A method for preparing a high-texture property curdlan

Abstract

The application discloses a method for improving the texture properties of dextrin, and specifically adds CoCl2 in a fermentation medium, wherein the components of the medium include: 80-100 g / L sucrose, 1-3 g / L diammonium hydrogen sulfate, 1-3 g / L potassium dihydrogen phosphate, 1-2 g / L magnesium sulfate heptahydrate, 1-3 g / L calcium carbonate, and 0.0005%-0.004% (w / v) CoCl2. By adding CoCl2 with different concentrations in the medium, the yield of dextrin is increased by 10.7%, the gel strength is increased by 33.6%, the hardness is increased by 21.3%, the elasticity is increased by 5.5%, the chewiness is increased by 67.3%, and the molecular weight is increased by 5.6%. The fermentation medium disclosed by the application is used for producing dextrin, and can significantly improve the gel strength, hardness and chewiness of dextrin, enhance the texture properties of dextrin, and improve the competitiveness of dextrin products.

Description

Technical Field

[0001] This invention belongs to the field of bio-fermentation and food additive production technology, and relates to a method for preparing high-texture properties of guar gum. Background Technology

[0002] Curdlan is a dextran polymer produced by Agrobacterium sp. or Rhizobium sp., linked by β-1,3-D-glycosidic bonds. Its molecular formula is (C6H2O) 10 O5) n It has an average degree of polymerization of 450 and an average molecular weight of 74,000. Gel gum has unique heat-gelling properties and is also known as a gel polysaccharide.

[0003] Cludran gum is insoluble in water and most organic solvents, but readily soluble in aqueous solutions containing sodium hydroxide, dimethyl sulfoxide, and formic acid, which can disrupt its hydrogen bonds. X-ray diffraction experiments show that cludran gum molecules exhibit a triple helix conformation, with sugar chains linked by hydrogen bonds. In aqueous solutions, cludran gum molecules primarily exist in three forms: single helix, triple helix, and random coils. The structural characteristics of cludran gum determine its diverse applications. The spatial structure of cludran gum changes under different temperature conditions. At room temperature, it primarily exhibits a single helix structure with a small amount of triple helix structure. Upon heating to 120°C and then cooling, it primarily exhibits a triple helix structure, and this process is irreversible, resulting in a strong gel. The spatial conformation of cludran gum also changes under different alkali concentrations. At low alkali concentrations, cludran gum maintains an ordered helical conformation, but as the alkali concentration increases, the molecular conformation changes to random coils.

[0004] Corduroy gum possesses properties such as gelling characteristics, thermal stability, freeze resistance, and dehydration shrinkage resistance, making it suitable as a food additive to improve food quality. For example, adding an appropriate amount of corduroy gum to flour can improve the viscoelasticity, water retention, and stability of noodles; adding corduroy gum to jelly gives it elasticity and chewiness, making it more suitable for current market demands.

[0005] Currant is not absorbed by the human body and can be used as a component of food to make weight-loss related foods. As a food additive, it can improve food quality and taste, and can be added to meat products such as sausages and hamburgers to improve water retention and enhance flavor. Currant enhances immune activity and has pharmaceutical and pharmacological effects, including anti-tumor, antibacterial, and antiviral activities. It can also serve as a delivery carrier for bioactive macromolecular drugs, delaying drug release. In building materials, currant can be used as a binder to improve the plasticity of concrete.

[0006] Texture Profile Analysis (TPA) is a method used to comprehensively describe the physical properties of food. Texture parameters relevant to human sensory evaluation can be derived from the TPA texture curve. By compressing the sample twice, the pressure exerted by the probe on the gellan gum during this process is measured, along with related texture parameters such as hardness, springiness, and chewiness. This simulates two chewing actions in the human mouth, yielding sensory evaluation results and objectively assessing the quality characteristics of gellan gum. Hardness is the maximum peak during the first compression; the hardness value of gellan gum appears at the point of maximum deformation. Springiness is the ratio of the recovery height of the gellan gum detected in the second compression to the deformation of the first compression. Chewiness is the energy required to chew the gellan gum to a stable state for swallowing, numerically expressed as the product of adhesiveness and springiness. TPA data can objectively characterize the quality characteristics of gellan gum.

