Hawthorn puree and preparation method thereof

Abstract

The present application relates to the technical field of hawthorn beverages, and specifically discloses a hawthorn puree and a preparation method thereof, which can improve the high water temperature and long time of the pre-cooking process before hawthorn pulping, as well as the high viscosity of the pulp after beating, which leads to the problem of difficulty in subsequent processing, and can significantly increase the amount of precipitation of hawthorn flavonoids. The preparation method of the hawthorn puree includes: cooling the hawthorn fruit to -25°C~-18°C at a cooling rate of 0.1~0.2°C / min, freezing the hawthorn fruit; taking out the frozen hawthorn fruit and thawing it in an ambient temperature until the fruit is completely melted; the thawed hawthorn fruit continues to be stored in an ambient temperature, so that the pectin in the hawthorn fruit is degraded; the degraded hawthorn fruit is pre-cooked in 75~85°C hot water for 4-6min; the pre-cooked hawthorn fruit is deseeded, and the remaining pulp is pulped, and the slurry is filtered to obtain a hawthorn coarse pulp; the hawthorn coarse pulp is homogenized to obtain the hawthorn puree.

Description

Technical Field

[0001] The present application relates to the technical field of hawthorn beverages, and more specifically, to a method for preparing hawthorn puree with moderate viscosity, high hawthorn flavonoid content and low processing cost. Background Art

[0002] Hawthorn beverage production often involves a pulping process to create a pulp-containing puree, which is then used to formulate various hawthorn beverages. The traditional pulping process involves washing the hawthorn berries and then heating them in a batch-type pre-cooker at 90-95°C for 20-30 minutes to fully soften the fruit. This high temperature and prolonged heating process significantly damages hawthorn's nutritional components, such as hawthorn flavonoids and vitamin C. Furthermore, since hawthorn has the highest pectin content of all fruits, typically accounting for 6-8% of the berry's weight, the pulp obtained from pre-cooked hawthorn contains a high amount of pectin, resulting in very high viscosity. For example, for the "Yanranhong" hawthorn variety, the viscosity of a pulp with a soluble solids content of 7.5 Brix can reach over 2800 centipoise, severely impacting subsequent processing applications, such as pumping difficulties, severe adhesion to equipment and piping, and reduced sterilization and heat transfer efficiency. Furthermore, high-viscosity hawthorn pulp cannot be finely ground using equipment such as homogenizers. Consequently, the concentration of the original hawthorn puree must be reduced, typically to a soluble solids content below 4.5 Brix. Later concentration is costly and can easily lead to nutrient loss, limiting the development of high-concentration hawthorn juice. Furthermore, the inability to finely grind the pulp also affects the release of nutrients, such as hawthorn flavonoids, from the pulp into the liquid fraction, impacting taste and nutrient absorption. Traditionally, the high viscosity of hawthorn puree has been addressed by adding pectinase to the pulp to produce a clear, low-viscosity juice. However, this process requires enzymatic hydrolysis, increasing investment and production costs. Furthermore, the enzymatic hydrolysis process is rapid, making it difficult to control the extent of pectin degradation. Consequently, this process is typically used to produce clear hawthorn juice, failing to produce a cloudy, pulp-containing hawthorn juice (puree). Summary of the Invention

[0003] In view of the fact that the traditional process for improving the high viscosity of hawthorn puree requires an enzymatic hydrolysis process, which increases investment and production costs, and the enzymatic hydrolysis speed is fast, it is difficult to control the degree of pectin degradation, so that this process is usually used to produce clear hawthorn juice, and it is impossible to obtain hawthorn turbid juice containing pulp. This application proposes a method for preparing hawthorn puree to solve this problem.

[0004] In the first aspect, the present application proposes a method for preparing hawthorn puree and adopts the following technical solution.

