A method for extracting carrageenan

Abstract

The present invention provides a method for extracting carrageenan, and belongs to the technical field of carrageenan extraction. The extraction method of the present invention comprises the following steps: (1) red algae is treated with alkali and then washed with water until neutral; (2) the washed red algae is chopped and soaked in a composite bacterial solution; (3) after the soaking, the red algae is taken out and mixed with water to boil gelatin, and a filtrate is obtained by solid-liquid separation; (4) the filtrate is cooled, gelled, and dried to obtain the carrageenan. The present invention performs bacterial solution treatment after alkali treatment and then boils gelatin, and utilizes the decomposition of cellulose by microorganisms to reduce impurities in carrageenan, thereby improving the purity and yield of carrageenan.

Description

Technical Field

[0001] The invention relates to the technical field of carrageenan extraction, and in particular to a method for extracting carrageenan. Background Art

[0002] Carrageenan is a hydrophilic colloid, also known as Eucheuma gel, Gelidium agar, Carrageenan, and Carrageenan. It is a general term for polysaccharides extracted from red algae seaweeds such as Eucheuma, Gelidium agar, and Carrageenan. It has the properties of gelling, thickening, emulsification, film forming, and stable dispersion. It is widely used in dairy products, ice cream, fruit juice drinks, bread, hydrogels, meat products, condiments, canned foods, etc.

[0003] At present, there are two main methods for extracting carrageenan. One is hot water extraction, purification, alcohol precipitation, and then drying and crushing to obtain a refined product, but the yield of this method is low; the second method is to use concentrated alkali solution for short-term high-temperature continuous circulation feeding treatment, and then precipitation, drying and crushing. This method has a higher yield, but the molecular weight is severely degraded, and the product is a semi-refined product containing some fiber. Generally speaking, refined or semi-refined carrageenan can meet the quality index requirements of FAO / WHO. The viscosity of 1.5% carrageenan solution at 75°C is above 5 cp, but the refined gel is pure and transparent. The semi-refined carrageenan contains a certain amount of fiber, so the viscosity measurement value is always higher, and the carrageenan solution is turbid, or there is often fiber precipitation, and the transparency is poor. With the advancement of science and technology and the improvement of living standards, the demand for carrageenan is gradually increasing, but people's requirements for the quality of carrageenan are also getting higher and higher. Therefore, it is urgent to provide an extraction method that can improve the yield of carrageenan and improve the quality of carrageenan. Summary of the invention

[0004] The purpose of the present invention is to provide a method for extracting carrageenan. The present invention performs bacterial liquid treatment after alkali treatment and then boils the carrageenan, utilizing the decomposition of cellulose by microorganisms to reduce impurities in the carrageenan, thereby improving the purity and yield of the carrageenan.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for extracting carrageenan, comprising the following steps:

[0007] (1) After the red algae is treated with alkali, it is washed with water until it is neutral;

[0008] (2) chopping the washed red algae and soaking them in a composite bacterial liquid;

[0009] (3) after the soaking is completed, the red algae is taken out and mixed with water to boil the gelatin, and a filtrate is obtained by solid-liquid separation;

[0010] (4) The filtrate is cooled, gelled, and dried to obtain the carrageenan.

[0011] Preferably, the alkali solution used for the alkali treatment contains KOH and NaOH, the mass concentration of KOH in the alkali solution is 6-8%, and the mass concentration of NaOH is 5-7%; the mass ratio of the red algae to the alkali solution is 1:(8-15); the time of the alkali solution treatment is 2-5 h, and the temperature during the treatment is 80-85°C.

[0012] Preferably, the particle size of the chopped red algae is (5-12) mm×(5-12) mm.

[0013] Preferably, the composite bacterial solution includes a cellulomonas solution and a yeast solution, and the concentration of the cellulomonas solution is (7-9)×10 7 cfu / mL, the concentration of the yeast solution is (1~3)×10 5 cfu / mL; the volume ratio of the cellulomonas bacterial solution to the yeast bacterial solution is (0.5~2): (0.5~2).

[0014] Preferably, the mass volume ratio of the washed red algae to the composite bacteria liquid is 1 g: (12-18) mL; and the soaking time is 72-120 h.

[0015] Preferably, the mass ratio of the red algae to the water after the soaking is 1:20-30; the temperature of the gelatin boiling is 75-100° C., and the time is 0.5-1 h.

