CN104086667A - Method for preparing pectin from citrus fruit peel residues by employing ultrasonic-assisted extraction - Google Patents

Abstract

The invention relates to a process for preparing high-specification pectin by using citrus fruit pomace. The citrus pomace is used as a raw material, and after raw material pretreatment and other process steps, the original pectinase activity in the pericarp is destroyed, and then cellulase is added for enzymatic hydrolysis. Cellulose in the cell wall of the peel, and then the pectin is extracted by ultrasonic-assisted acid solution. The pectin crude extract is ethanol-precipitated, washed, and vacuum-dried to obtain high-quality pectin products. Using biological enzymatic hydrolysis and ultrasonic-assisted acid method to extract pectin from the remaining processed citrus peel, this extraction process greatly shortens the extraction time, overcomes the negative impact of long-term heating on pectin degradation under strong acid conditions, thereby increasing the yield of pectin . The pectin prepared by the method has good color, high purity and high yield.

Description

A method for preparing citrus pomace pectin by ultrasonic-assisted extraction

technical field

The invention relates to the field of natural product extraction and processing, in particular to a method for preparing citrus peel pectin by ultrasonic-assisted extraction.

Background technique

Pectin is a high-molecular polymer that widely exists in the cell wall and interstitium of higher plants. It is usually white or light yellow powder, odorless, slightly sweet, slightly sour, and insoluble in organic solvents such as ethanol and methanol. Soluble in hot water, slightly soluble in cold water. Since pectin is derived from natural extracts, it is non-toxic, harmless, safe and reliable, and has excellent gelation and emulsification stability. It is often used as a natural food such as gelling agent, stabilizer, emulsifier, thickener, and tissue modifier. Additives are often used in food processing and chemical products. In addition, pectin also has antibacterial, detumescence, detoxification, antidiarrheal, lowering blood pressure and other effects, and is also widely used in the field of medicine. With the development and research of functional polysaccharides, pectin, as a water-soluble dietary fiber, has attracted more and more attention from scholars and processing industries.

The present invention uses citrus peels as raw materials, and extracts pectin from it, which not only improves economic benefits, but also helps protect the environment, and realizes in-depth development and resource recycling of agricultural product processing waste.

Ultrasonic waves refer to mechanical waves with a frequency range of 20KHz, a wave velocity of generally 1500m/s, and a wavelength of 0.01-10cm. It is composed of a series of longitudinal waves that are dense and alternate, and propagates around through the liquid medium. Ultrasonic waves can destroy the tissues and cells of citrus peels, allowing the solvent to penetrate into the tissue cells, which is conducive to the leaching and separation of pectin substances. This is because the action of ultrasonic waves is a physical process, and there is no chemical reaction in the leaching process. It will not change the structure and properties of pectin, increase the leaching speed and shorten the extraction time.

Contents of the invention

The purpose of the present invention is to provide a method that can shorten the reaction time, improve product quality, and facilitate industrial operation to prepare citrus peel pectin by ultrasonic-assisted extraction.

The above purpose is achieved through the following schemes:

A method for preparing citrus peel pectin by ultrasonic-assisted extraction, characterized in that:

Carry out impurity removal and enzyme inactivation pretreatment on citrus fruit pomace, add cellulase for enzymolysis, and then use ultrasonic-assisted extraction equipment to adjust the pH of the extract to acidity, perform ultrasonic-assisted acid water extraction of pectin, and centrifuge the extract , filter, take the supernatant, concentrate in vacuum, precipitate with about 95% ethanol, stir fully at the same time, wash and centrifuge, collect the precipitate, and vacuum freeze-dry to obtain the pectin product.

