more objective and accurate, which improves the evaluation benchmark of the drying process, thereby further improving the retention rate of nutrients.

[0042] Furthermore, the present invention determines the drying rate again after adjusting the unqualified electric field intensity, and determines the correction method of the water absorption index of the sea buckthorn fruit powder according to the color difference evaluation value of the sea buckthorn fruit powder based on the qualified drying process. The larger the color difference, the less water content in the raw materials for making the sea buckthorn fruit powder, and the deviation of the water absorption index of the prepared sea buckthorn fruit powder is large, which needs to be corrected; the water absorption index is related to the dissolution rate of the sea buckthorn fruit powder, and the water solubility index is related to the dissolution uniformity of the sea buckthorn fruit powder. The larger the water absorption index and the water solubility index, the faster the dissolution rate of the sea buckthorn fruit powder and the better the dissolution uniformity. The presence of fruit oil and pulp will increase the flavor of the sea buckthorn fruit powder, but the presence of too much fruit oil and fruit powder will reduce the dissolution rate and dissolution uniformity of the sea buckthorn fruit powder. Parameters are adjusted in a targeted manner based on the unqualified separation process, thereby improving the retention rate of nutrients. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The process flow chart of the preparation method of seabuckthorn fruit powder according to the embodiment of the present invention;

[0044] Figure 2 This is a flow chart of a method for preparing seabuckthorn fruit powder according to an embodiment of the present invention;

[0045] Figure 3 A flow chart of determining whether the drying process of seabuckthorn fruit powder is qualified according to an embodiment of the present invention;

[0046] Figure 4 The present invention is a flow chart for determining whether the separation process of the fruit oil is qualified. DETAILED DESCRIPTION

[0047] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0049] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0050] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] See also Figure 1-Figure 4 As shown, Figure 1 The process flow chart of the preparation method of seabuckthorn fruit powder according to the embodiment of the present invention; Figure 2 This is a flow chart of a method for preparing seabuckthorn fruit powder according to an embodiment of the present invention; Figure 3 A flow chart of determining whether the drying process of seabuckthorn fruit powder is qualified according to an embodiment of the present invention; Figure 4The present invention is a flowchart for determining whether the separation process of the fruit oil is qualified.

[0052] The embodiment of the present invention provides a method for preparing seabuckthorn fruit powder, comprising:

[0053] Step S1, picking seabuckthorn branches and fruits, freezing the seabuckthorn branches and fruits, breaking them up, threshing them and washing them, draining them and sending them to a pulper for pulping to obtain pulp, squeezing the pulp and separating and removing impurities from the peel to obtain a coarse pulp;

[0054] Step S2, using an oil-water centrifuge to separate part of the fruit oil from the crude pulp, using an ultrasonic vibration screen to separate part of the pulp, and after separation, performing a degassing treatment to obtain a raw pulp to be sterilized;

[0055] Step S3, sterilizing the raw puree to be sterilized at high temperature and then transporting it to a filling room for filling and storage to obtain seabuckthorn raw puree, and placing the seabuckthorn raw puree in a vacuum freeze dryer equipped with a low-voltage electrostatic field device for freeze drying to obtain seabuckthorn fruit powder;

[0056] Step S4, obtaining a drying rate curve of the seabuckthorn fruit powder, determining whether the drying process of the seabuckthorn fruit powder is qualified based on the drying rate curve, and for an unqualified drying process, adjusting the electric field strength by adjusting the distance between the electrode plates to determine again whether the drying process of the seabuckthorn fruit powder is qualified;

[0057] Step S5, based on the qualified drying process, the water absorption index of the sea buckthorn fruit powder is corrected according to the color difference evaluation value of the sea buckthorn fruit powder to determine whether the separation process of the fruit oil is qualified, and whether the separation process of the pulp is qualified according to the water solubility index of the sea buckthorn fruit powder, and the rotation speed of the oil-water centrifuge and / or the vibration frequency of the ultrasonic vibration screen are adjusted for unqualified processes.

