Establishing what is already out there depends on a working definition of nanomaterials, which has not yet been established in the food sector. However, most observers differentiate between deliberately engineered nanomaterials – particularly insoluble and ‘bio-persistent’ metals - and those already present in everyday foods such as fats and proteins.
For example, fruit juice contains plant material built from nanoscale components, a glass of Bailey's contains nano-emulsions with an average droplet size of just 190-nanometres(nm), while tea, beer and coffee all contain naturally-occurring particles smaller than 100nm. Meanwhile, look at eggs, soy or milk under a powerful microscope and you will routinely find protein structures of 300-800nm.
What’s already on the market?
Currently, there are just five foods listed on the Project on Emerging Nanotechnologies (PEN) website (which should be viewed with caution as the claims the products make are not validated independently) from canola cooking oil containing nano-encapsulated vitamins, minerals and phytochemicals, to a chocolate milkshake using a nano silica-based compound to enhance its taste, and a tea using nanotechnology to deliver a more bioavailable form of selenium.
There are just over 30 ‘cooking’ and ‘storage’ applications including chopping boards and food storage containers using nanosilver as an antimicrobial agent, nanosilver sprays for disinfecting surfaces, and plastic beer bottles imbued with nanoclay to provide a stricter barrier between the carbon dioxide molecules trying to escape and oxygen molecules trying to get in, keeping the beer fresher and increasing its shelf-life.
Finally PEN features more than 40 dietary supplements allegedly made using nanotechnology, including products from German firm Aquanova, which uses nano-encapsulation to enable soft drinks firms to produce clear liquids containing water and fat-soluble bioactive ingredients such as vitamin E and omega-3s with enhanced bioavailability.
Potential applications in packaging and food production:
- SHELF-LIFE EXTENSION: The biggest applications of nanotechnology in the food industry are in packaging, where nanomaterials can be used to reduce bacterial growth and improve resistance to oxygen permeability, boosting shelf-life in bottled beer and other products.
- ANTI-FOULING NANO-COATINGS: Nano-coatings are also being trialled on food production equipment and pipework to prevent bacterial contamination and reduce fouling, cutting cleaning costs and increasing efficiency.
- NANO SENSORS: There is also growing interest in nano sensors, which could be used in packaging to alert retailers or consumers when the contents are not safe to eat or if a chill chain has been broken, or in food analysis to detect food poisoning bacteria or viruses more quickly.
- SMART FILTERS TO REMOVE ALLERGENS: Other applications include smart filters that could selectively remove allergenic ingredients such as lactose from milk, and novel mixing technologies able to create ultra-fine, ultra-stable emulsions that are lower in fat and do not need emulsifiers.
- COMPOSTIBLE PACKAGING: Some firms are looking at materials normally be regarded as waste such as stalks from cereal plants, processing the cellulose into nanostructured material and combining it with other materials such as nanoclays to provide new compostable packaging materials.
- CONDUCTIVE INKS:Nanoparticle-based conductive inks could be used to print radio-frequency identification (RFID) tags, while nanomaterials could also be used in printing ink to change the colour of the label to indicate the remaining shelf-life of a perishable food.
- NANO SIEVES: Speaking at the recent House of Lords enquiry, Dr Mike Knowles from Coca-Cola also highlighted the potential of ‘nano-sieves’ to purify water.
Potential applications in food and drink:
- SALT REDUCTION: At 5-10 microns, salt particles developed by Nottingham-based firm Eminate are a fraction of the size of standard salt (c.200-500 microns), and deliver an intense, salty hit on the taste buds enabling manufacturers of bread, cheese and other foods to slash salt without impacting taste. While particles this size are moving into the realms of nanotechnology, however, they dissolve on the tongue so are not comparable to the engineered and insoluble nanomaterials causing food safety concerns, stress bosses.
- 'INGENIOUS EMULSIONS': The Institute of Nanotechnology (IoN) predicts we will see “ever more ingenious emulsion technologies, allowing multiple nutrients/minerals to be stably incorporated in different foodstuffs according to their solubility”.
- LOW-FAT FOODS: The IoN also expects to see “lower fat, lower salt and lower sugar processed foods that from the consumer's perspective will still taste the same".
- NANOENCAPSULATION OF BIOACTIVES: In relation to food, the most common reference is to the nanoencapsulation of vitamins and other bioactives in order to protect them and ensure more targeted delivery to certain parts of the body.
- UNDERSTANDING FOOD STRUCTURE: Unilever told the recent House of Lords enquiry that it was using nanoscience to “gain a better understanding of the structure of food in order to affect its functionality, composition, appearance, texture and taste, using a variety of materials and assembly methods”.
- LOWER-FAT PRODUCTS: The Royal Society of Chemistry (RSC) meanwhile, has highlighted the potential of using proteins to lower fat content in emulsion-based products and using nanoscale films on confectionery, based on oxides of silicon or titanium with antimicrobial properties, in order to increase shelf-life.
- EDIBLE NANOFILMS: The RSC also raises the possibility of edible nanofilms for fruit, vegetables, meat, and chocolate baked goods that provide specific protection from moisture, lipids and gases and serve as carriers of colours, flavours, antioxidants, nutrients, anti-browning agents, enzymes and antimicrobials.