[0007] To achieve large-scale industrial production of glaucon, my country has conducted in-depth research on glaucon in recent years. Much of the research on culture medium optimization has focused on optimizing carbon and nitrogen sources in fermentation media to increase glaucon yield, but research on their impact on the quality characteristics of the fermentation product glaucon is scarce.

[0008] Inorganic salts are essential components for microbial growth and metabolism, and certain inorganic salts often stimulate the fermentation of polysaccharides. For example, in the synthesis of xanthan gum, calcium, magnesium, and manganese ions significantly promote polysaccharide formation. [1] In the production of curdlan, different strains of bacteria have different requirements for the addition of inorganic salts. Kuge et al. found that metal ions such as magnesium, potassium, and ferrous ions play an important role in the fermentation of many microbial polysaccharides. [2] .

[0009] There are few studies on the effect of inorganic salts on the properties of curdlan gum, and existing literature yields inconsistent conclusions regarding this effect. (Zhang Hailong et al.) [3] It is believed that various inorganic salts have almost no effect on the gel strength of guar gum. T. Funami et al. [4] Studies have shown that the presence of salt ions has a negative impact on gel formation, according to Ji Wuke et al. [5] Experimental results indicate that the two salts can respectively enhance gel strength or lower the initial gel temperature. (Wang Xiaoyu et al.) [6] It was found that MgSO4 and KH2PO4 had a significant impact on gel yield. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing high-texture glucan. This invention discovers that adding an appropriate amount of the inorganic salt CoCl2 can improve the molecular weight, yield, gel strength, hardness, elasticity, and chewiness of glucan. This inorganic salt is readily available in low quantities, the method is simple, and it significantly improves the textural properties of glucan. This method can be applied to the fermentation process of glucan to enhance its quality.

[0011] This invention provides a method for preparing high-quality textured gelatin, characterized by comprising the following steps:

[0012] (1) Seed culture: After rapidly thawing the cryopreservation solution containing seeds, add it to the seed culture medium for culture. The culture temperature is 28℃-32℃, the rotation speed is 250-300rpm, and the culture time is 16-20h.

[0013] (2) Fermentation culture: The cultured seed liquid is inoculated into the fermentation medium at an inoculation rate of 6%-10% (v / v), the culture temperature is 28℃-32℃, the rotation speed is 250-300rpm, and the culture time is 96-144h.

[0014] (3) Preparation of kerogen gum: Add a 1.2%-3.6% (w / v) NaOH solution to the fermentation broth obtained in step (2), stir and let stand for 15-30 min, centrifuge to collect the supernatant, add 3M HCl to adjust the pH to 7.0; then wash and filter with distilled water and 95% ethanol, and then dry at 40℃-60℃. After complete drying, grind the product into powder using a grinder and sieve it through a 60-120 mesh screen to obtain the kerogen gum product.

[0015] In step (1), the seed is a rhizobium strain Rhizobium sp. ATCC 31749.

[0016] The Rhizobium sp. ATCC 31749 strain described in this invention was purchased by the applicant on March 19, 2014, through Beijing Zhongyuan Heju Trade Co., Ltd., the sole agent in China for ATCC in the United States, and then deposited in the Food Microbiology Technology Laboratory of the School of Life Sciences, East China Normal University. Therefore, no deposit certificate is required.

[0017] In step (1), the components and contents of the seed culture medium are: 20-30 g / L sucrose, 1-2 g / L potassium dihydrogen phosphate, 5-10 g / L diammonium hydrogen phosphate, 1-2 g / L magnesium sulfate heptahydrate, 2-4 g / L calcium carbonate, and the pH value is 6.8-7.2.

