CN107319509B

CN107319509B - Method for continuously preparing pectin and fiber from fruits

Info

Publication number: CN107319509B
Application number: CN201710363722.7A
Authority: CN
Inventors: 吕广; 王姣姣; 史杰
Original assignee: Hebei Brothers Ilong Food Technology Co ltd
Current assignee: Hebei Brothers Ilong Food Technology Co ltd
Priority date: 2017-05-22
Filing date: 2017-05-22
Publication date: 2020-07-14
Anticipated expiration: 2037-05-22
Also published as: WO2018214753A1; CN107319509A

Abstract

The invention discloses a method for continuously preparing pectin and fiber from fruits, which comprises the steps of juicing fruits, separating to obtain solid components, carrying out heat preservation treatment on the solid components by high-temperature hot water, and filtering to obtain a filtrate I and a residue I; then adding the residue I into water, carrying out high-temperature heat preservation treatment under an acidic condition, and filtering to obtain a filtrate II and a residue II; mixing the first filtrate and the second filtrate, removing impurities, and extracting pectin; carrying out high-temperature alkali treatment on the residue II and then bleaching or bleaching and then carrying out high-temperature alkali treatment on the residue II, and collecting solids to obtain a residue III, wherein the high-temperature alkali treatment is that the residue II is added into water and is subjected to high-temperature heat preservation treatment under an alkaline condition; and finally, mixing the residue III, water and a dispersing agent, adjusting the pH value to 6-8, homogenizing and drying to obtain a fiber finished product. The fiber finished product obtained by the method provided by the invention has excellent dispersibility, water swelling property and long-term use stability.

Description

Method for continuously preparing pectin and fiber from fruits

Technical Field

The invention belongs to the field of food, and particularly relates to a method for continuously preparing pectin and fiber from fruits.

Background

International food structures are today being adjusted towards fibrous foods. The consumption demand in japan and the usa also increases at a rate of 10% per year. Dietary/fiber has been added to food for many years in the european and american market, and the sales of food to which dietary fiber is added in japan, taiwan, korea is increasing. Some drinks have been added with dietary fiber in china. Survey data shows that global dietary fiber market size will reach $ 43.1 billion in 2020, and compound annual growth rate will reach 13.2%. It is certain that dietary fiber drinks or foods will be further developed in china in the near future.

At present, dietary fiber is mostly applied to food as a functional component, and the research on improving the stable state of the food is less; the research on the dietary fiber mostly focuses on the aspects of extraction, content determination and modification research (increasing the content of soluble fiber) of the dietary fiber, and the research on the application of the insoluble dietary fiber is less.

Insoluble fiber in the dietary fiber has water holding capacity and expansibility. The insoluble fiber is applied to beverages and dairy products, absorbs water to swell under certain process conditions, increases the viscosity of a system, and can provide suspending force in the system by self dispersion and suspension, reduce aggregation and sedimentation of protein and maintain the stability of the system. And the fiber belongs to food raw materials, but not food additives, and can replace additives in food, so that the effect of cleaning the label is achieved. Researchers comparatively find that the water swelling effect of the citrus fiber is the best among a plurality of insoluble fibers.

The application of the citrus fibre AQplus produced by Herbafood in Germany has good verification results. Other citrus fibers in the market, such as 100FG, 125FG and 100M40 of CITRIFI company and 7000F of CEAMSA company, have good application effect in beverages, dairy products, meat products and baked products, but have poorer water swelling effect compared with AQ, and can not form a good suspension system and maintain the stability of the system when additionally added in a liquid product. However, the AQ product has complex process, high price and cost and improved application property.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for continuously preparing pectin and fiber from fruits, so that the process of continuously preparing pectin and fiber is realized, and the water swelling property and suspension stability of a fiber finished product are effectively improved.