[0016] Preferably, the temperature of the cooled filtrate is 28-35°C.

[0017] Preferably, the gel is prepared by adding KCl to the cooled filtrate to cause the carrageenan to flocculate and precipitate; the amount of KCl added is 0.2-0.6% of the mass of the cooled filtrate; and the gel time is 35-50 min.

[0018] Preferably, the drying temperature is 55-70° C., and the drying is performed to a moisture content of 8-15%.

[0019] The present invention provides a method for extracting carrageenan. The present invention removes the wax layer on the surface of red algae by alkali treatment, and simultaneously removes part of the pigment and impurities, so as to facilitate the subsequent dissolution of colloid. Then, a composite bacterial solution composed of cellulomonas and yeast is used to treat the red algae, and the cellulomonas is used to degrade the cellulose in the cell wall of the red algae, so as to destroy the interaction between cellulose or between cellulose and colloid, so as to facilitate the dissolution of colloid; at the same time, under the action of aerobic respiration, the yeast further degrades the product after cellulose degradation to generate carbon dioxide and water, consumes the nutrients in the fermentation liquid, improves the purity and yield of colloid, and does not need to purify the carrageenan, which is beneficial to reduce the production cost of carrageenan and improve the economic benefit. DETAILED DESCRIPTION

[0020] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention. Example 1

[0021] The present invention selects KOH alkali solution with a mass concentration of 12%, NaOH alkali solution with a mass concentration of 12%, and a composite alkali solution composed of KOH with a mass concentration of 7% and NaOH with a mass concentration of 5% to treat red algae, and uses the gel strength and extraction yield of carrageenan as indicators to investigate the effects of different alkali reagents on the extraction results of carrageenan. The specific process is as follows:

[0022] After washing the red algae Eucheuma with water, put them into 12 times the mass of KOH alkali solution, NaOH alkali solution and compound alkali solution respectively, soak them at 85℃ for 3h, then wash them with clean water until they are neutral, and take out the red algae Eucheuma.

[0023] The red algae Eucheuma treated with alkali solution was cut into pieces with a particle size of 10 mm × 10 mm, and the red algae Eucheuma was mixed with water at a mass ratio of 1:25, heated to 95°C to boil the gel for 1 hour, and then filtered with a 200-mesh screen to obtain a filtrate. After the filtrate was cooled to 30°C, 0.4% KCl by mass of the filtrate was added and allowed to stand for 40 minutes to flocculate and precipitate the carrageenan. The obtained flocculated precipitate was squeezed and dehydrated with a filter press, and then dried at 60°C to a water content of 10% to obtain carrageenan.

[0024] The test results show that the gel strength of carrageenan treated with KOH solution is 1573.6 g / cm 2 The extraction rate is 19.2%; the gel strength of carrageenan treated with NaOH is 1025.1g / cm 2 The extraction rate is 18.7%; the gel strength of carrageenan treated with composite alkali solution is 1952.5g / cm 2The extraction rate was 19.5%. The results showed that the three alkali solutions had little effect on the extraction rate of carrageenan, but had a greater effect on the gel strength of carrageenan. The composite alkali solution treatment of red algae could significantly improve the gel strength of carrageenan. Example 2

[0025] The carrageenan solution obtained in Example 1 was turbid, with low transparency and low purity after being dissolved in water. Therefore, based on Example 1, the present invention tried to use a concentration of 8×10 7 cfu / mL of Cellulomonas bacterial solution, with a concentration of 8×10 7 cfu / mL of Cellulomonas and a concentration of 2×10 5 The red algae treated with alkali were soaked in a composite bacterial solution composed of 100 cfu / mL yeast bacterial solution (volume ratio 1:1), and the gel strength and extraction yield of carrageenan were used as indicators to investigate the effects of different bacterial species on the extraction results of carrageenan. The specific process is as follows:

[0026] After washing the red algae Eucheuma with water, weigh 1 kg of red algae, put it into 12 kg of KOH alkali solution, NaOH alkali solution, and composite alkali solution respectively, soak it at 85°C for 3 hours, then wash it with clean water until it is neutral, and take out the red algae Eucheuma.