A method for preparing citrus peel pectin by ultrasonic-assisted extraction is characterized in that it comprises the following steps:

(1) Rinse with warm water at 35-55°C for several times, then heat to 85-95°C, keep warm for 10-20 minutes; rinse with warm water at 35-55°C for several times, dry and crush to about 80 meshes, that is Obtain the citrus fruit pomace after removing impurities and deactivating enzymes;

(2) Before adding the enzyme, adjust the pH condition at 3.5-5.5, and at the same time control the ratio of solid to liquid at 1:20-30, add cellulase 0.1-0.5U/g, enzymolysis temperature 35-65℃, enzymolysis time 65-90min, after the enzymolysis is completed, the boiling water bath is 85-95℃, and the time is about 5min to inactivate the enzyme activity;

(3) Adjust the pH to 1.8-2.4 using the acid extraction solution of a combination of organic and inorganic acids, ultrasonically assisted extraction for 45-75min, heat preservation at 60-85°C, and ultrasonic power at 225-250W;

(4) Rotate at 4200-6000r/min, centrifuge for 15-25min, keep the supernatant, which is the centrifugate;

(5) The centrifugate is concentrated to 4-6% of the original volume at a temperature of 45-65 °C, and then cooled rapidly to room temperature;

(6) Add about 95% ethanol equivalent to 2-4 times the volume of the concentrated solution, keep the temperature at about 4°C, settle for 1-2 hours, centrifuge at about 3600rmp for about 10min, filter through gauze, and then pass through anhydrous Wash with ethanol for 1-2 times to obtain wet pectin after alcohol precipitation;

(7) Pre-freeze the wet pectin after alcohol precipitation at -18°C for 24-36 hours, and then vacuum freeze-dry to obtain dry pectin powder.

A method for preparing citrus peel pectin by ultrasonic-assisted extraction, characterized in that: the acid extraction solution of the combination of the organic acid and the inorganic acid is composed of one or more of hydrochloric acid, sulfuric acid, sulfurous acid, citric acid, etc. derived from the combination;

A method for preparing citrus peel pectin by ultrasonic-assisted extraction, characterized in that: the acid extraction solution of the combination of the organic acid and the inorganic acid is composed of hydrochloric acid, sulfuric acid, sulfurous acid, and citric acid in a ratio of 1:1:1 : 1 ratio obtained by mixing.

The beneficial effects of the present invention are:

(1) Using processed waste citrus fruit peels as raw materials has low raw material cost, which can realize the value-added utilization of waste peels and avoid environmental pollution.

(2) Passivate the original pectinase in the peel, which can prevent the decomposition of pectin during the extraction process, thereby increasing the yield of pectin.

(3) Use cellulase to degrade the cellulose in the cell wall of the peel, so that the pectin can be better dissolved.

(4) Ultrasonic-assisted extraction is beneficial to the efficient dissolution of pectin substances, shortens the extraction time, and improves the extraction rate of pectin.

Detailed ways

Now take the laboratory implementation as an example, and the non-limiting examples are described as follows:

Embodiment 1,

Determination of enzymatic hydrolysis conditions: before adding enzymes, use citric acid-sodium citrate (buffer) to adjust the pH (control the enzymatic hydrolysis pH at 3.5-5.5), and at the same time, strictly control the ratio of solid to liquid in the range of 1:20-30. Add 0.1-0.5 U/g of cellulase, the enzymolysis temperature is 35-65°C, and the enzymolysis time is 65-90min.

Raw material pretreatment: The citrus pomace is processed in two steps: removing impurities and inactivating enzymes (pectinase in the pomace). The purpose is to remove a large amount of glycosides, starch, pigments, acids, salts and other substances in the peel. The method is: rinse repeatedly with warm water (35-55°C), then heat (85-95°C) and keep warm for 10-20 minutes to passivate the original pectinase; then rinse repeatedly with warm water (35-55°C), further Remove impurities, dry, crush (80 mesh), and set aside.

Enzymolysis process: Accurately weigh 10.000g of pretreated citrus peel residue, according to the "enzymolysis conditions to determine" solid-liquid ratio, and add distilled water to stir evenly, enzymolysis. After the enzymatic hydrolysis is completed, quickly inactivate the enzyme activity (boiling water bath 85-95°C, time 5min).

