Prune powder preparation method and product

Abstract

The invention discloses a preparation method of prune powder and a product thereof, the preparation method comprises the steps of freezing prune pulp before homogenizing treatment and homogenizing the prune pulp at low temperature, so that the release of nutrient substances is promoted, the damage to nutrient components in the prune pulp is reduced, the loss of polyphenol substances is reduced, and the quality of the prune powder is improved. The technology disclosed by the invention has the advantages of high efficiency, safety and the like, and the prune fruit powder prepared by the technology provided by the invention has the advantages of high polyphenol content, no additive and the like.

Description

Technical Field

[0001] The invention relates to the technical field of food production and processing, and in particular to a preparation method and product of prune fruit powder. Background Art

[0002] Prune, also known as European plum, is the fruit of the prune tree (Prunus domestica L.) of the genus Prunus in the Rosaceae family. Prunes are rich in dietary fiber, organic acids, minerals, vitamins and other nutrients. It is particularly worth mentioning that prune pulp is rich in polyphenols. Polyphenol compounds are a class of plant secondary metabolites with a wide variety. Their basic chemical structure is a benzene ring with multiple hydroxyls connected to it, which can block free radical chain reactions and have a good free radical scavenging effect. They are recognized antioxidants. Polyphenol compounds have many health benefits such as anti-oxidation, anti-tumor, prevention of cardiovascular disease, relief of visual fatigue, anti-inflammatory and protection of nerves. Unfortunately, polyphenol compounds themselves are easily oxidized, resulting in a decrease in their biological activity and reduced commodity attributes. In addition, polyphenols in fruits and vegetables exist in two forms in fruits and vegetables, one is free and the other is bound; polyphenols in bound form are often not easy to extract. Summary of the invention

[0003] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the object of the present invention is to provide a method for preparing prune fruit powder and a product.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A first aspect of the present invention provides a method for preparing prune fruit powder, comprising the steps of:

[0006] The prune pulp obtained by pre-treating fresh prune fruits is frozen to form ice crystals with free water in the prune pulp;

[0007] When the temperature of the prune pulp is -5℃-0℃, homogenize the prune pulp;

[0008] adding enzymes to the prune pulp homogenate for enzymatic hydrolysis;

[0009] After enzymatic hydrolysis, the insoluble matter is removed to obtain prune juice;

[0010] Prune juice is dried to obtain prune powder.

[0011] In the present invention, the prune pulp is firstly subjected to a freezing treatment before being homogenized, so that the free water in the prune pulp forms a large number of ice crystals with a large volume, and the formed ice crystals can pierce the prune pulp cells and promote the release of nutrients in the cells; the prune pulp is homogenized at a low temperature, so that the damage of the heat generated during the homogenization to the heat-sensitive components in the prune pulp is reduced, the loss of polyphenols is reduced, and the yield of the prune fruit powder and the total polyphenol content thereof are increased.

[0012] In one or more embodiments, the freezing treatment refers to placing the pre-treated prune pulp in an environment below -20°C for more than 8 hours.

[0013] In one or more embodiments, if necessary, water may be added to the prune pulp slurry before homogenization. It is understood that in order to avoid the increase of the pulp temperature after adding water, low-temperature water, such as 0-2°C water, needs to be added.

[0014] In one or more embodiments, if necessary, water may be added to the prune pulp slurry before homogenization, and the mass ratio of the added water to the prune pulp is 1:(1-2).

[0015] In one or more embodiments, the enzymes contain cellulases and cellobiacas.

[0016] The present invention adopts a composite enzymatic hydrolysis and extraction technology of cellulase combined with cellobiase to hydrolyze and extract the prune pulp homogenate, so as to release polyphenols and other nutrients in the prune fruit to the maximum extent, increase the polyphenol content of the product, and hydrolyze the bound polyphenols into free polyphenols, thereby improving the water solubility of the product.

[0017] The cellulase and cellobiase used in the present invention are preferably cellulases and cellobiases that comply with the "GB2760-2024 Food Additives Usage Standard", such as cellulases from Trichoderma viride, cellulases from Trichoderma reesei, cellulases from Aspergillus niger or cellulases from Penicillium oxalicum, and cellobiase from Aspergillus niger.

[0018] In one or more embodiments, the enzyme consists of cellulase and cellobiase in a mass ratio of 1:(1-10).

[0019] In one or more embodiments, the enzyme consists of cellulase and cellobiase in a mass ratio of 1:(1-5).