[0058] Specifically, the embodiment of the present invention adopts a wet milling process to prepare sea buckthorn fruit powder. First, a low-temperature quick-freezing flat-cut sea buckthorn picking technology is adopted. The sea buckthorn branches and fruits are stored in a cold storage at -40°C and frozen for 48 hours, and then broken up and threshed. After separation, they are washed; the water on the surface of the washed sea buckthorn peel is drained, and then the drained sea buckthorn fruit is sent to a pulper for pulping to obtain a slurry; the slurry and residue are squeezed by a screw press; the pressed sea buckthorn raw pulp is separated to remove peel impurities to obtain a coarse slurry; the coarse slurry is separated from part of the fruit oil by an oil-water centrifuge, and part of the fine pulp is separated by an ultrasonic vibration screen; degassing is performed after separation; the degassed raw pulp is then sent to the UHT Sterilize in a high-temperature instantaneous sterilizer; after sterilization, transport to the aseptic filling and sealing machine in the filling room through a pipeline pump for filling and storage; put the stored sea buckthorn puree into a tray and place it in a vacuum freeze dryer equipped with a low-voltage electrostatic field device, apply an electrostatic field during the entire freeze-drying process, and finally refrigerate the obtained sea buckthorn fruit powder at -30°C for future use.

[0059] Specifically, excessive content of fruit oil and pulp in sea buckthorn puree will affect the solubility of sea buckthorn fruit powder, making it difficult to disperse evenly in water, and the fruit oil will produce unpleasant flavors such as rancid taste during long-term storage, affecting the taste.

[0060] Specifically, there is no limitation on the models of the screw press, oil-water centrifuge and ultrasonic vibrating screen, as long as they can meet the requirements.

[0061] Specifically, the process of determining whether the drying process of seabuckthorn fruit powder is qualified based on the drying rate curve includes:

[0062] Periodically test the moisture content of sea buckthorn puree in the vacuum freeze dryer;

[0063] Draw a drying rate curve with the detection time as the horizontal axis and the moisture content as the vertical axis;

[0064] Calculate respectively a first area enclosed by the drying rate curve and the horizontal and vertical axes, and a second area enclosed by the standard drying rate curve and the horizontal and vertical axes;

[0065] comparing the first area to the second area;

[0066] Based on the comparison result that the first area is greater than the second area, it is determined that the drying process of the sea buckthorn fruit powder is unqualified.

[0067] Specifically, the value range of the detection period is set to [10min, 60min], and 30min is preferred in the embodiment of the present invention.

[0068] Specifically, the moisture content detection process includes:

[0069] Weigh the first preset weight m 1 Sea buckthorn puree;

[0070] The sea buckthorn puree is dried in a vacuum oven at a preset temperature to a constant weight m 2 ;

[0071] M 1 With m 2 Make a difference to obtain the difference Δm;

[0072] Δm and m 1 The ratio is the moisture content.

[0073] Specifically, the first preset weight m 1 The value of is not limited; the value range of the preset temperature is set to [68°C, 72°C], and 70°C is preferred in the embodiment of the present invention.

[0074] Specifically, the conditions for applying a low-voltage electrostatic field to freeze-dry the seabuckthorn puree are: the cold trap temperature is -30°C, pre-freezing for 48 hours and then freeze-drying for 48 hours.

[0075] Specifically, the process of adjusting the electric field strength for an unqualified drying process includes:

[0076] subtracting the first area from the second area to obtain an area difference;

[0077] comparing the area difference value with a preset area difference value;

[0078] Determining to reduce the electrode plate spacing by a first amplitude based on a comparison result that the area difference is greater than the preset area difference;

[0079] Determining to reduce the electrode plate spacing by a second amplitude based on a comparison result that the area difference is less than or equal to the preset area difference;

[0080] The smaller the distance between the electrode plates, the greater the electric field strength.

[0081] Specifically, the electrode plates are arranged in parallel.

[0082] Specifically, the value range of the preset area difference is set to [5, 15], and 10 is preferably selected in the embodiment of the present invention.

