Silver nanoparticles cannot currently be added directly to foods as little is known about their adverse effects on human health and their impact on ecological systems. However, the university's current research programme is examining how silver nanoparticules could work as an antimicrobial in foods, with the goal of developing food-related applications such as microbe-resistant fabrics or non-biofouling surfaces. Silver nanoparticles are emerging as one of the fastest growing nanomaterials with wide applications. However, Brehm-Stecher, an Iowa State University assistant professor in food science and human nutrition, admitted that the science of silver nanoparticles on food is currently at a basic point. Brehm-Stecher hopes that his research could change this. Nanotechnology in food Nanotechnology, which uses tiny particles measuring one billionth of a metre, is already used for various applications in areas such as food supplements, functional food ingredients and in food packaging. In broad terms, nanotechnology refers to controlling matter at an atomic or molecular scale of between one and 100 nanometres (nm) - one millionth of a millimetre. At present, the main uses for foods are said to be in food packaging and barrier materials, with some applications in nutraceutical delivery. Other uses under investigation include processing - such as programming of foods to release flavour at a particular time, or nutrients in a certain part of the body where they can have an effect. Tiny silver Silver is thought to have anti-microbial properties, and according to Brehm-Stecher, research has found that impregnating other materials with silver nanoparticles is a practical way to exploit its germ-fighting properties. Major consumer goods manufacturers already produce goods that utilise the antibacterial properties of silver nanoparticles. Current applications for silver nanoparticle-impregnated materials include household items, clothing (for example, socks to prevent foot infections for soldiers deployed in jungles), and laundry detergents. In the food industry, the technology has a variety of uses including detecting bacteria in packaging. Silver nanoparticles are already being used in food packaging to extend the shelf life of fruits by soaking up the plant-ripening hormone ethylene, Brehm-Stecher explained. Concerns However, despite the potential that nanotechnology could hold for the food sector, the technology has suffered from a lack of public understanding and consumer concerns over the safety of some of its applications. As a result, recent research and development efforts have focused on the impact of further developments in the uses of nanotechnology on health and the environment. Brehm-Stecher explained that Iowa University's research hopes to learn more about how silver nanoparticles exert their antimicrobial activities by testing QSI-Nano Silver for its ability to interact with microbial cells. QSI-Nano silver is a metallic nano material supplied by QuantumSphere, a manufacturer of metallic nanopowders, which worked with Brehm-Stecher on the project. "This may lead to new approaches for killing foodborne pathogens and enhancing food safety," Brehm-Stecher said. QSI-Nano Silver is prepared from pure metallic silver that is vaporised in the presence of an inert gas, then condensed under controlled conditions to form discrete particles smaller than 100 nanometers in diameter. "One of the things we do in my lab is to develop multi-ingredient antimicrobial mixtures. I was interested in finding antimicrobials that would be physically compatible with other compounds that we're working with. It looked like the nanoparticles could provide us with a good solution," said Brehm-Stecher.