[0020] In one or more embodiments, the enzymatic activity of the cellulase is not less than 10,000 U / mL, and the enzymatic activity of the cellobiase is not less than 10,000 U / mL.

[0021] In one or more embodiments, the mass ratio of the enzyme to the fresh prune fruit is (1-3):500.

[0022] In one or more embodiments, the enzymatic hydrolysis refers to enzymatic hydrolysis at 40-45° C. for 3-5 hours.

[0023] In one or more embodiments, the pretreatment includes washing the fresh prune fruit. Impurities on the surface of the fresh fruit can be removed by washing. There is no particular limitation on the washing method, and the washing method commonly used in the art can be used, such as using a fruit and vegetable washing machine to wash and remove impurities.

[0024] In one or more embodiments, the pretreatment further comprises blanching the washed fresh prunes.

[0025] In one or more embodiments, the pretreatment further comprises blanching the washed fresh prunes and then removing the pits.

[0026] In the present application, the polyphenol oxidase in the fresh prune fruit is destroyed by blanching.

[0027] In one or more embodiments, the blanching treatment includes at least one of traditional high temperature hot water and steam blanching, high temperature short time blanching, ultrasonic assisted heat blanching, far infrared blanching, ohmic blanching, microwave blanching and radio frequency blanching.

[0028] In one or more embodiments, the blanching treatment refers to high temperature short time blanching, and the high temperature short time blanching is performed at a temperature of 93-97° C. for 1-3 min.

[0029] The present application found that high temperature short-time blanching has a good destructive effect on polyphenol oxidase in fresh prunes, especially high temperature short-time blanching at a temperature of 93-97°C for 1-3 minutes.

[0030] In one or more embodiments, removing the insoluble matter comprises removing the insoluble matter by at least one of centrifugation and filtration.

[0031] In one or more embodiments, removing the insoluble matter comprises removing the insoluble matter by centrifugation, such as removing the insoluble matter by centrifugation in a tubular high-speed centrifuge, wherein the centrifugation refers to centrifugation at a rotation speed of 10,000-20,000 rpm.

[0032] In one or more embodiments, the prune juice further comprises sterilizing the prune juice before drying.

[0033] In one or more embodiments, the sterilization treatment includes at least one of pasteurization and ultra-high temperature sterilization (UHT).

[0034] In one or more embodiments, the sterilization treatment refers to ultra high temperature instantaneous sterilization (UHT), and the ultra high temperature instantaneous sterilization (UHT) refers to maintaining at 135-150° C. for 2-8 seconds.

[0035] In one or more embodiments, the prune juice is freeze-dried to obtain prune fruit powder.

[0036] In one or more embodiments, the freeze-drying refers to pre-freezing at -80°C to -30°C for 5-10 hours, maintaining the freezing temperature at -50°C to -30°C, and vacuuming at 10-50Pa. After 4-12 hours, the temperature is slowly raised in steps to 25°C within 4-8 hours, and the vacuum is maintained at 10-50Pa.

[0037] The second aspect of the present invention provides a prune fruit powder prepared by the preparation method described in the first aspect.

[0038] The third aspect of the present invention provides a product comprising prune fruit powder prepared by the preparation method described in the first aspect.

[0039] In one or more embodiments, the product includes food, medicine and health care products.

[0040] The beneficial effects of the present invention are:

[0041] The preparation method provided by the present invention includes freezing and low-temperature homogenization steps, which has little damage to the nutrition of prunes, promotes the release of nutrients, can increase the product yield, and improve the content of polyphenol compounds in prune fruit powder products. In addition, the technology disclosed in the present invention has the advantages of high efficiency and safety; and the prune fruit powder prepared according to the technology provided by the present invention has the advantages of high polyphenol content and no additives. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a process flow chart for preparing prune fruit powder. DETAILED DESCRIPTION

[0043] The present invention provides a method for preparing prune powder, and the preparation process flow chart is as follows: Figure 1 As shown, the following steps are included:

[0044] A water-soluble prune fruit powder rich in polyphenols and a preparation method thereof, comprising the following steps:

[0045] S1. Wash and remove impurities from fresh prunes, preferably by using a fruit and vegetable washing machine;

[0046] S2, blanching the washed and impurity-removed fresh prune fruit, preferably putting the washed and impurity-removed fresh prune fruit into a blanching machine, and treating it at a temperature of 93-97° C. for 1-3 min to destroy the polyphenol oxidase in the fresh prune fruit;