[0018] Preferably, the seed culture medium comprises the following components and contents: 20 g / L sucrose, 1.5 g / L potassium dihydrogen phosphate, 5 g / L diammonium hydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 3 g / L calcium carbonate, and a pH of 7.0.

[0019] In step (1), the culture temperature is preferably 30℃; the rotation speed is preferably 250rpm; and the culture time is preferably 18h.

[0020] In step (2), the components and contents of the fermentation medium are: 80-100 g / L sucrose, 1-3 g / L diammonium hydrogen sulfate, 1-3 g / L potassium dihydrogen phosphate, 1-2 g / L magnesium sulfate heptahydrate, 1-3 g / L calcium carbonate, and 0.0005%-0.004% (w / v) CoCl2; the pH value of the fermentation medium is 6.8-7.2.

[0021] Preferably, the fermentation medium comprises the following components and contents: 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, with a CoCl2 concentration of 0.002% (w / v) and a pH of 7.0.

[0022] In step (2), the seed inoculation amount is preferably 10% (v / v); the culture temperature is preferably 30℃; the rotation speed is preferably 250 rpm; and the culture time is preferably 144 h.

[0023] In step (3), the mass ratio of the fermentation broth to the NaOH solution is 1.2%-3.6%; preferably, it is 2.4%.

[0024] In step (3), the stirring operation takes 10-20 minutes; preferably, it takes 15 minutes.

[0025] In step (3), the settling time after the stirring operation is preferably 15-30 minutes; preferably, it is 30 minutes.

[0026] In step (3), the centrifugation speed is 9000rpm-10000rpm; preferably, it is 10000rpm.

[0027] In step (3), the centrifugation operation takes 20-30 minutes; preferably, it takes 20 minutes.

[0028] In step (3), the temperature of the centrifugation operation is 20℃-25℃; preferably, it is 25℃.

[0029] In step (3), the volume of the distilled water is 2-4 times that of the fermentation liquid; preferably, it is 3 times.

[0030] In step (3), the volume of the 95% ethanol is 2-4 times the volume of the fermentation liquid; preferably, it is 2 times.

[0031] In step (3), the time for standing after washing with 95% ethanol is 10 min to 20 min; preferably, it is 20 min.

[0032] In step (3), drying at 60°C is preferred.

[0033] In step (3), it is preferable to use a 60-mesh sieve for sieving.

[0034] The present invention also provides a fermentation medium for improving the high-texture properties of gellan gum, wherein the components and contents of the fermentation medium are: 80-100 g / L sucrose, 1-3 g / L diammonium hydrogen sulfate, 1-3 g / L potassium dihydrogen phosphate, 1-2 g / L magnesium sulfate heptahydrate, 1-3 g / L calcium carbonate, and 0.0005%-0.004% (w / v) CoCl2; the pH value of the fermentation medium is 6.8-7.2.

[0035] Preferably, the fermentation medium comprises the following components and contents: 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, with a CoCl2 concentration of 0.002% (w / v) and a pH of 7.0.

[0036] The present invention also provides the application of the fermentation medium described herein in improving the high textural properties of gellan gum.

[0037] The beneficial effects of this invention include: By adding CoCl2 to the fermentation medium, this invention improves the textural properties of gellan gum, thus mitigating the influence of inorganic salts on the textural properties of gellan gum. Adding 0.002% CoCl2 to the medium increases gellan gum yield by 10.7%, gel strength by 33.6%, hardness by 21.3%, elasticity by 5.5%, chewiness by 67.3%, and molecular weight by 5.6%. The fermentation medium described in this invention, when used to produce gellan gum, can significantly improve its gel strength, hardness, and chewiness, enhancing its textural properties and facilitating its further promotion. Attached Figure Description

[0038] Figure 1 These are images showing the finished products of 2% gels with different concentrations of CoCl2 added according to the present invention. From left to right, the concentrations of CoCl2 added are 0%, 0.0005%, 0.001%, 0.002%, and 0.004%.

