BSH Ingredients, the leading supplier of curdlan gum powder in China, is committed to providing international buyers with not only high-quality products but also a clear understanding of industry Curdlan standards. To support our global partners, BSH Ingredients has translated the Chinese National Standard QB/T 4322-2012 Curdlan into English. This translation enables our buyers to better understand the specifications, quality requirements, testing methods, and packaging parameters for curdlan gum.
If you have any inquiries regarding bulk quantities of curdlan gum powder, please feel free to contact BSH Ingredients for more details and professional support. Below are the detailed Curdlan Standard QB/T 4322-2012.
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the China National Light Industry Council.
This standard is under the jurisdiction of the National Technical Committee on Food Industry Standardization (SAC/TC64).
Drafting organizations of this standard: Shandong Kehua Bio-Technology Co., Ltd., Shandong Institute of Food and Fermentation Industries, Tonghua Amber Bio-Technology Co., Ltd., Institute of Process Engineering of the Chinese Academy of Sciences, and China Biotech Fermentation Industry Association.
Main drafters of this standard: Du Jun, Li Xiaoyan, Ji Wuke, Yan Ximei, Zhang Shoujun, Chen Hongzhang, Liu Jie, Wang Lan, Wan Liping, Jiang Ruisen, Liu Fankun.
1 Scope
This standard specifies the product classification, requirements, test methods, inspection rules, marking, packaging, transportation, and storage of curdlan.
This standard applies to curdlan produced with sucrose or glucose as the main raw material, obtained through fermentation, (separation) purification, drying, and pulverization. It is applicable to production, inspection, and sales.
2 Normative References
The following documents are indispensable for the application of this document. For dated references, only the version cited applies. For undated references, the latest version including all amendments applies.
- GB/T 191 Packaging – Pictorial marking for handling of goods
- GB/T 601 Chemical reagents – Preparation of standard volumetric solutions
- GB/T 603 Chemical reagents – Preparation of test solutions used in test methods
- GB/T 600 Chemical reagents – General method for determination of total nitrogen
- GB 4789.2 National food safety standard – Food microbiological examination – Enumeration of total bacterial count
- GB 4789.3 National food safety standard – Food microbiological examination – Enumeration of coliforms
- GB 5009.3 National food safety standard – Determination of moisture in foods
- GB 5009.4 National food safety standard – Determination of ash in foods
- GB/T 5009.74 Test for heavy metal limits in food additives
- GB/T 6678 General principles for sampling chemical products
- GB/T 6679 General rules for sampling solid chemical products
- GB/T 6682 Water for analytical laboratory use – Specifications and test methods
- GB 7718 National food safety standard – General standard for labeling of prepackaged foods
- GB/T 9724 Chemical reagents – General rules for determination of pH
3 Chemical Name, Molecular Formula, and Structural Formula
- English name: Curdlan
- Chemical name: β-1,3-glucan
- Molecular formula: (C₆H₁₀O₅)ₙ
- Relative molecular mass: 168 × n (according to the 2007 International Table of Atomic Weights)
- Degree of polymerization (n): n ≥ 250
- Structural formula:
4 Product Classification
The product is classified into Grade I and Grade II according to its content.
5 Requirements
5.1 Sensory Requirements
Shall comply with the specifications in Table 1.
Table 1 Sensory Requirements
| Item | Requirement |
| Color | White or off-white |
| Odor | Characteristic fermentation odor, without abnormal odor |
| Form | Powder |
5.2 Physicochemical Requirements
Shall comply with the specifications in Table 2.
Table 2 Physicochemical Requirements
| Item | Grade I | Grade II |
| Content/% (calculated as anhydrous glucose) ≥ | 80 | 70 |
| Gel strength/(g/cm²) (2% aqueous solution) ≥ | 600 | 400 |
| pH (1% aqueous solution) | 6.0-7.5 | 6.0-7.5 |
| Loss on drying/% ≤ | 10.0 | 10.0 |
| Ash/% ≤ | 6.0 | 6.0 |
| Total nitrogen/% ≤ | 1.0 | 1.0 |
5.3 Hygienic Requirements
Shall comply with the specifications in Table 3.
