The application of Nisin in condiments

As a natural biological preservative, Nisin aligns with the condiment industry’s demand for green preservation due to its advantages of safety, non-toxicity, and easy digestibility by the human body. Currently, application research has been carried out in various condiments such as soy sauce, pickles, salad dressings, covering both the optimization of single preservation schemes and the development of composite systems. Meanwhile, it can address industry pain points such as high salt content and easy flavor loss in condiments. The specific research content is elaborated as follows:

Soy Sauce and Soy Sauce-Based Condiments

Soy sauce is prone to contamination by spoilage bacteria such as lactobacilli during fermentation and storage. Traditional pasteurization tends to destroy its flavor, while Nisin application can balance preservation and flavor retention. Studies have shown that when the addition level reaches 50–100 μg/mL, Nisin can effectively inhibit and kill spoilage bacteria in soy sauce. It can also replace chemical preservatives such as sodium benzoate, reducing the intensity of pasteurization for soy sauce and avoiding nutrient loss and color changes caused by excessive heat treatment. In addition, research has attempted to compound Nisin with natamycin (an antifungal agent) for soy sauce preservation. This scheme compensates for Nisin’s weak inhibitory effects on yeasts and molds, forming a comprehensive antimicrobial system and providing a better combination for natural preservation of soy sauce. China’s national standard clearly stipulates the maximum addition level of Nisin in soy sauce as 0.2 g/kg, providing a standard basis for its industrial application.

Pickled Vegetable Condiments

Traditional pickles rely on high salt content (approximately 10%–20%) to create a high-osmotic pressure environment for preservation, but high-salt diets are prone to health issues. The addition of Nisin can effectively reduce the salt content of pickles while ensuring preservation efficacy. Studies have indicated that adding 100 mg/kg Nisin can effectively inhibit the growth of residual miscellaneous bacteria such as Clostridium spores in pickles, allowing the salt concentration of pickles to be reduced to 7%–9%. Meanwhile, Nisin exerts a synergistic effect in the pasteurization process of pickles, reducing the damage to the crisp texture and flavor substances during sterilization. It does not impart off-odors to pickles, making it more acceptable to consumers compared to chemical preservatives.

Salad Dressings and Compound Condiments

Salad dressings and similar sauces often experience reduced preservation capacity due to low-fat and low-salt reforms, and Nisin exhibits significant preservation optimization effects on such products. Studies have shown that adding 0.05–0.2 g/kg Nisin can effectively inhibit the growth of lactobacilli and spores in salad dressings, extending the shelf life of low-fat and low-salt salad dressings by more than 3 times. Beyond salad dressings, Nisin also has compliant application space in compound condiments—China’s national standard specifies a maximum addition level of 0.2 g/kg in compound condiments. For compound seasoning broths containing spices, sufficient heat treatment is likely to destroy spice flavors; adding 0.1–0.2 g/kg Nisin can effectively inhibit the proliferation of mesophilic bacterial spores, extending shelf life without the need for high-intensity heat treatment.

Vinegar and Other Condiments

As an acidic condiment, the environment of vinegar is conducive to maintaining Nisin’s activity. China’s national standard permits a maximum addition level of 0.15 g/kg Nisin in vinegar. Relevant studies have shown that Nisin can inhibit common Gram-positive spoilage bacteria in vinegar, forming a synergistic antimicrobial effect with vinegar’s inherent acidic environment and reducing flavor deterioration caused by bacterial contamination during vinegar storage and transportation. In addition, in some fermented seasoning sauces and other products, Nisin can stabilize product quality by inhibiting miscellaneous bacterial contamination in the late fermentation stage, avoiding the impact of miscellaneous bacterial metabolites on the taste and safety of seasoning sauces.

Furthermore, to further expand the application boundaries of Nisin in condiments, current research focuses on optimizing compounding technologies. For example, compounding Nisin with EDTA, lactic acid, etc., can enhance its inhibitory effects on some Gram-negative bacteria, addressing the issue of its narrow antimicrobial spectrum. Research in this direction will promote the efficient application of Nisin in more types of condiments.