The impact of Nisin on food safety

As a natural antibacterial peptide produced by the fermentation of bacteria belonging to the genus Streptococcus lactis,nisin is an internationally widely recognized "GRAS" (Generally Recognized as Safe)-grade food additive. Its impact on food safety can be comprehensively evaluated from aspects such as its inherent safety, protective effect on food quality, potential risks, and control measures.

I. Inherent Safety of Nisin

The core advantages of nisin in terms of inherent safety lie in its natural origin and human tolerance. As a microbial metabolite, its chemical nature is a polypeptide composed of 34 amino acid residues. After entering the human body, it is rapidly degraded by proteases (e.g., trypsin) in the digestive tract into amino acids or small peptide fragments. These products are consistent with the decomposition products of proteins in food, can be normally absorbed and utilized by the human body, do not accumulate in the body, and do not produce toxic metabolites.

A large number of toxicological studies have confirmed that nisin has extremely low acute toxicity. Its median lethal dose (LD₅₀) is much higher than the dosage of conventional food additives (e.g., the oral LD₅₀ in rats is ＞2000 mg/kg). Long-term feeding experiments have found no genotoxicity such as teratogenicity, carcinogenicity, or mutagenicity, nor does it cause damage to major organs such as the liver and kidneys. Currently, food safety regulatory authorities in most countries and regions around the world, including China, the United States, and the European Union, have approved nisin for use in various foods such as dairy products, meat products, canned foods, and baked goods, and have set clear maximum usage limits (usually 0.03–0.1 g/kg, varying by food category), further ensuring its safety within the scope of rational use.

II. Positive Role in Food Safety

The core value of nisin in promoting food safety lies in reducing the risks of food spoilage and foodborne diseases by inhibiting the growth of harmful microorganisms. It has a strong inhibitory effect on Gram-positive bacteria that cause food spoilage and foodborne poisoning (e.g., Staphylococcus aureus, Listeria monocytogenes, Clostridium botulinum, Bacillus cereus). Its mechanism of action is to destroy the integrity of bacterial cell membranes, form ion channels, leading to the loss of nutrients in bacteria, metabolic disorders, and ultimately bacterial death. Compared with chemical preservatives, it is less likely to induce bacterial resistance.

In food processing, the application of nisin can significantly extend the shelf life of food and reduce food waste caused by microbial spoilage. At the same time, it can reduce the intensity of extreme conditions such as high temperature and high salt during food processing (e.g., reducing the amount of nitrite in meat products and appropriately lowering the sterilization temperature in canned foods). This not only reduces the damage to food nutrients (e.g., vitamins) caused by extreme processing conditions but also lowers the intake risk of potentially harmful additives such as high salt and nitrite, indirectly improving the overall safety of food.

III. Potential Risks and Control Measures

The safety of Nisin depends on the premise of "rational use":

Allergic risks for sensitive groups: A very small number of sensitive individuals may experience mild allergic reactions to nisin (e.g., skin itching, gastrointestinal discomfort). However, such cases are extremely rare worldwide and are mostly related to the special immune status of individuals. No large-scale allergic incidents have been reported so far. Therefore, regulatory authorities do not require it to be listed as a "common allergen" mandatorily, but food manufacturers usually clearly label it in the ingredient list to facilitate identification by sensitive groups.

Limitations of antibacterial activity: The antibacterial activity of nisin is limited—it is only effective against Gram-positive bacteria and has no inhibitory effect on Gram-negative bacteria, fungi, etc. If used alone, it may not fully cover all harmful microorganisms in food. Therefore, it needs to be combined with other preservation methods (e.g., low-temperature storage, pH adjustment, and synergistic use of compound preservatives) to avoid microbial control failure caused by "over-reliance on nisin alone" and the subsequent risk of food spoilage.

Influence of processing conditions on stability: The stability of nisin is greatly affected by food processing conditions (e.g., high temperature, high pH, strong oxidants). If improper processes lead to premature degradation of Nisin during processing, it may lose its antibacterial effect and indirectly affect food safety. Therefore, it is necessary to optimize processing processes (e.g., controlling sterilization temperature, adjusting food pH to neutral or weakly acidic) to ensure its activity.

On the premise of complying with food safety standards and rational use regulations, the positive impact of nisin on food safety far outweighs its potential risks: it has high biological safety and does not cause harm to the human body; at the same time, it can significantly improve the shelf stability and edible safety of food by inhibiting harmful microorganisms and optimizing processing processes. In the future, with the increasing demand of the food industry for "natural, green, and safe" additives, Nisin will be more widely used in replacing chemical preservatives and ensuring "clean labels" for food. By continuously optimizing production processes (e.g., improving nisin purity) and improving risk monitoring systems (e.g., tracking sensitive groups), its role in ensuring food safety will be further enhanced.