Role of ZnO Nanoparticles for improvement of Antibacterial Activity in Food Packaging
Saira Sehar*, Amiza, Dr. I. H Khan
Department of Chemistry, School of Science, Minhaj University, Lahore, Pakistan.
*Corresponding Author E-mail: saharrana111@gmail.com
ABSTRACT:
Nanotechnology advancement leads to development of antimicrobial agents like ZnO nanoparticles. These nanoparticle have their main applications in food packaging. when these nanoparticles incorporate into the food surface, it will kill all bacterias residing on the surface and food become free of bacteria. In this way, food can be stored for a long time because its shelf life is improved. Antimicrobial activity of ZnO nanoparticles can be improved by increasing surface area, reducing particle size and large concentration of ZnO –NPS. Antimicrobial activity increases by increasing intensity of UV light. As UV light fall on ZnO nanoparticles, it increases ZnO surface area and hence anrtimicrobial activity will be increased. Exact mechanism of Antimicrobial activity is still unknown but some processes have been presented.
KEYWORDS: ZnO nanoparticles, Antimicrobial, Food pakaging, Surface area, UV illumination, Shelf life, Active packaging, Smart packaging.
INTRODUCTION:
ZnO Nanoparticles as antimicrobial agents have been studied on micro and nanoscale. Due to decrease in size of ZnO, its properties also changes like electrical, optical and chemical properties changes. Some authors observed that these changes might be occur due to Quantum confinement surface2.
Now days, ZnO NPS have major applications in food packaging as antibacterial/antimicrobial agent. When these particles are introduced into packaging, it decreases the amount of bacteria or microbes in food products. Furthermore, ZnO NPS play important role in eliminating pathogens contamination and enlarging shelf life of food products3.
The factors which are used for improvement of antibacterial activity in food packaging are Ultra Violet illumination effect, ZnO nanoparticles morphology, and its size and concentration etc4.
Thus, in this review antibacterial activity and mechanism of ZnO NPS in food packaging and factors for enhancing antibacterial activity in food packaging have been discussed.
ZnO Nanoparticles:
ZnO NPS are explained as functional and universal inorganic material having broad range of applications. It is known as two and six semiconductors, since Zinic and Oxygen are present in two and six groups of periodic table respectively. ZnO nanoaprticles has universal optical and electrical conductivity and piezoelectric properties5.
Antibacterial / Antimicrobial Food Pakaging:
Antimicrobial packaging is active packaging which cause interaction with the product to hinder the growth of microorganisms that reside on food surfaces6.
Food packaging play major role in safety and stabilize the quality of food. Food packaging having advance functions called as active packaging7. According to regulations of European Union, active packaging is termed as active substance that may in contact with food, having capability to change composition of food or atmosphere all around it8. Introduction of ZnO NPS as antibacterial into packaging materials allow slow l diffusion of target bactericidal compounds into matrix of food. In addition, researchers have proved the antimicrobial packaging as an additional hardle to food contamination after non thermal process, hence they play vital role in eliminating the risk of pathogen contamination and enlarging shelf life of food.
Antibacterial Mechanism of Zno Nanoparticles:
Actual antibacterial mechanism of ZnO nanoparticls is not known. But many phenomenon such as generation of Reactive Oxygen Species, nanoparticles interaction with bacteria, damaging of bacterial cell and release of Zn+ 2ions have been proposed9. Past studies indicate that ROS formation is main antibacterial mechanism of ZnO NPS10. It also shows that ZnO NPS or powder in aqueous solution has ability to form many Reactive Oxygen Species such as Hydroxal radical, singlet Oxygen and superoxide anion. The formation of hydroxal radical and singlet oxygen in ZnO suspension can be explained by ESR11. While hydrogen per oxide formation can be determined by Direct quantification methods12. Hydroxyl radicals and singlet oxygen species have negatively charges that have not ability to penetrate to cell membrane. Whereas, hydrogenper oxide can penetrate easily into cell. ROS generation depends upon surface area of ZnO NPS, higher surface area, ROS production will be greater13. According to these experimental studies, direct influence of ZnO nanoparticles on surface of bacteria with ROS producion takes to cell membrane destruction. Therefore antibacterial mechanism of ZnO nanoparticles is still unknown. The Zn+2 ions have ability to enlarge the lag phase of bacteria and contribute towards antibacterial activity14. However, low concentrations of soluble Zn2+ enhance the growth of bacteria and cause complete retardation of E.Coli growth when concentration of ZnO NPs > of mM.15 showed that E.Coli reacted with 1mM of ZnO NPS and increase the number of colony forming unit CFU compare with control because of low concentration of Zn+2 in growth medium.16 also marked as ZnO NPS suspension in low concentration (0.01-1mM) had low antibacterial activity against E.Coli bacteria due to presence of Zn+2 ions.