[0047] S3. The blanched prune fruits are pitted by a pitting machine, and the pulp is placed in a clean container (such as a stainless steel barrel or a sealed can), placed in a low-temperature cold storage, and slowly frozen to a central temperature of -15°C to -10°C, so that the free water in the prune pulp forms a large number of large ice crystals to pierce the prune pulp cells and promote the release of nutrients in the cells;

[0048] S4, taking the frozen prune pulp out of the low-temperature cold storage, appropriately heating it to -5°C to 0°C, preferably -5°C to -1°C, and grinding it into a homogenous slurry in a pulping machine, adding water (such as pure water) if necessary, and the mass ratio of the added water to the prune pulp is 1: (1-2);

[0049] S5, adding a certain amount of a mixture of cellulase and cellobiase to the prune pulp homogenate obtained after step S4, and performing enzymolysis at 40-45° C. for 3-5 hours, so that the cellulose in the prune pulp is gradually enzymolyzed and the polyphenols in the pulp are gradually released. At the same time, the combined enzymolysis hydrolyzes the bound polyphenols in the prune pulp into free polyphenols, thereby improving the water solubility of the polyphenol compounds and increasing the yield. The mass ratio of the added enzyme mixture to the fresh prune is (1-3):500, and the mass ratio of the cellulase to the cellobiase is 1:(1-10);

[0050] S6. The prune pulp homogenate after the composite enzymatic hydrolysis is filtered through a plate and frame filter press or directly centrifuged to remove insoluble matter (i.e., residue), the filtrate is homogenized by a high-pressure homogenizer, sterilized, and then freeze-dried to obtain a prune fruit powder product.

[0051] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0052] The cellulase used in the embodiments of the present invention is Cellulase CE-10.

[0053] The cellobiase used in the embodiments of the present invention is β-Glucoside transaminase GT-120.

[0054] Example 1

[0055] The method for preparing prune powder in this embodiment comprises the following steps:

[0056] (1) Wash and remove impurities from 10 kg of fresh prunes;

[0057] (2) The fresh prunes were put into a blanching machine at 95°C for 90 seconds;

[0058] (3) Remove the core of the fruit and place the pulp in a sealed container;

[0059] (4) Place the pulp in a low-temperature cold storage at a temperature below -20°C for more than 8 hours;

[0060] (5) Take the frozen prune pulp out of the low-temperature cold storage and place it at room temperature for a period of time until the pulp temperature rises to -3±1°C. After the frozen pulp begins to loosen, put the pulp into a pulping machine (colloid mill), add 0°C ice water in an equal proportion to the pulp, and grind it into a homogenous slurry;

[0061] (6) The homogenate was transferred into a stainless steel reaction tank, 20 g of cellulase and 20 g of cellobiase were added, and the mixture was heated at 45 ± 1 °C for 3 h for enzymatic hydrolysis;

[0062] (7) the prune pulp homogenate after enzymatic hydrolysis was centrifuged in a tubular high-speed centrifuge at 15000 rpm to remove the residue;

[0063] (8) The upper centrifuge liquid was sterilized by UHT (140°C, 3s) and then directly dried in a freeze dryer. It was pre-frozen at -80°C for 10 h and kept at a freezing temperature of -50°C to -30°C with a vacuum degree of about 15 Pa. After 10 h, the temperature was slowly raised to 25°C in a stepwise manner within 6 h, and the vacuum degree was maintained at 15 Pa. 1.574 kg of prune fruit powder product was obtained.

[0064] Example 2

[0065] (1) Wash and remove impurities from 10 kg of fresh prunes;

[0066] (2) The fresh prunes were put into a blanching machine at 95°C for 90 seconds;

[0067] (3) Remove the core of the fruit and place the pulp in a sealed container;

[0068] (4) Place the pulp in a low-temperature cold storage at a temperature below -20°C for more than 8 hours;

[0069] (5) Take the frozen prune pulp out of the low-temperature cold storage and place it at room temperature for a period of time until the pulp temperature rises to -3±1°C. After the frozen pulp begins to loosen, put the pulp into a pulping machine (colloid mill), add water in an equal proportion to the pulp, and grind it into a homogenous slurry;

[0070] (6) The homogenate was transferred into a stainless steel reaction tank, 40 g of cellulase and 40 g of cellobiase were added, and the mixture was heated at 45 ± 1 °C for 3 h for enzymatic hydrolysis;

[0071] (7) the prune pulp homogenate after enzymatic hydrolysis was centrifuged in a tubular high-speed centrifuge at 15000 rpm to remove the residue;

[0072] (8) The upper centrifuge liquid was sterilized by UHT (140°C, 3s) and then directly dried in a freeze dryer. It was pre-frozen at -80°C for 10 h and kept at a freezing temperature of -50°C to -30°C with a vacuum degree of about 15 Pa. After 10 h, the temperature was slowly raised to 25°C in a stepwise manner within 6 h, and the vacuum degree was maintained at 15 Pa. 1.633 kg of prune fruit powder product was obtained.

