CN100463941C - Preparation method of gel for medium carrier - Google Patents

Abstract

The invention relates to a preparation method of a gel used for a culture medium carrier, belonging to the field of polymer materials. The gel contains sodium polyacrylate, xanthan gum and locust bean gum, and the specific preparation method is as follows: respectively pulverize sodium polyacrylate, xanthan gum and locust bean gum, and pass through a sieve above 160 mesh; The raw gum and the locust bean gum are uniformly mixed in a mass ratio of 3:2-5; the above-mentioned mixture and the pulverized sodium polyacrylate are uniformly mixed in a mass ratio of 5:0.8-2.0 to obtain the gel. The gel can be used as a culture medium carrier of a microbiological rapid assay card, overcomes the disadvantage of poor water absorption in existing gels, and has the excellent characteristics of high water absorption and high viscosity.

Description

Preparation method of gel for medium carrier

【Technical field】

The invention relates to a preparation method of a gel used for a culture medium carrier, belonging to the field of polymer materials.

【Background technique】

Microbiological rapid test card refers to the use of paper, paper film, film, etc. as the medium carrier, on which specific medium and chromogenic substances are adhered to it through a specific gel, and determined by the growth and coloration of microorganisms on it. Methods of Microorganisms in Food. In 1955, German scholar FJ. Forg invented a simple and fast rapid detection method for coliform bacteria - the paper method, which shortened the original detection cycle from 72 hours to 15 hours, reduced the cost of materials by 3/4, and greatly Simplified operating procedures. Since then, this detection method integrating chemistry, macromolecular science and microbiology began to develop. Rapid assay card detection has significant advantages: first, it can measure a small amount of test items, does not need to prepare reagents, does not require a large number of glassware, and is easy and fast to operate; it is easy to sterilize and store, easy to transport, easy to carry, low in price, and removes paper There is no other waste liquid and waste outside the carrier such as tablets, which greatly reduces or eliminates the pollution to the environment, and does not require cleaning work after the test, reducing the workload. In addition, it avoids the defect that the hot agar method is not suitable for the recovery of damaged bacteria and fungi, so it is suitable for use in laboratories, production sites and field environments. Second, it can be inoculated at the same time when sampling, and the result can better reflect the real number of bacteria and fungi in the sample at that time, and prevent the increase in the number of bacteria and fungi caused by the proliferation of bacteria and fungi when the inoculation time is prolonged. Third, the conventional method generally takes a long time to prepare the culture medium and utensils for testing, which makes it impossible for many grassroots units and food companies to implement on-site testing. The rapid test card not only does not need to be prepared before use, but also greatly shortens the time. In recent years, the domestic use of filter paper as the carrier and the US 3M Company's assay card with Petrifilm as the carrier have begun to gradually expand their applications. However, because the filter paper is opaque, the bacteria growing in it are often invisible to the naked eye, resulting in less counting results; and ordinary gels have poor water absorption performance, and cannot achieve the corresponding results when used in assay cards; at the same time, imported products are expensive and difficult to obtain. Accepted by the domestic testing market. Therefore, to overcome the shortcomings of filter paper and ordinary gels, and to develop new domestic gels has become an urgent need for rapid detection of microorganisms.

During the preparation of assay cards, it is very important to choose a good gelling agent. A good gel requires no toxicity to the growth of microorganisms, can absorb a large amount of cold water in a short time, and microorganisms can grow on it to form a single colony and be easy to count. At present, there are no reports about new gels in China.

【Content of invention】

The invention aims to provide a preparation method of a gel agent for medium carrier with good water absorption, high viscosity and low cost.