The technical scheme of the invention is as follows:

a process for the continuous preparation of pectin and fiber from fruit comprising the steps of:

step 1, juicing fruits, separating to obtain solid components, carrying out heat preservation treatment on the solid components by high-temperature hot water, and filtering to obtain a filtrate I and a residue I;

step 2, adding the residue I into water, performing high-temperature heat preservation treatment under an acidic condition, and filtering to obtain a filtrate II and a residue II;

step 3, mixing the first filtrate and the second filtrate, removing impurities, and extracting pectin;

step 4, performing high-temperature alkali treatment on the residue II, bleaching or bleaching and then performing high-temperature alkali treatment, and collecting solids to obtain residue III, wherein the high-temperature alkali treatment is high-temperature heat preservation treatment of adding the residue II into water under an alkaline condition;

and 5, mixing the residue III, water and a dispersing agent, adjusting the pH value to 6-8, homogenizing and drying to obtain a fiber finished product.

Further, the step 1 of squeezing the fruit and separating to obtain the solid component may be squeezing the fruit and then cleaning the peel and pulp to obtain the solid component, or drying and crushing to obtain the solid component. Further, the temperature of the drying may be 50 to 100 ℃.

Further, the high-temperature hot water heat-preservation treatment in step 1 may be performed by dispersing the solid components in water and preserving the heat at 90 to 100 ℃ for 5 to 30 minutes.

Further, the step 1 of subjecting the solid component to high-temperature hot water heat preservation treatment may be to convert the solid component into dry matter, add water in a weight ratio of the dry matter to the water of 1:15 to 1:25, and then perform heat preservation treatment.

Further, the step 2 of adding the first residue into water may be to convert the first residue into dry matter weight, and then add water according to the weight ratio of the dry matter to the water of 1:15-1: 25.

Further, the high-temperature heat preservation treatment under the acidic condition in the step 2 can be carried out by adding the residue I into water, adjusting the pH value to 1-2.5, and preserving the heat for 60-120min at the temperature of 70-85 ℃.

Further, the pectin extraction in step 3 is performed by ethanol precipitation. Further, ethanol precipitation is performed by adding 80-95% ethanol, and the precipitation pH value is 1-2.5, and the time is 1-2 h.

Further, the high-temperature alkali treatment in the step 4 can be to add the residue two into water, adjust the pH value to be alkaline, then heat up to 75-95 ℃, and preserve heat for 30-120 min. Further, the pH is adjusted to a range of 7.5 to 14.

Furthermore, in the step 4, the residue two is added into the water, namely, the residue two is converted into the weight of dry matter, and then the water is added according to the weight ratio of the dry matter to the water of 1:15-1: 25.

Further, the bleaching process in step 4 may be carried out by dispersing the residue in water and adding 1-2 vol.% of H₂O₂Then, thenSealing, keeping the temperature at 30-60 deg.C for 10-30min, filtering, and washing with water.

Further, in the step 5, the proportion of the residue three, the water and the dispersing agent can be that the residue three is converted into the weight of dry matter, and the water is added according to the weight ratio of the dry matter to the water of 1:40-1: 70; adding a dispersing agent according to 0-40% of the weight of dry matter.

Further, the dispersing agent in the step 5 can be sodium carboxymethyl cellulose, and the mixing temperature of the residue three, the water and the dispersing agent can be 40-65 ℃.

Further, in the step 5, the homogenizing temperature can be 40-65 ℃, the homogenizing pressure can be 10-30MPa, and the homogenizing times can be 1-3 times.

(1) squeezing fruit to obtain juice, washing peel and pulp residue, oven drying at 50-100 deg.C, pulverizing, and collecting;

(2) weighing the dry powder in the step (1), adding water according to a solid-to-liquid ratio of 1:15-1:25, preserving heat at 90-100 ℃ for 5-30min, filtering, and collecting filtrate and residues for later use;

(3) weighing the residue obtained in the step (2), converting into dry matter weight, adding water according to a solid-to-liquid ratio of 1:15-1:25, adjusting pH to 1-2.5, keeping the temperature at 70-85 ℃ for 60-120min, filtering, and collecting filtrate and residue for later use;

