The potential of Nisin in beverage preservation

Nisin (a natural antimicrobial peptide produced by Lactococcus lactis), characterized by high safety, strong antimicrobial activity, and easy digestibility in the human body, shows significant potential in beverage preservation. Its application value is mainly reflected in 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, against which nisin has a natural inhibitory effect. It is particularly effective against lactic acid bacteria (e.g., Lactococcus, Leuconostoc) that cause beverage acidification and turbidity, as well as spore-forming bacteria like 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 proliferation of lactic acid bacteria; in plant protein beverages, it can inhibit the germination of bacilli, reducing the formation of precipitates and off-odors. Additionally, for thermophilic bacteria that may remain after beverage processing (e.g., Bacillus stearothermophilus), nisin exerts its inhibitory effect by disrupting their cell membrane structure (forming pores and causing leakage of intracellular substances), compensating for the insufficiency of traditional heat sterilization in controlling thermophilic bacteria.

In terms of synergistic preservation strategies, combining nisin with other technologies can further expand its preservation potential. Synergy with mild heat treatment is a typical approach. For instance, 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 especially suitable for heat-sensitive beverages (e.g., fresh-squeezed fruit juices, vegetable juices), as it retains nutrients such as vitamins and flavor compounds while extending shelf life. Compounding with other natural preservatives also enhances efficacy: when nisin is combined with lysozyme or plant extracts (e.g., cinnamaldehyde, rosemary extract), it exerts synergistic antimicrobial effects by acting on different microbial targets (e.g., cell membranes, cell walls, enzyme systems), and can even inhibit some Gram-negative bacteria (e.g., Escherichia coli), expanding the control range over complex microbial communities in beverages.

From the perspective of beverage quality compatibility, Nisin has little impact on the taste or color of beverages. With a small molecular weight (approximately 3.4 kDa) and high stability under acidic conditions (stable activity at pH 2.0-6.0), it is suitable for acidic beverages (e.g., citrus juice, apple vinegar drinks) and does not introduce off-odors or precipitates, unlike some chemical preservatives. In neutral beverages (e.g., plant-based milk drinks), microencapsulation technology (e.g., wrapping nisin with chitosan or maltodextrin) can improve its stability in neutral environments and avoid adverse interactions with proteins and minerals in the beverage, ensuring consistent sensory quality of the product.

However, several challenges remain in applying nisin to beverage preservation: first, its inhibitory effect on Gram-negative bacteria is limited, which needs to be addressed through compounding or structural modification (e.g., conjugation with fatty acids to enhance membrane penetration); second, certain components in beverages (e.g., high-concentration sugars, proteins) may adsorb nisin, reducing its effective concentration, requiring dosage form optimization (e.g., nano-drug delivery systems) to improve utilization efficiency; third, cost control: although its natural origin aligns with the "clean label" trend, optimizing fermentation processes in industrial production is necessary to reduce costs, adapting to large-scale application needs.

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. Particularly in the beverage market pursuing natural and healthy products, its application potential will be further unleashed with technological breakthroughs.