The gelling agent of the present invention contains sodium polyacrylate, xanthan gum and locust bean gum, and its preparation method comprises the following steps:

(1) preparing a final mass concentration of 30% sodium hydroxide solution with deionized water;

(2) Add the sodium hydroxide solution dropwise to 18.53 mL of acrylic acid stirred by a constant temperature magnetic stirrer at 25° C. with a basic burette to achieve a neutralization degree of 75%;

(3) Add 1.16 mL of deionized water to adjust the mass concentration of acrylic acid monomer to 50%, and then transfer the mixture to a plastic three-neck bottle;

(4) After adding the crosslinking agent N, N-methylenebisacrylamide and mixing, add 0.0271g, which is 0.1% of the mass of the acrylic acid monomer;

(5) Add initiator ammonium persulfate under the situation of nitrogen blowing, the addition is 0.5% of the mass of acrylic acid monomer, i.e. 0.1355g;

(6) Blow nitrogen to drive oxygen to seal, and place in a constant temperature drying oven at 75°C for 4 hours of polymerization;

(7) Wash with 75% ethanol, 30 mL each time, for three times, to remove unreacted monomers, oligomers, etc.;

(8) Cut the colloid into small pieces and dry it at 105°C;

(9) the fritter that dries is pulverized with traditional Chinese medicine pulverizer, crosses 160 mesh sieves;

(10) Measure the water absorption rate: 158.0g/g, absorb 9g/L NaCl physiological saline, it is: 31.2g/g;

(11) Mix 0.5 g of pulverized sodium polyacrylate with 0.08 g of xanthan gum and locust bean gum mixture, and the mixture can be used as a gelling agent for the medium carrier;

(12) Measure the water absorption rate of the mixture: 155.3g/g, absorb 9g/L NaCl of physiological saline: 30.5g/g;

(13) The measured viscosity value is 1920mpa.s.

or include the following steps:

(1) preparing a final mass concentration of 30% sodium hydroxide solution with deionized water;

(2) Add the sodium hydroxide solution dropwise to 18.53 mL of acrylic acid stirred by a constant temperature magnetic stirrer at 25° C. with a basic burette to achieve a neutralization degree of 75%;

(3) Add 13.7mL deionized water to adjust the monomer mass concentration to 30%, and then transfer the mixture to a plastic three-neck bottle;

(4) After adding the crosslinking agent N, N-methylenebisacrylamide and mixing, the addition amount is 0.0678g, which is 0.25% of the mass of the acrylic acid monomer;

(5) Add initiator ammonium persulfate under the condition of blowing nitrogen, the addition amount is 0.4% of the mass of acrylic acid monomer, i.e. 0.1084g;

(6) Blow nitrogen to drive oxygen to seal, and place in a constant temperature drying oven at 70°C for 4 hours of polymerization;

(7) Wash with 75% ethanol, 30ml each time, wash three times, remove unreacted monomers, oligomers, etc.;

(8) Cut the colloid into small pieces and dry it at 105°C;

(9) the fritter that dries is pulverized with traditional Chinese medicine pulverizer, crosses 160 mesh sieves;

(10) The measured water absorption rate is: 142.0g/g, and the physiological saline absorbing 9g/L NaCl is: 38.3g/g;

(11) Mix 0.5 g of pulverized sodium polyacrylate with 0.08 g of xanthan gum and locust bean gum mixture, and the mixture can be used as a gelling agent for the medium carrier;

(12) The measured water absorption rate is: 122.0g/g, and the physiological saline that absorbs 9g/L NaCl is: 35.6g/g;

(13) The measured viscosity value is 1875mpa.s.

Sodium polyacrylate is a white powder, non-toxic, odorless, tasteless, dissolved in water to become a transparent viscous colloid. Due to its large water absorption, strong water retention, safety and non-toxicity, it has been widely used in daily chemical industry, fragrance materials, hygiene products, crop breeding, medicine and other fields. Synthetic methods include: aqueous solution polymerization, reverse suspension polymerization, reverse emulsion polymerization, microwave method and radiation polymerization. Xanthan gum is a "pentasaccharide repeating unit" structural polymer composed of D-glucose, D-mannose, D-glucuronic acid, acetic acid and pyruvic acid; Strong viscosity; high biological stability, most enzymes cannot degrade it. Locust bean gum is a colorless, odorless polysaccharide refined from plant endosperm. Locust bean gum is a galactomannan with mannose as the main chain. Locust bean gum itself has no gel properties, and its most important feature is that it has a good gel synergistic effect with hydrocolloids such as agar, carrageenan and xanthan gum, which can make the dosage level after compounding very low and improve the gel structure structure. When xanthan gum and locust bean gum are mixed in a ratio of 3:2, the viscosity of the solution can be effectively increased, and a small amount can achieve high viscosity. The present invention adopts the aqueous solution polymerization method to synthesize sodium polyacrylate, with sodium polyacrylate, xanthan gum and locust bean gum as the main components, through the optimization of the formula, a new type of gel that can be applied to the rapid determination card of microorganisms is obtained. It overcomes the disadvantage of poor water absorption in the existing gels, and effectively increases the viscosity of the gels through the optimized combination with xanthan gum and locust bean. Compared with imported gels, it is cheaper and suitable for Domestic use. In recent years, with the development of microbiology, the specific physiological and biochemical reactions of many microorganisms have been clarified. A variety of foodborne pathogenic microorganisms (such as Staphylococcus aureus, Salmonella, hemolytic streptococcus, Listeria etc.) Chromogenic substrates and culture media for specific enzymes have been developed successively. These chromogenic culture media are organically integrated with the excellent gel obtained in the present invention, and can be made into a rapid assay card for specific microorganisms, which will play an important role in promoting the rapid detection of food microbial safety in my country.

