CN101148482A - A kind of extraction method of pectin in banana peel - Google Patents

Abstract

The invention discloses a method for extracting pectin from banana peel. Using banana peel as raw material, microwave treatment is used to extract pectin by salting out method. The traditional heating extraction method requires high temperature and a long time, and the pectin in the raw material will inevitably be denatured and decomposed. The invention can greatly retain the natural activity of the separated components, shorten the extraction time, increase the pectin yield, save resources and reduce costs.

Description

A kind of extraction method of pectin in banana peel

technical field

The invention belongs to the field of natural product processing, in particular to a method for extracting pectin from banana peels.

Background technique

Pectin is a complex polysaccharide polymer and a water-soluble vegetable gum with good gelling and emulsifying properties. Its basic structure is a long chain of D-galactopyranuronic acid connected by 1,4 glycoside chains, usually in a partially methylated state, and its molecular formula is C _14n+14 H _20n+22 O _12n+13 ( n=30～300), the molecular weight is between 100,000～400,000. It widely exists in the tissue cells of higher plants and is an important part of plants.

Pectin has many uses. In the food industry, pectin can be used as a stabilizer for pulp, jelly, candy, fruit juice, juice emulsifier, milk thickener and biodegradable tableware, etc.; in the field of medicine, it can be used as a laxative, artificial plasma and antidote for heavy metals , and has physiological functions such as auxiliary treatment of diabetes, lowering blood sugar and cholesterol; it can replace starch as a lubricant in the textile industry; it can be used as a cleaning agent in the electronics industry; it can be used as an oil-water emulsifier in oil drilling. The annual demand for pectin in the world is nearly 20,000 tons. According to relevant experts, the demand for pectin will still increase at an annual rate of 15% in a considerable period of time. my country consumes more than 1,500 tons of pectin every year, and imports account for about 80 %. Due to the limitation of raw material sources and production technology, the production scale of domestic pectin is small, mainly relying on imports from abroad, but the price of imported pectin is very expensive. Banana is one of the main fruits in the tropics and subtropics. The annual output is large, and the skin weight accounts for about 30% of the fruit weight. However, most of the banana peels have not been developed and utilized, which not only wastes resources, but also pollutes the environment. According to reports, the white skin layer of banana peel is rich in pectin, and the quality is good, it can be used as raw material for producing pectin in industry.

Pectin is mainly extracted from plant tissues, and the commonly used methods include aluminum salt salting out method, ion exchange method, microbial method, supercritical extraction method and so on. At present, the pectin production in my country basically uses the traditional heating method to extract, which requires high temperature and a long time. The pectin in the raw material will inevitably be denatured and decomposed. Microwave heating has the advantages of uniform heating, rapid heating, easy instantaneous control, and environmental protection. features. At the same time, microwave also has the characteristics of strong selectivity, low solvent consumption, high yield of target components, and can greatly retain the natural activity of the separated components. Using microwave to extract pectin can avoid these problems and improve the yield.

Contents of the invention

The purpose of the present invention is to provide a method for extracting pectin from banana peels with microwaves.

The specific steps are:

(1) Pretreatment of raw materials: mash fresh and clean banana peels with a masher, add water and bathe at 80°C for 10 minutes to inactivate enzymes, and rinse repeatedly to remove pigments, bitter substances and sugar in banana peels as much as possible and other impurities, and dry most of the water;

(2) Acid extraction: use 37% hydrochloric acid or acetic acid to prepare an acid extraction solution with a pH of 1-2. After the banana peel is pretreated, put it in a beaker, add hydrochloric acid or acetic acid extraction solution with a pH of 1 to 2, the mass ratio of solid to liquid is 1:10 to 20, and extract for 5 to 6 minutes under the condition of microwave power 500 to 600W. Filter the extract, rinse the filter residue with hot water and filter, and combine the filtrate;

(3) Aluminum salt precipitation: Keep the filtrate in a constant temperature water-soluble pot at a constant temperature to 50-60°C, slowly add aluminum sulfate, the amount of aluminum sulfate is 25% of the banana peel, and adjust the pH value to 4 with ammonia water with a concentration of 30%. Around, precipitate out;

(4) Desalination and washing: After the precipitate is precipitated, place it for 1 to 2 hours for centrifugal filtration, wash and drain the precipitate, crush it, treat it with acidified ethanol, stir fully to completely replace the metal ions, press filter, and wash repeatedly with 60% neutral ethanol Precipitate until the washing solution is neutral;

(5) Drying: the precipitate is dried in a drying oven at 40-50°C for 10-12 hours, and crushed to obtain pectin products.

Advantages of the present invention:

(1) The extraction time is short. Compared with the traditional method, microwave radiation can greatly accelerate the hydrolysis of the tissue, shortening the extraction time of pectin from 90 minutes in the traditional method to 5-6 minutes.

(2) Using the salting-out process, the process of concentrating the pectin solution is omitted, the extraction time is greatly shortened, the amount of ethanol is small, the consumption is small, and the overall cost is relatively low.

