A kind of preparation method and application of carrot dietary fiber

Abstract

The invention discloses a preparation method and application of carrot dietary fiber, comprising the following steps: S1, pretreatment of carrots; S2, preparation of carrot slurry; S3, microwave treatment; S4, enzymatic hydrolysis of carrot residue. S5, preparation of carrot dietary fiber. The method grinds nano calcium carbonate whiskers and carrot slurry together, then uses acid treatment and microwave treatment to destroy plant cell wall materials, maximizes the dissolution of soluble dietary fiber in carrots, and finally enzymatic hydrolyzes the residue twice to convert part of insoluble dietary fiber into soluble dietary fiber, thereby significantly improving the extraction rate of carrot soluble dietary fiber.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural product processing, and particularly relates to a preparation method and application of carrot dietary fiber. Background Art

[0002] Dietary fiber is a complex mixture, which can be divided into soluble dietary fiber and insoluble dietary fiber according to its solubility. Both types of dietary fiber have unique functions, which can improve the structure of intestinal flora, reduce the intestinal absorption of glucose and lipids, lower blood sugar, blood lipids, and cholesterol indicators, and reduce the risk of cardiovascular and cerebrovascular diseases, diabetes and certain cancers.

[0003] Although dietary fiber cannot be digested and absorbed by digestive enzymes in the human body, it is one of the nutrients necessary for a balanced diet structure. It has completely different physiological effects from the six major nutrients, namely carbohydrates, fats, proteins, vitamins, minerals, and water, and is called the "seventh nutrient" by nutritionists. It not only has the functions of water retention, oil retention, and water absorption and swelling, but also has multiple biological functions, such as reducing serum cholesterol levels, preventing and treating cardiovascular diseases such as hypertension, heart disease, and atherosclerosis, reducing serum glucose levels and insulin response after meals, and regulating blood sugar levels in diabetics.

[0004] At present, the methods for preparing dietary fiber are mainly divided into three categories: physical, chemical and biotechnology methods, and there are also methods that combine the above methods. Among them, the biotechnology method is divided into enzymatic method and microbial fermentation method. The enzymatic method is to add biological enzymes such as protease, cellulase, saccharifying enzyme, hemicellulase, etc. to the raw materials after adjusting the optimal pH value required for the enzymatic reaction, and degrade the non-fiber components and IDF components such as cellulose and hemicellulose in the raw materials by controlling the reaction conditions to generate SDF components such as small molecular monosaccharides. The enzymatic extraction of DF is efficient, and the physiological activity loss of the DF obtained is small, the color is light, and the purity is high. However, due to the high production cost of enzyme preparations, it cannot be widely promoted in actual operation. Microbial fermentation is a relatively safe, effective and low-cost method. It uses amylase, cellulase and other enzymes secreted by itself to consume starch and protein in the raw materials, loosen the structure, so that insoluble macromolecules such as cellulose and hemicellulose are more easily degraded, IDF is converted into SDF, and the purpose of increasing the yield of SDF is achieved.

[0005] Carrots are also known as "longevity vegetables", "earth ginseng" and "golden bamboo shoots". They belong to the Umbelliferae family and contain many nutrients that are beneficial to the human body, such as protein, sugar, vitamins, iron, calcium, potassium, etc. They are a common vegetable in residents' homes. Studies have shown that carrots and their products can enhance human immunity, resist aging, lower blood pressure, and prevent cancer. They have important medicinal value and health functions, and they have high nutritional value, unique flavor, and bright color. They occupy a very important position in health food and food processing and production.

[0006] Chinese patent application CN104799314A discloses a method for preparing carrot residue dietary fiber powder, which uses fresh, non-sour and non-mildewed carrot residue produced by making vegetable noodles with carrots as raw materials, and obtains carrot residue dietary fiber powder through grinding, slurry sand removal, slurry enzymolysis, slurry enzyme inactivation, slurry separation, and air flow drying. The carrot residue dietary fiber powder obtained by the method is rich in dietary fiber, can be used as a raw material for a new dietary fiber food additive, and is widely used in the food industry. However, the content recorded in the invention cannot know the extraction rate of its carrot dietary fiber, nor can it be seen that the effect of the carrot dietary fiber.

