CN115804440A

CN115804440A - Preparation method of pomace gel

Info

Publication number: CN115804440A
Application number: CN202211668009.0A
Authority: CN
Inventors: 王岚; 姚长洪; 陈洪章
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2022-12-23
Filing date: 2022-12-23
Publication date: 2023-03-17

Abstract

The invention provides a preparation method of pomace gel, which comprises the following steps: (1) Performing steam explosion treatment on the pomace to obtain steam exploded coarse pomace; (2) Screening the steam explosion coarse pomace obtained in the step (1), separating components without wall breaking, and carrying out solid-liquid separation to obtain steam explosion pomace; (3) And (3) placing the steam exploded pomace obtained in the step (2) in a mold, carrying out ultrasonic treatment, freezing and standing, and removing water to obtain pomace gel. The preparation method does not need to add a cross-linking agent, improves the utilization rate of the pomace, further improves the nutritional value of the product, simplifies the production process and shortens the production period.

Description

Preparation method of pomace gel

Technical Field

The invention belongs to the field of food processing, relates to a preparation method of gel, and particularly relates to a preparation method of pomace gel.

Background

The pomace is the remaining solid part of a plant fruit after squeezing to extract the juice or oil thereof, and generally includes components such as peel, pulp, seeds, stalks, and the like. Pomace is a common food processing byproduct, and is usually generated in large quantities during the fruit juice processing. Taking apple juice processing as an example, about 0.8 ton of wet apple pomace is discharged per 1 ton of juice produced, and more than 50 million tons of apple pomace can be produced per year in Shaanxi province only. Although the pomace still has high nutritional value, nearly 70% of pomace is difficult to effectively utilize due to the lack of a reasonable utilization mode and is treated as garbage, and the serious putrefaction and deterioration of the nutrition in the pomace finally become a source of environmental pollution.

The reason why the pomace is difficult to utilize is mainly due to its own complex nutritional ingredients. Firstly, the components such as polyphenol in the pomace are easy to oxidize, and the loss of nutrition is more serious under the high-temperature condition, so the traditional drying method and other methods are not suitable for preserving the nutritional components of the pomace. Meanwhile, certain moisture and reducing sugar exist in the fruit residues, and the fruit residues also contain protein and fat in different proportions according to the types of fruits, so that the possibility of putrefaction and deterioration of the fruits is greatly increased. Meanwhile, the harvest of the fruit processing raw materials has strong seasonality, so that the subsequent treatment of the fruit residues has simple, convenient and fast requirements. The traditional processing mode usually depends on drying to prolong the shelf life of the product, but the processing time is too long, so that the production period of the product is greatly increased, and obviously, the traditional processing mode is not preferable. Therefore, the processing of the pomace products needs to be free of or less dependent on drying.

Because of the large amount of active ingredients in the apple pomace, how to simply and efficiently separate the active ingredients is always a hot point for the utilization of the apple pomace. However, the difficulty of separating the active ingredients is high due to the obstruction of the cell wall. Pectic substances are one of plant cell wall components, are present in intercellular spaces between adjacent cell walls and play a role in connecting cells in tissues, so that the acting force between pectin and the cell wall is strong, and pectin in the pectin is difficult to extract under the condition of not breaking the wall. The polyphenol substances mainly comprise extractable polyphenol and non-extractable polyphenol in cells, wherein the extractable polyphenol is in a free state in the cells, and the non-extractable polyphenol mainly refers to components such as hydrated tannic acid, procyanidine and the like combined with cell walls, so that the extraction difficulty is high. Therefore, the wall breaking becomes a key problem for extracting the active substances of the apple pomace. The existing wall breaking method can be roughly divided into a dry method and a wet method, wherein the dry method mainly comprises the steps of drying and the like to dry and then crush the apple pomace, which is a commonly used method at present, but the production period is greatly increased due to the time consumption of the drying process, and the method has low production capacity and is difficult to process a large amount of apple pomace in a short time. The wet wall breaking is mainly implemented by wall breaking process under high water content, such as wall breaking machine. The wet wall breaking method has the characteristics of short time consumption and simple treatment, so that the method has production potential.