[0083] Specifically, reducing the electrode plate spacing by a first amplitude is to reduce the electrode plate spacing by a first spacing adjustment coefficient, the value range of the first spacing adjustment coefficient is set to [0.9, 0.95], and 0.92 is preferably used in the embodiment of the present invention; reducing the electrode plate spacing by a second amplitude is to reduce the electrode plate spacing by a second spacing adjustment coefficient, the value range of the second spacing adjustment coefficient is set to [0.8, 0.89], and 0.85 is preferably used in the embodiment of the present invention.

[0084] Specifically, the detection process of the water absorption index includes:

[0085] Weigh the second preset weight m s The sea buckthorn fruit powder is placed in a centrifuge tube, a preset volume of distilled water is added, and the mixture is stirred for a preset time and then centrifuged;

[0086] Pour the supernatant after centrifugation into the evaporating dish and weigh the remaining gel. g ;

[0087] m g With m s The ratio is the water absorption index.

[0088] Specifically, the second preset weight is 0.2 g, the preset volume is 5 ml, the preset time is 20 min, and the stirring rate is 3000 r / min.

[0089] Specifically, the evaporation pan is coated with asphalt.

[0090] Specifically, under qualified drying process conditions, the process of correcting the water absorption index of seabuckthorn fruit powder based on the color difference evaluation value includes:

[0091] Comparing the color difference evaluation value with a preset evaluation value;

[0092] Determining to reduce the water absorption index by a preset index correction coefficient based on a comparison result that the color difference evaluation value is greater than the preset evaluation value;

[0093] Based on the comparison result that the color difference evaluation value is less than or equal to the preset evaluation value, it is determined that the water absorption index is not corrected.

[0094] Specifically, the calculation process of the color difference evaluation value is:

[0095] Obtain the coordinate values ​​of the three components L, a and b of the color of the seabuckthorn fruit powder in the CIELAB color space, where L represents brightness, a represents the red-green color index (positive values ​​tend to be red, negative values ​​tend to be green), and b represents the yellow-blue color index (positive values ​​tend to be yellow, negative values ​​tend to be blue);

[0096] Substitute the following formula to calculate the color difference evaluation value:

[0097] ,

[0098] Where ΔE represents the color difference evaluation value, ΔL = L - L 标准 , Δa = a - a 标准 , Δb = b - b 标准 , L 标准 、a 标准 and b 标准 Represents the coordinate values ​​of the three components L, a and b of the color of standard sea buckthorn fruit powder in the CIELAB color space.

[0099] It can be understood that standard sea buckthorn fruit powder is sea buckthorn fruit powder that meets production requirements and has an orange-yellow or yellow-red color.

[0100] Specifically, ΔE < 1: imperceptible color difference, that is, the difference between the two colors is difficult to distinguish with the naked eye;

[0101] 1 ≤ ΔE < 2: Slight color difference, which can only be detected with careful observation;

[0102] 2 ≤ ΔE < 3.5: General color difference, which can be clearly noticed by the naked eye.

[0103] ΔE ≥ 3.5: Significant color difference, which is very easy to detect and may have a significant impact on the appearance quality of the product.

[0104] Specifically, the value range of the preset evaluation value is set to [0.3, 3.5], and the preferred value in the embodiment of the present invention is 0.8; the value range of the preset index correction coefficient is set to [0.6, 0.95], and the preferred value in the embodiment of the present invention is 0.9.

[0105] Specifically, the water solubility index detection process includes:

[0106] Weigh the solid mass m obtained by evaporating the supernatant ds ;

[0107] m ds With m s The ratio is the water solubility index.

[0108] Specifically, the process of determining whether the separation process of the fruit oil is qualified based on the water absorption index includes:

[0109] comparing the water absorption index with a preset water absorption index;

[0110] Determining that the separation process of the fruit oil is unqualified based on the comparison result that the water absorption index is less than the preset water absorption index;

[0111] The separation process of the fruit oil is determined to be qualified based on the comparison result that the water absorption index is greater than or equal to the preset water absorption index.

[0112] Specifically, the greater the water absorption index, the faster the dissolution rate of sea buckthorn fruit powder in water.

[0113] Specifically, the preset water absorption index is the water absorption index of sea buckthorn fruit powder that has passed the drying process.