[0007] Carrots are rich in nutrients such as vitamins and minerals, and contain a large amount of dietary fiber, which is higher than bean dregs and apple dregs. Therefore, it is of great significance to develop a method for efficiently producing dietary fiber from carrots. Summary of the invention

[0008] In view of the deficiencies in the prior art, the object of the present invention is to provide a preparation method and application of carrot dietary fiber. The method comprises the following steps: grinding nano calcium carbonate whiskers and carrot slurry together, then subjecting the plant cell wall material to acid treatment and microwave treatment to maximize the dissolution of soluble dietary fiber in the carrot, and finally subjecting the filter residue to two enzymatic hydrolysis steps to convert part of the insoluble dietary fiber into soluble dietary fiber, thereby significantly improving the extraction rate of the carrot soluble dietary fiber.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for preparing carrot dietary fiber comprises the following steps:

[0011] S1. Pretreatment of carrots: washing and slicing the carrots, blanching them in boiling water, removing them from the water after blanching, crushing them, filtering the juice, drying the carrot residues, crushing them, and passing them through a 100-mesh sieve to obtain carrot powder;

[0012] S2, preparation of carrot slurry: adding deionized water to the carrot powder prepared in step S1, stirring evenly and then standing, then adding nano calcium carbonate whiskers and ball milling to obtain carrot slurry;

[0013] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid, adjust the pH to 5-6, stand for reaction and then perform microwave treatment, after the treatment, adjust the pH to 7, filter to obtain carrot filtrate, and dry the filter residue for later use;

[0014] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water, followed by adding cellulase for primary enzymatic hydrolysis, after which β-glucanase is added for secondary enzymatic hydrolysis, after which the enzyme is inactivated, filtered, and an enzymatic hydrolyzate is obtained.

[0015] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed and desalted, and then concentrated under reduced pressure to 1 / 4 of the volume. After deproteinization, alcohol precipitation, and freeze-drying, carrot dietary fiber is obtained.

[0016] Preferably, in step S1, the blanching time is 3-5 minutes, and the drying temperature is 50-60° C. for 8-12 hours.

[0017] More preferably, in step S1, the blanching time is 3-4 minutes, and the drying temperature is 55-60° C. for 8-10 hours.

[0018] In the present invention, the blanching treatment in step S1 can soften the cell wall, making it easier for the nano-calcium carbonate whiskers to pierce the cell wall. At the same time, the surface area of ​​the carrot powder is increased by crushing and sieving, which is beneficial for subsequent processing.

[0019] Preferably, in step S2, the mass ratio of carrot, deionized water and nano-calcium carbonate whisker is 30-40:70-110:15-20, and the diameter of the nano-calcium carbonate whisker is 100-200 nm and the length is 2-5 μm.

[0020] More preferably, in step S2, the mass ratio of carrot, deionized water and nano-calcium carbonate whisker is 35-40:90-110:17-20, and the diameter of the nano-calcium carbonate whisker is 100-150 nm and the length is 2-5 μm.

[0021] Preferably, the ball milling speed in step S2 is 3000-4000 r / min, and the time is 20-30 min.

[0022] More preferably, the ball milling speed in step S2 is 3500-4000 r / min, and the time is 20-25 min.

[0023] In the present invention, the nano calcium carbonate whiskers added in step S2 can provide additional mechanical grinding effect during the ball milling process, and on the other hand, the nano whiskers may penetrate into the cell wall structure and generate carbon dioxide gas in the cell during the subsequent reaction with acid, thereby increasing the blasting effect.

[0024] Preferably, the mass concentration of the dilute hydrochloric acid in step S3 is 3-6%, the standing temperature is 20-30° C., and the time is 1-2 h; the power of the microwave treatment is 300-350 W, and the time is 5-8 min.

[0025] More preferably, the mass concentration of the dilute hydrochloric acid in step S3 is 4-5%, the standing temperature is 20-25° C., and the time is 1.5-2 h; the power of the microwave treatment is 320-350 W, and the time is 5-7 min.

[0026] In the present invention, the synergistic effect of acid and microwaves may more effectively destroy plant tissues. The acid will react with the nano-calcium carbonate whiskers to generate carbon dioxide, causing gas to be generated inside the extraction system. The microwaves will heat up the inside of the cells, and the gas will expand to form high pressure, thereby causing an "explosion" effect at the microscopic level, which can maximize the destruction of plant cell wall materials and improve the extraction rate of soluble dietary fiber.