[0039] Figure 2This is a gel permeation chromatogram for determining the molecular weight of gellan gum with different concentrations of CoCl2 added according to the present invention. In Figure AE, the concentrations of CoCl2 are 0, 0.0005%, 0.001%, 0.002%, and 0.004%, respectively. Wherein, Retention Volume is the retention volume, Refractive Index is the differential refractive index, Right Light Scattering is the right-angle light scattering value, Low Angle Light Scattering is the low-angle light scattering value, and Molecular Weight is the weight-average molecular weight. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the specific embodiments and accompanying drawings. Except for the contents specifically mentioned below, the processes, conditions, and experimental methods for implementing the present invention are all common knowledge and general knowledge in the art, and the present invention does not have any particular limitations.

[0041] This invention provides a method for preparing high-quality textured gelatin.

[0042] In this invention, the properties of glucon can be obtained by analyzing a 2% concentration of glucon gel using a texture analyzer. The main parameters measured are gel strength and texture profile analysis (TPA). The effect of inorganic salts on the glucon fermentation process is characterized by detecting the glucon yield of the fermentation broth after 144 hours of cultivation at 30°C and 250 rpm on a shaker. The effect of inorganic salts on the quality of the glucon product is characterized by measuring the gel strength and performing TPA on the 2% concentration of glucon. Furthermore, the molecular weight of high-quality glucon samples is determined to further assess the quality of the glucon product.

[0043] Example 1 (Control Example): Fermentation Production of Glycol on CoCl2-Free Medium

[0044] Seed culture medium components and contents:

[0045] 20 g / L sucrose, 1.5 g / L potassium dihydrogen phosphate, 5 g / L diammonium hydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 3 g / L calcium carbonate, pH 7.0.

[0046] Fermentation medium components and contents:

[0047] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, pH 7.0.

[0048] Seed activation:

[0049] The cryopreservation solution containing Rhizobium sp. ATCC 31749 in a -80℃ glycerol storage tube was rapidly thawed and poured into seed culture medium. The solution was then cultured in a shaker at 30℃ and 250 rpm for 18 hours to obtain the seed culture.

[0050] Inoculation and fermentation:

[0051] The seed culture was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured in a shaker at 30°C and 250 rpm for 144 h.

[0052] Curriculum yield determination:

[0053] The fermentation broth was centrifuged at 9000 rpm for 10 min, the supernatant was removed, and the solids were washed with 2 volumes of 95% ethanol (after thorough shaking with a glass rod, let stand for 15 min). The broth was centrifuged at 9000 rpm for 10 min, the supernatant was removed, and the precipitate was dried in a 65℃ oven to constant weight. The yield was calculated by weighing.

[0054] Preparation of kerogen gum:

[0055] Take 200 mL of fermentation broth, stir and add 200 mL of 2.4% (w / v) NaOH solution, stir for 15 min, let stand for 30 min, centrifuge at 25℃ and 9000 rpm for 20 min, take the supernatant, slowly add 3M HCl and stir, and adjust the pH to 7.0.

[0056] The product was filtered and washed with distilled water using an 80-mesh filter cloth, and the washing process was repeated twice. Then, 95% ethanol was added, and the product was filtered and washed again. The product was then dried overnight at 60°C.

[0057] After complete drying, the product is ground into powder using a grinder and then sieved through a 60-mesh sieve to obtain the kerogen gum product.

[0058] 2% premium gel strength test:

[0059] 2% gellan gum gel was prepared according to the method of GB 28304-2012. 0.3 g of gellan gum sample was accurately weighed and dissolved in 15 mL of distilled water. The solution was dispersed at 8000 rpm for 5 min using a high-speed homogenizer. The dispersion was transferred to an 18 mm × 180 mm test tube, and after evacuating the tube with a circulating water vacuum pump for 4 min, it was heated in a 95 °C water bath for 10 min, followed by a cold water bath.