The pomace after the juice processing still contains more nutritional ingredients, and particularly polyphenol and dietary fiber in the pomace are almost not lost completely. Taking the citrus pomace as an example, the content of dietary fiber in the citrus pomace is 39.17-49.72 g/100g DW, the content of pectin is 19.12-26.56 g/100g DW, and the content of polyphenol is 23.17-43.67 mg/g DW. In addition, the fruits are valuable food materials, and the development of the squeezed fruit residues into related food is completely feasible in safety and practical value. The apple pomace contains tissues such as fruit peel, fruit seeds and fruit stalks with certain content besides fruit pulp, and different tissues have different mechanical properties and different nutrient content. For example, the mechanical strength of the peel is higher than that of the pulp, and the peel contains more polyphenols and pectin; the fruit core contains a trace amount of hydrocyanic acid, and is harmful to human body after being eaten for a long time. Therefore, different tissues in the pomace need to be classified, so that different tissues are processed in different manners, and the maximum utilization of the components of the pomace is realized. The existing separation method mainly adopts a wet wall breaking device such as a beater and the like to separate different tissues by modes such as filtration and the like after crushing. CN201510697112.1 discloses a method for directly preparing dispersed apple pulp high-fiber powder from apple pomace, and a cold crushing beater is used for separating and removing components such as fruit peel. Although wet-process wall breaking devices such as a beater can separate components in apple pomace, the separation efficiency and the separation degree are very limited. Therefore, a method for efficiently separating different components in apple pomace needs to be found.

The gel food has attracted wide attention due to its unique taste, portability and easy eating. Gel confectionery products currently account for over half of the sales in the field of vitamin, mineral and functional foods for children. Therefore, the development of gel food has also received a great deal of attention. CN201410074236.X discloses a preparation process of edible gel, which comprises extracting active substances from apple pomace by acidolysis, and adding edible agar, locust bean gum and other components as cross-linking agent to obtain the edible gel. The method is complicated and has more steps, and the nutrients in the apple pomace, such as insoluble dietary fiber, are not effectively utilized. CN200910039373.9 discloses a preparation method of a fruit pomace paper-type food, which adds a large amount of additives in fruit pomace pulp to assist food forming. The low ratio of the pomace reduces the utilization rate of the pomace and increases the production cost of the product, which is not beneficial to the popularization of the product. CN201910292556.5 discloses an application of apple pomace in preparing fruit and vegetable paper and a preparation method of fruit and vegetable paper, wherein a paper-type food is prepared by homogenizing, averaging, decocting, mixing and concentrating fruit juice and/or vegetable juice to apple pomace. However, the method cannot effectively separate different components in the apple pomace in the homogenizing process, so that the taste of the product is seriously influenced, and meanwhile, the apple cores contain a certain content of hydrocyanic acid which causes harm to health, so that the development of related foods of the apple pomace is not facilitated.

For the raw materials such as pomace and the like which do not have the gel property, an additional cross-linking agent needs to be added in the processing process to promote the raw materials to form a gel structure. Therefore, the preparation of gel food at present mainly depends on the use of cross-linking agents, and the commonly used cross-linking agents comprise xanthan gum, tara gum, carrageenan and the like. However, excessive use of these additives presents a food safety concern. Animal experiments have shown that degraded carrageenan may cause ulcers in the gastrointestinal tract. And may cause gastrointestinal discomfort in some persons. In addition, the use of the cross-linking agent increases the production cost of the product, reduces the proportion of the pomace in the product and influences the development of pomace gel food.

Therefore, the need for an effective method for fractionating pomace, which is capable of separating the active ingredients and processing the same to produce gel food without depending on additional additives, is a problem to be solved.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides the preparation method of the pomace gel, which does not need to add a cross-linking agent, improves the utilization rate of pomace, further improves the nutritional value of products, simplifies the production process and shortens the production period.

In order to achieve the technical effect, the invention adopts the following technical scheme:

(1) Performing steam explosion treatment on the pomace to obtain steam exploded coarse pomace;

(2) Screening the steam explosion coarse pomace obtained in the step (1), separating components without wall breaking, and carrying out solid-liquid separation to obtain steam explosion pomace;

(3) And (3) placing the steam exploded pomace obtained in the step (2) in a mold, carrying out ultrasonic treatment, freezing and standing, and removing water to obtain pomace gel.

In the invention, the edible gel is produced by using the pomace as the only raw material. The steam explosion technology is adopted to release the original pectin in the apple pomace as a cross-linking agent, and no additional cross-linking agent is added, so that the production cost is reduced. Meanwhile, the original structure of the cell wall is destroyed by steam explosion treatment, so that the active ingredients such as polyphenol in the cell wall are released. The grain size of the pomace is reduced by steam explosion, so that components such as insoluble dietary fiber and the like in the pomace can be more easily exerted, and the nutritional value of the product is improved.