Table 3 Hygienic Requirements
| Item | Limit |
| Lead (Pb)/(mg/kg) ≤ | 0.5 |
| Total bacterial count/(CFU/g) ≤ | 3000 |
| Coliforms/(MPN/g) ≤ | 0.1 |
6 Test Methods
The water used in the test methods shall be deionized or distilled water conforming to GB/T 6682. Unless otherwise specified, reagents shall be of analytical grade. Preparation of standard solutions and reagents shall comply with GB/T 601 and GB/T 603.
6.1 Sensory
Take about 5 g of the sample, place it on a clean, dry white porcelain plate, observe its color and physical state under natural light, and smell its odor.
6.2.1 Solubility Test
6.2 Identification Tests
The sample is insoluble in water and ethanol.
6.2.2 Alkali Solubility Test
Weigh 0.2 g of the sample, add 2 to 5 mL of water, and stir to form a suspension. Add 1 mL of sodium hydroxide solution with a concentration of 3 mol/L while stirring continuously. The sample dissolves.
6.2.3 Gel Test
Weigh 0.2 g of the sample, place it into a test tube of 18 mm × 180 mm containing 10 mL of water, stir to form a suspension, heat in a boiling water bath for 10 minutes, then cool to room temperature. A gel should form.
6.2.4 Precipitation Reaction with Copper Tartrate
- 6.2.4.1 Reagents
- Copper sulfate: Weigh 69.3 g of copper sulfate pentahydrate (CuSO₄·5H₂O), dissolve in water, and dilute to 1000 mL. If insoluble matter remains, filter with filter paper.
- Potassium sodium tartrate: Weigh 346 g of potassium sodium tartrate and 100 g of sodium hydroxide, dissolve in water, and dilute to 1000 mL.
- 6.2.4.2 Analytical Procedure
Take 2 mL of the sample solution, concentrate to 5 mL, transfer into a 100 mL conical flask, shake well, heat on an electric furnace to boiling, then remove and set aside.
From a 2% sample solution, take 10 mL, add 5 mL of sodium hydroxide solution, heat in a boiling water bath for 30 minutes, then cool. Neutralize with 20% acetic acid solution. Centrifuge in a separating funnel at 900 g, take the supernatant, then take 1 mL of the supernatant and add it into 5 mL of hot copper tartrate solution. A brick-red precipitate is formed.
6.3 Physicochemical Indices
6.3.1 Content
Measured according to the method specified in Appendix A.
6.3.2 Gel Strength
Measured according to the method specified in Appendix B.
6.3.3 pH
Measured according to the method specified in GB/T 9724.
6.3.4 Loss on Drying
Measured according to the method specified in GB 5009.3. The arithmetic mean of the parallel test results shall be taken as the test result. The absolute difference between parallel results shall not exceed ±0.2%.
6.3.5 Ash
Measured according to the method specified in GB 5009.4.
- Total Nitrogen
Measured according to the method specified in GB/T 600.
6.4 Hygienic Indices
6.4.1 Lead
Measured according to GB/T 5009.74, using wet digestion for sample preparation.
6.4.2 Total Bacterial Count
Measured according to GB 4789.2.
6.4.3 Coliforms
Measured according to GB 4789.3.
7 Inspection Rules
7.1 Batch Formation and Sampling
The number of batch units shall be determined according to GB/T 6678. Sampling shall be performed in accordance with GB/T 6679.
7.2 Classification of Inspection
Inspection is divided into exit-factory inspection and type inspection.
7.3 Exit-factory Inspection
7.3.1 Each batch of products shall be inspected and approved by the enterprise quality inspection department and accompanied by a certificate of conformity before leaving the factory.
7.3.2 The items for exit-factory inspection are sensory, gel strength, pH, loss on drying, ash, and total nitrogen.
7.4 Type Inspection
7.4.1 Type inspection shall be carried out under the following circumstances:
a) Once per year under normal production conditions.
b) When production resumes after a shutdown of more than three months.
c) When there are significant changes in the main raw materials or processes.
d) When required by national quality supervision authorities or customers.
e) When the results of exit-factory inspection show a significant difference from the last type inspection results.