[0027] Preferably, in step S4, the solid-liquid ratio of the carrot residue to deionized water is 1:15-25, the dosage of the cellulase is 0.1-0.3% of the mass of the residue, the temperature of the primary enzymatic hydrolysis is 38-42° C., and the time is 20-30 min.

[0028] More preferably, in step S4, the solid-liquid ratio of the carrot residue to deionized water is 1:15-20, the amount of the cellulase used is 0.1-0.2% of the mass of the residue, the temperature of the primary enzymatic hydrolysis is 40-42° C., and the time is 20-25 min.

[0029] Preferably, the dosage of the β-glucanase in step S4 is 0.1-0.2% of the mass of the filter residue, the temperature of the secondary enzymolysis is 40-45° C., and the time is 15-25 min.

[0030] More preferably, the dosage of the β-glucanase in step S4 is 0.1-0.15% of the mass of the filter residue, the temperature of the secondary enzymolysis is 42-45° C., and the time is 15-20 min.

[0031] In the present invention, the filter residue is subjected to two enzymatic hydrolysis processes. Since the filter residue has been subjected to ball milling, acid and microwave treatment, the filter residue can have a good enzymatic hydrolysis effect even under the action of a small amount of cellulase and beta-glucanase, thereby increasing the proportion of insoluble dietary fiber converted into soluble dietary fiber and increasing the total extraction rate of carrot soluble dietary fiber.

[0032] Preferably, the pressure of the reduced pressure concentration in step S5 is 10-20 kPa, and the protein removal method is the Sevag method for protein removal.

[0033] More preferably, the pressure of the reduced pressure concentration in step S5 is 10-15 kPa, and the protein removal method is the Sevag method for protein removal.

[0034] The present invention also protects a carrot dietary fiber prepared by the method as described above.

[0035] The present invention also protects the use of the carrot dietary fiber as described above in functional foods and medicines.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The preparation method of carrot dietary fiber provided by the present invention comprises the following steps: firstly, the carrot is blanched to soften the cell wall, so that the nano calcium carbonate whisker can more easily pierce the cell wall, and at the same time, the surface area of ​​the carrot powder is increased by crushing and sieving, which is beneficial to subsequent processing; and by adding the nano calcium carbonate whisker for blending and ball milling, during the ball milling process, the shear force and friction force during the ball milling process are increased, and the nano calcium carbonate whisker can act as a "micro needle" to pierce the cell wall of the carrot, thereby effectively destroying the cell wall structure and dissolving dietary fiber such as intracellular polysaccharides. More importantly, the process is carried out at room temperature and only through physical action, it is not easy to destroy the polysaccharide structure and affect its activity. Subsequently, a hydrochloric acid solution is added, which reacts with calcium carbonate to generate carbon dioxide, so that gas is generated inside the extraction system. After microwave treatment, the temperature inside the cell rises, and the gas expands to form high pressure, so that the cell wall ruptures. The present invention causes a "blasting" effect at a microscopic level through acid treatment and microwave treatment, which can destroy the cell wall material of the plant, reduce the degree of polymerization of cellulose, partially degrade hemicellulose, and soften lignin, thereby greatly improving the extraction rate of soluble dietary fiber.

[0038] (2) The preparation method of carrot dietary fiber provided by the present invention comprises the following steps: subjecting the carrot residue after microwave treatment to enzymatic hydrolysis twice. Due to the ball milling, acidification and microwave treatment, the residue can also have a good enzymatic hydrolysis effect under the action of a small amount of cellulase and β-glucanase, thereby destroying the structure of cellulose and hemicellulose in the residue, and converting part of the insoluble dietary fiber in the residue into soluble dietary fiber. By treating carrots with the method of the present invention, not only the extraction rate of soluble dietary fiber is improved, but also the amount of enzyme used can be reduced, thereby reducing costs. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the present invention, the nano calcium carbonate whiskers are purchased from Wuhan Kemik Biomedical Technology Co., Ltd., with a diameter of 100-200 nm and a length of 2-5 μm.

