Nano in Food, Inside and Out

by Ravithree Senanayake

With the global population at nearly 8 billion, there is a growing demand for a safer and more sustainable ways of food production. New technologies are constantly being developed to help keep food fresh and flavorful while also enhancing its quality and nutrition. Nanotechnology is playing a big role in many of these innovations!

Nanotechnology in general is any technology that uses engineered particles in the size range of 10^-9 m (a billionth of a meter!). It has great potential to make advances in various aspects of the food industry, including flavor, nutrition, color, packaging, and storage. The application of nanoscience in food comes in two forms: ^1,2

1. Nano inside the food (food additives or processing)
2. Nano outside the food (food packaging)

Nano Inside Food

There are many ways that “nano inside” can be incorporated into the process of transforming agricultural and animal products into food. For example, in nanoencapsulation, one can embed bioactive ingredients into the nanosized capsules to prevent them from exposing to environmental conditions such as high temperatures, oxygen, light, pH variations, and interactions that deteriorate the substances. Nanoencapsulation carries the advantage of having reduced particles sizes in nanoscale with enhanced surface-to-volume ratio, with improved absorption.³

Another example of using nanotechnology in food is nano-scale edible thin films made of food-grade materials. Edible films can protect foods from gases, humidity, and lipids. Such edible films can be made from multiple layers that are 1–100 nm thick and are physically or chemically bonded to the food. They can also improve the texture of foods or carry colors, flavors, nutrients, vitamins, antioxidants, and antimicrobials. Nano-antimicrobials help safeguard the food from deterioration, extending its shelf life. ^4,5  Examples of such antimicrobials are metal and metal oxide nanomaterials. The blog post by Ese Ehimiaghe, “Nanoparticles & Food Part 1: Vitamins” explains in detail how nanoparticles are used in food supplements. For example, lipid nanoparticles are used in oral delivery of drugs to increase drug absorption in the gastrointestinal tract as it improves mucosal adhesion due to their small particle size and increased residence time. Protein nanoparticles are used in foods in the form of casein micelles, which are available in bovine milk and other dairy products.

Titanium dioxide (TiO₂) is one example of a nanoparticle that has been used extensively to enhance food appearance. TiO₂ is an approved food additive with limited use (should not exceed 1% w/w (percent weight of the substance by total weight).⁶ It can also be mixed with silicon dioxide (SiO₂) and/or aluminum oxide (Al₂O₃) with not more than 2% of the total – these particles can be used with nanoencapsulation as one way to incorporate fragrances or flavors into food. SiO₂ is also used for thickening of pastes or as an anticaking agent to maintain flow properties in powdered products.

Nano Outside Food

The use of nanotechnology on the outside of food is related to packaging and food safety ⁷. Food can get contaminated or degraded at multiple stages of the food chain; therefore, safe, nontoxic, cost-effective, good-quality packaging material is key.  Nanomaterials can play a role in packaging through controlling and measuring acidity (pH), temperature, moisture, and freshness. Nanotechnology-driven food packaging can be divided into categories as antimicrobial packing and smart packing through sensing.

Some nano-packaging is antimicrobial because it actively reduces microbial growth. Active nanomaterials like antimicrobials and oxygen scavenging materials can be used in packaging to delay oxidation, microbial growth, and moisture migration in the food. Polyethylene films infused with carbon nanotubes have prevented fungal invasion in Mazafati dates for up to 90 days.⁸

Nanoparticles in food can be either organic or inorganic (molecules based on carbon atoms or not), and this composition along with the different sizes and shapes of the particles impacts what happens to them in our bodies.⁹ Silver, silicon dioxide, iron oxide, titanium dioxide, and zinc oxide are a few examples of inorganic nanoparticles used in food industry. Silver nanoparticles are used as antimicrobial agents in food packaging, chopping boards, storage containers, refrigerators, and health supplements. Zinc and zinc oxide nanoparticles are essential nutrients for human health and hence it is used as an additive in supplements and functional foods for nutrition.  Zinc oxide nanoparticles are also used to prevent food from contamination from harmful bacteria in food packaging.¹⁰ On the other hand, organic nanoparticles are composed of organic substances such as carbohydrates, proteins, or lipids. You can also read our previous blog post “Keeping Our Food Safe – Nanomaterial Style” by Laura Olenick to learn more on how nanomaterials are used for food packaging.

Nano-packaging can also reduce food spoiling by improving the quality of the package itself or by helping to monitor what’s going on inside. Nano has helped enhancing the heat resistance and mechanical characteristics in food packaging materials. It can also help detect changes in food products, such as pathogens growing on the surface. For example, companies including British Airways and Nestlé have reportedly used chemical sensors that quickly detect any color change.¹¹ Nanotechnology can also help food industries prevent contamination through authenticating and tracking the trace features of a food product using nanobarcodes.¹²

Safety of Nano in Food

Although nanotechnology has many benefits to offer the food industry, it is always important to consider possible health impacts of new technologies. There are two main safety concerns on using nanoparticles in food: allergies and heavy metal release. Making sure these materials are safe in food requires a proper detailed understanding of the properties of nanomaterials like size, solubility, surface chemistry, and composition.

The US Environmental Protection Agency (USEPA), National Institute for Occupational Safety and Health (NIOSH), Health and Consumer Protection Directorate of the European Commission (HCPDEC), and Food and Drug Administration (FDA) are a few of the regulatory bodies that have passed guidelines to prevent potential risks posed by food nanotechnology. Nanoparticle toxicity and possible environmental and health hazards need to be thoroughly evaluated. As a research center, part of what the NSF Center for Nanotechnology (CSN) does is investigate and characterize biological responses towards various nanoparticles. Our research helps inform efforts to minimize potential harm by nanoparticles that get released into the environment through industrial and agricultural applications. Another aspect of CSN research that’s relevant to food is exploring the benefits of using nanoparticles to help make plants more resilient and resistant to disease. (You can read “Nanotechnology and Modern Agriculture” or “Why nanoscientists and farmers both care about plant leaves” to learn more about this nano-agriculture work.)

Conclusion

It is crucial to establish a healthy and sustainable food industry, including full research exploration of nanotechnology’s potential positive and negative effects in food. The examples of nanosensors to help control environmental contamination or nano-additives to improve nutrition while enhancing flavor are just the beginning of where the technology could go. With careful research and regulation, I think nanotechnology has great potential to contribute to a safe and sustainable food industry.

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REFERENCES

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