[0060] The prepared 2% gel was cut horizontally at a point 20-35 mm from the bottom, according to national standards, ensuring a smooth cut surface. The gel strength and rupture displacement were then determined using a texture analyzer via a puncture method. The measuring probe was a p / 5 stainless steel cylindrical probe. The test parameters were: pre-test speed: 4.17 mm / s, mid-test speed: 4.17 mm / s, post-test speed: 4.17 mm / s, test distance: 10 mm, deformation: 10%, trigger type: automatic, sensing force: 10 g.

[0061] The force exerted on the probe during its descent, when the gel ruptures, is its gel strength value, expressed in g / cm³. 2 .

[0062] Texture profile (TPA) analysis of 2% gel:

[0063] The prepared 2% gel was cut flat at a point 5-10 mm from the bottom, and the TPA was analyzed using a texture analyzer with a two-stage chewing method.

[0064] Molecular weight determination:

[0065] Accurately weigh 3-5 mg of sample into a sample preparation tube and place it in a water bath at 100°C with a magnetic stirrer for 4 hours. After cooling, filter twice through a 0.22 μm microporous membrane and then perform analysis using a gel permeation chromatograph.

[0066] Example 2: Fermentation production of galvanic gum using a culture medium containing 0.0005% CoCl2.

[0067] Fermentation medium components and contents:

[0068] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, CoCl2 concentration of 0.0005% (w / v), pH 7.0;

[0069] The components and contents of the seed culture medium are the same as in Example 1.

[0070] Seed activation: Same as in Example 1.

[0071] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.0005%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0072] Determination of kerogen yield: Same as in Example 1.

[0073] Preparation of kerogen gum: Same as in Example 1.

[0074] 2% premium gel strength test: same as in Example 1.

[0075] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0076] Molecular weight determination: Same as in Example 1.

[0077] Example 3: Fermentation production of galvanic gum using a culture medium containing 0.001% CoCl2.

[0078] Fermentation medium components and contents:

[0079] The concentrations of the following ingredients were: 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, and 0.001% (w / v) CoCl2. The pH value was 7.0.

[0080] The components and contents of the seed culture medium are the same as in Example 1.

[0081] Seed activation: Same as in Example 1.

[0082] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.001%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0083] Determination of kerogen yield: Same as in Example 1.

[0084] Preparation of kerogen gum: Same as in Example 1.

[0085] 2% premium gel strength test: same as in Example 1.

[0086] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0087] Molecular weight determination: Same as in Example 1.

[0088] Example 4: Fermentation production of galvanic acid using a culture medium containing 0.002% CoCl2.

[0089] Fermentation medium components and contents:

[0090] The concentrations of the following ingredients were: 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, and 0.002% (w / v) CoCl2. The pH value was 7.0.

[0091] The components and contents of the seed culture medium are the same as in Example 1.

[0092] Seed activation: Same as in Example 1.

[0093] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.002%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0094] Determination of kerogen yield: Same as in Example 1.

[0095] Preparation of kerogen gum: Same as in Example 1.

[0096] 2% premium gel strength test: same as in Example 1.

[0097] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0098] Molecular weight determination: Same as in Example 1.

[0099] Example 5: Fermentation production of galvanic gum using a culture medium containing 0.004% CoCl2.

[0100] Fermentation medium components and contents:

[0101] The concentrations of the following ingredients were: 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, and 0.004% (w / v) CoCl2. The pH value was 7.0.

[0102] The components and contents of the seed culture medium are the same as in Example 1.

[0103] Seed activation: Same as in Example 1.

[0104] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0105] Determination of kerogen yield: Same as in Example 1.

[0106] Preparation of kerogen gum: Same as in Example 1.

[0107] 2% premium gel strength test: same as in Example 1.

[0108] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0109] Molecular weight determination: Same as in Example 1.

[0110] Comparative Example 1: Fermentation production of galvanic acid using a culture medium containing 0.01% FeCl3.

