To determine whether the content of sodium carboxymethyl cellulose (CMC) in food meets the standard, it is necessary to conduct detection and analysis based on relevant national standards and detection methods. The following are general processes and methods:
1. Sample collection and preparation: Randomly select an appropriate amount of representative samples from the food batch to be tested. Different types of food may require different pretreatments. For example, solid foods (such as bread and cakes) may need to be crushed and sieved; liquid foods (such as beverages and soy sauce) may need to be appropriately diluted; for foods containing a large amount of oil (such as salad dressing), defatting may also be required to prepare a sample solution suitable for testing.
2. Select the detection method: At present, the commonly used methods for detecting the content of sodium carboxymethyl cellulose in food are gravimetric method, volumetric method, high performance liquid chromatography, etc.
Gravimetric method: Sodium carboxymethyl cellulose is precipitated and separated under specific conditions, and then its content is determined by weighing the mass of the precipitate. This method is relatively simple to operate, but has low sensitivity and is suitable for testing samples with high content.
Volumetric method: Based on the chemical reaction between sodium carboxymethyl cellulose and certain reagents, the content is calculated by titrating the volume of reagents consumed. This method requires the selection of appropriate titrants and indicators, and has high operational requirements.
High-performance liquid chromatography (HPLC): The retention time and peak area of sodium carboxymethyl cellulose in the chromatographic column are used for comparative quantification with the standard. HPLC has the advantages of high separation efficiency, high sensitivity, and good accuracy. It can accurately determine the trace content of sodium carboxymethyl cellulose in food and is currently a more commonly used detection method.
3. Standard curve drawing: A series of standard solutions of different concentrations are prepared using sodium carboxymethyl cellulose standards of known purity and concentration. These standard solutions are measured according to the selected detection method, and the corresponding detection signals are recorded (such as the precipitate mass in the weight method, the titration volume in the volumetric method, the peak area in the HPLC method, etc.). The standard curve is drawn with the concentration of the standard solution as the horizontal axis and the detection signal as the vertical axis.
4. Sample detection: The prepared sample solution is measured according to the same detection method as the standard solution to obtain the detection signal of the sample. According to the standard curve, calculate the content of sodium carboxymethyl cellulose in the sample.
5. Result determination: Compare the content of sodium carboxymethyl cellulose in the food tested with the maximum use limit of sodium carboxymethyl cellulose in this type of food specified in the relevant national standards. If the test result is lower than or equal to the maximum use limit, it means that the content of sodium carboxymethyl cellulose in the food meets the standard; if the test result is higher than the maximum use limit, it means that the content of sodium carboxymethyl cellulose in the food exceeds the standard and does not meet the standard.
In China, there are strict national standards and regulations for the use and testing of food additives, such as the "Standards for the Use of Food Additives" (GB 2760), etc. Testing institutions and personnel should strictly follow these standards and methods to ensure the accuracy and reliability of the test results.