[0041] Example 1

[0042] A method for preparing carrot dietary fiber comprises the following steps:

[0043] S1. Carrot pretreatment: wash and slice the carrots, blanch them in boiling water for 4 minutes, remove them from the water after blanching, crush them, filter the juice, bake the carrot residue at 55° C. for 10 hours, crush them, and pass them through a 100-mesh sieve to obtain carrot powder;

[0044] S2, preparation of carrot slurry: 35g of carrot powder in step S1 was added to 90g of deionized water, stirred evenly and allowed to stand for 1.5h, then 18g of nano calcium carbonate whiskers were added, zirconium oxide grinding balls were added, and the mixture was ball-milled at 3500r / min for 25min to obtain carrot slurry;

[0045] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid with a mass concentration of 5%, stand for reaction at 25°C for 1.5 hours to allow the calcium carbonate whiskers to react completely, then adjust the pH to 5.5, then microwave treatment at a power of 330W for 6 minutes, add a 3% NaOH solution after the treatment to adjust the pH to 7, filter to obtain carrot filtrate, and dry the filter residue for later use;

[0046] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:20), then 0.2% of cellulase by weight of the residue is added, and enzymolysis is carried out at 40°C for 25 min. After the enzymolysis is completed, 0.15% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 43°C for 20 min. After the enzymolysis is completed, the enzyme is inactivated at 105°C, filtered, and an enzymolyzate is obtained.

[0047] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 15 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0048] Example 2

[0049] A method for preparing carrot dietary fiber comprises the following steps:

[0050] S1. Carrot pretreatment: wash and slice the carrots, blanch them in boiling water for 4 minutes, remove them from the water after blanching, crush them, filter the juice, bake the carrot residue at 55° C. for 10 hours, crush them, and pass them through a 100-mesh sieve to obtain carrot powder;

[0051] S2, preparation of carrot slurry: 35g of carrot powder in step S1 was added to 100g of deionized water, stirred evenly and allowed to stand for 1.5h, then 17g of nano calcium carbonate whiskers were added, zirconium oxide grinding balls were added, and the mixture was ball-milled at 3000r / min for 30min to obtain carrot slurry;

[0052] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid with a mass concentration of 4%, stand and react at 25°C for 1.5 hours to allow the calcium carbonate whiskers to react completely, then adjust the pH to 6, then microwave treat for 7 minutes at a power of 320W, add a NaOH solution with a mass concentration of 3% after the treatment to adjust the pH to 7, filter to obtain a carrot filtrate, and dry the filter residue for later use;

[0053] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:20), then 0.15% of cellulase by weight of the residue is added, and enzymolysis is carried out at 40° C. for 30 min. After the enzymolysis is completed, 0.15% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 42° C. for 15 min. After the enzymolysis is completed, the enzyme is inactivated at 105° C. and filtered to obtain an enzymolysis solution.

[0054] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 15 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0055] Example 3

[0056] A method for preparing carrot dietary fiber comprises the following steps:

[0057] S1. Carrot pretreatment: wash and slice the carrots, blanch them in boiling water for 3 minutes, remove them from the water after blanching, crush them, filter the juice, bake the carrot residue at 50° C. for 12 hours, crush them, and pass them through a 100-mesh sieve to obtain carrot powder;

[0058] S2, preparation of carrot slurry: 30g of carrot powder in step S1 was added to 70g of deionized water, stirred evenly and allowed to stand for 1h, then 15g of nano calcium carbonate whiskers were added, zirconium oxide grinding balls were added, and the mixture was ball-milled at 3000r / min for 30min to obtain carrot slurry;

[0059] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid with a mass concentration of 3%, stand for reaction at 20°C for 2h, adjust the pH to 6 after the calcium carbonate whiskers are completely reacted, then microwave treatment at a power of 300W for 8min, add NaOH solution with a mass concentration of 3% after the treatment is completed to adjust the pH to 7, filter to obtain carrot filtrate, and dry the filter residue for later use;

[0060] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:15), then 0.1% of cellulase by weight of the residue is added, and enzymolysis is carried out at 38°C for 30 min. After the enzymolysis is completed, 0.1% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 40°C for 25 min. After the enzymolysis is completed, the enzyme is inactivated at 105°C, filtered, and an enzymolyzate is obtained.

