LU102492B1

LU102492B1 - Green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues

Info

Publication number: LU102492B1
Application number: LU102492A
Authority: LU
Inventors: Xingqian Ye; Shiguo Chen; Jianle Chen; Huan Cheng
Original assignee: Univ Zhejiang
Priority date: 2019-06-26
Filing date: 2020-05-11
Publication date: 2021-06-11
Also published as: LU102492A1; CN110200292A; ZA202100172B; WO2020259098A1

Abstract

The disclosure provides a green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues, which, employing fruit and vegetable residues as the raw materials, comprises the following steps: the fruit and vegetable residue powder is firstly hydrolyzed with an acid and filtered, resulting in a filter residue I and a filtrate I respectively; the filter residue I is hydrolyzed with a base and filtered, resulting in a filter residue II and a filtrate II respectively; the filtrate I is mixed with the filtrate II, resulting in a mixed liquor containing water-soluble dietary fibers; the filter residue II is decolorized and then post-treated, resulting in insoluble dietary fibers.

Description

GREEN PREPARATION METHOD FOR SOLUBLE AND LU102492

INSOLUBLE DIETARY FIBERS FROM FRUIT AND VEGETABLE RESIDUES

TECHNICAL FIELD The disclosure pertains to the technical field of agricultural product processing, and specifically pertains to a green preparation method for soluble and insoluble dietary fiber from fruit and vegetable residues.

BACKGROUD Polysaccharide carbohydrates and lignin which cannot be digested by human body are called dietary fiber. In the modern life with more and more refined diet, dietary fiber is called the seventh nutrient of human body. Dietary fiber can be divided into two classes of water-soluble dietary fiber (SDF) and water-insoluble dietary fiber (IDF), wherein SDF is mainly composed of some colloidal substances and polysaccharide substances; while the main components of IDF are cellulose, hemicellulose, lignin, protopectin and chitosan and the like.

Dietary fiber has a variety of functions, such as lowering cholesterol and triglyceride levels in the blood, resisting diarrhea, preventing cancers such as bowel cancer, treating constipation, detoxifying, preventing and treating intestinal diverticulosis, controlling body weight, reducing the blood sugar level in adult patients with diabetes, etc.

The American Cancer Society recommends a daily intake of dietary fiber of 30~40 grams for each person, and the Chinese Nutrition Society recommends a daily intake of dietary fiber of 25~35 grams for each person. However, people’s daily dietary fiber intake is factually far below this recommended value, so that dietary fiber becomes more and more important in daily diet.

The extraction methods for dietary fibers can be classified into: (I) Chemical separation, wherein direct water extraction, flocculation method, basic process, acid process and the like are mainly used to separate dietary fiber; 2 Coarse separation, which can change the relative content of each component in the raw material, but the products extracted by this method are impure; © Separation by the combination of enzymes and chemical reagents, in which chemical reagents are added at the same time as saccharifying enzymes, F amylase, cellulase, and protease are used, and the dietary fiber obtained by this kind of methods has a higher purity; 1

@ Enzymatic process, in which proteins are removed with protease and starches are dissolved){102492 with amylase to get dietary fiber; © Fermentation method, in which a microbial fermentation method is used to prepare dietary fiber from appropriate bacteria; 6) Membrane separation, which is used to prepare dietary fiber by changing the molecular weight of the membrane.