(4) combining the filtrates in the steps (2) and (3), centrifuging, filtering to remove impurities, concentrating, adding 80-95% ethanol to precipitate, and extracting pectin, wherein the pH value of the precipitate is 1-2.5, and the time is 1-2 h;

(5) grinding the residue in the step (3) into slurry by a colloid mill, filtering by a 40-80 mesh sieve, and collecting filter residue for later use;

(6) taking the filter residue obtained in the step (5), converting the filter residue into dry matter weight, adding water according to a solid-to-liquid ratio of 1:15-1:25, adjusting the pH to be alkaline, and preserving the heat at 75-95 ℃ for 30-120 min;

(7) cooling the solution obtained in the step (6) to 30-60 ℃, and adding H with the volume ratio of 1-2%₂O₂Sealing, keeping the temperature at 30-60 deg.C for 10-30min, filtering, washing with water, and collecting residue;

(8) taking the residue in the step (7), converting the residue into dry matter weight, adding water with the temperature of 40-65 ℃ according to the solid-to-liquid ratio of 1:40-1:70,

adding sodium carboxymethylcellulose 0-40 wt% of dry matter, stirring for 15min, adjusting pH of the solution to 6-8, and homogenizing at 40-65 deg.C under 10-30MPa for 1-3 times;

(9) and (4) drying the homogenized solution in the step (8) by using spray drying or roller drying equipment to obtain a fiber finished product.

Further, in the above method for continuously preparing pectin and fiber from fruit, the fruit in step 1 may be citrus fruit.

The pectin or fiber product prepared by the method is applied to food.

The method extracts pectin and fiber from the pomace at one time, reduces the cost of two raw materials, and maximizes economic benefit. Meanwhile, the later is used as a food raw material, a better thickening and suspending scheme is provided for liquid food, the effects of cleaning labels and improving the product quality are achieved, and the label is more promising in market prospect.

The invention takes the squeezed peel and pulp as raw materials to extract pectin and citrus fiber, and after the pectin is extracted, the citrus fiber prepared by using the residues generated in the production process can achieve the quality of foreign fiber and even better, can replace additives in beverages and dairy products, provides better suspension and thickening effects, achieves the effects of cleaning labels and improving the product quality, and has great market prospect.

According to the invention, the solid components obtained by separating the squeezed fruits are subjected to high-temperature hot water heat preservation treatment, so that the fibers are swollen by absorbing water and become loose and soft, the efficiency of later-stage fiber treatment is obviously improved, meanwhile, the pectinase is inactivated at high temperature, the extraction rate and quality of pectin are favorably improved, the viscosity of peanut milk can be effectively improved, the wall built-up is reduced, and the dispersibility of system fibers is improved.

After the pectin is extracted by acid treatment, the aggregation and crystallization degree of the fiber is higher under the acidic condition, the fiber cannot achieve better thickening and suspending effects when being directly processed, and the aggregation and crystallization fiber and hydrogen bonds in a fiber network can be reduced by high-temperature alkali treatment, so that the dispersion of the fiber is facilitated, and the water absorption expansion capacity of the fiber can be effectively improved.

In the prior art, the fiber is prepared by adopting acid-base treatment during fiber extraction, but the purpose of the alkali treatment is only to remove alkali-soluble impurities, the treatment temperature is low, and the treatment time is short. The viscosity of the peanut milk can be effectively improved through high-temperature alkali treatment, the wall hanging is reduced, and the suspension capacity and the fiber dispersibility of the system are improved.

The bleaching treatment of the invention can achieve the same effect before and after the alkali treatment, and can be carried out according to the actual situation.

The invention completely opens the aggregated and crystallized fibers by a high-pressure shearing method through homogenization, disperses the fibers and improves the water absorption expansion capacity of the fibers, thereby achieving better application effect.