In the invention, tissues (hereinafter referred to as non-wall-broken components) such as peels, seeds and the like which are not subjected to steam explosion and are subjected to wall breaking are separated from pulp tissues subjected to steam explosion and wall breaking through screening treatment, and the screened solution is subjected to solid-liquid separation to obtain pulp (namely steam explosion pomace) and soluble components, wherein the soluble components and the non-wall-broken components can be used for separating active ingredients, and the steam explosion pomace can be used for separating the active ingredients or preparing edible pomace gel.

As the preferable technical scheme of the invention, the pressure maintaining pressure of the steam explosion treatment in the step (1) is 0.5-1.2 MPa, and the pressure maintaining time is 1-8 min. The pressure maintaining pressure may be 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, 1.1MPa or 1.2MPa, and the pressure maintaining time may be 1min, 2min, 3min, 4min, 5min, 6min, 7min or 8min, but the pressure maintaining pressure is not limited to the values listed above, and other values not listed above in the ranges of the respective values are also applicable.

As a preferable technical scheme of the invention, the steam exploded coarse pomace is mixed with water before the screening treatment in the step (2).

In the invention, the step (2) mixes the steam exploded coarse pomace with water for stirring, aiming at eliminating the agglomeration of the pomace.

Preferably, the mass volume ratio of the steam exploded coarse marc to the water is 1.

As a preferable embodiment of the present invention, the mesh number of the screen for the screening treatment in the step (2) is 30 to 50 meshes.

As a preferable technical scheme of the invention, the steam exploded coarse pomace is washed for 2-3 times by using water after the screening treatment in the step (2).

In the present invention, the solid-liquid separation method in the step (2) is preferably centrifugation.

As the preferable technical scheme of the invention, the steam exploded pomace and the non-wall-broken component in the step (2) are used for extracting active components.

Preferably, the active components include polyphenols, pectins and insoluble dietary fibres.

In the present invention, the active ingredients are not limited to the above-mentioned polyphenols, pectin and insoluble dietary fiber, and if the pomace contains other active ingredients, the active ingredients can also be extracted by a reasonable method, which is not limited herein.

In the invention, the method for extracting the active components can be separating polyphenol by an alcohol extraction method, separating pectin by an acid-heat method and separating insoluble dietary fiber by an ultrasonic-assisted alkali method.

In the invention, the method for separating polyphenol by alcohol extraction can be as follows: adding 75% ethanol solution into the steam exploded pomace according to the material-liquid ratio of 1.

In the invention, the method for separating pectin by acid-thermal method can be as follows: adding drinking water into the pomace after polyphenol extraction according to a material-liquid ratio of 1-10 to 1 (w: v) to 20 (w: v), adjusting the pH to 1-3, heating the used acid solution to 60-80 ℃ in a water bath kettle by using common acid reagents such as hydrochloric acid or sulfuric acid and the like, centrifuging for 1h, taking supernatant, and treating the supernatant according to the method in the step (3) to obtain pectin.

In the invention, the method for separating pectin by acid-thermal method can be as follows: adding drinking water into the pomace after extracting the polyphenol according to a material-liquid ratio of 1. Adding 3-5 times volume of anhydrous ethanol into the supernatant, stirring, standing for 1h, centrifuging, removing supernatant, and washing with 75% ethanol for 2-3 times to obtain pectin.

In the present invention, pectin can be extracted from the liquid phase obtained by the solid-liquid separation in step (2) by the following method: and (3) performing rotary evaporation on the obtained soluble component at the temperature of 60 ℃, adding absolute ethyl alcohol into the concentrated liquid according to the ratio of 1.

In a preferred embodiment of the present invention, the time of the ultrasonic treatment in step (3) is 2-5 min, such as 2min, 2.5min, 3min, 3.5min, 4min, 4.5min or 5min, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.

As a preferred embodiment of the present invention, the temperature of the freezing and standing step (3) is not higher than-20 ℃, such as-20 ℃, -25 ℃, -30 ℃, -35 ℃, -40 ℃, -45 ℃, or-50 ℃, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.

In a preferred embodiment of the present invention, the method for removing water in step (3) is freeze-drying.

As a preferred embodiment of the present invention, the pomace comprises any one or at least two combinations of apple pomace, citrus pomace, grapefruit pomace or peach pomace, typical but non-limiting examples of which include: the combination of apple pomace and orange pomace, the combination of orange pomace and peach pomace, the combination of peach pomace and apple pomace or the combination of apple pomace, orange pomace and orange pomace, and the like. The pomace used in the present invention is not limited to the above-listed pomace, and other pectin-rich pomaces are also suitable for use in the present invention.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) The invention provides a preparation method of pomace gel, which can realize the comprehensive utilization of pomace raw materials;

(2) The invention provides a preparation method of pomace gel, which utilizes pomace as the only raw material to produce edible gel; the steam explosion technology is adopted to release the original pectin in the apple pomace as a cross-linking agent, no additional cross-linking agent is added, the production cost is reduced, and the utilization rate of the pomace is improved.