So far, all processes for preparing water-soluble dietary fiber are to obtain the water-soluble dietary fiber by alcohol precipitation after impurity removing and extraction. For example, the invention of application No. CN 201510855098.3 discloses a method for preparing dietary fiber from purple potato residues as the raw material, in which an enzymatic treatment is required, the filter residue obtained after impurity removing and filtration is the insoluble dietary fiber, and the filtrate is precipitated with ethanol to get the soluble dietary fiber; CN 201510380700.2 discloses a garlic straw active dietary fiber and a preparation method thereof, in which alcohol precipitation, drying and crushing are required; CN 201510380003.7 discloses a Maca dietary fiber and a preparation method and an application thereof; the separation and purification in step (3) are: the samples extracted in step (2) are subjected to alcohol precipitation and then washed with ethanol and acetone to obtain Maca dietary fiber; CN 201510983708.8 discloses a method of extracting and preparing bamboo shoot dietary fiber from bamboo shoot scraps, in which the extracting solution of step (2) is subjected to a solid-liquid separation, the filter residue is flushed with water, the flushing fluid is combined with the filtrate, precipitated with 95 wt% ethanol at a volume of 4 times at 60°C, and dried to get the soluble dietary fiber; (4) the filter residue in the step (3) is dried in vacuum to get the insoluble dietary fiber; CN 201510617096.0 discloses a preparation method for soluble and insoluble dietary fiber from wild jujube residue; in which wild jujube residue is used as the raw material, and basic hydrolysis and alcohol precipitation are employed to prepare water-soluble dietary fiber and water-insoluble dietary fiber.

Acid-base hydrolysis and alcohol precipitation processes will result in the discharge of a large amount of acid and alkali wastewater as well as the waste of ethanol, which makes the cost of dietary fiber high.

2

SUMMARY LU102492 The technical issue to be solved in the disclosure is to provide a green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues.

To solve the above technical issue, the disclosure provides a green preparation method for soluble and insoluble dietary fiber from fruit and vegetable residues by direct extraction, which employs fruit and vegetable residues as the raw materials, the fruit and vegetable residues are fruit and vegetable residues which have been treated through enzyme inactivation and defatting, wherein the method comprises the following steps: 1) The fruit and vegetable residues are dried and crushed to get fruit and vegetable residue powder; 2) Following a solid-liquid ratio of 1 g/10-20 ml, the fruit and vegetable residue powder obtained in the step 1) is mixed with an organic acid solution or a multi-element inorganic acid solution at a mass concentration of 0.1~1.0%, hydrolyzed with an acid at 20~60°C for a hydrolysis period of 30-100 min, and then filtered, resulting in a filter residue I and a filtrate I respectively; 3) Following a solid-liquid ratio of 1 g/1~2 ml (the filter residue I is calculated on the basis of wet weight), the filter residue I is added a basic solution at a mass concentration of 0.1-0.9% to conduct a basic hydrolysis at 10~50°C for a hydrolysis period of 10-50 min; and then filtered, resulting in a filter residue II and a filtrate II respectively; 4) The filtrate I is mixed with the filtrate II, resulting in a mixed liquor, the mixed liquor is used as an electrolyte drink; 5) Following a solid-liquid ratio of 1 g/1~2 ml (the filter residue II is calculated on the basis of wet weight), the filter residue II is added hydrogen peroxide at a mass concentration of 14~16% to soak for 60~90 minutes to achieve decolorization, then adjusted to pH 5~8, and washed with water, filtered and separated, and dried, to get insoluble dietary fibers.

As an improvement of the green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues of the disclosure: The fruit and vegetable residues comprise residues from citrus fruits, kernel fruits, stone fruits, nut fruits, and vegetables (especially Cruciferous vegetables).

As a further improvement of the green preparation method for soluble and insoluble dietary 3 fibers from fruit and vegetable residues of the disclosure: LU102492 The organic acid is citric acid, malic acid, tartaric acid, oxalic acid, succinic acid, lactic acid or acetic acid; The multi-element inorganic acid is phosphoric acid.

As a further improvement of the green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues of the disclosure: The base is sodium hydroxide, potassium hydroxide.

As a further improvement of the green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues of the disclosure: The mixed liquor (pH 2-9) obtained in the step 4) is concentrated and dried to get water-soluble dietary fiber as dry powder.

In this disclosure, an electrolyte drink rich in dietary fiber can be obtained by mixing the acidic extracting solution and the basic extracting solution, without the need of alcohol precipitation, no pollution and with a low preparation cost.