[0005] A method for preparing hawthorn puree, comprising:

[0006] Cooling the hawthorn berries to -25°C~-18°C at a cooling rate of 0.1~0.2°C / min to freeze the hawthorn berries;

[0007] Take out the frozen hawthorn fruit and thaw it at ambient temperature until the fruit is completely thawed;

[0008] Continuing to store the thawed hawthorn berries at ambient temperature causes the pectin in the hawthorn berries to degrade;

[0009] Pre-cook the degraded hawthorn fruit in hot water at 75-85°C for 4-6 minutes;

[0010] The pre-cooked hawthorn fruit is deseeded, the remaining pulp is pulped, and the pulp is filtered to obtain a coarse hawthorn pulp;

[0011] The hawthorn coarse pulp is ultrafinely ground and homogenized to obtain the hawthorn puree.

[0012] Because hawthorn berries contain a certain amount of pectinase, they can degrade the pectin in the flesh. However, due to the low moisture content of hawthorn fruit and the presence of a large amount of lignin and cellulose, the water activity is low, and the enzymatic hydrolysis process is slow. In the aforementioned process of freezing and thawing hawthorn fruit, the freezing speed must be controlled to be moderate, preventing the cells from being relatively intact after quick freezing and failing to release sufficient active water after thawing. At the same time, the freezing speed must also be controlled to be moderate, as this will result in the fruit being too soft after thawing and storage, leading to severe damage during continuous pre-cooking, thus affecting subsequent processing. Therefore, experiments have determined that hawthorn fruit can be cooled to -25°C to -18°C at a rate of 0.1-0.2°C / min. After freezing, the frozen hawthorn fruit can be stored for long periods of time in cold storage at temperatures below -18°C, ensuring that its nutrients remain intact over time.

[0013] Thawed hawthorns need to be stored at an appropriate temperature to facilitate the activation of pectinase in the fruit pulp and degrade the pectin. After the freeze-thaw cycle, the hawthorn fruit is already substantially softened. At this point, the pre-cooking process before pulping can be performed at a lower temperature and for a shorter time, simply to inactivate the pectinase present in the hawthorn fruit. Pre-cooking in hot water at 75-85°C for 4-6 minutes has been shown to meet these requirements. Lowering the boiling temperature and time not only minimizes the loss of hawthorn's nutrients but also improves production efficiency and reduces energy consumption.

[0014] The subsequent ultrafine grinding and homogenization of the hawthorn pulp can also effectively release the nutrients in the hawthorn cell tissue, and significantly increase the content of free nutrients such as hawthorn flavonoids in the hawthorn juice.

[0015] As an improvement to the preparation method of the hawthorn puree, the ambient temperature for thawing the hawthorn fruit is 15-30° C., and the thawing time is 3-4 hours.

[0016] By adopting this technical solution, the ice crystals in the hawthorn fruit melt and the tissue softens after thawing. Thawing hawthorn fruit at a common ambient temperature of 15-30°C can save energy. A thawing temperature that is too high can easily cause the hawthorn fruit to deteriorate, while a temperature that is too low can affect thawing efficiency.

[0017] As an improvement to the preparation method of the hawthorn puree, storage at ambient temperature is stopped when the pectin content in the hawthorn fruit decreases to 4-5%.

[0018] By adopting the above technical solution, when the pectin mass content in hawthorn fruit is reduced to 4-5%, the pulp is significantly softened, and the viscosity of the hawthorn pulp after beating can be reduced to 1400-1700 centipoise. The hawthorn pulp with this viscosity meets the requirements of smooth operation and further fine processing in the processing equipment.

[0019] As an improvement to the preparation method of the hawthorn puree, the ambient temperature of the pectin degradation process is 15-30° C., and the degradation time is 10-12 hours.

[0020] By adopting the above technical solution, excessively high degradation temperatures can easily lead to hawthorn deterioration, while excessively low temperatures can affect the efficiency of pectinase. By selecting room temperature storage of 15-30°C for 10-12 hours, multiple tests have shown that the pectin content can be reduced to 4-5%. The soluble solids content of the crude hawthorn pulp prepared by beating is around 7.5 Brix, and the viscosity can be reduced to 1400-1700 centipoise. During subsequent conveying, homogenization, and sterilization processes, the hawthorn pulp flows smoothly in the equipment and is less likely to stick to the equipment, improving pumping efficiency, heat transfer during thermal sterilization, and reducing undesirable phenomena such as scorching and deterioration caused by local overheating.