(3) The invention provides a preparation method of pomace gel, which releases active ingredients such as polyphenol in pomace, reduces the grain size of pomace, enables insoluble dietary fibers and other ingredients to play a role more easily, and improves the nutritional value of products; meanwhile, the steam explosion process is adopted, so that the problem of overlong drying period is avoided, the production process is greatly simplified, and the production period is shortened.

Drawings

FIG. 1 is a graph showing the relative extraction rates of polyphenols in examples 1-5 and comparative example 1;

FIG. 2 is a graph showing the relative extraction rates of pectin in examples 1-5 and comparative example 1;

FIG. 3 is a graph showing the relative extraction of fiber from the insoluble diet in examples 1-5 and comparative example 1;

FIG. 4 is a schematic view of a gel sample obtained in comparative example 1;

FIG. 5 is a schematic diagram of a gel sample obtained in example 1 before and after rehydration.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

Detailed Description

To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:

example 1

This embodiment provides a preparation method of pomace gel, including the following steps:

(1) Carrying out steam explosion treatment on the apple pomace, wherein the pressure maintaining pressure of the steam explosion treatment is 0.5MPa, and the pressure maintaining time is 2min, so as to obtain steam explosion coarse pomace;

(2) Mixing the steam explosion coarse pomace obtained in the step (1) with water according to a mass-volume ratio of 1;

(3) And (4) placing the steam exploded pomace obtained in the step (3) in a mold, carrying out ultrasonic treatment for 2min, freezing and standing at-20 ℃ for 12 hours, and carrying out freeze drying to obtain pomace gel.

The active ingredient extraction steps are as follows:

placing the non-wall-broken components or the rest steam-exploded fruit residues on gauze or absorbent paper, and air-drying until no water drops. And then adding a 75% ethanol solution into the steam-exploded pomace according to a material-liquid ratio of 1.

Adding drinking water into the pomace after polyphenol extraction according to a material-liquid ratio of 1.

Adding NaOH solution into the pomace after pectin extraction according to a material-liquid ratio of 1:20 (w: v), performing ultrasonic treatment for 1h, centrifuging after treatment to remove supernatant, washing the solid with water, adding 3% hydrogen peroxide solution for decolorization, washing with drinking water for 3 times after filtration, washing with 75% ethanol for 3 times, and drying at the drying temperature of 105 ℃ to obtain the apple insoluble dietary fiber.

Example 2

(1) Carrying out steam explosion treatment on the apple pomace, wherein the pressure maintaining pressure of the steam explosion treatment is 1.0MPa, and the pressure maintaining time is 2min, so as to obtain steam explosion coarse pomace;

The active ingredient extraction steps are as follows:

placing the components without wall breaking or the rest steam exploded fruit residue on gauze or absorbent paper, and air drying until no water drops. And then adding a 75% ethanol solution into the steam-exploded pomace according to a material-liquid ratio of 1.

Adding drinking water into the pomace after polyphenol extraction according to a material-liquid ratio of 1 (w: v) to 15 (w: v), adjusting the pH to 2, heating the used acid solution to 70 ℃ in a water bath, centrifuging for 1h to obtain a supernatant, combining the supernatant with the soluble components in the step (2), performing rotary evaporation at 60 ℃, adding absolute ethyl alcohol into the concentrated liquid according to a ratio of 1.

Adding NaOH solution into the pomace after pectin extraction according to a material-liquid ratio of 1.

Example 3

(1) Carrying out steam explosion treatment on the apple pomace, wherein the pressure maintaining pressure of the steam explosion treatment is 1.2MPa, and the pressure maintaining time is 2min, so as to obtain steam explosion coarse pomace;

(2) Mixing the steam explosion coarse pomace obtained in the step (1) with water according to a mass-to-volume ratio of 1;

The active ingredient extraction steps are as follows:

Example 4

(1) Carrying out steam explosion treatment on the apple pomace, wherein the pressure maintaining pressure of the steam explosion treatment is 0.8MPa, and the pressure maintaining time is 1min, so as to obtain steam explosion coarse pomace;

The active ingredient extraction steps are as follows:

placing the components without wall breaking or the rest steam exploded fruit residue on gauze or absorbent paper, and air drying until no water drops. And then adding a 75% ethanol solution into the steam-exploded pomace according to the material-liquid ratio of 1.