The method of the disclosure is simple; the used acid and base raw materials can be directly neutralized and utilized after treatment; edible electrolyte drinks are generated without the need of alcohol precipitation, having no pollution to environment, and contain flavone and other nutritive components; meanwhile soluble and insoluble dietary fibers could be obtained from fruit and vegetable residues; the method is a practical technique for preparing active dietary fiber.

The present disclosure has the following beneficial effects: (1) By the disclosure, soluble and insoluble dietary fibers can be obtained from fruit and vegetable residues at the same time; the prepared soluble dietary fiber and insoluble dietary fiber can be further proportioned to exert their respective effects simultaneously, which is beneficial to their application in food processing; (2) The method of the disclosure is simple, the acid-base water is neutralized to generate edible electrolyte drink directly, which is rich in dietary fiber, flavone and other nutritive components, for which the resource utilization rate is high and the preparation is convenient.

(3) The disclosure provides a method for preparing water-soluble dietary fiber in large scale without the need of ethanol precipitation, avoiding the use of ethanol, enhancing the safety of 4 production, reducing the cost of plant construction, and decreasing the emission pollutionu102492 Therefore, the method of the disclosure is a processing technology of low cost, high efficiency and environmental friendliness. In summary, the disclosure provides a green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues. This method employs fruit and vegetable residues as the raw materials to prepare water-soluble dietary fiber through acid and basic hydrolysis. For the disclosure, the acid is an organic acid or a multi-element inorganic acid, and the base may be a strong base such as sodium hydroxide and potassium hydroxide. The solution obtained after hydrolysis is filtered and mixed, and then directly concentrated and dried to get water-soluble dietary fiber. In the disclosure, the portion which cannot be hydrolyzed is water-insoluble dietary fiber. The preparation method of dietary fiber in the disclosure does not require alcohol precipitation, has little emission pollution and low preparation cost, and can prepare water-soluble and water-insoluble dietary fibers simultaneously, thus solving the emission problem in the traditional process of extracting dietary fiber from fruit and vegetable residues, improving the effective utilization rate of resources and having the features of environmental-friendliness and green preparation.

DESCRIPTION OF THE EMBODIMENTS The disclosure will be further described in combination with specific embodiments, but the protection scope of the disclosure is not limited to this. The filtration in the following embodiments is conventional filtration through a filtering cloth. Embodiment 1-1 1) The yellow cortex of grapefruit or sweet orange was removed and then the white cortex was diced (if coming from a juice crushing plant, the yellow cortex was directly separated mechanically), cooked in boiling water (the cooking time was about 1 min, and the solid-liquid ratio was 1 g/20 ml) for enzyme inactivation, then defatted with 80% ethanol (that is, the diced white cortex after being cooked in boiling water was put into 80% ethanol at room temperature to defat for 10 minutes, the solid-liquid ratio was 1 g/15 ml), and then dried (drying at 45°C to a water content < 8%) and crushed into powder (sieving over a screen of 40 meshes), resulting in fruit and vegetable residue powder. 5

2) A citric acid solution at a mass concentration of 0.6% was mixed with the fruit andJ102492 vegetable residue powder obtained in the step 1) at 10 ml/1 g and hydrolyzed with an acid at 50°C for a hydrolysis period of 70 min, and then filtered, resulting in a filter residue I and a filtrate I respectively; 3) The filter residue I obtained in the step 2) was added a sodium hydroxide solution at a mass concentration of 0.3%, at a solid-liquid ratio of 1 g/1 ml (the filter residue I is on the basis of wet weight), hydrolyzed with a base at 30°C for a hydrolysis period of 20 min, and filtered, resulting in a filter residue II and a filtrate II respectively; 4) The filtrate I is mixed with the filtrate II to get a mixed liquor (about pH 6), which can be adirectly edible electrolyte drink; 5) The mixed liquor in the step 4) was concentrated (being concentrated in vacuum at a temperature of 70°C to 50% of its original volume), and dried (drying at 45°C to a constant weight), resulting in water-soluble dietary fiber.

