阅读说明：本技术 一种从江蓠中提取琼胶的方法 (Method for extracting agar from gracilaria ) 是由 蔡鹰 李思东 吴湛霞 胡章 杨磊 黄娜 *** 梁远维 于 2019-10-25 设计创作，主要内容包括：本发明提供一种从江蓠中提取琼胶的方法,包括如下步骤：1)碱处理：将除杂的江蓠属植物置于碱溶液中处理,处理结束后,去除碱液；2)粉碎：将步骤1)制得的江蓠进行粉碎处理,得到粉碎后的料液；3)加热提胶：向步骤2)所得的料液补水,加热提胶；4)通过板框过滤进行脱渣处理；5)采用活性炭进行脱色处理；6)脱水干燥,得到琼胶。本发明将碱处理后的江蓠通过机械粉碎形成胶体溶液,加热提胶压榨过滤后的胶液使用粉状活性炭进行脱色,冷冻脱水或压榨脱水,干燥后所得琼胶产品产率、质量比较稳定,外观微黄或白色。加工生产全过程不需使用盐酸、草酸等,也不需使用化学漂白剂,用水量只是传统方法的40％左右,产生的废水量也大幅下降。(The invention provides a method for extracting agar from gracilaria, which comprises the following steps: 1) alkali treatment: treating the purified Gracilaria plant in an alkali solution, and removing the alkali solution after the treatment is finished; 2) crushing: smashing the gracilaria prepared in the step 1) to obtain smashed feed liquid; 3) heating and extracting glue: supplementing water to the feed liquid obtained in the step 2), and heating and extracting the glue; 4) carrying out deslagging treatment by plate-and-frame filtration; 5) decoloring by using activated carbon; 6) and (5) dehydrating and drying to obtain the agar. The invention mechanically crushes the gracilaria subjected to alkali treatment to form a colloidal solution, decolours the colloidal solution after heating, extracting the glue, squeezing and filtering by using powdered activated carbon, and then carries out freeze dehydration or squeezing dehydration, and the obtained agar product after drying has relatively stable yield and quality and yellowish or white appearance. Hydrochloric acid, oxalic acid and the like are not needed in the whole processing and production process, a chemical bleaching agent is not needed, the water consumption is only about 40% of that of the traditional method, and the amount of generated waste water is greatly reduced.)

1. A method for extracting agar from Gracilaria, which is characterized by comprising the following steps:

1) alkali treatment: placing the purified Gracilaria plant in an alkaline solution for treatment, and removing the alkaline solution after the treatment to obtain the Gracilaria subjected to alkaline treatment;

2) crushing: smashing the gracilaria prepared in the step 1) to obtain smashed feed liquid;

3) heating and extracting glue: supplementing water to the feed liquid obtained in the step 2), and heating and extracting the glue;

4) carrying out deslagging treatment by plate-and-frame filtration;

5) decoloring by using activated carbon;

6) and (5) dehydrating and drying to obtain the agar.

2. The method of claim 1, wherein: in the step 4), perlite and diatomite are used for assisting filtration in a synergistic mode, and the feed liquid obtained by heating and extracting the gel is subjected to deslagging.

3. The method of claim 2, wherein: in the step 4), the fineness of the adopted perlite and the diatomite is 100-120 meshes.

4. The method of claim 2, wherein: in the step 4), during filtering, perlite is pre-coated on the plate-and-frame filter, then diatomite is added into the glue solution, and after uniform mixing, the filtering and deslagging are carried out by adopting a plate-and-frame filter press with the pre-coated glue solution, so as to obtain the filtered glue solution.

5. The method of claim 4, wherein: in the step 4), during precoating, adding the required perlite according to the amount of 1-1.5 kg of perlite in each plate frame, starting the machine until filtrate is clear, and finishing precoating to obtain a precoated plate-and-frame filter press;

and/or in the step 4), adding water to adjust the concentration of the pre-coating liquid to be 3-6 wt%, wherein the temperature of the added water is 80-90 ℃;

and/or in the step 4), the temperature of the glue solution is 70-90 ℃;

and/or in the step 4), the weight of the added diatomite is 2-5% of the weight of the glue solution.