[0027] The red algae Eucheuma treated with alkali solution was cut into pieces with a particle size of 10mm×10mm. The chopped red algae Eucheuma was placed in the cellulomonas bacterial solution and the composite bacterial solution at a ratio of 1g:15ml and soaked for 80h. After soaking, the red algae Eucheuma was taken out, and the red algae Eucheuma was mixed with water at a mass ratio of 1:25, heated to 95℃ and boiled for 1h, and then filtered with a 200-mesh screen to obtain a filtrate. After the filtrate was cooled to 30℃, 0.4% KCl of the filtrate mass was added and allowed to stand for 40min to flocculate and precipitate the carrageenan. The obtained flocculated precipitate was squeezed and dehydrated with a filter press, and then dried at 60℃ to a water content of 10% to obtain carrageenan.

[0028] The test showed that the gel strength of carrageenan obtained by treating the cellulomonas bacterial solution was 1897.1 g / cm 2 The extraction rate was 21.4%; the carrageenan gel strength obtained by the composite bacterial solution treatment was 2058.2 g / cm 2 The extraction rate was 24.3%. The transparency of the two carrageenans was compared after they were dissolved in water. The carrageenan obtained by the composite bacterial solution treatment had higher transparency, indicating that the composite bacterial solution treatment of red algae can significantly improve the extraction rate and purity of carrageenan. Example 3

[0029] The present invention has also investigated the effect of the concentration of the composite bacterial solution on the carrageenan extraction results.7 cfu / mL of Cellulomonas and a concentration of 5×10 4 cfu / mL of yeast culture liquid in a volume ratio of 1:1, and a composite culture liquid A with a concentration of 8×10 7 cfu / mL of Cellulomonas and a concentration of 1×10 6 cfu / mL of yeast culture liquid in a volume ratio of 1:1. According to the process of Example 2, the alkali-treated red algae Eucheuma was chopped and immersed in the above-mentioned composite culture liquid A and composite culture liquid B respectively, and then carrageenan was obtained according to the method of Example 2.

[0030] After testing, the carrageenan gel strength obtained by treating with composite bacterial solution A was 1799.3 g / cm 2 The extraction rate was 20.4%; the carrageenan gel strength obtained by the treatment of composite bacterial liquid B was 1821.6 g / cm 2 The extraction rate was 19.8%. The two carrageenans were dissolved in water and compared with the carrageenan obtained in Example 2. The carrageenan obtained by the composite bacterial solution in Example 2 had higher transparency, indicating that the composite bacterial solution needs to be at a specific concentration to improve the extraction rate and purity of carrageenan.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting carrageenan, characterized in that: The steps include: (1) After the red algae is treated with alkali, it is washed with water until it is neutral; (2) chopping the washed red algae into small pieces and soaking them in a composite bacterial liquid; (3) after the soaking is completed, the red algae is taken out and mixed with water to boil the gelatin, and a filtrate is obtained by solid-liquid separation; (4) cooling, gelling, and drying the filtrate to obtain the carrageenan; The alkali solution used for the alkali treatment comprises KOH and NaOH, wherein the mass concentration of KOH in the alkali solution is 6-8%, and the mass concentration of NaOH is 5-7%; the mass ratio of the red algae to the alkali solution is 1:(8-15); the alkali solution treatment time is 2-5 hours, and the temperature during the treatment is 80-85°C; The composite bacterial solution includes a cellulomonas bacterial solution and a yeast bacterial solution, and the concentration of the cellulomonas bacterial solution is (7-9)×10 7 cfu / mL, the concentration of the yeast solution is (1-3)×10 5 cfu / mL; the volume ratio of the cellulomonas bacterial solution to the yeast bacterial solution is 1:1; The mass volume ratio of the washed red algae to the composite bacterial liquid is 1 g: (12-18) mL; and the soaking time is 72-120 h.

2. The extraction method according to claim 1, characterized in that The particle size of the chopped red algae is (5-12) mm×(5-12) mm.

3. The extraction method according to claim 2, characterized in that The mass ratio of the red algae to the water after the soaking is 1:20-30; the temperature of the gelatin boiling is 75-100° C., and the time is 0.5-1 hour.

4. The extraction method according to claim 3, characterized in that The temperature of the cooled filtrate is 28-35°C.

5. The extraction method according to claim 4, characterized in that The gelling process is to add KCl to the cooled filtrate to make the carrageenan flocculate and precipitate; the amount of KCl added is 0.2-0.6% of the mass of the cooled filtrate; and the gelling time is 35-50 minutes.

6. The extraction method according to claim 5, characterized in that The drying temperature is 55-70° C., and the drying is performed to a moisture content of 8-15%.