6) At a solid-liquid ratio of 1 g/1 ml (the filter residue II is calculated on the basis of wet weight), the filter residue II obtained in the step 3) was added 15% (percent by volume) hydrogen peroxide to soak for 90 minutes to achieve decolorization, then adjusted to pH 7 (adjusting with a HCI solution at a concentration of 0.1 wt%), washed with water (the amount of water was 10 times the volume of the filter residue II), filtered and separated, and dried (drying at 45°C to a constant weight), resulting in insoluble dietary fiber.

The water-soluble dietary fiber prepared by this method has the following main components: pectin polysaccharide: 70%, sodium citrate: 21%, small molecular components such as monosaccharide and flavone: 8%.

The main components of the insoluble dietary fiber are cellulose and hemicellulose.

Embodiment 1-2. The kind of acid used in the step 2) of Embodiment 1-1 was changed as below (as shown in Table 1); the remaining was the same as in Embodiment 1-1. The results were as described in Table 1.

Table 1 Kind of | Concentration of Acid Acid fiber 6 polysaccharid | ding components Isu¢h2492 e sodium as salts of | monosaccharide acid and flavone 1-1 Emb | Organic odi | acid men acid acid Multi-ele | Phosphoric | 0.6% 66% 26% 7% ment acid inorganic acid Embodiment 1-3. The kind or concentration of base used in the step 3) of Embodiment 1-1 was changed as below (as shown in Table 2); the remaining was the same as in Embodiment 1-1. The results were as described in Table 2. Table 2 Kind of Base Concentratio n of Base fiber Pectin Sodium Small polysacch | citrate or | molecular aride potassium components 7 citrate such a6) 102492 monosacchari de and flavone 1-1 hydroxide citrate) 1-3 hydroxide citrate) cer hydroxide citrate) Potassium 0.3% 67% 25% 7% hydroxide (potassium citrate) Comparative embodiment 1. The order of step 2) and step 3) of Embodiment 1-1 was reversed, i.e., hydrolysis with a base firstly, and then hydrolysis with an acid; the remaining was the same as in Embodiment 1-1.

The prepared water-soluble dietary fiber has the following main components: pectin polysaccharide: 56%, sodium citrate: 35%, small molecular components such as monosaccharide and flavone: 8%. It can be seen that the content of pectin was significantly less than that in Embodiment 1-1.

Comparative embodiment 2. The citric acid solution used in the step 2) of Embodiment 1-1 is changed to a hydrochloric acid solution, with its concentration and amount being unchanged, the remaining was the same as in Embodiment 1-1.

The prepared water-soluble dietary fiber has the following main components: pectin polysaccharide: 69%, sodium chloride: 23%, small molecular components such as monosaccharide and flavone: 7%. It tasted a tad saltier, and further desalination was required. However, the products in the above Embodiment 1-1 have no such a problem.

Embodiment 2 1) The apples were pressed into dregs, cooked in boiling water (the cooking time was about 8

1 min, and the solid-liquid ratio was 1 g/20 ml) for enzyme inactivation, then defatted with 804102492 ethanol (that is, the apple dregs after being cooked in boiling water was put into 80% ethanol at room temperature to defat for 10 minutes, the solid-liquid ratio was 1 g/15 ml), and then dried (drying at 45°C to a water content < 8%) and crushed into powder (sieving over a screen of 40 meshes), resulting in fruit and vegetable residue powder.