[0061] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 10 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0062] Example 4

[0063] A method for preparing carrot dietary fiber comprises the following steps:

[0064] S1. Carrot pretreatment: wash and slice the carrots, blanch in boiling water for 5 minutes, remove from the water after blanching, crush and filter the juice, bake the carrot residue at 60° C. for 8 hours, crush and pass through a 100-mesh sieve to obtain carrot powder;

[0065] S2, preparation of carrot slurry: 40g of carrot powder in step S1 was added into 110g of deionized water, stirred evenly and allowed to stand for 2h, then 20g of nano calcium carbonate whiskers were added, zirconium oxide grinding balls were added, and the mixture was ball-milled at 4000r / min for 20min, and carrot slurry was obtained after ball-milling;

[0066] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid with a mass concentration of 6%, stand for reaction at 30°C for 1 hour, adjust the pH to 5 after the calcium carbonate whiskers are completely reacted, then microwave treatment at a power of 300W for 5 minutes, add a 3% NaOH solution after the treatment to adjust the pH to 7, filter to obtain carrot filtrate, and dry the filter residue for later use;

[0067] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:25), then 0.3% of cellulase by weight of the residue is added, and enzymolysis is carried out at 42°C for 20 min. After the enzymolysis is completed, 0.2% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 45°C for 15 min. After the enzymolysis is completed, the enzyme is inactivated at 105°C, filtered, and an enzymolyzate is obtained.

[0068] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 20 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0069] Comparative Example 1

[0070] A method for preparing carrot dietary fiber comprises the following steps:

[0071] S1. Carrot pretreatment: wash and slice the carrots, blanch them in boiling water for 4 minutes, remove them from the water after blanching, crush them, filter the juice, bake the carrot residue at 55° C. for 10 hours, crush them, and pass them through a 100-mesh sieve to obtain carrot powder;

[0072] S2, preparation of carrot slurry: 35g of carrot powder in step S1 was added to 90g of deionized water, stirred evenly and allowed to stand for 1.5h, zirconium oxide grinding balls were added, and ball milled at 3500r / min for 25min, and carrot slurry was obtained after ball milling;

[0073] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid with a mass concentration of 5%, stand for reaction at 25°C for 1.5 hours to allow the calcium carbonate whiskers to react completely, then adjust the pH to 5.5, then microwave treatment at a power of 330W for 6 minutes, add a 3% NaOH solution after the treatment to adjust the pH to 7, filter to obtain carrot filtrate, and dry the filter residue for later use;

[0074] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:20), then 0.2% of cellulase by weight of the residue is added, and enzymolysis is carried out at 40°C for 25 min. After the enzymolysis is completed, 0.15% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 43°C for 20 min. After the enzymolysis is completed, the enzyme is inactivated at 105°C, filtered, and an enzymolyzate is obtained.

[0075] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 15 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0076] Compared with Example 1, in this comparative example, no nano calcium carbonate whiskers were added in step S2.

[0077] Comparative Example 2

[0078] A method for preparing carrot dietary fiber comprises the following steps:

[0079] S1. Carrot pretreatment: wash and slice the carrots, blanch them in boiling water for 4 minutes, remove them from the water after blanching, crush them, filter the juice, bake the carrot residue at 55° C. for 10 hours, crush them, and pass them through a 100-mesh sieve to obtain carrot powder;

[0080] S2, preparation of carrot slurry: 35g of carrot powder in step S1 was added to 90g of deionized water, stirred evenly and allowed to stand for 1.5h, then 18g of nano calcium carbonate whiskers were added, zirconium oxide grinding balls were added, and the mixture was ball-milled at 3500r / min for 25min to obtain carrot slurry;

[0081] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, and microwave treat it at a power of 330 W for 6 minutes. After the treatment, add a 3% NaOH solution to adjust the pH to 7, filter to obtain a carrot filtrate, and dry the filter residue for later use;

[0082] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:20), then 0.2% of cellulase by weight of the residue is added, and enzymolysis is carried out at 40°C for 25 min. After the enzymolysis is completed, 0.15% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 43°C for 20 min. After the enzymolysis is completed, the enzyme is inactivated at 105°C, filtered, and an enzymolyzate is obtained.

[0083] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 15 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0084] Compared with Example 1, dilute hydrochloric acid was not added in step S3 in this comparative example.