7.4.2 The items of type inspection shall include all technical requirements specified in this standard.
7.5 Determination Rules
If one to two indices in the inspection results do not meet the requirements of this standard, a re-inspection shall be conducted by taking double samples. If any item still fails to meet the requirements upon re-inspection, the entire batch shall be judged as nonconforming.
8 Marking, Packaging, Transportation, and Storage
8.1 Marking
8.1.1 The label shall comply with GB 7718. The external label on the packaging container shall indicate: product name, name and address of manufacturer, net content, production date, batch number, shelf life, and the number of the standard implemented.
8.1.2 The packaging and transportation pictorial markings shall comply with GB/T 191.
8.2 Packaging
Packaging materials and containers shall be clean, hygienic, and undamaged.
8.3 Transportation
During transportation, the products shall be covered to avoid rain and sunlight exposure. They shall not be mixed or transported together with toxic substances.
8.4 Storage
The products shall be stored in a cool, clean, and dry place, and shall not be stored together with harmful, toxic, or corrosive substances.
Appendix A (Normative)
Determination of Curdlan Content
A.1 Reagents
a) Glucose
b) Sulfuric acid
c) Sodium hydroxide solution: 0.1 mol/L
d) Phenol solution: 5%
A.2 Apparatus
Spectrophotometer.
A.3 Analytical Procedure
A.3.1 Preparation of Sample Solution
Accurately weigh 100 mg of the sample, add about 90 mL of 0.1 mol/L sodium hydroxide solution, and stir until dissolved. Transfer into a 100 mL volumetric flask, make up to volume with water, and mix well. Pipette 5 mL of this solution into another 100 mL volumetric flask, dilute to volume with water, and mix well. Then pipette 1 mL of this diluted solution, add 1 mL of 5% phenol solution and 5 mL of sulfuric acid, shake vigorously, and cool in cold water for later use.
A.3.2 Preparation of Standard Solution
Prepare the standard solution in the same manner using 0.1 mol/L sodium hydroxide solution and accurately weighed 100 mg of glucose.
A.3.3 Determination
Using a 1 cm cuvette, measure the absorbance of both the sample solution and the standard solution at 490 nm, with water as the blank.
A.4 Calculation of Results
The mass percentage of curdlan content (calculated as anhydrous glucose) is determined according to Formula (A.1):
Where:
- X1 – Mass percentage of curdlan content (calculated as anhydrous glucose)
- AT – Absorbance value of the sample solution
- AS – Absorbance value of the standard solution
- 0.9 – Ratio of the molecular weight of anhydrous glucose to that of glucose
- WS – Weight of glucose used in the standard solution, in milligrams (mg)
- WT – Weight of the sample, in milligrams (mg)
A.5 Permissible Error
The arithmetic mean of the parallel test results shall be taken as the test result. The absolute difference between parallel results shall not exceed ±0.2%.
Appendix B (Normative)
Determination of Gel Strength of Curdlan
B.1 Apparatus
Imported or domestic texture analyzer and gelometer capable of meeting the conditions listed in B.2.
B.2 Test Conditions
a) Setting mode: No. 4
b) Shape and size of probe: stainless steel piston-type cylinder with a diameter of 0.5 cm
c) Probe moving speed: 250 mm/min
B.3 Analytical Procedure
Weigh 0.3 g of the sample and disperse it in 15 mL of water using a cylindrical homogenizer at 3500 r/min for 5 minutes. Transfer the suspension into a test tube of 18 mm × 180 mm. Aerate for 3 minutes under atmospheric conditions, then immediately place the test tube in a boiling water bath for 10 minutes, followed by cooling in cold water for 30 minutes. Remove the gel from the test tube, cut a segment of about 10 mm in length from a section located 20 mm to 30 mm in height, and measure using the gelometer. The gel strength is calculated based on the load-time (f-t) curve recorded.
B.4 Calculation of Results
Gel strength is calculated according to Formula (B.1):
Where:
- W1 – Gel strength, in grams per square centimeter (g/cm²)
- f – Reading at the inflection point of the load-time curve when the gel breaks, in grams (g)
- 0.196 – Cross-sectional area of the cylindrical probe, in square centimeters (cm²)
B.5 Permissible Error
The arithmetic mean of the parallel test results shall be taken as the test result. The absolute difference between parallel results shall not exceed ±0.5%.
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