Adding drinking water into the pomace after polyphenol extraction according to a material-liquid ratio of 1 (w: v) to 15 (w: v), adjusting the pH to 2, heating the used acid solution to 80 ℃ in a water bath, centrifuging for 1h to obtain a supernatant, combining the supernatant with the soluble components in the step (2), performing rotary evaporation at 60 ℃, adding absolute ethyl alcohol into the concentrated liquid according to a ratio of 1.

Adding NaOH solution into the pomace after pectin extraction according to a material-liquid ratio of 1:15 (w: v), performing ultrasonic treatment for 1h, centrifuging after treatment to remove supernatant, washing the solid with water, adding 3% hydrogen peroxide solution for decolorization, washing with drinking water for 2 times after filtration, washing with 75% ethanol for 2 times, and drying at the drying temperature of 105 ℃ to obtain the apple insoluble dietary fiber.

Example 5

(1) Carrying out steam explosion treatment on the apple pomace, wherein the pressure maintaining pressure of the steam explosion treatment is 0.8MPa, and the pressure maintaining time is 5min, so as to obtain steam explosion coarse pomace;

(3) And (4) placing the steam exploded pomace obtained in the step (3) in a mold, carrying out ultrasonic treatment for 2min, freezing and standing at-20 ℃ for 12 hours, and carrying out freeze drying to obtain the pomace gel.

The active ingredient extraction steps are as follows:

Adding drinking water into the pomace after polyphenol extraction according to a material-liquid ratio of 1 (w: v) to adjust the pH value to 2, heating the used acid solution to 70 ℃ in a water bath by using common acid reagents such as hydrochloric acid or sulfuric acid and the like, centrifuging after 1h to obtain a supernatant, combining the supernatant with the soluble components in the step (2), performing rotary evaporation at 60 ℃, adding absolute ethyl alcohol into the concentrated liquid according to a ratio of 1.

Comparative example 1

(1) Placing the apple pomace in a mold, carrying out ultrasonic treatment for 2min, freezing and standing at-20 ℃ for 12 hours, and then carrying out freeze drying.

The active ingredient extraction steps are as follows:

placing the fruit residues on gauze or absorbent paper, and air drying until no water drops. And then adding a 75% ethanol solution into the steam-exploded pomace according to a material-liquid ratio of 1.

Adding drinking water into the pomace after polyphenol extraction according to a material-liquid ratio of 1,

After drying, no gel was formed from the marc and there was almost no cross-linking between the marc as shown in fig. 4.

The results of the tests of examples 1 to 5 and comparative example 1 were compared in the form of bar graphs, and as shown in fig. 1 to 3, it can be seen from fig. 1, 2 and 3 that the separation degree of components in apple pomace after steam explosion was significantly increased and bound polyphenols and pectins were significantly separated.

The applicant states that the present invention is described by the above embodiments to explain the detailed structural features of the present invention, but the present invention is not limited to the above detailed structural features, that is, it is not meant to imply that the present invention must be implemented by relying on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are all within the protection scope of the present invention.

It should be noted that, in the above embodiments, the various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present invention does not separately describe various possible combinations.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A preparation method of pomace gel is characterized by comprising the following steps:

2. The preparation method according to claim 1, wherein the pressure maintaining pressure of the steam explosion treatment in the step (1) is 0.5-1.2 MPa, and the pressure maintaining time is 1-8 min.

3. The method according to claim 1, wherein the steam exploded coarse marc is mixed with water before the sieving treatment of the step (2);

the mass volume ratio of the steam explosion coarse pomace to water is 1.

4. The method according to claim 1, wherein the sieve of the step (2) has a mesh size of 30 to 50 mesh.

5. The preparation method according to claim 1, wherein the steam exploded coarse marc is washed 2 to 3 times with water after the sieving treatment of the step (2).

6. The method according to claim 1, wherein the steam exploded pomace and the non-wall broken components of step (2) are used to extract active components;

the active components include polyphenols, pectin and insoluble dietary fiber.

7. The method according to claim 1, wherein the time for the ultrasonic treatment in the step (3) is 2 to 5min.

8. The method according to claim 1, wherein the temperature of the frozen and rested state in the step (3) is not higher than-20 ℃.

9. The method according to claim 1, wherein the moisture removal method in step (3) is freeze-drying.

10. The method according to claim 1, wherein the pomace of step (1) comprises any one or a combination of at least two of apple pomace, citrus pomace, grapefruit pomace and peach pomace.