2) A citric acid solution at a mass concentration of 0.6% was mixed with the fruit and vegetable residue powder obtained in the step 1) at 10 ml/1 g and hydrolyzed with an acid at 50°C for a hydrolysis period of 70 min, and then filtered, resulting in a filter residue I and a filtrate I respectively; 3) The filter residue I obtained in the step 2) was added a sodium hydroxide solution at a mass concentration of 0.3%, at a solid-liquid ratio of 1 g/1 ml (the filter residue I is on the basis of wet weight), hydrolyzed with a base at 30°C for a hydrolysis period of 20 min, and filtered, resulting in a filter residue II and a filtrate II respectively; 4) The filtrate I is mixed with the filtrate II to get a mixed liquor (about pH 7), which can be adirectly edible electrolyte drink; 5) The mixed liquor in the step 4) was concentrated (being concentrated in vacuum at a temperature of 70°C to 50% of its original volume), and dried (drying at 45°C to a constant weight), resulting in water-soluble dietary fiber.

6) At a solid-liquid ratio of 1 g/1 ml (the filter residue II is calculated on the basis of wet weight), the filter residue II obtained in the step 3) was added 15% (percent by volume) hydrogen peroxide to soak for 60 minutes to achieve decolorization, then adjusted to pH 7 (adjusting with a HCI solution at a concentration of 0.1 wt%), washed with water, filtered and separated, and dried, resulting in insoluble dietary fiber.

The water-soluble dietary fiber prepared by this method has the following main components: pectin polysaccharide: 68%, sodium citrate: 24%, small molecular components such as monosaccharide and flavone: 7%.

Finally, it also should be noted that the above listed are only a few specific embodiments of the disclosure. Obviously, the disclosure is not limited to the above embodiments, many variations of which are allowed. All variations which can be directly derived or conceived by 9 ordinary technical personnel in the art from the context disclosed in the disclosure should all b&)102492 covered within the protection scope of the disclosure.

Claims

Claims LU102492 WHAT IS CLAIMED IS:

1. A green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues, which employs fruit and vegetable residues as the raw materials, the fruit and vegetable residues are fruit and vegetable residues which have been treated through enzyme inactivation and defatting, wherein the method comprises the following steps: 1) The fruit and vegetable residues are dried and crushed to get fruit and vegetable residue powder; 2) Following a solid-liquid ratio of 1 g/10~20 ml, the fruit and vegetable residue powder obtained in the step 1) is mixed with an organic acid solution or a multi-element inorganic acid solution at a mass concentration of 0.1~1.0%, hydrolyzed with an acid at 20~60°C for a hydrolysis period of 30-100 min, and then filtered, resulting in a filter residue I and a filtrate I respectively; 3) Following a solid-liquid ratio of 1 g/1~2 ml (the filter residue I is calculated on the basis of wet weight), the filter residue I is added a basic solution at a mass concentration of 0.1~0.9% to conduct a basic hydrolysis at 10~50°C for a hydrolysis period of 10~50 min; and then filtered, resulting in a filter residue II and a filtrate II respectively; 4) The filtrate I is mixed with the filtrate II, resulting in a mixed liquor, the mixed liquor is used as an electrolyte drink; 5) Following a solid-liquid ratio of 1 g/1~2 ml (the filter residue II is calculated on the basis of wet weight), the filter residue II is added hydrogen peroxide at a mass concentration of 14~16% to soak for 60~90 minutes to achieve decolorization, then adjusted to pH 5~8, and washed with water, filtered and separated, and dried, to get insoluble dietary fibers.

2. The green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues according to claim 1, wherein: The fruit and vegetable residues comprise residues from citrus fruits, kernel fruits, stone fruits, nut fruits, and vegetables.

3. The green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues according to claim 1 or 2, wherein: The organic acid is citric acid, malic acid, tartaric acid, oxalic acid, succinic acid, lactic acid or acetic acid; The multi-element inorganic acid is phosphoric acid.

4. The green preparation method for soluble and insoluble dietary fibers from fruit and vegetable residues according to claim 1, 2 or 3, wherein: 11

The base is sodium hydroxide, potassium hydroxide.

5. The green preparation method for soluble and insoluble dietary fibers from fruit and 0492 vegetable residues according to claim 1, wherein: The mixed liquor obtained in the step 4) is concentrated and dried to get water-soluble dietary fiber as dry powder. 12