【Detailed ways】

One, the preparation method 1 of the gel agent that is used for culture medium carrier:

(1) prepare the sodium hydroxide solution that final concentration is 30% (g/g) with deionized water;

(2) Add the sodium hydroxide solution dropwise to 18.53 mL of acrylic acid stirred by a magnetic stirrer at a constant temperature (25° C.) with a basic burette to achieve a neutralization degree of 75%;

(3) Add 1.16 mL of deionized water to adjust the concentration of acrylic acid monomer to 50% (g/g), and then transfer the mixture to a plastic three-necked bottle;

(4) After adding the crosslinking agent N, N-methylenebisacrylamide and mixing, add 0.0271g, which is 0.1% (g/g) of the acrylic acid monomer;

(5) Add initiator ammonium persulfate under the situation of nitrogen blowing, the addition is 0.5% (g/g) of acrylic acid monomer, i.e. 0.1355g;

(6) Blow nitrogen to drive oxygen to seal, and place in a constant temperature drying oven at 75°C for 4 hours of polymerization;

(7) Wash with 75% ethanol (30 mL each time, wash three times) to remove unreacted monomers, oligomers, etc.;

(8) Cut the colloid into small pieces and dry it at 105°C;

(9) the fritter that dries is pulverized with traditional Chinese medicine pulverizer, crosses 160 mesh sieves;

(10) Measured water absorption rate: 158.0 (g/g), absorbing physiological saline (9g/L NaCL): 31.2 (g/g);

(11) Mix 0.5 g of pulverized sodium polyacrylate with 0.08 g of xanthan gum and locust bean gum mixture, and the mixture can be used as a gelling agent for the medium carrier;

(12) Measure the water absorption rate of the mixture: 155.3 (g/g), absorb physiological saline (9g/L NaCL): 30.5 (g/g);

(13) The measured viscosity value is 1920mpa.s.

Two, the preparation method 2 of the gel agent that is used for culture medium carrier:

(1) prepare the sodium hydroxide solution that final concentration is 30% (g/g) with deionized water;

(2) Add the sodium hydroxide solution dropwise to 18.53 mL of acrylic acid stirred by a magnetic stirrer at a constant temperature (25° C.) with a basic burette to achieve a neutralization degree of 75%;

(3) Add 13.7 mL of deionized water to adjust the monomer concentration to 30% (g/g), and then transfer the mixture to a plastic three-necked bottle;

(4) After adding the crosslinking agent N, N-methylenebisacrylamide and mixing, the addition amount is 0.0678g, which is 0.25% (g/g) of the acrylic acid monomer;

(5) Add initiator ammonium persulfate under the situation of nitrogen blowing, the addition is 0.4% (g/g) of acrylic acid monomer, i.e. 0.1084g;

(6) Blow nitrogen to drive oxygen to seal, and place in a constant temperature drying oven at 70°C for 4 hours of polymerization;

(7) Wash with 75% ethanol (30ml each time, wash three times) to remove unreacted monomers, oligomers, etc.;

(8) Cut the colloid into small pieces and dry it at 105°C;

(9) the fritter that dries is pulverized with traditional Chinese medicine pulverizer, crosses 160 mesh sieves;

(10) The measured water absorption rate is: 142.0 (g/g), and the absorption of physiological saline (9g/L NaCL) is: 38.3 (g/g);

(11) Mix 0.5 g of pulverized sodium polyacrylate with 0.08 g of xanthan gum and locust bean gum mixture, and the mixture can be used as a gelling agent for the medium carrier;

(12) The measured water absorption rate is: 122.0 (g/g), and the absorption of physiological saline (9g/L NaCL) is: 35.6 (g/g);

(13) The measured viscosity value is 1875mpa.s.

