The antibacterial spectrum of Nisin

Nisin, a natural antimicrobial peptide, exhibits significant potential in beverage preservation due to its high safety, strong antimicrobial activity, and easy digestibility by the human body. Its application value is mainly reflected in the targeted inhibition of microbial contamination, synergistic enhancement with processing technologies, and compatibility with beverage quality. The specific exploration directions are as follows:

From the perspective of antimicrobial targets, common spoilage microorganisms in beverages (such as lactic acid bacteria, bacilli, and thermophilic bacteria) are mostly Gram-positive bacteria, and nisin has a natural inhibitory effect on such bacteria. It is particularly effective against lactic acid bacteria (such as lactococci and leuconostocs) that cause beverage acidification and turbidity, as well as spore-forming Bacillus subtilis. For example, adding an appropriate amount of nisin to fruit juice beverages can effectively delay pH decline and flavor deterioration caused by excessive reproduction of lactic acid bacteria; in plant protein beverages, it can inhibit the germination of bacilli, reducing the formation of precipitates and odors. In addition, for thermophilic bacteria that may remain during beverage processing (such as Bacillus stearothermophilus), nisin can exert an inhibitory effect by destroying their cell membrane structure (forming pores and causing leakage of intracellular substances), making up for the deficiency of traditional heat sterilization in controlling thermophilic bacteria.

In terms of synergistic preservation strategies, the combination of nisin with other technologies can further expand its preservation potential. Synergy with mild heat treatment is a typical direction. For example, in fruit juice processing, low-temperature heat sterilization at 60-70°C combined with nisin (usually at a concentration of 50-200 IU/mL) can reduce thermal damage while increasing sterilization efficiency by 1-2 orders of magnitude. This is particularly suitable for heat-sensitive beverages (such as fresh squeezed fruit juices and vegetable juices), which can retain nutrients such as vitamins and flavor substances while extending the shelf life. Compound use with other natural preservatives can also enhance the effect. For instance, when nisin is compounded with lysozyme or plant extracts (such as cinnamaldehyde and rosemary extract), it can produce synergistic antimicrobial effects by acting on different targets of microorganisms (such as cell membranes and cell walls, enzyme systems, etc.), and can even inhibit some Gram-negative bacteria (such as Escherichia coli), expanding the control range of complex bacterial communities in beverages.

From the perspective of beverage quality compatibility, the application of nisin has little impact on the taste and color of beverages. With a small molecular weight (about 3.4 kDa) and high stability under acidic conditions (stable activity at pH 2.0-6.0), it is suitable for use in acidic beverages (such as citrus juice and apple vinegar drinks) and does not bring peculiar smells or precipitates like some chemical preservatives. In neutral beverages (such as plant milk drinks), microcapsule embedding technology (such as wrapping nisin with chitosan or maltodextrin) can improve its stability in neutral environments and avoid adverse interactions with proteins and minerals in the beverages, ensuring the sensory consistency of the products.

However, the application of nisin in beverage preservation still needs to solve some problems: first, its inhibitory effect on Gram-negative bacteria is limited, which needs to be overcome through compounding or structural modification (such as combining with fatty acids to enhance membrane penetration); second, some components in beverages (such as high-concentration sugars and proteins) may adsorb nisin, reducing its effective concentration, so it is necessary to improve utilization efficiency through dosage form optimization (such as nano-drug delivery systems); third, cost control. Although its natural origin makes it in line with the "clean label" trend, it is necessary to optimize fermentation processes (such as improving production efficiency) to reduce costs, so as to adapt to large-scale application needs in the beverage industry.

With advantages such as targeted antimicrobial activity, synergistic enhancement, and quality compatibility, nisin is expected to become an important alternative to chemical preservatives in beverage preservation. Especially in the beverage market pursuing natural and healthy products, its application potential will be further released with technological breakthroughs.