(3) The yield of pectin is high.

(4) The sample quality is good. The pectin extracted by microwave method has reached or exceeded the national quality standard, and has good gel performance and thickening effect.

Detailed ways

Example 1:

Weigh 10g of banana peel, crush it with a masher, add water and bathe at 80°C for 10 minutes to inactivate the enzyme, rinse repeatedly, and dry most of the water; use 37% hydrochloric acid to prepare hydrochloric acid with a pH of 2 for extraction solution; after the banana peel is pretreated, put it in a beaker, add 160ml of hydrochloric acid extract with a pH of 2, extract for 5min under the condition of microwave power 540W, filter the extract while it is hot, wash the filter residue with hot water and filter, combine the filtrate, Keep the filtrate in a constant temperature water-soluble pot at a constant temperature to 50°C, slowly add 2.5g of aluminum sulfate, adjust the pH value to about 4 with 30% ammonia water, and place the precipitate for 1 hour to centrifugally filter, wash and drain the precipitate, and crush it. Treat with acidified ethanol, stir fully to replace the metal ions completely, and then use G3 sand core funnel to suction filter and wash the precipitate repeatedly with 60% neutral ethanol until the washing liquid is neutral. The gel yield was 6.77%.

Example 2:

Weigh 10g of banana peel, crush it with a masher, add water and bathe at 80°C for 10 minutes to inactivate the enzyme, rinse repeatedly, and dry most of the water; use 37% hydrochloric acid to prepare hydrochloric acid with a pH of 2 for extraction liquid; after pretreatment, put it in a beaker, add 160ml of hydrochloric acid extract with a pH of 2, extract under the condition of microwave power 540W for 6min, filter the extract while it is hot, wash the filter residue with hot water and filter, combine the filtrate, and filter the filtrate Keep the temperature in a constant temperature water-soluble pot to 50°C, slowly add 2.5g of aluminum sulfate, adjust the pH value to about 4 with 30% ammonia water, and place the precipitate for 1 hour for centrifugal filtration, wash and drain the precipitate, crush it, and use acidification Ethanol treatment, fully stirred to completely replace the metal ions, and then use G3 sand core funnel to suction filter and wash the precipitate repeatedly with 60% neutral ethanol until the washing liquid is neutral, and dry the precipitate in a drying oven at 40°C for about 10 hours, pectin production The rate is 7.26%.

Example 3:

Weigh 10g of banana peel, crush it with a masher, add water and bathe at 80°C for 10 minutes to inactivate the enzyme, rinse repeatedly, and dry most of the water; use 37% hydrochloric acid to prepare hydrochloric acid with a pH of 1 for extraction liquid; after pretreatment, put it in a beaker, add 160ml of hydrochloric acid extract with a pH of 1, extract under the condition of microwave power 540W for 6min, filter the extract while it is hot, wash the filter residue with hot water and filter, combine the filtrate, and filter the Keep the temperature in a constant temperature water-soluble pot to 50°C, slowly add 2.5g of aluminum sulfate, adjust the pH value to about 4 with 30% ammonia water, and place the precipitate for 1 hour for centrifugal filtration, wash and drain the precipitate, crush it, and use acidification Ethanol treatment, fully stirred to completely replace the metal ions, and then use G3 sand core funnel to suction filter and wash the precipitate repeatedly with 60% neutral ethanol until the washing liquid is neutral, and dry the precipitate in a drying oven at 40°C for about 10 hours, pectin production The rate is 6.03%.

Claims (1)

1. an extracting method of pectin in banana peel, is characterized in that taking banana peel as raw material, concrete steps are: (1) Mash fresh and clean banana peels with a masher, add water and bathe in 80°C water bath for 10 minutes to achieve the effect of inactivating enzymes, rinse repeatedly, and dry most of the water; (2) Use hydrochloric acid or acetic acid with a concentration of 37% to prepare an acid extract with a pH of 1 to 2. After the banana peel is pretreated, put it in a beaker, add hydrochloric acid or acetic acid with a pH of 1 to 2, and the feed solution The mass ratio is 1:10-20, extracting under the condition of microwave power 500-600W for 5-6min, filtering the extract while it is hot, washing the filter residue with hot water and filtering, and combining the filtrate; (3) Keep the filtrate in a constant temperature water-soluble pot at a constant temperature to 50-60°C, slowly add aluminum sulfate, the amount of aluminum sulfate is 25% of the banana peel, adjust the pH value to about 4 with ammonia water with a concentration of 30%, and precipitate out ; (4) After the precipitate is precipitated, place it for 1 to 2 hours for centrifugal filtration, wash and drain the precipitate, crush it, treat it with acidified ethanol, stir fully to completely replace the metal ions, and press filter, wash the precipitate repeatedly with 60% neutral ethanol until the washing liquid neutral (5) The precipitate is dried in a drying oven at 40-50°C for 10-12 hours, and crushed to obtain pectin products.