[0021] As an improvement to the method for preparing the hawthorn puree, the ultrafine grinding and homogenization includes first performing a shearing pretreatment and then performing a fine grinding treatment.

[0022] By employing this technical solution, high-shear pulverization of hawthorn pulp effectively releases nutrients from hawthorn cell tissue, significantly increasing the content of nutrients, such as hawthorn flavonoids, in hawthorn juice. Multiple batch tests have shown that the total flavonoid content in hawthorn puree using this process is significantly higher than that achieved using traditional methods.

[0023] As an improvement to the method for preparing the hawthorn puree, the shear pretreatment is performed using a shear pump, and the rotation speed of the shear pump is 4000-5000 rpm.

[0024] By adopting the above technical solution, the fibers in the hawthorn pulp can be cut into pieces and the flesh can be reduced to smaller pieces.

[0025] As an improvement to the preparation method of the hawthorn puree, the fine grinding process is performed using a homogenizer, and the homogenizing pressure of the homogenizer is 22-24 MPa.

[0026] By adopting the above technical solution, the hawthorn tissue cells can be further broken, the particle size of the pulp can be effectively reduced, and more nutrients can be released, such as more hawthorn flavonoids, which is also beneficial to improving the suspension stability of the pulp in the terminal beverage.

[0027] On the second aspect, the present application also proposes a hawthorn puree and adopts the following technical solution.

[0028] A hawthorn puree is prepared according to the above-mentioned preparation method.

[0029] By adopting the above technical solution, the pectin content of hawthorn is reduced at a lower preparation cost, the viscosity of hawthorn is reduced to a range suitable for later processing, the heating intensity is reduced, and the nutritional components are retained to a large extent. The final hawthorn puree has a high content of free hawthorn flavonoids.

[0030] In summary, the hawthorn puree and preparation method thereof of the present application have the following beneficial effects:

[0031] The hawthorn fruit is cooled to -25℃~-18℃ at a cooling rate of 0.1~0.2℃ / min to freeze the hawthorn fruit. When freezing, part of the water in the hawthorn pulp will form expanded and hard ice crystals, causing damage to the tissue cell walls, which is conducive to the outflow of cell fluid during thawing.

[0032] Thawing frozen hawthorns at 15-30°C allows the fruit to completely melt, soften, and dissolve ice crystals. This allows for a certain amount of active moisture to form within the flesh, facilitating the activation of pectinase, which reduces pectin content and pulp viscosity. This reduced viscosity makes it possible to produce high-concentration hawthorn pulp beverages (containing at least 60% hawthorn puree, equivalent to a soluble solids content of at least 4.5 Brix).

[0033] The above process of freezing, thawing, and then storing the pectin to degrade it does not require the addition of enzymes, but rather utilizes hawthorn's own pectinase, etc. By controlling the room temperature and storage time, the rate of enzymatic degradation of the pectin can be controlled, thereby achieving a pectin content and pulp viscosity that meets beverage production requirements. This process for reducing the viscosity of hawthorn pulp does not use pectinase or enzymatic hydrolysis, resulting in relatively low processing costs.

[0034] Precooking hawthorn in hot water fully softens the pulp and inactivates enzymes, maintaining stable physical and chemical properties like viscosity. Based on the aforementioned freeze-thaw storage method, the traditional precooking temperature (90-95°C) and time (20-25 minutes) for hawthorn can be significantly reduced, thereby minimizing the loss of nutrients in the fruit during thermal processing.