[0085] Comparative Example 3

[0086] A method for preparing carrot dietary fiber comprises the following steps:

[0087] S1. Carrot pretreatment: wash and slice the carrots, blanch them in boiling water for 4 minutes, remove them from the water after blanching, crush them, filter the juice, bake the carrot residue at 55° C. for 10 hours, crush them, and pass them through a 100-mesh sieve to obtain carrot powder;

[0088] S2, preparation of carrot slurry: 35g of carrot powder in step S1 was added to 90g of deionized water, stirred evenly and allowed to stand for 1.5h, then 18g of nano calcium carbonate whiskers were added, zirconium oxide grinding balls were added, and the mixture was ball-milled at 3500r / min for 25min to obtain carrot slurry;

[0089] S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid with a mass concentration of 5%, adjust the pH to 5.5 after the calcium carbonate whiskers are completely reacted, stand and react at 25°C for 1.5h, then add a NaOH solution with a mass concentration of 3% to adjust the pH to 7, filter to obtain a carrot filtrate, and dry the filter residue for later use;

[0090] S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water (solid-liquid ratio is 1:20), then 0.2% of cellulase by weight of the residue is added, and enzymolysis is carried out at 40°C for 25 min. After the enzymolysis is completed, 0.15% of β-glucanase by weight of the residue is added, and enzymolysis is carried out at 43°C for 20 min. After the enzymolysis is completed, the enzyme is inactivated at 105°C, filtered, and an enzymolyzate is obtained.

[0091] S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed for desalination, and then concentrated under reduced pressure at 15 kPa to 1 / 4 of the volume, deproteinized by the Sevag method (the volume ratio of chloroform to n-butanol is 3:1), and 4 times the volume of anhydrous ethanol is added for alcohol precipitation. After freeze-drying, carrot dietary fiber is obtained.

[0092] Compared with Example 1, this comparative example did not perform microwave treatment in step S3.

[0093] The carrot dietary fiber obtained in Examples 1-4 and Comparative Examples 1-3 was weighed, and the extraction rate was calculated according to the following formula. The results are shown in Table 1:

[0094]

[0095] Wherein, M is the mass of carrot powder (g), and M1 is the mass of carrot dietary fiber (g).

[0096] Table 1

[0097] Group Extraction rate % Example 1 11.48 Example 2 11.07 Example 3 10.35 Example 4 10.89 Comparative Example 1 7.96 Comparative Example 2 8.41 Comparative Example 3 7.39

[0098] As can be seen from Table 1 above, by ball-milling carrots with nano-calcium carbonate whiskers and then treating them with hydrochloric acid and microwaves, a "blasting" effect is created at the microscopic level, which can destroy the cell wall materials of the plant and significantly improve the extraction rate of carrot dietary fiber, which has good application prospects.

[0099] The carrot dietary fiber prepared in Example 1 of the present invention was subjected to a mouse test to verify its intestinal moistening and laxative effect, as follows:

[0100] Fifty SPF Kunming male mice with a body weight of 18-22 g were selected and randomly divided into 5 groups (n=10): control group, model group, low-dose group, medium-dose group, and high-dose group. Except for the blank group, all groups were gavaged with 10 mg / kg·bw compound diphenoxylate once a day for 7 consecutive days. All mice had free access to water and food to establish a constipation model.

[0101] Preparation of ink: Accurately weigh 100g of gum arabic, add 800mL of water, boil until the solution becomes transparent, weigh 50g of activated carbon (powdered) and add it to the above solution and boil it three times. After the solution cools, add water to make up to 1000mL, store in a refrigerator at 4℃, and shake well before use.

[0102] The low-dose group, the medium-dose group, and the high-dose group were given 0.5 g / kg, 1 g / kg, and 2 g / kg of the carrot dietary fiber of Example 1 respectively every day, and the control group and the model group were given an equal volume of distilled water for continuous gavage for 15 days, and all mice were free to drink water and eat. During the feeding period, the feces of the mice in the blank group, the model group, the low-dose group, the medium-dose group, and the high-dose group were all oval and granular, and the feces were normal, and no abnormal phenomena such as diarrhea and loose stools were observed.