[0111] Fermentation medium components and contents:

[0112] The concentrations of FeCl3 were 0.01% (w / v) and the total concentration was 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, and 2 g / L calcium carbonate. The pH value was 7.0.

[0113] The components and contents of the seed culture medium are the same as in Example 1.

[0114] Seed activation: Same as in Example 1.

[0115] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0116] Determination of kerogen yield: Same as in Example 1.

[0117] Preparation of kerogen gum: Same as in Example 1.

[0118] 2% premium gel strength test: same as in Example 1.

[0119] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0120] Molecular weight determination: Same as in Example 1.

[0121] Comparative Example 2: Fermentation production of galvanic acid using a culture medium containing 0.04% FeCl3.

[0122] Fermentation medium components and contents:

[0123] The concentrations of FeCl3 were 0.04% (w / v) and the total concentration was 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, and 2 g / L calcium carbonate. The pH value was 7.0.

[0124] The components and contents of the seed culture medium are the same as in Example 1.

[0125] Seed activation: Same as in Example 1.

[0126] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0127] Determination of kerogen yield: Same as in Example 1.

[0128] Preparation of kerogen gum: Same as in Example 1.

[0129] 2% premium gel strength test: same as in Example 1.

[0130] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0131] Molecular weight determination: Same as in Example 1.

[0132] Comparative Example 3: Fermentation production of galvanic acid using a culture medium containing 0.08% FeCl3.

[0133] Fermentation medium components and contents:

[0134] The concentrations of FeCl3 were 0.08% (w / v) and the total concentration was 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, and 2 g / L calcium carbonate. The pH value was 7.0.

[0135] The components and contents of the seed culture medium are the same as in Example 1.

[0136] Seed activation: Same as in Example 1.

[0137] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0138] Determination of kerogen yield: Same as in Example 1.

[0139] Preparation of kerogen gum: Same as in Example 1.

[0140] 2% premium gel strength test: same as in Example 1.

[0141] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0142] Molecular weight determination: Same as in Example 1.

[0143] Comparative Example 4: Fermentation production of galvanic acid using a culture medium containing 0.01% MnCl2.

[0144] Fermentation medium components and contents:

[0145] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, MnCl2 concentration of 0.01% (w / v), pH value 7.0;

[0146] The components and contents of the seed culture medium are the same as in Example 1.

[0147] Seed activation: Same as in Example 1.

[0148] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0149] Determination of kerogen yield: Same as in Example 1.

[0150] Preparation of kerogen gum: Same as in Example 1.

[0151] 2% premium gel strength test: same as in Example 1.

[0152] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0153] Molecular weight determination: Same as in Example 1.

[0154] Comparative Example 5: Fermentation production of galvanic acid using a culture medium containing 0.04% MnCl2.

[0155] Fermentation medium components and contents:

[0156] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, MnCl2 concentration of 0.04% (w / v), pH value 7.0;

[0157] The components and contents of the seed culture medium are the same as in Example 1.

[0158] Seed activation: Same as in Example 1.

[0159] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0160] Determination of kerogen yield: Same as in Example 1.

[0161] Preparation of kerogen gum: Same as in Example 1.

[0162] 2% premium gel strength test: same as in Example 1.

[0163] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0164] Molecular weight determination: Same as in Example 1.

[0165] Comparative Example 6: Fermentation production of galvanic acid using a culture medium containing 0.08% MnCl2.

[0166] Fermentation medium components and contents:

[0167] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, MnCl2 concentration of 0.08% (w / v), pH value of 7.0;

[0168] The components and contents of the seed culture medium are the same as in Example 1.

[0169] Seed activation: Same as in Example 1.

[0170] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0171] Determination of kerogen yield: Same as in Example 1.

[0172] Preparation of kerogen gum: Same as in Example 1.

[0173] 2% premium gel strength test: same as in Example 1.

[0174] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0175] Molecular weight determination: Same as in Example 1.

[0176] Comparative Example 7: Fermentation production of galvanic acid using a culture medium containing 0.005% ZnCl2.