Pectin extraction and separation: use the acid extraction solution (adjusted by the ratio of 1:1:1:1) of organic acid and inorganic acid pH1.8-2.4), ultrasonic-assisted extraction for 45-75min, heat preservation at 60-85°C, ultrasonic power 225-250W. Then centrifuge at 4200-6000r/min for 15-25min, and keep the supernatant, which is the centrifugate. The centrifugate was rotary evaporated to 4-6% of the original volume at a temperature of 45-65 °C, and then cooled rapidly to room temperature.

Pectin precipitation and drying: add 2-4 times the volume of 95% ethanol to the concentrated solution, keep the temperature at 4°C, precipitate for 1-2 hours, centrifuge at 3600rmp for 10 minutes, filter through gauze, and wash with absolute ethanol for 1-2 hours times, that is, wet pectin. Pre-freeze the pectin after alcohol precipitation at -18°C for 24-36 hours, and then vacuum freeze-dry to obtain dry pectin powder.

the

Embodiment 2,

1. Raw material pretreatment: Properly process the remaining peels of citrus, mainly including two steps: remove impurities and inactivate enzymes, and pretreat raw peels by rinsing and blanching. The purpose is to remove a large amount of glycosides, starch, pigments, acids, salts and other substances in the peel. The method is: rinse repeatedly with warm water (35-55°C), then heat (85-95°C) and keep warm for 10-20 minutes to passivate the original pectinase in the peel; then rinse repeatedly with warm water (35-55°C) , further remove impurities, dry, crush (80 mesh), and set aside.

2. Enzymatic hydrolysis: before adding enzyme, adjust the pH with citric acid-sodium citrate (control the pH condition of enzymatic hydrolysis at 3.5-5.5), and at the same time, strictly control the ratio of solid to liquid in the range of 1:20-30. Add 0.1-0.5 U/g of cellulase, the enzymolysis temperature is 35-65°C, and the enzymolysis time is 65-90min. After the enzymatic hydrolysis is completed, quickly inactivate the enzyme activity (boiling water bath 85-95°C, time 5min).

3. Acid extraction: using a combination of organic acids and inorganic acids (including: a combination of one or more acids such as hydrochloric acid, sulfuric acid, sulfurous acid, citric acid, etc., according to the ratio of 1:1:1:1) acid extraction solution (adjust the pH to 1.8-2.4), ultrasonic-assisted extraction for 45-75min, heat preservation at 60-85°C, and ultrasonic power of 225-250W.

4. Centrifugation: Rotate at 4200-6000r/min, centrifuge for 15-25min, keep the supernatant, which is the centrifugate.

5. Vacuum concentration: The centrifugate is rotatively evaporated to 4-6% of the original volume at a temperature of 45-65 ℃, and then cooled to room temperature rapidly.

6. Alcohol precipitation: Add 2-4 times the volume of 95% ethanol to the concentrated solution, keep the temperature at 4°C, precipitate for 1-2 hours, centrifuge at 3600rmp for 10 minutes, filter through gauze, and then wash 1-2 times with absolute ethanol , to get wet pectin.

7. Drying: pre-freeze the alcohol-precipitated pectin below -18°C for 24-36 hours, and then vacuum freeze-dry to obtain dry pectin powder.

Embodiment 3,

A described method for preparing citrus peel pectin by ultrasonic-assisted extraction comprises the following steps:

(1) After rinsing with warm water at 45°C for 3 times, then heating to 95°C and holding for 10 minutes; then rinsing with warm water at 35°C for 2 times, then drying and crushing to 80 meshes to obtain citrus after removing impurities and enzymes fruit pomace;

(2) Before adding enzyme, adjust the pH condition to 4.5, and control the ratio of solid to liquid at 1:25, add cellulase 0.4U/g, enzymolysis temperature is 45°C, enzymolysis time is 68min, after enzymolysis is completed, boil water bath 95°C for 5 minutes to inactivate the enzyme activity;