[0114] Specifically, the process of determining whether the pulp separation process is qualified based on the water solubility index includes:

[0115] comparing the water solubility index with a preset water solubility index;

[0116] Determining that the pulp separation process is unqualified based on the comparison result that the water solubility index is less than the preset water solubility index;

[0117] The pulp separation process is determined to be qualified based on the comparison result that the water solubility index is greater than or equal to the preset water solubility index.

[0118] Specifically, the larger the water solubility index, the better the dissolution uniformity of the sea buckthorn fruit powder.

[0119] Specifically, the preset water solubility index is the water solubility index of sea buckthorn fruit powder that has passed the drying process.

[0120] Specifically, based on the condition that the separation process of the fruit oil is unqualified, several adjustment methods are set for the rotation speed of the oil-water centrifuge according to the water absorption difference between the preset water absorption index and the water absorption index, and each adjustment method increases the rotation speed by a different amount.

[0121] Specifically, the increase in the rotation speed caused by each adjustment method is positively correlated with the difference in water absorption. The greater the difference in water absorption, the greater the increase in the rotation speed.

[0122] Specifically, based on the condition that the pulp separation process is unqualified, several adjustment methods are set for the vibration frequency of the ultrasonic vibration screen according to the preset water solubility index and the water solubility difference of the water solubility index, and each adjustment method increases the vibration frequency by a different amount.

[0123] Specifically, the increase in vibration frequency caused by each adjustment method is positively correlated with the difference in water solubility. The greater the difference in water solubility, the greater the increase in vibration frequency.

[0124] Embodiment: 1 kG of No. 1 seabuckthorn fruit powder sample with electrostatic field applied and No. 2 seabuckthorn fruit powder sample without electrostatic field applied were respectively taken, and the nutritional components were tested according to the relevant provisions of the national standard. The test results are shown in Table 1.

[0125] The freeze-drying process of sea buckthorn fruit powder with electrostatic field applied is pre-freezing for 48 hours at -30°C and then freeze-drying for 48 hours. The freeze-drying process of sea buckthorn fruit powder without electrostatic field applied is pre-freezing for 5 hours at -42°C and then placing it in a vacuum freeze dryer with the cold trap temperature set at -42°C and the vacuum degree set at 0.2 mbar for drying. The drying time is 36 hours.

[0126] Table 1 Nutritional component test results

[0127]

[0128] As shown in Table 1, the freeze-drying process of sea buckthorn fruit powder using a low-voltage electrostatic field retains more nutrients.

[0129] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for preparing seabuckthorn fruit powder, characterized in that: include: Picking seabuckthorn branches and fruits, freezing the seabuckthorn branches and fruits, breaking them up, threshing them and washing them, draining them and sending them to a pulping machine for pulping to obtain pulp, squeezing the pulp and separating and removing impurities from the peel to obtain a coarse pulp; The crude pulp is separated into a part of the fruit oil by using an oil-water centrifuge, and a part of the fruit pulp is separated by using an ultrasonic vibration screen, and after the separation, degassing is performed to obtain the raw pulp to be sterilized; The raw pulp to be sterilized is sterilized at high temperature and then transported to a filling room for filling and storage to obtain seabuckthorn raw pulp, and the seabuckthorn raw pulp is placed in a vacuum freeze dryer equipped with a low-voltage electrostatic field device for freeze drying to obtain seabuckthorn fruit powder; Obtaining a drying rate curve of the seabuckthorn fruit powder, determining the eligibility of the drying process of the seabuckthorn fruit powder based on the drying rate curve, and for an unqualified drying process, adjusting the electric field strength by adjusting the distance between the electrode plates to determine again whether the drying process of the seabuckthorn fruit powder is qualified; Based on the qualified drying process, the water absorption index of the seabuckthorn fruit powder is corrected according to the color difference evaluation value of the seabuckthorn fruit powder to determine whether the separation process of the fruit oil is qualified, and whether the separation process of the fruit pulp is qualified according to the water solubility index of the seabuckthorn fruit powder, and the rotation speed of the oil-water centrifuge and / or the vibration frequency of the ultrasonic vibration screen are adjusted for unqualified processes; Under qualified drying process conditions, the process of correcting the water absorption index of seabuckthorn fruit powder based on the color difference evaluation value includes: Comparing the color difference evaluation value with a preset evaluation value; Determining to reduce the water absorption index by a preset index correction coefficient based on a comparison result that the color difference evaluation value is greater than the preset evaluation value; The calculation process of the color difference evaluation value is: Obtaining the coordinate values ​​of the three components of the color of the seabuckthorn fruit powder in the CIELAB color space, including L, a and b, wherein L represents brightness, a represents red-green color index, and b represents yellow-blue color index; Substitute the following formula to calculate the color difference evaluation value: ， Where ΔE represents the color difference evaluation value, ΔL = L - L 标准 , Δa = a - a 标准 , Δb = b - b 标准 , L 标准 、a 标准 and b 标准 Represents the coordinate values ​​of the three components L, a and b of the color of the standard seabuckthorn fruit powder in the CIELAB color space; The process of determining whether the separation process of the fruit oil is qualified based on the water absorption index comprises: comparing the water absorption index with a preset water absorption index; The separation process of the fruit oil is determined to be unqualified based on the comparison result that the water absorption index is less than the preset water absorption index.