Factors That Enhance Antibacterial/Microbial Activity of Zno NPS:
UV Illumination Effect:
ZnO tend to absorbs UV light17, it produce best response towards Ultra Violet light and its conductivity also increases. This characteristic stimulate the interaction of ZnO nanoparticles to bacteria. When UV light interact with ZnO, it can generate negatively charged species (oxygen radical and hydroxal radical).18 ZnO NPS present in aqueous solution investigated under influence of UV light cause phototoxic effect that produced Reactive Oxygen Species19. These species are important for bio applications.20 These species can undergoe cell and have ability to kill all microorganisms21. As concentration of UV light enhances, ROS production will be enhance, Therefore, it has more ability to kill all microorganisms22.
ZnO morphology:
Its morphology determined by Synthesis process of ZnO. These ZnO NPS can produce best response towards antibacterial activity23. ZnO NPS having different morphologies contain active facets, which leads to enhance their antibacterial activity24.
Particle Size and Concentration of ZnO nanoparticles:
ZnO NPS Concentration and particle size is more important towards antibacterial activity. Antibacterial activity of ZnO NPs can enhance or improve when ZnO Nps size reduces, surface area enhances and it exhibit large concentration25.
ZnO Nanoparticles Applications in Food Packaging:26
Tested the Zinic Oxide nanoparticles antimicrobial activity in orange juices. These results marked that ZnO nanoparticles can enlarge the shelf-life of fresh orange juice up to 28 days.27 explained the regulatory frameworks relevant to food and food packaging and nanotechnology applications.
The major goal of food packaging is to save food from microbes. ZnO nanoparticles are very beneficial for the process because they act to kill microbes. Once they are incorporated into matrix of polymeric form, it allows food to interact with packaging having functional parts in conservation like barrier property, constancy and mechanical ability also attained. It results new material with improve antibacterial activity also permit tracking of food during storage.28 Food packaging will be of two types:
Active packaging:
It is an advance phenomenon in food packaging that have changed conventional packaging to attain best performance. The conventional packaging utilized passive barrier to save food from microbes but active packaging create its antibacterial action on food and save the product from environment factors. When nanoparticles interact with food surface. Residing bacteria on surface quickly killed by these nanoparticles. Food shelf life is also improved. Active packaging allows direct interaction of NPS with food surface29
Smart Pakaging:
It possess the susceptibility of active packaging. In it direct interaction does not occur.
CONCLUSIONS:
The current review presented that ZnO NPS are very important. They act as antimicrobial agent when they interact with surface or material, residing bacteria on surface will quickly kill and food become free from microorganism. In this way food can be stored for a long time because its shelf life improved. Exact antibacterial activity mechanism has been still unknown but many alternative processes have been presented to explain its antibacterial process. Furthermore, more research on antibacterial mechanism of ZnO NPS in food packaging would be undertaken.
ACKNOWLEDGEMENT:
Authors are grateful to Dr Izhar Ul Haque Khan for his Guidance.
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Received on 13.12.2020 Modified on 19.01.2021
Accepted on 15.02.2021 ©Asian Pharma Press All Right Reserved
Asian Journal of Pharmaceutical Research. 2021; 11(2):128-131.
DOI: 10.52711/2231-5691.2021.00024