(3) Adjust the pH2 by using the acid extraction solution of a combination of organic acid and inorganic acid, ultrasonically assisted extraction for 60 minutes, keep warm at 65°C, and ultrasonic power 250W;

(4) Rotate at 6000r/min, centrifuge for 25min, keep the supernatant, which is the centrifugate;

(5) Concentrate the centrifugate to 5% of its original volume at a temperature of 5°C, and cool it down to room temperature rapidly;

(6) Add 95% ethanol equivalent to 3 times its volume to the concentrated solution, keep the temperature at 4°C, precipitate for 2 hours, centrifuge at 3600rmp for 10 minutes, filter through gauze, and wash twice with absolute ethanol to obtain alcohol precipitation After wet pectin;

(7) The wet pectin after alcohol precipitation was pre-frozen at -15 ℃ for 36 hours, and then vacuum freeze-dried to obtain dry pectin powder.

Claims (4)

1. utilize ultrasonic-assisted extraction to prepare a method for citrus skin slag pectin, it is characterized in that:

Citrusfruit skin slag is removed to impurity and the enzyme pre-treatment of going out, add cellulase to carry out enzymolysis, recycling ultrasonic-assisted extraction equipment, it is acid regulating extracting solution PH, carry out ultrasonic wave auxiliary acid water extraction pectin, extract is carried out centrifugal, filter, get supernatant liquor, vacuum concentration, the ethanol precipitation of 95% left and right fully stirs simultaneously, washing is also centrifugal, and collecting precipitation thing, vacuum lyophilization obtain pectin finished product.

2. a kind of method of utilizing ultrasonic-assisted extraction to prepare citrus skin slag pectin according to claim 1, is characterized in that: comprise the following steps:

(1) with after 35-55 DEG C of warm water rinsing for several times, be then heated to 85-95 DEG C, insulation 10-20 min; Use again after 35-55 DEG C of warm water rinsing for several times, dry, be crushed to 80 order left and right, the citrusfruit skin slag that must remove impurity and go out after enzyme;

(2) before enzyme-added, regulate pH condition at 3.5-5.5, control solid-liquid ratio at 1:20-30 simultaneously, add cellulase 0.1-0.5U/g, hydrolysis temperature is 35-65 DEG C, enzymolysis time 65-90min, and boiling water bath 85-95 DEG C after enzymolysis completes, the enzyme that goes out about time 5min is lived;

(3) utilize the acid extraction liquid of the combination of organic acid and mineral acid to adjust pH1.8-2.4, ultrasonic-assisted extraction 45-75min, insulation 60-85 DEG C, ultrasonic power is 225-250W;

(4) rotating speed 4200-6000r/min, centrifugal 15-25min, retains supernatant liquor, is centrifugate;

(5) centrifugate is concentrated into the 4-6% of original volume under temperature 45-65 DEG C condition, is cooled to rapidly room temperature;

(6), to the ethanol that adds 95% left and right that is equivalent to its 2-4 times volume in concentrated solution, keep 4 DEG C of left and right of temperature, precipitation 1-2 h, with centrifugal 10min left and right, 3600rmp left and right, through filtered through gauze, then through absolute ethanol washing 1-2 time, obtain the hygrometric state pectin after alcohol precipitation;

(7) by the pre-freeze 24-36 h below-18 DEG C of the hygrometric state pectin after alcohol precipitation, then vacuum lyophilization, pectin power-product obtained.

3. utilize ultrasonic-assisted extraction to prepare the method for citrus skin slag pectin according to one kind of claim 1, it is characterized in that: the acid extraction liquid of described organic acid and the combination of mineral acid by hydrochloric acid, sulfuric acid, sulfurous acid, citric acid etc. one or more combination and obtain.

4. utilize ultrasonic-assisted extraction to prepare the method for citrus skin slag pectin according to one kind of claim 1, it is characterized in that: the acid extraction liquid of described organic acid and the combination of mineral acid is obtained by mixing in 1:1:1:1 ratio by hydrochloric acid, sulfuric acid, sulfurous acid, citric acid.