[0103] After 15 days, mice in each group were fasted but not watered for 12 hours; then each group was gavaged for the last time, and ink was given 1 hour after gavage, 30 minutes later, and mice were killed by dislocation 15 minutes later, the abdominal cavity was opened to separate the mesentery, the small intestine was cut, the ink advancement distance was measured, and the small intestine advancement rate (%) was calculated. The test results are shown in Table 2:

[0104] Propulsion rate (%) = ink propagation length (cm) / total length of small intestine (cm) × 100%

[0105] Table 2 Results of small intestinal propulsion experiment

[0106] Number of mice Small intestinal propulsion rate / % Blank group 10 78.2±13.9 Model control group 10 <![CDATA[47.9±9.2 ## ]]> Low dose group 10 57.4±11.8 Medium dose group 10 61.3±12.1* High dose group 10 64.7±12.5**

[0107] Note: Compared with the blank group, ## :P<0.01; compared with the model group, *:P<0.05, **:P<0.01

[0108] As can be seen from Table 2 above, the small intestinal propulsion rate of the model control group was significantly lower than that of the blank group, indicating that the constipation model was successful. At the same time, the small intestinal propulsion rate of the carrot dietary fiber prepared by the present invention (medium dose group and high dose group) was significantly higher than that of the model control group, indicating that it can effectively promote intestinal peristalsis and accelerate the excretion of feces.

[0109] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing carrot dietary fiber, characterized in that: The following steps are involved: S1. Pretreatment of carrots: washing and slicing the carrots, blanching them in boiling water, removing them from the water after blanching, crushing them, filtering the juice, drying the carrot residues, crushing them, and passing them through a 100-mesh sieve to obtain carrot powder; S2, preparation of carrot slurry: adding deionized water to the carrot powder prepared in step S1, stirring evenly and then standing, then adding nano calcium carbonate whiskers and ball milling to obtain carrot slurry; S3, microwave treatment: add 3 times the weight of deionized water to the carrot slurry in step S2, then add dilute hydrochloric acid, adjust the pH to 5-6, stand for reaction and then perform microwave treatment, after the treatment, adjust the pH to 7, filter to obtain carrot filtrate, and dry the filter residue for later use; S4, enzymatic hydrolysis of carrot residue: the carrot residue in step S3 is added into deionized water, followed by adding cellulase for primary enzymatic hydrolysis, after which β-glucanase is added for secondary enzymatic hydrolysis, after which the enzyme is inactivated, filtered, and an enzymatic hydrolyzate is obtained. S5. Preparation of carrot dietary fiber: The carrot filtrate in step S2 and the enzymatic hydrolyzate in step S4 are mixed, dialyzed and desalted, and then concentrated under reduced pressure to 1 / 4 of the volume. After deproteinization, alcohol precipitation, and freeze-drying, carrot dietary fiber is obtained.

2. The preparation method according to claim 1, characterized in that: In step S1, the blanching time is 3-5 minutes, and the drying temperature is 50-60° C. for 8-12 hours.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the carrot, deionized water and nano-calcium carbonate whisker in step S2 is 30-40:70-110:15-20, and the diameter of the nano-calcium carbonate whisker is 100-200nm and the length is 2-5μm.

4. The preparation method according to claim 1, characterized in that: The ball milling speed in step S2 is 3000-4000 r / min, and the time is 20-30 min.

5. The preparation method according to claim 1, characterized in that: In step S3, the mass concentration of the dilute hydrochloric acid is 3-6%, the standing temperature is 20-30° C., and the time is 1-2 h; the power of the microwave treatment is 300-350 W, and the time is 5-8 min.

6. The preparation method according to claim 1, characterized in that: In step S4, the solid-liquid ratio of the carrot residue to deionized water is 1:15-25, the dosage of the cellulase is 0.1-0.3% of the mass of the residue, the temperature of the primary enzymolysis is 38-42° C., and the time is 20-30 min.

7. The preparation method according to claim 1, characterized in that: The dosage of the β-glucanase in step S4 is 0.1-0.2% of the mass of the filter residue, the temperature of the secondary enzymolysis is 40-45° C., and the time is 15-25 min.

8. The preparation method according to claim 1, characterized in that: The pressure of the reduced pressure concentration in step S5 is 10-20 kPa, and the protein removal method is the Sevag method for protein removal.

9. A carrot dietary fiber prepared by the method according to any one of claims 1 to 8.

10. Use of the carrot dietary fiber according to claim 9 in functional foods and medicines.

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