Nanosensors may be able to overcome many of these limitations. Researchers at Technische Universität München in Germany, for example, are developing disposable carbon nanotube-based gas sensors that can be sprayed onto the surfaces of clear plastic packaging film. The nanosensors gauge product freshness by detecting small changes in carbon dioxide and other gases.
Laboratory nanosensors are being constructed from nano-gold, nano-silver, magnetic nanoparticles, and quantum dots. In a recently published technical overview of nanosensors, B. Stephen Inbaraj and B.H. Chen, food science researchers at Taiwan’s Fe Jen Catholic University, describe a “quartz-crystal microbalance DNA sensor” to detect E coli; a reusable immunosensor based on gold nanoparticles to detect Salmonella; and the addition of “superparamagnetic nanoparticles” coated with antibodies to detect Listeria monocytogenes using a high-transition temperature superconducting quantum interference device, or SQUID. Such nanosensors “provide advantages of rapid, sensitive, and user-friendly detection, enabling portability for in-field application,” Inbaraj and Chen write.
Nanofood Safety Concerns
Last year the Center for Food Safety unveiled a searchable online database of about 300 different food and food-related products found to contain more than 40 different types of nanomaterials. The products included an array of brand-name candies, breakfast cereals, seasonings, mayonnaise, as well as baby bottles and plastic storage containers. Nano-silver and titanium dioxide were the two largest categories, followed by nano-encapsulation and nano-silica.
“The FDA is failing to prevent nano-laced foods from being sold,” says the Center for Food Safety’s Hanson. “Our food safety agency should demand that these products be taken off the market, as companies are using food additives and food contact materials not approved at the nano scale.”
After several years of deliberation, in June 2014 FDA issued industry guidance documents on nanotechnology in food. The agency said it will consider nanomaterials to be like any other food additive. While noting nanotechnology was not “intrinsically benign or harmful,” its use could warrant new or additional food safety evaluations. “For food ingredients and food-contact materials, we will examine nanotechnology products for safety using our pre-existing regulatory frameworks, on a case-by-case basis,” explains Marianna Naum, PhD, FDA spokesperson. “This requires that valid scientific data must demonstrate…that there is a reasonable certainty of no harm from the proposed use of the substance under its intended conditions of use,” she tells Food Quality & Safety magazine.
Late last year, the European Commission decided to go further and published a final novel foods regulation specifying that engineered nanomaterials will require prior authorization before being used in food, with safety being assessed by the European Food Safety Authority. Food company applicants must demonstrate that they have used the most recent methods to test engineered nanomaterials. Food items containing nanomaterials will be required to disclose that information on the label.
While the regulatory science remains in flux, the genie is clearly out of the bottle. Only time and further testing will clarify the ultimate risks and rewards of food nanotechnology.
Examples of Food Nanotech Applications
- Nanoscale coatings to prevent biofouling (bacterial contamination) of food contact surfaces
- Nanoparticles to selectively bind and remove pathogens and chemicals
- Nanoencapsulation, nanoemulsions, and nanoparticles to improve the bioavailability of nutraceuticals and deliver flavor enhancers
- Nanotubes and nanoparticles as gelation and viscosifying agents
- Biodegradable nanosensors for temperature, moisture, and time monitoring
- Nanoclays and nanofilms as barrier materials to prevent spoilage
- Nanosilver and other nanoparticle surface coatings with antibacterial properties
- Fluorescent nanoparticles with attached antibodies to detect chemicals and foodborne pathogens
- Silicate nanoparticles to create lighter, stronger, and heat-resistant films
- Nanocapsules to deliver pesticides, fertilizers, and other agrichemicals
- Nanosensors to detect animal and plant pathogens
- Nanosensors to monitor soil conditions, crop growth
Sources: Nanowerk, industry news releases.