6. The method of claim 1, wherein: in the step 5), when the temperature of the glue solution is reduced to 60-65 ℃, adding powdered activated carbon, wherein the fineness of the powdered activated carbon is 140-200 meshes, the weight of the added powdered activated carbon is 0.3-0.8% of the weight of the glue solution, and keeping the temperature for 20-25 min after adding the powdered activated carbon.

7. The method of claim 1, wherein: in the step 5), after the adsorption treatment of the activated carbon is finished, adding perlite into the glue solution, and filtering to obtain a filtered glue solution, wherein the weight of the added perlite is preferably 1.5-3.0% of the weight of the glue solution.

8. The method of claim 1, wherein: in the step 1), the concentration of the alkali solution is 10-25 wt%, the using amount of the alkali solution is 5-6L/Kg of gracilaria plants, the alkali solution is heated to 60-65 ℃ during alkali solution treatment, and the treatment time is 12-16 hours during alkali solution treatment.

9. The method of claim 1, wherein: in the step 2), water is added during crushing, and the weight of the water is 5-8 times of that of the dried gracilaria products.

10. The method of claim 1, wherein: in the step 3), water is added to the feed liquid obtained in the step 2) until the total weight of the feed liquid is 15-25 times of the weight of the dried gracilaria product, and the feed liquid is heated until boiling, and the boiling state is kept for 10-15 min.

Technical Field

The invention relates to the technical field of light chemical industry, in particular to a method for extracting agar from gracilaria.

Background

The production process of extracting agar from Gracilaria includes the main steps of alkali treatment, alkali removing and cleaning, acidification treatment, bleaching, deacidification and bleaching agent cleaning, heating to extract agar, freeze dewatering or squeezing dewatering, etc. For example, chinese patent publication No. CN106496364A discloses a water-saving method for extracting agar from gracilaria, the whole process includes more chemical treatment steps, uses a large amount of chemical materials such as acid, alkali and bleaching agent, and consumes 150-200 tons of water per 1 ton of gracilaria, especially, the water consumption of the acidification and bleaching steps accounts for most of the water used in the whole process, and simultaneously generates a large amount of waste water containing compounds, thereby increasing the production cost and environmental protection pressure.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention aims to provide a method for extracting agar from Gracilaria, which is used to solve the problems of the prior art, such as large water consumption, generation of a large amount of waste water containing compounds, increase of production cost and environmental protection pressure, etc.

In order to achieve the above objects and other related objects, the present invention provides a method for extracting agar from Gracilaria, comprising the steps of:

1) alkali treatment: placing the purified Gracilaria plant in an alkaline solution for treatment, and removing the alkaline solution after the treatment to obtain the Gracilaria subjected to alkaline treatment;

2) crushing: crushing the gracilaria prepared in the step 1) to obtain crushed feed liquid, wherein the feed liquid is suspension;

3) heating and extracting glue: supplementing water to the feed liquid obtained in the step 2), and heating and extracting the glue;

4) carrying out deslagging treatment;

5) carrying out decoloring treatment;

6) and (5) dehydrating and drying to obtain the agar.

According to the invention, after the alkali treatment, the acid treatment and the bleaching treatment are not carried out any more, the subsequent heating submission is promoted by crushing, then the insoluble substances are removed by deslagging treatment, and the agar is obtained after the decoloring treatment, so that the water consumption is effectively reduced, the acid and the bleaching agent are not used any more, the pollution of the waste water to the environment is effectively reduced, and the controllability of the process is improved. The alkali treatment mainly plays roles of removing sulfate radicals and pigments, improving strength and the like.

In an embodiment of the present invention, in the step 1), the gracilaria plant is dry product, and the moisture content of the dry product is usually about 20%.

In one embodiment of the present invention, in the step 1), the gracilaria plant is selected from at least one of gracilaria verrucosa and gracilaria tenuistipitata. Of course, this is only a partial list, and other Gracilaria plants are also suitable for use in the present invention.

In an embodiment of the invention, in the step 1), the alkali solution is selected from an aqueous sodium hydroxide solution.

In an embodiment of the invention, in the step 1), the concentration of the alkali solution is 10 to 25 wt%.

In an embodiment of the invention, in the step 1), the amount of the alkali solution is 5 to 6L/kg of the gracilaria.

In an embodiment of the invention, in the step 1), the alkali solution is heated to 60 to 65 ℃ during the alkali solution treatment.