[0035] The pre-cooked hawthorns are sequentially passed through a deseeder to separate the seeds, a pulper to pulp, and a 20-mesh filter to remove impurities, resulting in a coarse hawthorn pulp. This pulp is then pre-treated with a shear pump (at a speed differential of 4000-5000 rpm) and then finely pulverized in a high-pressure homogenizer (at a homogenization pressure of 22-24 MPa) to obtain the hawthorn puree. This fine pulverization of the hawthorn pulp allows for the extraction of more nutritional components from the tissue. Combined with the freeze-thaw process to decompose tissue cells and shorten the heat treatment softening time, the resulting hawthorn pulp contains a significantly increased concentration of total flavonoids. The viscosity of the hawthorn pulp, with a soluble solids content of 7.5 Brix, is between 1400 and 1700 centipoise. Implementation Method

[0036] The following describes in detail some embodiments and comparison methods of the method for preparing the hawthorn puree of the present application. Example

[0037] In a normal temperature environment of 15~25℃, the same batch of hawthorn fruits were divided into three groups and placed in a cold storage. The three groups of hawthorn samples were cooled to -36±3.5℃, -21.5±3.5℃ and -10±3.5℃ respectively at a cooling rate of 0.1℃ / min. They were kept for a total of 24 hours from the time of storage to freeze the hawthorns. -36℃, -21.5℃ and -10℃ were the set temperatures, and ±3.5℃ was the fluctuating temperature in the cold storage after reaching the set temperature. The frozen hawthorn berries were taken out and stored at 15-20°C for 3 hours to thaw. After thawing, they were stored at 20-25°C for 12 hours, then boiled in hot water at 75-80°C for 4 minutes. After deseeding, pulping, and filtering, a coarse hawthorn pulp was obtained. After pretreatment with a shear pump (speed 4500 rpm), the coarse hawthorn pulp was homogenized using a homogenizer under a pressure of 24 MPa to obtain hawthorn pulp. The pectin content of the unfrozen hawthorn berries was measured to be an average of 6.3% (the percentage of pectin in the weight of the deseeded pulp). After being treated at the above different freezing temperatures and the same post-processing process, the pectin content of the three hawthorn pulps was tested. The weight ratio of the recovered pectin to the hawthorn berries was calculated based on the proportion of water added during the preparation process. The results are shown in Table 1:

[0038] Table 1 Effect of different freezing times on pectin content

[0039] Freezing temperature -36±3.5℃ -21.5±3.5℃ -10±3.5℃ Pectin content as a percentage of pulp weight 3.4% 4.4% 5.8%

[0040] The test method for pectin content is in accordance with the standard issued by the Ministry of Agriculture "NY / T 2016-2011 Determination of pectin content in fruits and their products - Spectrophotometric method".

[0041] Although the pectin content of the test group with a higher freezing temperature decreased more, the hawthorn fruits were too soft after thawing, resulting in a high rate of breakage and severe pulp loss during transportation in the subsequent continuous pre-cooking machine. Therefore, a freezing temperature of -21.5±3.5℃ was used. Example

[0042] Three different batches of fresh hawthorn fruits were taken and cooled to -21.5±3.5℃ at a cooling rate of 0.2℃ / min. They were placed for a total of 24 hours from the time of storage to freeze the hawthorns. The frozen hawthorn fruits were then taken out and stored at a temperature of 15-20℃ for 3 hours to thaw. After thawing, each batch was divided into three groups, and the three groups were stored at a room temperature of 20-25℃ for 1 hour, 6 hours, 10 hours, and 12 hours, respectively, to degrade pectin. They were then boiled in hot water at 80-85℃ for 6 minutes, deseeded, pulped, and filtered to obtain hawthorn pulp. After pretreatment using a shear pump (speed 4500 rpm), the hawthorn pulp was homogenized using a homogenizer under a pressure of 22 MPa to obtain hawthorn pulp.

[0043] The changes in pectin content due to different degradation times in each sample group were tested. Before the experiment, the pectin content of the fresh fruit was measured, as well as the pectin content of the 12 prepared hawthorn purees. The weight ratio of the recovered pectin to the hawthorn fruit was calculated based on the proportion of water added during the preparation process. The test results are shown in Table 2.