Claims (2)

1. preparation method who is used for the gelifying agent of culture medium carrier is characterized in that may further comprise the steps:

(1) preparing whole mass concentration with deionized water is 30% sodium hydroxide solution;

(2) dropwise sodium hydroxide solution is joined in the 18.53mL vinylformic acid under 25 ℃ of constant temperature blender with magnetic force stir with base buret, reach degree of neutralization 75%;

(3) adding 1.16mL deionized water adjusting Acrylic Acid Monomer mass concentration is 50%, mixture is transferred in the plastics there-necked flask then;

(4) add mixing behind the linking agent N,N methylene bis acrylamide, add 0.0271g, be 0.1% of Acrylic Acid Monomer quality;

(5) add initiator ammonium persulfate under the situation of nitrogen blowing, add-on is 0.5% of Acrylic Acid Monomer quality, i.e. 0.1355g;

(6) 75 ℃ of polymerization 4h in the thermostatic drying chamber are put in the sealing of nitrogen flushing gas drive oxygen;

(7) wash with 75% ethanol, each 30mL washs three times, removes unreacted monomer, oligopolymer etc.;

(8) colloid is cut into small pieces the back in 105 ℃ of oven dry;

(9) fritter of oven dry is pulverized with medicinal herb grinder, crossed 160 mesh sieves;

(10) surveying water-intake rate is: 158.0g/g, and the physiological saline of suction 9g/L NaCL, for: 31.2g/g;

(11) get the sodium polyacrylate 0.5g of pulverizing and xanthan gum and Viscogum BE mixture 0.08g and mix, this mixture promptly can be used as the gelifying agent of culture medium carrier;

(12) water-intake rate of survey mixture is: 155.3g/g, and the physiological saline of inhaling 9g/L NaCL is: 30.5g/g;

(13) measuring viscosity number is 1920mpa.s.

2. preparation method who is used for the gelifying agent of culture medium carrier is characterized in that may further comprise the steps:

(1) preparing whole mass concentration with deionized water is 30% sodium hydroxide solution;

(2) dropwise sodium hydroxide solution is joined in the 18.53mL vinylformic acid under 25 ℃ of constant temperature blender with magnetic force stir with base buret, reach degree of neutralization 75%;

(3) adding 13.7mL deionized water adjusting monomer mass concentration is 30%, mixture is transferred in the plastics there-necked flask then;

(4) add mixing behind the linking agent N,N methylene bis acrylamide, add-on 0.0678g is 0.25% of Acrylic Acid Monomer quality;

(5) add initiator ammonium persulfate under the situation of nitrogen blowing, add-on is 0.4% of Acrylic Acid Monomer quality, i.e. 0.1084g;

(6) 70 ℃ of polymerization 4h in the thermostatic drying chamber are put in the sealing of nitrogen flushing gas drive oxygen;

(7) wash with 75% ethanol, each 30ml washs three times, removes unreacted monomer, oligopolymer etc.;

(8) colloid is cut into small pieces the back in 105 ℃ of oven dry;

(9) fritter of oven dry is pulverized with medicinal herb grinder, crossed 160 mesh sieves;

(10) surveying water-intake rate is: 142.0g/g, and the physiological saline of inhaling 9g/L NaCL is: 38.3g/g;

(11) get the sodium polyacrylate 0.5g of pulverizing and xanthan gum and Viscogum BE mixture 0.08g and mix, this mixture promptly can be used as the gelifying agent of culture medium carrier;

(12) surveying water-intake rate is: 122.0g/g, and the physiological saline of inhaling 9g/L NaCL is: 35.6g/g;

(13) measuring viscosity number is 1875mpa.s.