Supply high-quality nisin powder

To assess the quality of nisin, you can consider the following aspects:

1.Appearance and Characteristics:

Nisin should be a white or slightly yellow crystalline powder or granules with a slightly salty taste. If the color, shape, or taste deviates from this standard description, the quality might be compromised.

2.Solubility:

The solubility of nisin increases as the pH decreases. For instance, at pH 2.5, the solubility is 12%; at pH 5.0, the solubility is 4%; at pH 7 or higher, it is almost insoluble. If the solubility at different pH levels does not match these standards, it may indicate poor quality.

3.Thermal Stability:

Nisin can be sterilized in dilute hydrochloric acid at pH less than 2.0 at 115.6°C without losing activity. However, at pH levels above 4, especially under heating conditions, it decomposes more rapidly in aqueous solution, reducing its activity. Therefore, stability tests under different pH and temperature conditions are important for evaluating quality.

4.Sensitivity to Enzymes:

Nisin is particularly sensitive to proteolytic enzymes such as trypsin, pepsin, salivary enzymes, and digestive enzymes, but not to crude rennet. Enzyme activity tests can be used to assess the purity or stability of nisin.

5.Purity Testing:

The standard purity of nisin is 2.5%, defined as 1×10^6 IU/g. Purity testing can confirm whether it meets this standard.

6.Safety Evaluation:

Although nisin is considered safe toxicologically, conducting a safety evaluation is still an important step in assessing quality. This includes evaluating parameters such as LD50 (lethal dose for 50% of subjects) and ADI (acceptable daily intake).

7.Production Source and Manufacturing Process:

Knowing the production source and manufacturing process of nisin is also crucial for evaluating its quality. High-quality products usually come from reliable manufacturers and follow stringent manufacturing processes.

Assessing the quality of nisin involves a comprehensive consideration of its appearance, solubility, thermal stability, enzyme sensitivity, purity, safety, and production source and manufacturing process.