In an embodiment of the invention, in the step 1), the treatment time in the alkali solution treatment is 12 to 16 hours.

In an embodiment of the invention, in the step 1), when removing the alkali liquor, after discharging the alkali liquor, the residual alkali liquor is removed by means of solid-liquid separation.

In one embodiment of the present invention, in the step 1), after removing the alkali solution, the gracilaria is soaked with water until the pH of the soaking water is 6.0-7.5, preferably 6.5.

In an embodiment of the invention, in the step 2), water is added during the pulverization, and the weight of the water is 5-8 times of the weight of the dried gracilaria product. The crushing function is mainly used for promoting the subsequent extraction of the agar.

In an embodiment of the invention, in the step 3), water is added to the feed liquid obtained in the step 2) until the total weight of the feed liquid is 15-25 times of the weight of the dried gracilaria product.

In an embodiment of the invention, in the step 3), the material liquid is heated until boiling, and the boiling state is maintained for 10 to 15min at a temperature of about 95 to 100 ℃.

In an embodiment of the invention, in the step 3), the boiling state is a slightly boiling state.

In an embodiment of the invention, in the step 4), perlite and diatomite are used for assisting filtration in a synergistic manner, and a glue solution formed by heating and extracting the agar is filtered and deslagged, so that the agar glue solution is separated from insoluble substances.

In an embodiment of the invention, in the step 4), the fineness of the perlite and the diatomite is 100-120 meshes.

In an embodiment of the present invention, in the step 4), the filtration mode is plate-and-frame filtration, and the function of the step is mainly to remove cellulose fragments and insoluble substances.

In one embodiment of the present invention, in the step 4), the plate-and-frame filter press used is provided with 18 to 32 press plate frames in total, and preferably 22 plate frames.

In an embodiment of the invention, in the step 4), the aperture of the filter membrane of the plate and frame filter press is 200 meshes.

In an embodiment of the invention, in the step 4), when filtering, the plate-and-frame filter press is pre-coated with perlite, then diatomaceous earth is added into the glue solution, and after mixing uniformly, the pre-coated plate-and-frame filter press is used for filtering and deslagging to obtain the filtered glue solution.

In an embodiment of the invention, in the step 4), during precoating, the required perlite is added according to the amount of 1-1.5 kg of perlite in each plate frame, and the plate frame filter press is started until filtrate is clear, so that precoating is completed, and the precoated plate frame filter press is obtained. The weight of the perlite added into each plate frame can be 1kg, 1.1kg, 1.2kg, 1.3kg, 1.4kg and 1.5 kg.

In an embodiment of the invention, in the step 4), water is added to adjust the concentration of the pre-coating liquid to be 3-6 wt%.

In an embodiment of the invention, in the step 4), the temperature of the added water is 80-90 ℃, and the temperature of the high-temperature precoating liquid also raises the temperature inside the plate-and-frame filter press, so that the next step of filtering the glue solution is facilitated.

In an embodiment of the invention, in the step 4), the temperature of the glue solution is 70 to 90 ℃, specifically 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃ and the like, preferably 75 to 85 ℃, and more preferably 80 ℃.

In an embodiment of the invention, in the step 4), the weight of the added diatomite is 2 to 5% of the weight of the glue solution, specifically may be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, and the like, preferably is 3 to 5%, more preferably is 4 to 5%, and more preferably is 5%.

In an embodiment of the invention, in the step 5), activated carbon is used for performing a decoloring treatment.

In an embodiment of the invention, in the step 5), powdered activated carbon is added when the temperature of the glue solution is reduced to 60-65 ℃.

In an embodiment of the invention, in the step 5), the fineness of the powdered activated carbon is 140 to 200 meshes, preferably the ratio of 160 meshes to 90% or more, and usually the ratio of 160 meshes to 98% of the powdered activated carbon.

In an embodiment of the invention, in the step 5), the weight of the added powdered activated carbon is 0.3-0.8% of the weight of the glue solution, and is about 0.3-0.8 g/100 mL. Experiments show that on one hand, when the using amount of the activated carbon is too low (namely, the weight of the powdered activated carbon is less than 0.3% of the weight of the glue solution), a good decoloring effect cannot be achieved, and on the other hand, when the using amount of the activated carbon is too high (namely, the weight of the powdered activated carbon is more than 0.8% of the weight of the glue solution), although a good decoloring effect can be achieved, excessive agar is adhered to the surface of the activated carbon, and the yield of the agar is further seriously reduced.