The surface of the fiber is provided with polar carbonyl groups and hydroxyl groups, carboxyl groups in the sodium carboxymethyl cellulose (CMC) adopted by the invention can form hydrogen bonds with the polar groups on the surface of the fiber or interact with the polar groups on the surface of the fiber by Van der Waals force, the fiber is wrapped in the CMC, and the homogenized fiber is more uniformly dispersed in water and is not easy to re-aggregate by electrostatic force, so that the better water absorption and expansion capacity is achieved, and the CMC plays a role in dispersing and expanding the fiber in the invention.

The invention adopts the fiber, water and dispersant to mix and homogenize, the homogenization can lead the fiber to rapidly disperse, absorb and swell water under the external pressure, and further improve the dispersibility, meanwhile, the adopted CMC plays the role of dispersing and expanding the fiber in the invention, and fully rubs with the fiber under the mechanical force of the homogenization, thereby being adsorbed on the surface of the fiber to form a protective film, further preventing the aggregation of the fiber, and the unexpected effect is achieved by adopting the CMC to combine with the homogenization.

According to the invention, firstly, the fiber is fully swelled by high-temperature hot water heat preservation treatment (cooking process), and meanwhile, the pectase is inactivated at high temperature, so that the extraction of pectin by subsequent high-temperature acid treatment is facilitated, and the extraction is more complete and thorough; the pectin can be fully dissolved and extracted by ethanol precipitation through high-temperature acid treatment, and the pectin can be dissolved and decontaminated through subsequent high-temperature alkali treatment, more importantly, the fiber can be further dispersed, the water absorption expansion capacity of the fiber is improved, and then the fiber can be further solidified through the subsequent homogenization process combined with a dispersing agent in the water absorption expansion performance, so that a finished product is obtained. In the preparation process of the invention, the steps are sequentially connected with each other, and are mutually promoted, so that the characteristics of the final fiber product are synergistically improved.

The invention extracts pectin from fruits, especially citrus pomace, and then prepares fiber, so that the cost of the two raw materials is greatly reduced, and the invention has better popularization prospect.

The prepared fiber can be used as a food raw material to provide a better thickening and suspending scheme for liquid food, so that the effects of cleaning labels and improving the product quality are achieved, and the fiber has a better market prospect.

Drawings

Fig. 1 is a preparation route diagram of peanut milk provided by the invention.

The specific implementation mode is as follows:

the preparation of peanut milk as described in the following examples is shown in fig. 1.

Example 1

This example provides a process for continuously preparing pectin and fiber from fruit comprising the steps of:

Further, in one embodiment, the method and process control may include the following steps:

(6) taking the filter residue obtained in the step (5), converting the filter residue into dry matter weight, adding water according to a solid-to-liquid ratio of 1:15-1:25, adjusting the pH to be alkaline, and preserving the heat at 75-95 ℃ for 3-120 min;

(8) taking the residue in the step (7), converting into dry matter weight, adding water of 40-65 ℃ according to a solid-to-liquid ratio of 1:40-1:70, adding sodium carboxymethylcellulose of 0-40% of the dry matter weight, stirring for 15min, adjusting the pH of the solution to 6-8, homogenizing at 40-65 ℃, and homogenizing under the homogenizing pressure of 10-30MPa for 1-3 times;

Example 2

In this example, pectin and fiber are prepared from citrus fruits, and the following tests are respectively performed for the different preparation processes provided in example 1:

1. high temperature hot water heat preservation process

Taking the dry powder obtained in the step (1) in the embodiment 1, adding water according to the solid-to-liquid ratio of 1:15, preserving the temperature at 90 ℃ for 30min, filtering, and collecting filtrate and residues for later use.

The prepared fiber (except for heat preservation and cooking, other steps are the same) is applied to peanut milk, and specific results are shown in the following table.

Method of treating fiber	pH	Viscosity cp	Particle size nm	Height of suspended sediment	Phenomenon of toppling over
						Thermal insulation cooking	7.26	7.68	237.9	Without obvious boundary	Thin wall hanging
Steaming without keeping temperature	7.29	6.00	241.5	0.7cm	Wall built-up is thick

Note: the viscosity measurement method is 61# rotor, 100r, 30 s.