[0044] Table 2 Effect of different degradation times on pectin content

[0045] Pectin content weight ratio % fresh fruit Degradation at room temperature for 1h Degradation at room temperature for 6 hours Degradation at room temperature for 10 hours Degradation at room temperature for 12 hours First batch 6.3 6.0 5.8 4.4 4.2 Second batch 7.1 7.0 6.8 4.9 4.6 The third batch 7.7 7.2 6.8 5.0 4.7

[0046] It can be seen that the longer the pectin degradation time after freeze-thaw, the greater the pectin degradation rate. Taking into account the viscosity requirements of the final pulp, as well as factors such as microbial control and production costs, the optimal method is to freeze hawthorn at -25-18°C, then thaw at room temperature of 15-30°C for 3-4 hours until the fruit is completely thawed. After thawing, the hawthorn is stored at room temperature of 15-30°C for 10-12 hours, and the room temperature storage is terminated when the pectin content decreases from 6-8% to 4-5%. Example

[0047] This example mainly verifies the changes in the detection amount of hawthorn flavonoids, the main nutrient component of hawthorn, after freezing, thawing, and pectin degradation relative to fresh fruit.

[0048] After freezing and thawing, the cell wall damage causes the exudation of cell fluid, which significantly promotes the release of nutrients. The following analysis was conducted to investigate changes in the content of hawthorn flavonoids, the main health-promoting component of hawthorn.

[0049] Test method: GB / T 19416-2003 Determination of juice content in hawthorn juice and its beverages, including Appendix A of the standard.

[0050] Testing unit: Hawthorn Tree Research Center, School of Food Engineering, Tianjin University of Science and Technology.

[0051] Take three groups of fresh hawthorn fruits, all of which are cooled to -21.5±3.5℃ at a cooling rate of 0.15℃ / min. Counted from the time of storage, they are placed for a total of 24 hours to freeze the hawthorns. Then, the frozen hawthorn fruits are taken out and stored at a temperature of 15~20℃ for 3 hours to thaw. After thawing, each group is divided into two samples. The two samples are stored at a room temperature of 20~25℃ for 1 hour and 12 hours respectively to degrade pectin. Then, they are boiled in hot water at 78~82℃ for 5 minutes, and then the seeds are removed, pulped, and filtered to obtain a rough hawthorn pulp. The hawthorn flavonoid content in the rough hawthorn pulp is detected, and the test results are calculated according to the process dilution ratio to restore the weight percentage of the original pulp. The test results are shown in Table 3 below:

[0052] Table 3 Effects of different degradation times on hawthorn flavonoid content

[0053] Total flavonoids content weight ratio % Group 1 Group 2 Group 3 fresh fruit 0.62 0.57 0.60 Degradation at room temperature for 1h 0.72 0.69 0.70 Degradation at room temperature for 12 hours 0.77 0.71 0.75

[0054] After being frozen and thawed, and then stored at room temperature (degradation at room temperature) for a period of time, the pectinase, cellulase, etc. contained in the hawthorn promote the decomposition of more cell tissues and promote the precipitation of hawthorn flavonoids. Example

[0055] This example mainly verifies the change in the detection amount of hawthorn flavonoids after hawthorn pulp is subjected to high shear and homogenization treatment.

[0056] Three groups of hawthorn fruits were taken and hawthorn coarse pulp was prepared according to the method of Example 3, wherein the room temperature degraded pectin was stored at room temperature of 20-25°C for 12 hours to prepare three groups of hawthorn coarse pulp. After pretreatment using a shear pump (speed 4500 rpm), the pulp was finely crushed by a high-pressure homogenizer (homogenization pressure 23 MPa) to obtain three groups of hawthorn puree. The hawthorn flavonoid content in the hawthorn puree was then detected and restored to the hawthorn flavonoid content of the hawthorn fruit. The results are shown in Table 4 below:

[0057] Table 4 Effects of shearing and fine grinding on the content of free hawthorn flavonoids

[0058] Total flavonoids content weight ratio % Group 1 Group 2 Group 3 fresh fruit 0.60 0.62 0.62 Freeze and thaw for 12 hours, then homogenize 0.85 0.86 0.89 Flavonoids increase ratio 41.7% 38.7% 43.5%

[0059] It can be seen that after adopting the process of Example 4, the detection amount of hawthorn flavonoids increased by about 40%.