[0073] Example 3

[0074] (1) Wash and remove impurities from 10 kg of fresh prunes;

[0075] (2) The fresh prunes were put into a blanching machine at 95°C for 90 seconds;

[0076] (3) Remove the core of the fruit and place the pulp in a sealed container;

[0077] (4) Place the pulp in a low-temperature cold storage at a temperature below -20°C for more than 8 hours;

[0078] (5) Take the frozen prune pulp out of the low-temperature cold storage and place it at room temperature for a period of time until the pulp temperature rises to -3±1°C. After the frozen pulp begins to loosen, put the pulp into a pulping machine (colloid mill), add water in an equal proportion to the pulp, and grind it into a homogenous slurry;

[0079] (6) The homogenate was transferred into a stainless steel reaction tank, 40 g of cellulase and 40 g of cellobiase were added, and the mixture was heated at 45 ± 1 °C for 5 h for enzymatic hydrolysis;

[0080] (7) the prune pulp homogenate after enzymatic hydrolysis was centrifuged in a tubular high-speed centrifuge at 15000 rpm to remove the residue;

[0081] (8) The upper centrifuge liquid was sterilized by UHT (140°C, 3s) and then directly dried in a freeze dryer. It was pre-frozen at -80°C for 10 h and kept at a freezing temperature of -50°C to -30°C with a vacuum degree of about 15 Pa. After 8 h, the temperature was slowly raised to 25°C in a stepwise manner within 8 h, and the vacuum degree was maintained at 15 Pa. 1.617 kg of prune powder was obtained.

[0082] Comparative Example 1

[0083] (1) Wash and remove impurities from 10 kg of fresh prunes;

[0084] (2) blanching at 95°C for 90 seconds;

[0085] (3) The fruit is pitted, and the pulp is added with an equal proportion of water and then put into a pulping machine (colloid mill) to grind into a homogenous slurry;

[0086] (4) The prune pulp is centrifuged in a tubular high-speed centrifuge at 15,000 rpm to remove the residue;

[0087] (5) The upper centrifuge liquid is sterilized by UHT (140°C, 3s) and then directly dried in a freeze dryer. It is pre-frozen at -80°C for 10 h and maintained at a freezing temperature of -50°C to -30°C with a vacuum degree of about 15 Pa. After 10 h, the temperature is slowly raised to 25°C in a stepwise manner within 8 h, and the vacuum degree is maintained at 15 Pa. 1.259 kg of prune fruit powder product is obtained.

[0088] Comparative Example 2

[0089] (1) Wash and remove impurities from 10 kg of fresh prunes;

[0090] (2) blanching at 95°C for 90 seconds;

[0091] (3) The fruit is pitted, and the pulp is added with an equal proportion of water and then put into a pulping machine (colloid mill) to grind into a homogenous slurry;

[0092] (4) The homogenate was transferred into a stainless steel reaction tank, 20 g of cellulase and 20 g of cellobiase were added, and the mixture was heated at 45 ± 1 °C for 3 h for enzymatic hydrolysis;

[0093] (5) the prune pulp homogenate after enzymatic hydrolysis was filtered out by a tubular high-speed centrifuge at 15000 rpm;

[0094] (6) The upper centrifuge liquid was sterilized by UHT (140°C, 3s) and then directly dried in a freeze dryer. It was pre-frozen at -80°C for 10 h and kept at a freezing temperature of -50°C to -30°C with a vacuum degree of about 15 Pa. After 8 h, the temperature was slowly raised to 25°C in a stepwise manner within 8 h, and the vacuum degree was maintained at 15 Pa. 1.480 kg of prune fruit powder product was obtained.

[0095] Test Case

[0096] In this test example, the polyphenol content of the prune fruit powder products of Examples 1-3 and Comparative Examples 1-2 was detected.

