Sodium benzoate, also known as sodium benzoate, is an organic substance with the chemical formula C7H5NaO2. It is a white granule or crystal powder, odorless or slightly odorless with benzoin, slightly sweet and astringent, with a relative molecular mass of 144.12. It is stable in the air and easily soluble in water. The pH value of its aqueous solution is 8 and it is soluble in ethanol.
Benzoic acid and its salts are broad-spectrum antimicrobial agents, but their antimicrobial effectiveness depends on the pH of the food. As the acidity of the medium increases, its bactericidal and bacteriostatic effects increase, but in alkaline media, the bactericidal and bacteriostatic effects are lost. The optimal pH value for antisepsis is 2.5~4.0.
Main applications of sodium benzoate:
1. Mainly used as food preservative, also used in pharmaceuticals, dyes, etc.
2. Used in the pharmaceutical industry and plant genetic research, and also used as dye intermediates, fungicides and preservatives
3. Preservatives; antimicrobial agents.
4. Sodium benzoate is also an important acid-type food preservative. Converts to the effective form benzoic acid when used. For the scope and dosage of use, please refer to benzoic acid. In addition, it can also be used as a preservative for feed.
5. This product is used as a food additive (preservative), a bactericide in the pharmaceutical industry, a mordant in the dye industry, a plasticizer in the plastics industry, and an intermediate in organic synthesis such as spices.
6. It is used as a co-solvent for serum bilirubin test, food additive (preservative), bactericide in the pharmaceutical industry, mordant in the dye industry, plasticizer in the plastic industry, and also used as an intermediate in organic synthesis such as spices.
Method for determining whether sodium benzoate complies with national standards:
Refer to the analysis methods specified in GB1902-94.
Method name: Sodium benzoate—Determination of sodium benzoate—Neutralization titration method
Scope of application: This method uses titration method to determine the content of sodium benzoate.
Principle of the method: Place the test sample in a separatory funnel, add 25 mL of water, 50 mL of ether and 2 drops of methyl orange indicator solution, titrate with hydrochloric acid titrant (0.5 mol/L), and shake with the drops until the water layer turns orange-red. ; Separate the water layer, place it in a stoppered Erlenmeyer flask, wash the ether layer with 5mL of water, merge the washing liquid into the Erlenmeyer flask, add 20mL of ether, continue titration with hydrochloric acid titrant (0.5mol/L), and shake with the drops. , stop the titration when the water layer shows a continuous orange-red color, read the amount of hydrochloric acid titrant used, and calculate the sodium benzoate content.
FAQ
Under what conditions is sodium benzoate most effective as a food preservative?
The antimicrobial effectiveness of sodium benzoate is highly dependent on the pH level of the food or medium it is added to. Its bactericidal (bacteria-killing) and bacteriostatic (bacteria-inhibiting) properties increase as the acidity of the medium increases, with the optimal pH range for preservation being between 2.5 and 4.0. In contrast, it completely loses its preservative and antimicrobial effects in alkaline environments.
What is the scientific principle behind determining if sodium benzoate complies with national standards?
According to the article, compliance with national standards (referencing GB1902-94) is verified using a neutralization titration method. The testing sample is placed in a separating funnel with water, ether, and a methyl orange indicator. It is then titrated with a hydrochloric acid solution until the water layer changes to a continuous orange-red color. The amount of hydrochloric acid titrant used is then measured to calculate the exact sodium benzoate content.