[0060] Comparative Example 1

[0061] The same batch of hawthorn fruits were placed in a cold storage at a room temperature of 15-25°C and cooled to -21.5±3.5°C at a cooling rate of 1°C / min. The fruits were then stored for a total of 24 hours from the time of storage to freeze the hawthorns. The frozen hawthorn fruits were removed and thawed at 15-20°C for 3 hours. After thawing, they were stored at 20-25°C for 12 hours. They were then boiled in hot water at 78-82°C for 5 minutes, deseeded, pulped, and filtered to obtain a crude hawthorn pulp. The crude hawthorn pulp was then homogenized using a homogenizer at a pressure of 23 MPa to obtain a raw hawthorn pulp.

[0062] The average pectin content of unfrozen hawthorn berries was measured at 6.3% (pectin as a percentage of the weight of the seeded flesh). The pectin content of raw hawthorn puree was measured, and based on the proportion of water added during the preparation process, the reconstituted pectin content was calculated to be 6.1% of the hawthorn berries' weight. Pectin degradation was minimal. This is because cooling the hawthorn berries at a rate of 1°C / min prevents the water within the berries from forming ice crystals that would otherwise penetrate the fibrous tissue. This maintains the berries' good structural integrity, limiting pectinase activity and reducing pectin binding, resulting in slow pectin degradation.

[0063] The hawthorn flavonoids content of the unfrozen hawthorn fruit was measured to be 0.58%. The hawthorn flavonoids content of the hawthorn puree was detected. According to the proportion of water added during the preparation process, the weight ratio of hawthorn flavonoids to hawthorn fruit was calculated to be 0.74%. The detected amount of hawthorn flavonoids increased by 27%, which was not as good as the result of Example 4. This was mainly because the hawthorn was cooled at a cooling rate of 1°C / min. The moisture in the hawthorn was not easy to form ice crystals, and thus it was not easy to pierce the fibrous tissue. The interior of the hawthorn maintained good structural integrity. The efficiency of the pectinase, cellulase, etc. contained in the hawthorn to promote the decomposition of cell tissue was low, resulting in less hawthorn flavonoids precipitated from the hawthorn.

[0064] The above description is merely a preferred embodiment of the present application. The scope of protection of the present application is not limited to the above embodiment. All technical solutions based on the concept of the present application are within the scope of protection of the present application. It should be noted that for those skilled in the art, certain improvements and modifications that do not depart from the principles of the present application should also be considered to fall within the scope of protection of the present application.

Claims

1. A method for preparing hawthorn puree, characterized in that: The preparation method comprises: Cooling the hawthorn berries to -25°C~-18°C at a cooling rate of 0.1~0.2°C / min to freeze the hawthorn berries; Take out the frozen hawthorn fruit and thaw it at ambient temperature until the fruit is completely thawed; Continuing to store the thawed hawthorn berries at ambient temperature will cause the pectin in the hawthorn berries to degrade; stop storing at ambient temperature when the pectin content in the hawthorn berries decreases to 4-5%. Pre-cook the degraded hawthorn fruit in hot water at 75-85°C for 4-6 minutes; The pre-cooked hawthorn fruit is deseeded, the remaining pulp is pulped, and the pulp is filtered to remove impurities to obtain a coarse hawthorn pulp; The hawthorn coarse pulp is ultrafinely ground and homogenized to obtain the hawthorn puree.

2. The method for preparing hawthorn puree according to claim 1, wherein The ambient temperature for thawing hawthorn fruit is 15~30℃, and the thawing time is 3~4h.

3. The method for preparing hawthorn puree according to claim 1, wherein The ambient temperature during the pectin degradation process is 15~30℃, and the degradation time is 10~12h.

4. The method for preparing hawthorn puree according to claim 1, wherein The ultrafine grinding and homogenization includes a shearing pretreatment and a fine grinding treatment.

5. The method for preparing hawthorn puree according to claim 4, wherein: The shear pretreatment is performed using a shear pump, and the rotation speed of the shear pump is 4000-5000 rpm.

6. The method for preparing hawthorn puree according to claim 4, wherein: The fine grinding process is carried out by using a homogenizer, and the homogenizing pressure of the homogenizer is 22-24 MPa.

7. A hawthorn puree, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 6.