In an embodiment of the invention, in the step 5), the temperature is maintained for 20-25 min after adding the powdered activated carbon.

In an embodiment of the invention, in the step 5), after the activated carbon adsorption treatment is finished, perlite is added into the glue solution, and the filtered glue solution is obtained by filtering.

In an embodiment of the invention, in the step 5), the weight of the added perlite is 1.5-3.0% of the weight of the glue solution.

In an embodiment of the invention, in the step 6), dewatering is performed by a press dewatering method, and drying is performed by sunlight. Of course, dehydration may be performed by oven drying, freeze drying or the like.

In an embodiment of the invention, in the step 6), the agar is dried until the water content of the agar is less than or equal to 10%.

In an embodiment of the present invention, in the step 6), after drying, crushing is performed to obtain a powdered agar product.

In an embodiment of the invention, in the step 6), the agar product is crushed to a fineness of 80-100 meshes.

The invention also provides the agar prepared by the method.

The difference of gracilaria raw materials usually causes the great difference of the gel strength of the finally obtained agar, and the gel strength is usually 300 g/cm²The above.

The invention also provides application of the agar in medicines, foods and cosmetics.

As mentioned above, the method for extracting agar from Gracilaria verrucosa of the invention has the following beneficial effects: the invention mechanically crushes the gracilaria subjected to alkali treatment to form a colloidal solution, decolours the colloidal solution after heating, extracting the glue, squeezing and filtering by using powdered activated carbon, and then carries out freeze dehydration or squeezing dehydration, and the obtained agar product after drying has relatively stable yield and quality and yellowish or white appearance. Hydrochloric acid, oxalic acid and the like are not needed in the whole process of processing and production, a chemical bleaching agent is not needed, the water consumption is only about 40-45% of that of the traditional method, and the amount of generated waste water is greatly reduced.

Detailed Description

The present invention is further illustrated by the following specific examples, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available.

Based on the defects of the prior art, a new green processing method for extracting agar from gracilaria is discussed, and the method has practical significance in product quality control, production economic cost and environmental protection.

Since the influence of each process on the quality of agar is large, if the control is not strict, the yield and quality of the product, such as gel strength, fluctuate to a large extent.

The prepared agar is mainly used in the fields of medicines, foods, cosmetics and the like.

In the following examples, the shredder used was a DZ-40H kelp seaweed beater, Nantong Fulaike fluid Equipment Ltd, and other similar shredders are also suitable for use in the present invention.

In the following examples, the plate and frame filter press used was a XAMY type filter press, a Shita mechanical group Co., Ltd., and a filter membrane having a pore size of 200 mesh, and other similar plate and frame filter presses were also used in the present invention.

In the following examples, the fineness of the perlite and the diatomite adopted in the plate-frame filter pressing is 100-120 meshes.

The yield in the following examples is the percentage of the weight (Kg) of the prepared powder agar product to the weight (Kg) of the gracilaria dry raw material, i.e. the yield is (weight of the powder agar product ÷ weight of the gracilaria dry raw material) × 100%.

In the following examples, the centrifugal filter used for the coarse filtration was a roller filter having a mesh size of 80 mesh, which was obtained from Wichhol mechanical Co., Ltd.

In the following examples, a UV-3200S type ultraviolet-visible spectrophotometer, which is available from Shanghai Mei Dyer instruments Ltd, was used for the transmittance measurement.

The decolorization ratio is calculated as follows: the absorbance was calculated from the light transmittance or the absorbance was measured simultaneously, and the decolorization ratio was (absorbance before treatment-absorbance after treatment) ÷ absorbance before treatment ×%.

In the following examples, the gel strength was determined as follows: weighing agar according to the proportion of 1.5g agar/100 mL water, mixing the agar with the water, heating to boil to completely dissolve the agar, adding the agar into a test cup, wherein the test cup is a beaker with the capacity of 150mL, the volume of the added glue solution is 50mL, placing the beaker at 20 ℃ for cooling for 12h, and measuring by using a hydraulic gel strength tester (the adopted device and method are disclosed in the Chinese utility model patent with the patent number of ZL 02271486.3).