[0177] Fermentation medium components and contents:

[0178] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, ZnCl2 concentration of 0.005% (w / v), pH value 7.0;

[0179] The components and contents of the seed culture medium are the same as in Example 1.

[0180] Seed activation: Same as in Example 1.

[0181] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0182] Determination of kerogen yield: Same as in Example 1.

[0183] Preparation of kerogen gum: Same as in Example 1.

[0184] 2% premium gel strength test: same as in Example 1.

[0185] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0186] Molecular weight determination: Same as in Example 1.

[0187] Comparative Example 8: Fermentation production of galvanic acid using a culture medium containing 0.02% ZnCl2.

[0188] Fermentation medium components and contents:

[0189] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, ZnCl2 concentration of 0.02% (w / v), pH value 7.0;

[0190] The components and contents of the seed culture medium are the same as in Example 1.

[0191] Seed activation: Same as in Example 1.

[0192] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0193] Determination of kerogen yield: Same as in Example 1.

[0194] Preparation of kerogen gum: Same as in Example 1.

[0195] 2% premium gel strength test: same as in Example 1.

[0196] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0197] Molecular weight determination: Same as in Example 1.

[0198] Comparative Example 9: Fermentation production of galvanic acid using a culture medium containing 0.04% ZnCl2.

[0199] Fermentation medium components and contents:

[0200] 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 2 g / L calcium carbonate, ZnCl2 concentration of 0.04% (w / v), pH value 7.0;

[0201] The components and contents of the seed culture medium are the same as in Example 1.

[0202] Seed activation: Same as in Example 1.

[0203] Inoculation and fermentation: Before inoculation, the inorganic salt mother liquor was filtered to remove bacteria, diluted at a ratio of 0.004%, and added to the basic fermentation medium. The seed liquid was inoculated at a rate of 10%, with six Erlenmeyer flasks per group, and cultured on a shaker at 30℃ and 250 rpm for 144 h.

[0204] Determination of kerogen yield: Same as in Example 1.

[0205] Preparation of kerogen gum: Same as in Example 1.

[0206] 2% premium gel strength test: same as in Example 1.

[0207] Texture profile analysis (TPA) of 2% gel: Same as in Example 1.

[0208] Molecular weight determination: Same as in Example 1.

[0209] The relevant test results of the gel samples prepared by adding different concentrations of CoCl2 solution in Examples 1-5 of this invention are shown in Table 1 below:

[0210] Table 1. Effects of different concentrations of CoCl2 on fermentation yield and textural properties of currant.

[0211]

[0212]

[0213] The relevant test results of the gel samples prepared by adding FeCl3 solution of different concentrations in Comparative Examples 1-3 of this invention are shown in Table 2 below:

[0214] Table 2. Effects of different FeCl3 concentrations on fermentation yield and textural properties of currant.

[0215]

[0216] The relevant test results of the gel samples prepared by adding MnCl2 solutions of different concentrations in Comparative Examples 4-6 of this invention are shown in Table 3 below:

[0217] Table 3. Effects of different concentrations of MnCl2 on fermentation yield and textural properties of currant.

[0218]

[0219] The relevant test results of the gel samples prepared by adding ZnCl2 solutions of different concentrations in Comparative Examples 7-9 of this invention are shown in Table 4 below:

[0220] Table 4. Effects of different ZnCl2 concentrations on fermentation yield and textural properties of currant.

[0221]

[0222]

[0223] The test results in the table above show that adding 0.002% CoCl2 to the culture medium increases gellan gum yield by 10.7%, gel strength by 33.6%, hardness by 21.3%, elasticity by 5.5%, chewiness by 67.3%, and molecular weight by 5.6%. Adding different concentrations of FeCl3, MnCl2, and ZnCl2 to the culture medium decreases gel strength, hardness, elasticity, and chewiness. The fermentation medium described in this invention, when supplemented with an appropriate concentration of CoCl2, can significantly improve the gel strength, hardness, and chewiness of gellan gum, thus enhancing its textural properties.

