Food Nanotech Under Wraps

While most major food companies publicly steer clear of nanotechnology, a large number of food and food-related items—including brand-name cereals, candy, cheese, chocolate, mayonnaise, plastic storage containers, and bottles—contain nanomaterials, added mainly to enhance color or extend shelf life. In fact, food nanotech, or the use of nanomaterials in food and food-related products, has been quietly growing over the past decade despite consumer mistrust and a lack of definitive knowledge over possible health harms.

Nanomaterials are engineered substances ranging in size from 1 to 100 nanometers (billionths of a meter). Because of their size, they have unique physico-chemical properties that are governed more by quantum mechanics than by ordinary chemistry. Food nanotech has the potential to enhance virtually all stages of production, from growing (nano-pesticides, nano-fertilizers), to preparation (nano-nutrients, nano-flavors), to packaging (nanofilms, nanosenor-enabled containers).

“For food and food-related science, engineered nanomaterials have the potential to transform how and what we eat through development of longer-lasting, better tasting, and safer, healthier foods,” says Chady Stephan, manager of global nanotechnology applications at PerkinElmer, which manufactures analytical and testing platforms for nanomaterials. Polymer nanotechnology, for example, “can provide new food packaging materials with improved mechanical barrier with antimicrobial properties together with nano-sensors for tracing and monitoring the condition of food during transport and storage,” Stephan tells Food Quality & Safety magazine.

Critics say that until the health effects are established, nanomaterials should be banned from foods or at least be strictly regulated. “Scientists agree that nanomaterials create novel risks that require new forms of toxicity testing. But very little testing and regulation of these new products exists, and consumers have almost no information,” says Jaydee Hanson, senior policy analyst at the Center for Food Safety.

Until a few years ago, Kraft Foods, Nestle, H.J. Heinz, Unilever, and other major food companies were enthusiastically pursuing food nanotech R&D, anticipating such innovations as nanoparticle emulsifiers to make food textures smoother and more uniform, nanoparticle colors and flavors to enhance appeal and taste, nanofilms and nanosensor-enabled “smart packaging” to detect, signal, and even prevent spoilage, and nanotech-enabled food contact surfaces to repel bacteria (see “Examples of Food Nanotech Applications” sidebar). But instead of responding positively, consumers have grown wary about the safety of nanotechnology. Most major food companies have halted their food nanotech programs or are keeping them tightly under wraps.

Chief among the health concerns is that nanomaterials in food can easily pass through biological barriers including cell membranes and cell nuclei. Nanoparticles can leach out of packaging material, such as transparent films, containers, and bottles. They can also be inhaled from the air and absorbed through the skin. Little is known about the health effects of nanomaterials as they move through the body and accumulate in tissues and organs. Research has found that some common nanomaterials, including nano-titanium dioxide (a whitening agent) and nano-silver (an anti-bacterial), can cause cellular dysfunction, including the over-production of reactive oxygen species and oxidative stress, a precursor to cellular damage, neurological disease, and cancer.

“Consumers are skeptical, even fearful of nanotechnology in food,” explained Carmen I. Moraru, PhD, associate professor of food science at Cornell University, Ithaca, N.Y. “This is understandable because we do not yet fully understand the interaction of nanoscale matter with the human body—very important when nanostructures are ingested,” she said during a presentation at the Cornell Institute for Food Systems Industry Partnership Program.

Despite the concerns, scores of researchers in the U.S. and worldwide are actively pursuing nanotechnology to enhance food quality and safety. They focus on two main areas: antimicrobial food packaging and food surface materials, and nanosensors capable of detecting minute levels of foodborne pathogens and toxins quickly and inexpensively.

Nanomaterials in Food Surfaces and Packaging

Dr. Moraru and her Cornell colleagues, working jointly with researchers at Rensselaer Polytechnic Institute, Troy, N.Y., have used an electrochemical process called anodization to create nanoscale pores on metal food surfaces that prevent bacteria from sticking. The nanopores become endowed with an electrical charge and surface energy that repel bacteria and prevent biofouling and biofilm formation. The pores can be as small as 15 nanometers (a sheet of paper is about 100,000 nanometers thick). In laboratory tests, nanopores in aluminum prevented E coli O157:H7 and Listeria monocytogenes surrogates from attaching to the metal’s surface.