The application of magnesium oxide nanoparticles as antimicrobial agent, the said application is magnesium oxide nanoparticles as a bacterial inhibitor of Pseudostelium tropicalis (Candida tropicalis); the magnesium oxide nanoparticles provided by the invention have the characteristics of non-toxic, good bacterial inhibiting efficiency to common beverage microorganisms, etc., with good potential to be used as acidic beverage preservative, especially for acidic beverage Pseudostelium tropicalis with obvious bacterial inhibiting effect, its preparation method is simple, the magnesium oxide powder of different particle sizes can be prepared by controlling the precursor calcination conditions, suitable for industrial production.
Application of magnesium oxide nanoparticles as antimicrobial agent (I) Technical field  The present invention relates to an application of magnesium oxide nanoparticles as an antimicrobial agent, specifically to magnesium oxide nanoparticles with growth inhibitory effect on tropical pseudomicrobial yeast (Candida tropicalis). (II) Background Technology  Beverages are a necessity in our daily life. Due to their rich nutritional content, beverages are very susceptible to microbial contamination during processing and distribution, for which a certain amount of preservatives are added to commercialized beverages. Preservatives are mainly divided into two categories: chemical preservatives and natural preservatives. Chemical preservatives are divided into organic preservatives and inorganic preservatives. The former mainly includes benzoic acid, sorbic acid, etc., while the latter mainly includes sulfites and nitrites, etc. Natural preservatives are usually extracted from the metabolites of animals, plants and microorganisms. Although natural food preservatives are non-toxic and harmless, they are currently expensive and have not yet been applied on a large scale. Currently in the food and beverage industry, chemical preservatives, especially benzoic acid and sorbic acid, are still the mainstream. However, with the improvement of people’s health requirements, people are more and more concerned about the research and application of preservatives.  Magnesium oxide nanoparticles are a new type of highly functional fine inorganic materials with wide applications in electronics, catalysis, ceramics, food and other fields. The magnesium oxide nanopowder, due to its special structure, has a large specific area and has certain antibacterial and bactericidal ability.
Magnesium oxide nanopowders with a particle size of about 4 nm and a specific surface of 1000 m2/g adsorb halogens and adsorb on the surface of bacteria and spores by electrostatic force, causing the destruction of cell walls and the flow of fluid from the cells, thus achieving the bactericidal effect. At present, there have been many reports on the preparation of magnesium oxide nanopowders and their bacteriostatic properties. The studies on its antibacterial properties are focused on neutral environment, and ZnO nanopowders show good antibacterial effect. There is no report about its application in acidic environment. In addition, magnesium is very beneficial to human health as a trace element that must be supplemented daily. For this reason, magnesium oxide nanopowders are very potential to be preservatives in the field of acidic beverages.