[0224] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of this invention are included in this invention and are protected by the appended claims.

[0225] References:

[0226] [1] Wang Ruqun, Li Bolin, Ou Jie. Effects of magnesium and manganese ions on xanthan gum biosynthesis [J]. Food Science, 2009, 30(13): 192-196.

[0227] [2]Kuge TSNN K.Heat-melt of.BETA.-1,3-D-glucan gel[J].Agriculturaland biological chemistry, 1977,7(41):1315-1316.

[0228] [3] Zhang Hailong, Guan Zhiwei, Yang Junjie. Properties and applications of guar gum [J]. China Food and Nutrition, 2010(01):36-39.

[0229] [4]Funami T,Nishinari K.Gelling characteristics of Curdlan aqueousdispersions in the presence of salts[J].Food Hydrocolloids,2007,21(1):59-65.DOI:10.1016 / j.foodhyd.2006.01.009.

[0230] [5] Ji Wuke, Zhang Yonggang, Wu Lin, et al. Study on changes in gel properties of kelp[J]. Chemical and Biological Engineering, 2012(07):60-62.

[0231] [6] Wang Xiaoyuzhu, Dong Jinjun, Xu Guochao, et al. Screening of strains for the production of guar gum and optimization of fermentation conditions [J]. Journal of Food and Biotechnology, 2018(07):732-738.

Claims

1. Use of a fermentation medium in increasing the weight average molecular weight of curdlan; The components and contents of the fermentation medium are: 90 g / L sucrose, 2 g / L diammonium hydrogen sulfate, 2 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, 3 g / L calcium carbonate, and 0.002% (w / v) CoCl2; and the pH value of the fermentation medium is 7.

0. The preparation method of the curdlan comprises the following steps: (1) Seed culture: after the frozen seed-containing solution is quickly thawed, it is added into a seed culture medium for shaking culture, the culture temperature is 30°C, the rotation speed is 250 rpm, and the culture time is 18 h; (2) Fermentation culture: the seed liquid cultured in step (1) is inoculated into a fermentation medium at a 10% (v / v) inoculation amount, the culture temperature is 30°C, the rotation speed is 250 rpm, and the culture time is 144 h; (3) Curdlan preparation: a 2.4% (w / v) NaOH solution is added into the fermentation liquid obtained in step (2), after stirring, it is left to stand, centrifuged to obtain the supernatant, 3M HCl is added to adjust the pH value to 7.0; then, the supernatant is washed with distilled water and 95% ethanol, left to stand, filtered, and then dried at 60°C; after complete drying, the product is ground by using a powder grinder, and then sieved by using an 80-mesh sieve, thereby obtaining the curdlan. In step (1), the seed is a Rhizobium sp. ATCC 31749 strain.

2. Use according to claim 1, wherein In step (1), the components and contents of the seed culture medium are: 20 g / L sucrose, 1.5 g / L potassium dihydrogen phosphate, 5 g / L diammonium hydrogen phosphate, 1 g / L magnesium sulfate heptahydrate, and 3 g / L calcium carbonate, and the pH value is 7.

0.

3. The use according to claim 1, wherein In step (3), the mass ratio of the fermentation liquid to the NaOH solution is 1.2%-3.6%.

4. The use according to claim 1, wherein In step (3), the stirring time is 10 min-20 min; and / or, the standing time is 15 min-30 min; and / or, the rotation speed of the centrifugation operation is 9000 rpm-10000 rpm; and / or, the centrifugation time is 20 min-30 min; and / or, the centrifugation temperature is 20°C-25°C.

5. The use according to claim 1, wherein In step (3), the volume of the distilled water is 2-4 times the volume of the fermentation liquid; and the volume of the 95% ethanol is 2-4 times the volume of the fermentation liquid.

6. The use according to claim 1, wherein In step (3), the standing time after the 95% ethanol washing is 10 min-20 min.

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