The application effect of Nisin in the preservation of condiments

Nisin, as a natural food preservative, demonstrates significant application value in the preservation of condiments. Its effects are mainly reflected in aspects such as antibacterial range, synergistic enhancement, safety, and impact on product quality, as detailed below:

I. Efficiently Inhibiting Gram-Positive Pathogens, Targeting Condiment Spoilage Issues

Condiments (such as soy sauce, vinegar, sauces, pickles, hot pot base, etc.) are rich in nutrients like proteins, carbohydrates, and fats, and may retain microorganisms during processing, making them susceptible to contamination by Gram-positive bacteria (e.g., Bacillus, Listeria, Staphylococcus aureus). This can lead to rancidity, flavor deterioration, or safety risks. Nisin has a strong inhibitory effect on such bacteria; its mechanism of action is to destroy the integrity of bacterial cell membranes, form transmembrane channels, cause leakage of intracellular substances and energy metabolism disorders, and ultimately kill or inhibit bacterial reproduction.

For example, in low-salt soy sauce, adding 0.05-0.1g/kg of nisin can significantly reduce the survival rate of Bacillus, extending the shelf life from 1-2 months to 3-4 months; in hot pot base after high-temperature sterilization, it can effectively inhibit the germination of heat-resistant spores, reducing rancidity caused by secondary pollution, which is particularly suitable for oil-based condiments that cannot withstand repeated high-temperature sterilization.

II. Synergizing with Other Preservation Methods to Reduce Preservation Costs

The antibacterial effect of nisin can be enhanced by combining with physical, chemical, or biological preservation technologies, thereby reducing the usage of a single method and minimizing the impact on product flavor.

Synergy with mild heat treatment: Traditional condiments often rely on high-temperature sterilization (e.g., 121℃ high-pressure sterilization), but this may destroy flavor substances (such as umami amino acids in soy sauce and volatile acids in vinegar). Adding nisin (0.03-0.08g/kg) before heat treatment can lower the sterilization temperature to 80-90℃, shorten the processing time, maintain antibacterial effects, and reduce flavor loss.

Compound use with other natural preservatives: When compounded with organic acids (e.g., lactic acid, citric acid) or plant extracts (e.g., cinnamaldehyde, carvacrol),nisin can enhance the permeability of other components by destroying bacterial cell membranes, expanding the antibacterial spectrum (covering some Gram-negative bacteria). For example, compounding nisin with lactic acid in broad bean paste can simultaneously inhibit Bacillus and E. coli, extending the shelf life by more than 50% compared to single use.

Combination with packaging technologies: In vacuum-packaged or modified atmosphere-packaged condiments,nisin can be slowly released into the local environment, forming a continuous antibacterial microenvironment. This is particularly suitable for high-moisture products such as pickles and fermented bean curd, reducing the risk of microbial contamination caused by packaging damage.

III. High Safety, Adapting to Healthy Consumption Demands

Nisin is a polypeptide substance produced by fermentation of Lactococcus lactis. It can be degraded into amino acids by proteases in the human digestive tract, with no residual toxicity. It has been classified as a GRAS (Generally Recognized as Safe) substance by FAO/WHO, with no restriction on ADI (Acceptable Daily Intake). This characteristic makes it particularly suitable for current consumers' demand for "clean labels" — compared to chemical preservatives (e.g., sodium benzoate, potassium sorbate), the addition of nisin can reduce consumers' concerns about "artificial additives" and enhance product market competitiveness.

For example, in children's condiments (such as low-salt soy sauce, vegetable paste), using nisin to replace some chemical preservatives can not only meet preservation needs but also conform to the "no additives" marketing positioning, becoming an important selling point for brand differentiation.

IV. Minimal Impact on Condiment Quality, Maintaining Original Flavor and Texture

Nisin has a small molecular weight (about 3.4kDa) and good stability in neutral to weakly acidic environments (especially in the pH range of 3-6), with little impact on the color, flavor, and texture of condiments. For example:

In soy sauce,nisin does not react with umami substances (sodium glutamate) and does not affect its reddish-brown color;

In high-oil hot pot base,nisin is not easily wrapped by fat and can be evenly dispersed in the aqueous phase, exerting antibacterial effects without changing the fluidity and aroma of the oil;

In fermented condiments (such as fermented black beans, fermented bean curd),nisin has a weak inhibitory effect on beneficial fermenting bacteria (e.g., lactic acid bacteria, yeast), without interfering with their maturation process, ensuring the formation of product flavor.

Application Limitations and Optimization Directions

The antibacterial effect of nisin is greatly affected by pH, temperature, and matrix components: it is easily inactivated in strongly alkaline environments (pH＞9) and its activity decreases in high-salt (salt concentration＞10%) or high-sugar environments. Therefore, in practical applications, the addition amount (usually 0.02-0.1g/kg) needs to be adjusted according to the characteristics of condiments, or its stability can be improved through microencapsulation technology. For example, embedding nisin in starch or chitosan microspheres can reduce the damage of sodium ions in high-salt soy sauce to its structure and extend the effective action time.

Nisin, with advantages such as targeted antibacterial activity, synergistic enhancement, high safety, and minimal impact on quality, has become an ideal alternative to chemical preservatives in condiment preservation. It is particularly suitable for heat-sensitive, high-nutrient, or "natural-oriented" condiments, providing an efficient solution for extending shelf life and ensuring food safety.