[0097] Using gallic acid as a reference substance, the polyphenol content of the product was determined by spectrophotometry. The specific operation is as follows:

[0098] (1) Draw a standard curve. Accurately pipette 0.00, 0.20, 0.40, 0.60, 1.00, and 1.50 mL of 0.2 mg / mL gallic acid standard solution into 10 mL volumetric flasks, dilute to scale with 60% ethanol solution to obtain gallic acid working solution; pipette 1.0 mL of gallic acid working solution into 10 mL colorimetric tubes, add 2.5 mL of Folin phenol reagent, shake well, add 2.5 mL of 15% sodium carbonate solution, dilute to scale with distilled water, shake well, place in a 40°C water bath for 60 min, and let stand to cool for 20 min; use the reagent blank solution as a control, and measure the absorbance value at a wavelength of 778 nm using a spectrophotometer; then draw a standard curve with gallic acid concentration as the horizontal axis and absorbance value as the vertical axis to obtain the standard curve equation.

[0099] (2) Determination of total polyphenol content in prune fruit powder. Accurately weigh 0.050 g prune fruit powder, place in a 100 mL beaker, add 30 mL 60% ethanol solution, ultrasonicate for 10 min, dilute to 50 mL volumetric flask with 60% ethanol solution, shake well, and filter. Pipette 1.0 mL of filtrate into a 10 mL colorimetric tube, measure the absorbance according to the operation of drawing a standard curve, and calculate the total polyphenol content in prune fruit powder using the standard curve equation.

[0100] The polyphenol contents of the prune fruit powder products of Examples 1-3 and Comparative Examples 1-2 are as follows:

[0101] The polyphenol content of the prune fruit powder product in Example 1 is 622.9 mg GAE / 100 g;

[0102] The polyphenol content of the prune fruit powder product in Example 2 is 695.3 mg GAE / 100 g;

[0103] The polyphenol content of the prune fruit powder product in Example 3 is 708.7 mg GAE / 100 g;

[0104] The polyphenol content of the prune fruit powder product in Comparative Example 1 was 409.6 mg GAE / 100 g;

[0105] The polyphenol content of the prune fruit powder product in Comparative Example 2 is 498.5 mg GAE / 100 g.

[0106] From the difference between Comparative Example 2 and Comparative Example 1, it can be seen that the compound enzyme hydrolysis can increase the yield of prune fruit powder and its total polyphenol content to a certain extent (the yield of prune fruit powder is increased by about 17.9%, and the total polyphenol content is increased by about 21.8%), indicating that the compound enzyme hydrolysis can hydrolyze the bound polyphenols in prunes into free polyphenols, promote the release of polyphenols, and increase the total polyphenol content of the product.

[0107] From the difference between Example 1 and Comparative Example 2, it can be seen that adding freezing treatment and low-temperature grinding can further increase the yield of prune fruit powder and its total polyphenol content (the yield of prune fruit powder increased by 6.1%, and the total polyphenol content increased by 24.9%), indicating that freezing treatment and low-temperature grinding can effectively promote the release of polyphenols in fresh prune fruits, reduce the loss of polyphenols, and thus increase the yield of prune fruit powder and its total polyphenol content. In addition, from the difference between Example 1, Example 2, and Example 3, it can be seen that increasing the amount of enzyme can increase the yield of prune fruit powder and its total polyphenol content to a certain extent.

[0108] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing prune powder, comprising the steps of: The prune pulp obtained by pre-treating fresh prune fruits is frozen to form ice crystals with free water in the prune pulp; When the temperature of the prune pulp is -5℃-0℃, homogenize the prune pulp; adding enzymes to the prune pulp homogenate for enzymatic hydrolysis; After enzymatic hydrolysis, the insoluble matter is removed to obtain prune juice; Prune juice is dried to obtain prune powder.

2. The preparation method according to claim 1, characterized in that: The freezing treatment refers to placing the pre-treated prune pulp in an environment below -20°C for more than 8 hours.

3. The preparation method according to claim 1, characterized in that: The enzymes contain cellulase and cellobiase.

4. The preparation method according to claim 3, characterized in that: The enzymes are composed of cellulase and cellobiase in a mass ratio of 1:(1-10).

5. The preparation method according to claim 1, characterized in that: The mass ratio of the enzyme to the fresh prune fruit is (1-3):

500.

6. The preparation method according to claim 1, characterized in that: The enzymolysis refers to enzymolysis at 40-45° C. for 3-5 hours.

7. The preparation method according to claim 1, characterized in that: The pretreatment also includes blanching the fresh prunes.

8. The preparation method according to claim 1, characterized in that: The method further comprises sterilizing the prune juice before drying.

9. Prune fruit powder prepared by the preparation method according to any one of claims 1 to 8.

10. A product comprising prune powder prepared by the preparation method according to any one of claims 1 to 8.

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