According to the data, when the fiber subjected to heat preservation and cooking is applied to peanut milk, the sample is high in viscosity, small in particle size, good in suspension effect and thin in wall hanging when poured. Therefore, the embodiment can ensure that the fiber dried in the step (1) absorbs water to swell, is more beneficial to the next treatment, and has the advantages of simple, convenient and effective method and easy process control.

2. High temperature acid treatment process

Weighing the residue obtained in the step (2) in the example 1, converting into dry matter weight, adding water according to a solid-to-liquid ratio of 1:25, adjusting pH to 1-2, keeping the temperature at 75 ℃ for 120min, filtering, and collecting filtrate and residue for later use.

Conversion mode of dry matter weight: m is m₁(1-w₁)

Wherein m is the weight of dry matter;

m₁weighing the weight of the residue;

w₁weighing the moisture content of the residue;

note: w is a₁And (3) quickly measuring by using a Mettler-toledo moisture meter.

Acid treated fibers of different pH (same other treatment steps) were applied to peanut milk, with specific results as shown in the table below.

Acid treatment of pH	pH	Viscosity of the oil	Particle size nm	Height of suspended sediment	Phenomenon of toppling over	The pectin yield is%
							1	7.15	7.32	232.5	Without obvious boundary	Thin wall hanging	12.55
2	7.15	7.37	224.6	Without obvious boundary	The hanging is thinner	12.88
							3	7.15	7.56	235.5	4cm, light color	The hanging is thinner	10.36
4	7.15	7.44	237.9	4cm	Thick wall hanging	8.27

Note: the viscosity measurement method is 61# rotor, 100r, 30 s.

From the data, the application performance of the fibers prepared under the acid treatment conditions with different pH values is slightly different, but the higher the pH value is, the wall built-up of the peanut milk is gradually obvious and coarse, and the yield of the pectin is reduced along with the increase of the pH value, so that within the pH range of the embodiment, the pectin is completely extracted as much as possible, and the application effect of the fibers is ensured.

3. High temperature alkaline treatment process

Weighing a certain amount of residue obtained in the step (3) in the example 1, converting the weight of dry matters, adding water according to the solid-to-liquid ratio of 1:20, adjusting the pH value to 8-14, and preserving the heat at 85 ℃ for 60 min. The dry matter conversion method is the same as above.

Different pH alkali treated fibers (same other treatment steps) were used in peanut milk, with the specific results shown in the table below.

pH of alkali treatment	pH	Viscosity of the oil	Particle size nm	Height of suspended sediment	Phenomenon of toppling over
						Without alkaline treatment	6.93	7.51	231.2	1.7cm	Wall built-up is thick
8	6.90	8.22	200.8	Without obvious boundary	Wall built-up thin wall
						10	6.88	8.40	202.6	Without obvious boundary	Wall-free type
13	6.87	8.46	202.8	Without obvious boundary	Wall-free type
						14	6.89	8.52	201.3	4cm	Wall built-up thin wall

Note: the viscosity measurement method is 61# rotor, 100r, 30 s.

From the above data, it can be seen that the water-swelling capacity of the fiber is improved after the pectin-extracted residue is subjected to an alkali treatment step. However, when the pH value is too high, the fiber hydrogen bonds are seriously broken, the intermolecular force of the fibers is too low, and the suspension property is reduced to some extent. Therefore, the application performance difference of the fibers prepared under the alkali treatment conditions with different pH values is obvious. Too low or too high a pH affects the thickener suspension effect of the fibers. In this example pH range, the fiber application performance is good.

4. Homogenizing process

Weighing a certain amount of the residue obtained in the step (7) in the example 1, converting the weight of the dry matter, weighing hot water according to the solid-to-liquid ratio of 1:50, adding sodium carboxymethylcellulose (CMC) accounting for 0-30% of the weight of the dry matter in the residue, stirring for 15min, adjusting the pH of the solution to 7, homogenizing at 60 ℃, and homogenizing under the homogenizing pressure of 25 MPa. The dry matter conversion method was the same as in example 2.