2. The method for preparing seabuckthorn fruit powder according to claim 1, characterized in that: The process of determining whether the drying process of seabuckthorn fruit powder is qualified based on the drying rate curve includes: Periodically test the moisture content of sea buckthorn puree in the vacuum freeze dryer; Draw a drying rate curve with the detection time as the horizontal axis and the moisture content as the vertical axis; Calculate respectively a first area enclosed by the drying rate curve and the horizontal and vertical axes, and a second area enclosed by the standard drying rate curve and the horizontal and vertical axes; comparing the first area to the second area; Based on the comparison result that the first area is greater than the second area, it is determined that the drying process of the sea buckthorn fruit powder is unqualified.

3. The method for preparing seabuckthorn fruit powder according to claim 2, characterized in that: The conditions for applying a low-voltage electrostatic field to freeze-dry the seabuckthorn puree are as follows: the cold trap temperature is -30°C, and the freeze-drying is performed for 48 hours after pre-freezing for 48 hours.

4. The method for preparing seabuckthorn fruit powder according to claim 3, characterized in that: The process of adjusting the electric field strength for an unacceptable drying process includes: subtracting the first area from the second area to obtain an area difference; comparing the area difference value with a preset area difference value; Determining to reduce the electrode plate spacing by a first amplitude based on a comparison result that the area difference is greater than the preset area difference; Determining to reduce the electrode plate spacing by a second amplitude based on a comparison result that the area difference is less than or equal to the preset area difference; The smaller the distance between the electrode plates, the greater the electric field strength.

5. The method for preparing seabuckthorn fruit powder according to claim 1, characterized in that: The detection process of the water absorption index includes: Weigh the second preset weight m s The sea buckthorn fruit powder is placed in a centrifuge tube, a preset volume of distilled water is added, and the mixture is stirred for a preset time and then centrifuged; Pour the supernatant after centrifugation into the evaporating dish and weigh the remaining gel. g ; m g With m s The ratio is the water absorption index.

6. The method for preparing seabuckthorn fruit powder according to claim 5, characterized in that: The process of determining whether the pulp separation process is qualified based on the water solubility index includes: comparing the water solubility index with a preset water solubility index; The pulp separation process is determined to be unqualified based on the comparison result that the water solubility index is less than the preset water solubility index.

7. The method for preparing seabuckthorn fruit powder according to claim 6, characterized in that: Based on the condition that the separation process of the fruit oil is unqualified, several adjustment methods are set for the rotation speed of the oil-water centrifuge according to the water absorption difference between the preset water absorption index and the water absorption index, and each adjustment method increases the rotation speed by a different amount.

8. The method for preparing seabuckthorn fruit powder according to claim 7, characterized in that: Based on the condition that the pulp separation process is unqualified, several adjustment methods are set for the vibration frequency of the ultrasonic vibration screen according to the preset water solubility index and the water solubility difference of the water solubility index, and each adjustment method increases the vibration frequency by a different amount.

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