Fibers treated under different homogenization conditions (same other treatment steps) were applied to peanut milk, and the specific results are shown in the following table.

Conditions of homogenization	pH	Viscosity of the oil	Particle size nm	Height of suspended sediment	Phenomenon of toppling over
						Non-homogeneous	6.86	6.24	204.9	8mm, dark color	Thick wall hanging and sticky bottom
Homogenizing with 0% CMC	6.85	6.56	217.6	1.2cm	Wall built-up is thick
						Homogenization with 10% CMC	6.86	7.32	206.7	4.5cm, light color	Wall built-up thin wall
Homogenizing with 20% CMC	6.85	7.40	219.5	6cm, light color	Wall built-up thin wall
						Homogenization with 30% CMC	6.85	7.46	218.6	5cm	Wall built-up thin wall
Homogenization with 40% CMC	6.85	7.52	221.3	4cm	Thick wall hanging

Note: the viscosity measurement method is 61# rotor, 100r, 30 s.

According to the data, the water absorption expansion capacity of the fibers which are not subjected to homogenization treatment is slightly poor, the viscosity of the corresponding peanut milk sample is low, the wall hanging is thick, the bottom is adhered, and the condition can be effectively improved after the homogenization process.

The compounded CMC can be used as a dispersing agent, and when the CMC is homogenized, the CMC and fiber particles are collided and rubbed under the action of mechanical force, so that the CMC is adsorbed on the surface of the fiber to form a protective film, the aggregation of the fiber is prevented, and the viscosity of a system can be effectively improved.

However, when the amount of CMC is too large, the bleeding swelling effect of the fiber is negatively affected. Within the range of the homogenization conditions in this example, the fiber application performance was good.

Example 3

Juicing fresh citrus fruits, drying residues of pericarp and pulp at 65 ℃, crushing, sieving with a 80-mesh sieve, and collecting dried powder below the sieve for later use. Weighing 40g of dry powder, adding water with the temperature of 100 ℃ according to the solid-to-liquid ratio of 1:20, preserving the temperature of 100 ℃ for 5min, filtering, and collecting the residue I for later use. And (3) adding water into the residue I according to the solid-to-liquid ratio of 1:20, adjusting the pH value to 2, keeping the temperature at 80 ℃ for 90min, filtering, and collecting the residue II. Converting residue two into dry matter, weighing water at a solid-to-liquid ratio of 1:20, adjusting pH to 12, maintaining at 80 deg.C for 90min, cooling to 40 deg.C, adding 6 vol% H₂O₂Keeping the temperature at 40 ℃ for 20min, filtering and collecting residue III. And (3) converting the residue three to the weight of dry matter, weighing hot water according to the solid-to-liquid ratio of 1:60, adding CMC accounting for 10% of the weight of the dry matter of the residue, stirring for 15min, adjusting the pH of the solution to 7, homogenizing at 50 ℃ once, and homogenizing under the pressure of 20 MPa. Mixing the homogenized solutionDrying at 65 ℃. Collecting the dried substance, pulverizing, sieving with 80 mesh sieve to obtain the undersize product as fiber finished product, and collecting for use.

Compared with other different fibers in the current market, the obtained fiber finished product has application effects in peanut milk, and the application effects are shown in the following table.

Note: the viscosity measurement method is 61# rotor, 100r, 30 s.

According to the data, the application effect of the fiber prepared by the embodiment and AQ in peanut milk is good, and the fiber prepared by the embodiment is remarkably superior to that of an AQ fiber product in the aspect of long-term application stability. And other samples have weak suspension capacity and poor dispersibility and cannot meet the product requirements. During the standing process, the dispersity of AQ in peanut milk is gradually reduced, and aggregation occurs. Therefore, the application effect of the fiber prepared by the invention is better.

In conclusion, the citrus fiber with excellent application effect can be prepared at low cost by adopting the method disclosed by the invention, the purposes of cleaning product labels and improving economic benefits are achieved, and a new method is provided for suspending a beverage system and thickening yoghourt by replacing suspended colloid with fiber belonging to food ingredients.

Claims

1. A process for the continuous preparation of pectin and fiber from fruit comprising the steps of:

step 5, mixing the residue III, water and a dispersing agent, adjusting the pH value to 6-8, homogenizing and drying to obtain a fiber finished product;

wherein the high-temperature heat preservation treatment under the acidic condition in the step 2 is to add the residue I into water, adjust the pH value to 1-2.5 and preserve heat for 60-120min at the temperature of 70-85 ℃; in the step 4, the high-temperature alkali treatment is to add the residue II into water, adjust the pH value to be alkaline, then heat up to 75-95 ℃, and keep the temperature for 30-120 min; in the step 5, the dispersant is sodium carboxymethylcellulose, and the mixing temperature of the residue III, the water and the dispersant is 40-65 ℃.

2. The method of claim 1, wherein the step of juicing the fruit and separating the juice from the juice to obtain the solid component comprises juicing the fruit and washing the peel and pulp of the fruit to obtain the solid component, or drying and crushing the fruit to obtain the solid component.

3. The process for the continuous production of pectin and fiber from fruit according to claim 2, wherein said drying temperature is 50-100 ℃.

4. The method for continuously preparing pectin and fiber from fruit according to claim 1, wherein the high temperature hot water holding treatment in step 1 is to disperse the solid components in water and hold at 90-100 ℃ for 5-30 minutes.

5. The method for continuously preparing pectin and fiber from fruit according to claim 1, wherein the heat preservation of the solid component in step 1 is performed by converting the solid component into dry weight, adding water according to the weight ratio of the dry weight to the water of 1:15-1:25, and then performing heat preservation.

6. The method of claim 1, wherein the step of adding the residue one to the water comprises converting the residue one to dry matter weight and adding water at a dry matter to water weight ratio of 1:15 to 1: 25.

7. The method for continuously preparing pectin and fiber from fruit according to claim 1, wherein the pectin is extracted in step 3 by ethanol precipitation.

8. The method for continuously producing pectin and fiber from fruit according to claim 1, wherein the step 4 of adding the second residue to water comprises converting the second residue to dry weight and adding water at a dry-to-water weight ratio of 1:15 to 1: 25.

9. The method of claim 1, wherein the bleaching step 4 comprises dispersing the residue in water, adding 1-2% by volume of H₂O_2，Sealing, keeping the temperature at 30-60 deg.C for 10-30min, filtering, and washing with water.

10. The method for continuously preparing pectin and fiber from fruit according to claim 1, wherein in step 5, the ratio of the residue three, water and the dispersing agent is that the residue three is converted into dry matter weight, and water is added according to the weight ratio of the dry matter to the water of 1:40-1: 70; adding a dispersing agent according to 0-40% of the weight of dry matter.

11. The method for continuously preparing pectin and fiber from fruit according to claim 1, wherein the homogenization temperature in step 5 is 40-65 ℃, the homogenization pressure is 10-30MPa, and the homogenization times are 1-3 times.

12. The method for continuously preparing pectin and fiber from fruit according to claim 7, wherein the ethanol precipitation is ethanol precipitation with the addition of 80-95% by mass concentration, and the precipitation pH value is 1-2.5, and the time is 1-2 h.

13. The process for the continuous production of pectin and fiber from fruit according to claim 1, wherein the pH is adjusted to alkaline pH in the range of 8-13.

14. A process for the continuous preparation of pectin and fiber from fruit comprising the steps of:

(2) weighing the solid components in the step (1), adding water according to a solid-to-liquid ratio of 1:15-1:25, preserving heat at 90-100 ℃ for 5-30min, filtering, and collecting filtrate and residues for later use;

15. The process for the continuous production of pectin and fiber from fruit according to claim 1 or 14, wherein in step 1 said fruit is a citrus fruit.

16. Use of the pectin or fiber product prepared according to claim 1 or 14 in a food product.